title: IZombie (TV series)

text: On May 22, 2016, it was announced that Aly Michalka had been promoted to series regular for the third season. On July 21, 2017, it was announced that Robert Knepper had been promoted to series regular for the fourth season. On September 27, 2018, it was announced that Bryce Hodgson had been promoted to series regular for the fifth and final season.


title: IZombie (TV series)

text: David Anders stated following Knepper's departure that while he had suggested Rutger Hauer to play his character's father, he believed Knepper did well in the role.


title: IZombie (TV series)

text: Late in 2017, in the wake of sexual assault allegations against Robert Knepper, The CW conducted an internal inquiry. Finding no evidence of misconduct transpiring on the set, it was announced he would be remaining on the series. McIver and Kohli released statements following the decision, with McIver stating she supported and admired the bravery of women coming forward in general; Kohli said he did not feel comfortable giving his full thoughts at the time.


title: IZombie (TV series)

text: Knepper personally announced his promotion in a video released at Comic Con; but did not partake in promotional interviews for his role following the allegations, nor did he attend the fourth-season wrap party.


title: IZombie (TV series)

text: On January 12, 2018, it was announced that the studio had conducted a second investigation. CW president Mark Pedowitz stated, "Again, the investigation related to the set and his behavior on the set. They found no wrongdoing on the set." Pedowitz elaborated that Knepper had signed on for a single season and that his exit from the series had already been planned.


title: IZombie (TV series)

text: The first season received generally positive reviews. Review aggregation website Rotten Tomatoes gave the series a 92% approval rating, with an average rating of 7.65/10, based on 52 reviews. The site's critical consensus states: "An amusing variation on the zombie trend, "iZombie" is refreshingly different, if perhaps too youth-oriented to resonate with adult audiences." Metacritic, which uses a weighted average, assigned a score of 74 out of 100, based on reviews from 38 critics, indicating "generally favorable reviews".


title: IZombie (TV series)

text: Amy Ratcliffe of IGN rated the pilot episode 8.4/10, praising the series' "casual take on zombies" and Rose McIver's performance as Liv. LaToya Ferguson of "The Onion"s "The A.V. Club" graded the series an A- and stated the series is better for diverging from its comic book origins. She praised the series for having the same quick-witted banter as "Veronica Mars" and observed it measures up well against "Pushing Daisies", noting: "Television can only be better for having the voices of Thomas and Ruggiero-Wright back on a weekly basis". Inkoo Kang of the "Dallas Observer" called the series, "dazzlingly, tirelessly witty" with an "acute attention to human relationships", and praised it as "the summer's most underrated series".


title: IZombie (TV series)

text: The second season was also met with positive reviews. It holds a 100% approval rating on Rotten Tomatoes, based on 14 reviews with an average score of 8.39/10. The website's consensus states: ""iZombie" smoothly shifts gears in its second season, moving between comedy and dramatic procedural while skillfully satirizing modern society along the way."


title: IZombie (TV series)

text: The third season received further praise with a score of 100% on Rotten Tomatoes, based on 10 reviews with an average rating of 8.56/10. The website's consensus reads, "Broodier and brainier, "iZombie"s third season may be its best yet".


title: IZombie (TV series)

text: The fourth season has been met with similar praise. It earned a score of 92% on Rotten Tomatoes, based on 12 reviews, with an average rating of 8.13/10. The website's consensus reads, ""iZombie"s fourth season boldly flips the board on the series narrative, injecting fresh blood into its amiable corpse and promising that it won't go stiff anytime soon".


title: IZombie (TV series)

text: The series finale was met with notable negative response, however. In March 2022, nearly three years after its airing, "Paste" reflected that both the finale and final season as a whole seemed to have suffered due to Rob Thomas' preoccupation with the concurrent revival of "Veronica Mars", and stated "The finale of "iZombie" was one of the worst TV viewing experiences I have ever had. As the minutes unfolded I became filled with horror watching everything fall apart. The characters I had loved for five seasons turned into strangers. And when the credits finally rolled, I found myself questioning all the love I had put into it." The same month, Rahul Kohli admitted dissatisfaction with the finale, saying that he felt that it "sucked" and was "super disappointing".


title: IZombie (TV series)

text: The fourth season received the ReFrame Stamp, which is awarded by the gender equity coalition ReFrame as a "mark of distinction" for film and television projects that are proven to have gender-balanced hiring, with stamps being awarded to projects that hire female-identifying people, especially those of color, in four out of eight critical areas of their production.


title: IZombie (TV series)

text: The first three seasons of the show have been released on DVD and Blu-ray by Warner Home Entertainment and the Warner Archive Collection respectively. The fourth season did not receive a release due to rights issues, according to Warner Archive. The fourth season cannot be purchased on digital stores, but is available for streaming on Netflix. The fifth season was not released either, supposedly due to the fourth season not being released. However, unlike the fourth season, the fifth season is available for purchase on digital stores.


title: Adam Schlesinger

text: Adam Lyons Schlesinger (October 31, 1967 – April 1, 2020) was an American musician, songwriter, composer, and record producer. He was a founding member of the bands Fountains of Wayne, Ivy, and Tinted Windows, and was a key songwriting contributor and producer for Brooklyn-based synth-pop duo Fever High. He also wrote songs for television and film, for which he won three Emmy Awards, a Grammy Award, and the ASCAP Pop Music Award, and was nominated for Academy, Tony, and Golden Globe Awards.


title: Adam Schlesinger

text: Schlesinger was born in New York City on October 31, 1967, the son of publicist Barbara (née Bernthal) and Stephen Schlesinger. He was a cousin of actor Jon Bernthal and the grandson of musician Murray Bernthal (1911–2010). He was raised in a secular Jewish family in the Manhattan borough of New York City and Montclair, New Jersey, attending Montclair High School in the latter. He received a Bachelor of Arts in philosophy from Williams College in Williamstown, Massachusetts.


title: Adam Schlesinger

text: In addition to writing and co-producing the title song to "That Thing You Do!", Schlesinger composed "Master of the Seas" for "", performed by Jennifer Lopez, Peter Dinklage and others. He wrote and produced three songs for "Music and Lyrics", and his music has also been featured in films such as "Shallow Hal" (which he scored with Ivy); "Robots"; "There's Something About Mary"; "Me, Myself & Irene"; "Josie and the Pussycats"; "Scary Movie"; "Art School Confidential"; "Fever Pitch"; "The Manchurian Candidate"; "Because of Winn-Dixie"; "Orange County"; "Two Weeks Notice"; and others.


title: Adam Schlesinger

text: Schlesinger and "The Daily Show" executive producer David Javerbaum co-wrote the songs for the musical theater adaptation of the John Waters film "Cry-Baby". "Cry-Baby" debuted at the La Jolla Playhouse in La Jolla, California in November 2007. Previews for the Broadway run began at the Marquis Theatre on March 15, 2008. Its official opening night was April 24, 2008.


title: Adam Schlesinger

text: Schlesinger and Javerbaum co-wrote the closing song "I Have Faith in You" for Javerbaum's play "An Act of God", which opened on Broadway on May 28, 2015. The song is performed by Jim Parsons, Chris Fitzgerald, and Tim Kazurinsky.


title: Adam Schlesinger

text: Schlesinger and Sarah Silverman collaborated on a musical titled "The Bedwetter", based on her book of the same name. The musical was set for previews to begin on May 9, 2020, at the Atlantic's Linda Gross Theater; opening night was scheduled for Wednesday, June 10, 2020. The dates were later postponed due to the COVID-19 pandemic. The musical ultimately premiered in previews in April 2022. At the time of his death, Schlesinger was also announced to be working on the music for a stage adaption of the television series "The Nanny".


title: Adam Schlesinger

text: Schlesinger and Javerbaum co-wrote the opening number of the 2011 Tony Awards ceremony "It's Not Just for Gays Anymore" as well as the opening and closing numbers of the 2012 Tony Awards, "What If Life Were More Like Theater" and "If I Had Time", all performed by Neil Patrick Harris. They wrote "TV Is a Vast Wonderland", the opening number of the 2011 Emmy Awards, performed by Jane Lynch and "The Number in the Middle of the Show", performed at the 2013 Emmy Awards by Neil Patrick Harris, Sarah Silverman, and Nathan Fillion.


title: Adam Schlesinger

text: Schlesinger's television composing work includes theme music, songs, and/or score for "I Love You, America" (Hulu), "The Maya Rudolph Show" (NBC), "", the 2011 and 2012 Tony Awards, the 2011 and 2013 Emmy Awards, "Big Time Rush", "T.U.F.F. Puppy" (Nickelodeon), "Good Luck Charlie" (Disney Channel), "The Fresh Beat Band" (Nickelodeon), "Kathy" (Bravo), "Crank Yankers", "Wedding Band" (TBS), the Billboard Music Awards, "Bubble Guppies" (Nick Jr.), "The Howard Stern Show", "Sesame Street", Comedy Central's "Night of Too Many Stars", Robert Smigel's cartoons for "Saturday Night Live", The Disney Parks Christmas Day Parade with Neil Patrick Harris, the Comedy Awards (Comedy Central), "American Dreams", Stephen King's "Kingdom Hospital", "The In-Laws", "The Man Show", "Supernoobs", "Too Late with Adam Carolla", "The Dana Carvey Show", "John Leguizamo's House Of Buggin'", "My Kind of Town", "Johnny Test", and others. His songs have been licensed for use on numerous television series, including "Scrubs", "The Hills", "Gossip Girl", "Melrose Place", "Felicity", "Roswell", and others.


title: Adam Schlesinger

text: He wrote songs for and was executive music producer of the scripted comedy "Crazy Ex-Girlfriend" on The CW.


title: Adam Schlesinger

text: As a record producer and mixer, he worked with the Monkees, Fever High, Dashboard Confessional, Swirl 360, Tahiti 80, Motion City Soundtrack, Verve Pipe, Robert Plant, America, the Sounds, They Might Be Giants, Fastball, and many other artists, as well as producing or co-producing five Fountains of Wayne albums and six Ivy albums.


title: Adam Schlesinger

text: Schlesinger was also in a side project band called Tinted Windows formed by guitarist James Iha, previously of The Smashing Pumpkins and A Perfect Circle, singer Taylor Hanson of Hanson, and Bun E. Carlos of Cheap Trick, and recorded and toured with them in 2009 and 2010. He also contributed to Iha's second solo album, "Look to the Sky" (2012).


title: Adam Schlesinger

text: Schlesinger was nominated for an Academy Award and a Golden Globe Award in 1997 for writing the title track of the Tom Hanks-directed film "That Thing You Do!", also contributing two other songs for the film.


title: Adam Schlesinger

text: Fountains of Wayne was nominated for two Grammy Awards in 2003 for Best New Artist and Best Pop Performance by a Duo or Group with Vocal for "Stacy's Mom".


title: Adam Schlesinger

text: Schlesinger and David Javerbaum received two Tony nominations in 2008 Best Musical and Best Original Score for the musical "Cry-Baby". They also received a 2009 Emmy nomination for Outstanding Music and Lyrics for their song "Much Worse Things", performed by Elvis Costello and Stephen Colbert on the television special and album "" The album, co-written by Schlesinger and Javerbaum, and co-produced by Schlesinger and Steven M. Gold, won the 2009 Grammy Award for Best Comedy Album.


title: Adam Schlesinger

text: Schlesinger received a 2013 Daytime Emmy nomination for Outstanding Original Song for his "Elmo the Musical" theme for "Sesame Street". He and Molly Boylan received a 2011 Daytime Emmy nomination for the song "I Wonder" from "Sesame Street".


title: Adam Schlesinger

text: Schlesinger and Javerbaum received a 2012 Emmy Award for Outstanding Music And Lyrics for their song "It's Not Just for Gays Anymore", performed by Neil Patrick Harris as the opening number of the 65th Tony Awards telecast; and a 2013 Emmy Award for Outstanding Music And Lyrics for their song "If I Had Time", performed by Neil Patrick Harris as the closing number of the 66th Tony Awards telecast.


title: Adam Schlesinger

text: Schlesinger received two 2016 Emmy nominations for his work on the CW series "Crazy Ex-Girlfriend": Outstanding Original Music and Lyrics for "Settle for Me" (co-written with Rachel Bloom and Jack Dolgen), and Outstanding Main Title Theme (co-written with Rachel Bloom).


title: Adam Schlesinger

text: He received a 2017 Emmy nomination for Outstanding Original Music and Lyrics for "We Tapped That Ass" (co-written with Rachel Bloom and Jack Dolgen) from the CW series "Crazy Ex-Girlfriend."


title: Adam Schlesinger

text: He won the 2019 Emmy Award for Outstanding Original Music and Lyrics for "Antidepressants Are So Not a Big Deal" and was nominated for Outstanding Original Main Title Theme Music for "Meet Rebecca" (Season 4 Theme) from "Crazy Ex-Girlfriend" (both co-written with Rachel Bloom and Jack Dolgen).


title: Adam Schlesinger

text: On January 30, 1999, Schlesinger married Katherine Michel, a graphic designer and Yale graduate. They met in 1996 at WXOU Radio Bar, a bar that Schlesinger used to frequent with Fountains of Wayne co-founder Chris Collingwood when they were starting the band. They divorced in 2013. Schlesinger and Michel had two daughters, Sadie and Claire.


title: Adam Schlesinger

text: On April 1, 2020, during the COVID-19 pandemic in the United States, Schlesinger died of complications from COVID-19 at a hospital in Poughkeepsie outside New York City at the age of 52. He had tested positive, and was hospitalized and placed on a ventilator for over a week before his death.


title: Adam Schlesinger

text: On June 16, 2020, the tribute album "Saving for a Custom Van" was released in Schlesinger's memory on Father/Daughter Records. The title is a reference to the Fountains of Wayne song "Utopia Parkway". The 31-track album features covers of songs Schlesinger wrote or performed by artists such as Kay Hanley, Ben Lee, and Prince Daddy & The Hyena. His collaborator Rachel Bloom and his Fountains of Wayne bandmate Jody Porter also participated. All proceeds from the album were donated to the MusiCares COVID-19 relief fund.


title: Elizabethan era

text: The Elizabethan era is the epoch in the Tudor period of the history of England during the reign of Queen Elizabeth I (1558–1603). Historians often depict it as the golden age in English history. The symbol of Britannia (a female personification of Great Britain) was first used in 1572, and often thereafter, to mark the Elizabethan age as a renaissance that inspired national pride through classical ideals, international expansion, and naval triumph over Spain.


title: Elizabethan era

text: This "golden age" represented the apogee of the English Renaissance and saw the flowering of poetry, music and literature. The era is most famous for its theatre, as William Shakespeare and many others composed plays that broke free of England's past style of theatre. It was an age of exploration and expansion abroad, while back at home, the Protestant Reformation became more acceptable to the people, most certainly after the Spanish Armada was repelled. It was also the end of the period when England was a separate realm before its royal union with Scotland.


title: Elizabethan era

text: The Elizabethan age contrasts sharply with the previous and following reigns. It was a brief period of internal peace between the Wars of the Roses in the previous century, the English Reformation, and the religious battles between Protestants and Catholics prior to Elizabeth's reign, and then the later conflict of the English Civil War and the ongoing political battles between parliament and the monarchy that engulfed the remainder of the seventeenth century. The Protestant/Catholic divide was settled, for a time, by the Elizabethan Religious Settlement, and parliament was not yet strong enough to challenge royal absolutism.


title: Elizabethan era

text: England was also well-off compared to the other nations of Europe. The Italian Renaissance had come to an end following the end of the Italian Wars, which left the Italian Peninsula impoverished. The Kingdom of France was embroiled in the French Wars of Religion (1562–1598). They were (temporarily) settled in 1598 by a policy of tolerating Protestantism with the Edict of Nantes. In part because of this, but also because the English had been expelled from their last outposts on the continent by Spain's tercios, the centuries-long Anglo-French Wars were largely suspended for most of Elizabeth's reign.


title: Elizabethan era

text: The one great rival was Habsburg Spain, with whom England clashed both in Europe and the Americas in skirmishes that exploded into the Anglo-Spanish War of 1585–1604. An attempt by Philip II of Spain to invade England with the Spanish Armada in 1588 was famously defeated. In turn England launched an equally unsuccessful expedition to Spain with the Drake–Norris Expedition of 1589. Three further Spanish Armadas also failed in 1596, 1597 and 1602. The war ended with the Treaty of London the year following Elizabeth's death.


title: Elizabethan era

text: England during this period had a centralised, well-organised, and effective government, largely a result of the reforms of Henry VII and Henry VIII, as well as Elizabeth's harsh punishments for any dissenters. Economically, the country began to benefit greatly from the new era of trans-Atlantic trade and persistent theft of Spanish and Portuguese treasures, most notably as a result of Francis Drake's circumnavigation.


title: Elizabethan era

text: The term "Elizabethan era" was already well-established in English and British historical consciousness, long before the accession of Queen Elizabeth II, and generally refers solely to the time of the earlier Queen of this name.


title: Elizabethan era

text: The Victorian era and the early 20th century idealised the Elizabethan era. The "Encyclopædia Britannica" maintains that "[T]he long reign of Elizabeth I, 1558–1603, was England's Golden Age... 'Merry England', in love with life, expressed itself in music and literature, in architecture and in adventurous seafaring". This idealising tendency was shared by Britain and an Anglophilic America. In popular culture, the image of those adventurous Elizabethan seafarers was embodied in the films of Errol Flynn.


title: Elizabethan era

text: In response and reaction to this hyperbole, modern historians and biographers have tended to take a more dispassionate view of the Tudor period.


title: Elizabethan era

text: Elizabethan England was not particularly successful in a military sense during the period, but it avoided major defeats and built up a powerful navy. On balance, it can be said that Elizabeth provided the country with a long period of general if not total peace and generally increased prosperity due in large part to stealing from Spanish treasure ships, raiding settlements with low defenses, and selling African slaves. Having inherited a virtually bankrupt state from previous reigns, her frugal policies restored fiscal responsibility. Her fiscal restraint cleared the regime of debt by 1574, and ten years later the Crown enjoyed a surplus of £300,000. Economically, Sir Thomas Gresham's founding of the Royal Exchange (1565), the first stock exchange in England and one of the earliest in Europe, proved to be a development of the first importance, for the economic development of England and soon for the world as a whole. With taxes lower than other European countries of the period, the economy expanded; though the wealth was distributed with wild unevenness, there was clearly more wealth to go around at the end of Elizabeth's reign than at the beginning. This general peace and prosperity allowed the attractive developments that "Golden Age" advocates have stressed.


title: Elizabethan era

text: The Elizabethan Age was also an age of plots and conspiracies, frequently political in nature, and often involving the highest levels of Elizabethan society. High officials in Madrid, Paris and Rome sought to kill Elizabeth, a Protestant, and replace her with Mary, Queen of Scots, a Catholic. That would be a prelude to the religious recovery of England for Catholicism. In 1570, the Ridolfi plot was thwarted. In 1584, the Throckmorton Plot was discovered, after Francis Throckmorton confessed his involvement in a plot to overthrow the Queen and restore the Catholic Church in England. Another major conspiracy was the Babington Plot – the event which most directly led to Mary's execution, the discovery of which involved a double agent, Gilbert Gifford, acting under the direction of Francis Walsingham, the Queen's highly effective spy master.


title: Elizabethan era

text: The Essex Rebellion of 1601 has a dramatic element, as just before the uprising, supporters of the Earl of Essex, among them Charles and Joscelyn Percy (younger brothers of the Earl of Northumberland), paid for a performance of Richard II at the Globe Theatre, apparently with the goal of stirring public ill will towards the monarchy. It was reported at the trial of Essex by Chamberlain's Men actor Augustine Phillips, that the conspirators paid the company forty shillings "above the ordinary" (i. e., above their usual rate) to stage the play, which the players felt was too old and "out of use" to attract a large audience.


title: Elizabethan era

text: In the Bye Plot of 1603, two Catholic priests planned to kidnap King James and hold him in the Tower of London until he agreed to be more tolerant towards Catholics. Most dramatic was the 1605 Gunpowder Plot to blow up the House of Lords during the State Opening of Parliament. It was discovered in time with eight conspirators executed, including Guy Fawkes, who became the iconic evil traitor in English lore.


title: Elizabethan era

text: While Henry VIII had launched the Royal Navy, Edward and Mary had ignored it and it was little more than a system of coastal defense. Elizabeth made naval strength a high priority. She risked war with Spain by supporting the "Sea Dogs", such as John Hawkins and Francis Drake, who preyed on the Spanish merchant ships carrying gold and silver from the New World. The Navy yards were leaders in technical innovation, and the captains devised new tactics. Parker (1996) argues that the full-rigged ship was one of the greatest technological advances of the century and permanently transformed naval warfare. In 1573 English shipwrights introduced designs, first demonstrated in the "Dreadnaught", that allowed the ships to sail faster and maneuver better and permitted heavier guns. Whereas before warships had tried to grapple with each other so that soldiers could board the enemy ship, now they stood off and fired broadsides that would sink the enemy vessel. When Spain finally decided to invade and conquer England it was a fiasco. Superior English ships and seamanship foiled the invasion and led to the destruction of the Spanish Armada in 1588, marking the high point of Elizabeth's reign. Technically, the Armada failed because Spain's over-complex strategy required coordination between the invasion fleet and the Spanish army on shore. Moreover, the poor design of the Spanish cannons meant they were much slower in reloading in a close-range battle. Spain and France still had stronger fleets, but England was catching up.


title: Elizabethan era

text: Parker has speculated on the dire consequences if the Spanish had landed their invasion army in 1588. He argues that the Spanish army was larger, more experienced, better-equipped, more confident, and had better financing. The English defenses, on the other hand, were thin and outdated; England had too few soldiers and they were at best only partially trained. Spain had chosen England's weakest link and probably could have captured London in a week. Parker adds that a Catholic uprising in the north and in Ireland could have brought total defeat.


title: Elizabethan era

text: The discoveries of Christopher Columbus electrified all of western Europe, especially maritime powers like England. King Henry VII commissioned John Cabot to lead a voyage to find a northern route to the Spice Islands of Asia; this began the search for the North West Passage. Cabot sailed in 1497 and reached Newfoundland. He led another voyage to the Americas the following year, but nothing was heard of him or his ships again.


title: Elizabethan era

text: In 1562 Elizabeth sent privateers Hawkins and Drake to seize booty from Spanish and Portuguese ships off the coast of West Africa. When the Anglo-Spanish Wars intensified after 1585, Elizabeth approved further raids against Spanish ports in the Americas and against shipping returning to Europe with treasure. Meanwhile, the influential writers Richard Hakluyt and John Dee were beginning to press for the establishment of England's own overseas empire. Spain was well established in the Americas, while Portugal, in union with Spain from 1580, had an ambitious global empire in Africa, Asia and South America. France was exploring North America. England was stimulated to create its own colonies, with an emphasis on the West Indies rather than in North America.


title: Elizabethan era

text: Martin Frobisher landed at Frobisher Bay on Baffin Island in August 1576; He returned in 1577, claiming it in Queen Elizabeth's name, and in a third voyage tried but failed to found a settlement in Frobisher Bay.


title: Elizabethan era

text: From 1577 to 1580, Francis Drake circumnavigated the globe. Combined with his daring raids against the Spanish and his great victory over them at Cádiz in 1587, he became a famous hero—his exploits are still celebrated—but England did not follow up on his claims. In 1583, Humphrey Gilbert sailed to Newfoundland, taking possession of the harbour of St. John's together with all land within two hundred leagues to the north and south of it.


title: Elizabethan era

text: In 1584, the queen granted Walter Raleigh a charter for the colonisation of Virginia; it was named in her honour. Raleigh and Elizabeth sought both immediate riches and a base for privateers to raid the Spanish treasure fleets. Raleigh sent others to found the Roanoke Colony; it remains a mystery why the settlers all disappeared. In 1600, the queen chartered the East India Company in an attempt to break the Spanish and Portuguese monopoly of far Eastern trade. It established trading posts, which in later centuries evolved into British India, on the coasts of what is now India and Bangladesh. Larger scale colonisation to North America began shortly after Elizabeth's death.


title: Elizabethan era

text: England in this era had some positive aspects that set it apart from contemporaneous continental European societies. Torture was rare, since the English legal system reserved torture only for capital crimes like treason—though forms of corporal punishment, some of them extreme, were practised. The persecution of witches began in 1563, and hundreds were executed, although there was nothing like the frenzy on the Continent. Mary had tried her hand at an aggressive anti-Protestant Inquisition and was hated for it; it was not to be repeated. Nevertheless, more Catholics were persecuted, exiled, and burned alive than under Queen Mary.


title: Elizabethan era

text: Elizabeth managed to moderate and quell the intense religious passions of the time. This was in significant contrast to previous and succeeding eras of marked religious violence.


title: Elizabethan era

text: Elizabeth said "I have no desire to make windows into men's souls". Her desire to moderate the religious persecutions of previous Tudor reigns – the persecution of Catholics under Edward VI, and of Protestants under Mary I – appears to have had a moderating effect on English society. Elizabeth, Protestant, but undogmatic one, reinstated the 1552 Book of Common Prayer with modifications which made clear that the Church of England believed in the (spiritual) Real Presence of Christ in the Holy Communion but without a definition how in favor of leaving this a mystery, and she had the Black Rubric removed from the Articles of Faith: this had allowed kneeling to receive communion without implying that by doing so it meant the real and essential presence of Christ in the bread and wine: she believed it so. She was not able to get an unmarried clergy or the Protestant Holy Communion celebrated to look like a Mass. The Apostolic Succession was maintained, the institution of the church continued without a break (with 98% of the clergy remaining at their posts) and the attempt to ban music in church was defeated. The Injunctions of 1571 forbade any doctrines that did not conform to the teaching of the Church Fathers and the Catholic Bishops. The Queen's hostility to strict Calvinistic doctrines blocked the Radicals.


title: Elizabethan era

text: Almost no original theological thought came out of the English Reformation: instead the Church relied on the Catholic Consensus of the first Four Ecumenical Councils. The preservation of many Catholic doctrines and practices was the cuckoos nest that eventually resulted in the formation of the Via Media during the 17th century. She spent the rest of her reign ferociously fending off radical reformers and Roman Catholics who wanted to modify the Settlement of Church affairs: The Church of England was Protestant, "with its peculiar arrested development in Protestant terms, and the ghost which it harboured of an older world of Catholic traditions and devotional practice".


title: Elizabethan era

text: For a number of years refrained from persecuting Catholics because she was against Catholicism, not her Catholic subjects if they made no trouble. In 1570, Pope Pius V declared Elizabeth a heretic who was not the legitimate queen and that her subjects no longer owed her obedience. The pope sent Jesuits and seminarians to secretly evangelize and support Catholics. After several plots to overthrow her, Catholic clergy were mostly considered to be traitors, and were pursued aggressively in England. Often priests were tortured or executed after capture unless they cooperated with the English authorities. People who publicly supported Catholicism were excluded from the professions; sometimes fined or imprisoned. This was justified on the grounds that Catholics were not persecuted for their religion but punished for being traitors who supported the Queen's Spanish foe; in practice, however, Catholics perceived it as religious persecution and regarded those executed as martyrs.


title: Elizabethan era

text: Lacking a dominant genius or a formal structure for research (the following century had both Sir Isaac Newton and the Royal Society), the Elizabethan era nonetheless saw significant scientific progress. The astronomers Thomas Digges and Thomas Harriot made important contributions; William Gilbert published his seminal study of magnetism, "De Magnete," in 1600. Substantial advancements were made in the fields of cartography and surveying. The eccentric but influential John Dee also merits mention.


title: Elizabethan era

text: Much of this scientific and technological progress related to the practical skill of navigation. English achievements in exploration were noteworthy in the Elizabethan era. Sir Francis Drake circumnavigated the globe between 1577 and 1581, and Martin Frobisher explored the Arctic. The first attempt at English settlement of the eastern seaboard of North America occurred in this era—the abortive colony at Roanoke Island in 1587.


title: Elizabethan era

text: While Elizabethan England is not thought of as an age of technological innovation, some progress did occur. In 1564 Guilliam Boonen came from the Netherlands to be Queen Elizabeth's first coach-builder —thus introducing the new European invention of the spring-suspension coach to England, as a replacement for the litters and carts of an earlier transportation mode. Coaches quickly became as fashionable as sports cars in a later century; social critics, especially Puritan commentators, noted the "diverse great ladies" who rode "up and down the countryside" in their new coaches.


title: Elizabethan era

text: Historians since the 1960s have explored many facets of the social history, covering every class of the population.


title: Elizabethan era

text: Although home to only a small part of the population the Tudor municipalities were overcrowded and unhygienic. Most towns were unpaved with poor public sanitation. There were no sewers or drains, and rubbish was simply abandoned in the street. Animals such as rats thrived in these conditions. In larger towns and cities, such as London, common diseases arising from lack of sanitation included smallpox, measles, malaria, typhus, diphtheria, scarlet fever, and chickenpox.


title: Elizabethan era

text: Outbreaks of the Black Death pandemic occurred in 1498, 1535, 1543, 1563, 1589 and 1603. The reason for the speedy spread of the disease was the increase of rats infected by fleas carrying the disease.


title: Elizabethan era

text: Child mortality was low in comparison with earlier and later periods, at about 150 or fewer deaths per 1000 babies. By age 15 a person could expect 40–50 more years of life.


title: Elizabethan era

text: The great majority were tenant farmers who lived in small villages. Their homes were, as in earlier centuries, thatched huts with one or two rooms, although later on during this period, roofs were also tiled. Furniture was basic, with stools being commonplace rather than chairs. The walls of Tudor houses were often made from timber and wattle and daub, or brick; stone and tiles were more common in the wealthier homes. The daub was usually then painted with limewash, making it white, and the wood was painted with black tar to prevent rotting, but not in Tudor times; the Victorians did this afterwards. The bricks were handmade and thinner than modern bricks. The wooden beams were cut by hand, which makes telling the difference between Tudor houses and Tudor-style houses easy, as the original beams are not straight. The upper floors of Tudor houses were often larger than the ground floors, which would create an overhang (or jetty). This would create more floor-surface above while also keeping maximum street width. During the Tudor period, the use of glass when building houses was first used, and became widespread. It was very expensive and difficult to make, so the panes were made small and held together with a lead lattice, in casement windows. People who could not afford glass often used polished horn, cloth or paper. Tudor chimneys were tall, thin, and often decorated with symmetrical patterns of molded or cut brick. Early Tudor houses, and the homes of poorer people, did not have chimneys. The smoke in these cases would be let out through a simple hole in the roof.


title: Elizabethan era

text: Mansions had many chimneys for the many fireplaces required to keep the vast rooms warm. These fires were also the only way of cooking food. Wealthy Tudor homes needed many rooms, where a large number of guests and servants could be accommodated, fed and entertained. Wealth was demonstrated by the extensive use of glass. Windows became the main feature of Tudor mansions, and were often a fashion statement. Mansions were often designed to a symmetrical plan; "E" and "H" shapes were popular.


title: Elizabethan era

text: The population of London increased from 100,000 to 200,000 between the death of Mary Tudor in 1558 and the death of Elizabeth I in 1603. Inflation was rapid and the wealth gap was wide. Poor men, women, and children begged in the cities, as the children only earned sixpence a week. With the growth of industry, many landlords decided to use their land for manufacturing purposes, displacing the farmers who lived and worked there. Despite the struggles of the lower class, the government tended to spend money on wars and exploration voyages instead of on welfare.


title: Elizabethan era

text: About one-third of the population lived in poverty, with the wealthy expected to give alms to assist the impotent poor. Tudor law was harsh on the able-bodied poor, i.e., those unable to find work. Those who left their parishes in order to locate work were termed vagabonds and could be subjected to punishments, including whipping and putting at the stocks.


title: Elizabethan era

text: There was an unprecedented expansion of education in the Tudor period. Until then, few children went to school. Those that did go were mainly the sons of wealthy or ambitious fathers who could afford to pay the attendance fee. Boys were allowed to go to school and began at the age of 4, they then moved to grammar school when they were 7 years old. Girls were either kept at home by their parents to help with housework or sent out to work to bring money in for the family. They were not sent to school. Boys were educated for work and the girls for marriage and running a household so when they married they could look after the house and children. Wealthy families hired a tutor to teach the boys at home. Many Tudor towns and villages had a parish school where the local vicar taught boys to read and write. Brothers could teach their sisters these skills. At school, pupils were taught English, Latin, Greek, catechism and arithmetic. The pupils practised writing in ink by copying the alphabet and the Lord's Prayer. There were few books, so pupils read from hornbooks instead. These wooden boards had the alphabet, prayers or other writings pinned to them and were covered with a thin layer of transparent cow's horn. There were two types of school in Tudor times: petty school was where young boys were taught to read and write; grammar school was where abler boys were taught English and Latin. It was usual for students to attend six days a week. The school day started at 7:00 am in winter and 6:00 am in summer and finished about 5:00 pm. Petty schools had shorter hours, mostly to allow poorer boys the opportunity to work as well. Schools were harsh and teachers were very strict, often beating pupils who misbehaved.


title: Elizabethan era

text: Education would begin at home, where children were taught the basic etiquette of proper manners and respecting others. It was necessary for boys to attend grammar school, but girls were rarely allowed in any place of education other than petty schools, and then only with a restricted curriculum. Petty schools were for all children aged from 5 to 7 years of age. Only the most wealthy people allowed their daughters to be taught, and only at home. During this time, endowed schooling became available. This meant that even boys of very poor families were able to attend school if they were not needed to work at home, but only in a few localities were funds available to provide support as well as the necessary education scholarship.


title: Elizabethan era

text: Boys from wealthy families were taught at home by a private tutor. When Henry VIII shut the monasteries he closed their schools. He refounded many former monastic schools—they are known as "King's schools" and are found all over England. During the reign of Edward VI many free grammar schools were set up to take in non-fee paying students. There were two universities in Tudor England: Oxford and Cambridge. Some boys went to university at the age of about 14.


title: Elizabethan era

text: England's food supply was plentiful throughout most of the reign; there were no famines. Bad harvests caused distress, but they were usually localized. The most widespread came in 1555–57 and 1596–98. In the towns the price of staples was fixed by law; in hard times the size of the loaf of bread sold by the baker was smaller.


title: Elizabethan era

text: Trade and industry flourished in the 16th century, making England more prosperous and improving the standard of living of the upper and middle classes. However, the lower classes did not benefit much and did not always have enough food. As the English population was fed by its own agricultural produce, a series of bad harvests in the 1590s caused widespread starvation and poverty. The success of the wool trading industry decreased attention on agriculture, resulting in further starvation of the lower classes. Cumbria, the poorest and most isolated part of England, suffered a six-year famine beginning in 1594. Diseases and natural disasters also contributed to the scarce food supply.


title: Elizabethan era

text: In the 17th century, the food supply improved. England had no food crises from 1650 to 1725, a period when France was unusually vulnerable to famines. Historians point out that oat and barley prices in England did not always increase following a failure of the wheat crop, but did do so in France.


title: Elizabethan era

text: England was exposed to new foods (such as the potato imported from South America), and developed new tastes during the era. The more prosperous enjoyed a wide variety of food and drink, including exotic new drinks such as tea, coffee, and chocolate. French and Italian chefs appeared in the country houses and palaces bringing new standards of food preparation and taste. For example, the English developed a taste for acidic foods—such as oranges for the upper class—and started to use vinegar heavily. The gentry paid increasing attention to their gardens, with new fruits, vegetables and herbs; pasta, pastries, and dried mustard balls first appeared on the table. The apricot was a special treat at fancy banquets. Roast beef remained a staple for those who could afford it. The rest ate a great deal of bread and fish. Every class had a taste for beer and rum.


title: Elizabethan era

text: The diet in England during the Elizabethan era depended largely on social class. Bread was a staple of the Elizabethan diet, and people of different statuses ate bread of different qualities. The upper classes ate fine white bread called manchet, while the poor ate coarse bread made of barley or rye.


title: Elizabethan era

text: The poorer among the population consumed a diet largely of bread, cheese, milk, and beer, with small portions of meat, fish and vegetables, and occasionally some fruit. Potatoes were just arriving at the end of the period, and became increasingly important. The typical poor farmer sold his best products on the market, keeping the cheap food for the family. Stale bread could be used to make bread puddings, and bread crumbs served to thicken soups, stews, and sauces.


title: Elizabethan era

text: At a somewhat higher social level families ate an enormous variety of meats, who could choose among venison, beef, mutton, veal, pork, lamb, fowl, salmon, eel, and shellfish. The holiday goose was a special treat. Rich spices were used by the wealthier people to offset the smells of old salt-preserved meat. Many rural folk and some townspeople tended a small garden which produced vegetables such as asparagus, cucumbers, spinach, lettuce, beans, cabbage, turnips, radishes, carrots, leeks, and peas, as well as medicinal and flavoring herbs. Some grew their own apricots, grapes, berries, apples, pears, plums, strawberries, currants, and cherries. Families without a garden could trade with their neighbors to obtain vegetables and fruits at low cost. Fruits and vegetables were used in desserts such as pastries, tarts, cakes, crystallized fruit, and syrup.


title: Elizabethan era

text: At the rich end of the scale the manor houses and palaces were awash with large, elaborately prepared meals, usually for many people and often accompanied by entertainment. The upper classes often celebrated religious festivals, weddings, alliances and the whims of the king or queen. Feasts were commonly used to commemorate the "procession" of the crowned heads of state in the summer months, when the king or queen would travel through a circuit of other nobles' lands both to avoid the plague season of London, and alleviate the royal coffers, often drained through the winter to provide for the needs of the royal family and court. This would include a few days or even a week of feasting in each noble's home, who depending on his or her production and display of fashion, generosity and entertainment, could have his way made in court and elevate his or her status for months or even years.


title: Elizabethan era

text: Among the rich private hospitality was an important item in the budget. Entertaining a royal party for a few weeks could be ruinous to a nobleman. Inns existed for travellers, but restaurants were not known.


title: Elizabethan era

text: Special courses after a feast or dinner which often involved a special room or outdoor gazebo (sometimes known as a folly) with a central table set with dainties of "medicinal" value to help with digestion. These would include wafers, comfits of sugar-spun anise or other spices, jellies and marmalades (a firmer variety than we are used to, these would be more similar to our gelatin jigglers), candied fruits, spiced nuts and other such niceties. These would be eaten while standing and drinking warm, spiced wines (known as hypocras) or other drinks known to aid in digestion. Sugar in the Middle Ages or Early Modern Period was often considered medicinal, and used heavily in such things. This was not a course of pleasure, though it could be as everything was a treat, but one of healthful eating and abetting the digestive capabilities of the body. It also, of course, allowed those standing to show off their gorgeous new clothes and the holders of the dinner and banquet to show off the wealth of their estate, what with having a special room just for banqueting.


title: Elizabethan era

text: While the Tudor era presents an abundance of material on the women of the nobility—especially royal wives and queens—historians have recovered scant documentation about the average lives of women. There has, however, been extensive statistical analysis of demographic and population data which includes women, especially in their childbearing roles.


title: Elizabethan era

text: The role of women in society was, for the historical era, relatively unconstrained; Spanish and Italian visitors to England commented regularly, and sometimes caustically, on the freedom that women enjoyed in England, in contrast to their home cultures. England had more well-educated upper-class women than was common anywhere in Europe.


title: Elizabethan era

text: The Queen's marital status was a major political and diplomatic topic. It also entered into the popular culture. Elizabeth's unmarried status inspired a cult of virginity. In poetry and portraiture, she was depicted as a virgin or a goddess or both, not as a normal woman. Elizabeth made a virtue of her virginity: in 1559, she told the Commons, "And, in the end, this shall be for me sufficient, that a marble stone shall declare that a queen, having reigned such a time, lived and died a virgin". Public tributes to the Virgin by 1578 acted as a coded assertion of opposition to the queen's marriage negotiations with the Duc d'Alençon.


title: Elizabethan era

text: In contrast to her father's emphasis on masculinity and physical prowess, Elizabeth emphasized the maternalism theme, saying often that she was married to her kingdom and subjects. She explained "I keep the good will of all my husbands – my good people – for if they did not rest assured of some special love towards them, they would not readily yield me such good obedience", and promised in 1563 they would never have a more natural mother than she. Coch (1996) argues that her figurative motherhood played a central role in her complex self-representation, shaping and legitimating the personal rule of a divinely appointed female prince.


title: Elizabethan era

text: Over ninety percent of English women (and adults, in general) entered marriage at the end of the 1500s and beginning of the 1600s, at an average age of about 25–26 years for the bride and 27–28 years for the groom, with the most common ages being 25–26 for grooms (who would have finished their apprenticeships around this age) and 23 for brides. Among the nobility and gentry, the average was around 19–21 for brides and 24–26 for grooms. Many city and townswomen married for the first time in their thirties and forties and it was not unusual for orphaned young women to delay marriage until the late twenties or early thirties to help support their younger siblings, and roughly a quarter of all English brides were pregnant at their weddings.


title: Elizabethan era

text: With William Shakespeare at his peak, as well as Christopher Marlowe and many other playwrights, actors and theatres constantly busy, the high culture of the Elizabethan Renaissance was best expressed in its theatre. Historical topics were especially popular, not to mention the usual comedies and tragedies.


title: Elizabethan era

text: Elizabethan literature is considered one of the "most splendid" in the history of English literature. In addition to drama and the theatre, it saw a flowering of poetry, with new forms like the sonnet, the Spenserian stanza, and dramatic blank verse, as well as prose, including historical chronicles, pamphlets, and the first English novels. Edmund Spenser, Richard Hooker, and John Lyly, as well as Marlowe and Shakespeare, are major Elizabethan writers.


title: Elizabethan era

text: Travelling musicians were in great demand at Court, in churches, at country houses, and at local festivals. Important composers included William Byrd (1543–1623), John Dowland (1563–1626) Thomas Campion (1567–1620), and Robert Johnson (c. 1583–c. 1634). The composers were commissioned by church and Court, and deployed two main styles, madrigal and ayre. The popular culture showed a strong interest in folk songs and ballads (folk songs that tell a story). It became the fashion in the late 19th century to collect and sing the old songs.


title: Elizabethan era

text: It has often been said that the Renaissance came late to England, in contrast to Italy and the other states of continental Europe; the fine arts in England during the Tudor and Stuart eras were dominated by foreign and imported talent—from Hans Holbein the Younger under Henry VIII to Anthony van Dyck under Charles I. Yet within this general trend, a native school of painting was developing. In Elizabeth's reign, Nicholas Hilliard, the Queen's "limner and goldsmith", is the most widely recognized figure in this native development; but George Gower has begun to attract greater notice and appreciation as knowledge of him and his art and career has improved.


title: Elizabethan era

text: Watching plays became very popular during the Tudor period. Most towns sponsored plays enacted in town squares followed by the actors using the courtyards of taverns or inns (referred to as inn-yards) followed by the first theatres (great open-air amphitheatres and then the introduction of indoor theatres called playhouses). This popularity was helped by the rise of great playwrights such as William Shakespeare and Christopher Marlowe using London theatres such as the Globe Theatre. By 1595, 15,000 people a week were watching plays in London. It was during Elizabeth's reign that the first real theatres were built in England. Before theatres were built, actors travelled from town to town and performed in the streets or outside inns.


title: Elizabethan era

text: Miracle plays were local re-enactments of stories from the Bible. They derived from the old custom of mystery plays, in which stories and fables were enacted to teach lessons or educate about life in general. They influenced Shakespeare.


title: Elizabethan era

text: There were many different types of Elizabethan sports and entertainment. Animal sports included bear and bull baiting, dog fighting and cock fighting.


title: Elizabethan era

text: The rich enjoyed tennis, fencing, and jousting. Hunting was strictly limited to the upper class. They favoured their packs of dogs and hounds trained to chase foxes, hares and boars. The rich also enjoyed hunting small game and birds with hawks, known as falconry.


title: Elizabethan era

text: Jousting was an upscale, very expensive sport where warriors on horseback raced toward each other in full armor trying to use their lance to knock the other off his horse. It was a violent sport--King Henry II of France was killed in a tournament in 1559, as were many lesser men. King Henry VIII was a champion; he finally retired from the lists after a hard fall left him unconscious for hours.


title: Elizabethan era

text: Other sports included archery, bowling, hammer-throwing, quarter-staff contests, troco, quoits, skittles, wrestling and mob football.


title: Elizabethan era

text: Dice was a popular activity in all social classes. Cards appeared in Spain and Italy about 1370, but they probably came from Egypt. They began to spread throughout Europe and came into England around 1460. By the time of Elizabeth's reign, gambling was a common sport. Cards were not played only by the upper class. Many of the lower classes had access to playing cards. The card suits tended to change over time. The first Italian and Spanish decks had the same suits: Swords, Batons/ Clubs, Cups, and Coins. The suits often changed from country to country. England probably followed the Latin version, initially using cards imported from Spain but later relying on more convenient supplies from France. Most of the decks that have survived use the French Suit: Spades, Hearts, Clubs, and Diamonds. Yet even before Elizabeth had begun to reign, the number of cards had been standardized to 52 cards per deck. The lowest court subject in England was called the "knave". The lowest court card was therefore called the knave until later when the term "Jack" became more common. Popular card games included Maw, One and Thirty, Bone-ace. (These are all games for small group players.) Ruff and Honors was a team game.


title: Elizabethan era

text: During the Elizabethan era, people looked forward to holidays because opportunities for leisure were limited, with time away from hard work being restricted to periods after church on Sundays. For the most part, leisure and festivities took place on a public church holy day. Every month had its own holiday, some of which are listed below:


title: Electroencephalography

text: Electroencephalography (EEG) is a method to record an electrogram of the spontaneous electrical activity of the brain. The biosignals detected by EEG have been shown to represent the postsynaptic potentials of pyramidal neurons in the neocortex and allocortex. It is typically non-invasive, with the EEG electrodes placed along the scalp (commonly called "scalp EEG") using the International 10-20 system, or variations of it. Electrocorticography, involving surgical placement of electrodes, is sometimes called "intracranial EEG". Clinical interpretation of EEG recordings is most often performed by visual inspection of the tracing or quantitative EEG analysis.


title: Electroencephalography

text: Voltage fluctuations measured by the EEG bioamplifier and electrodes allow the evaluation of normal brain activity. As the electrical activity monitored by EEG originates in neurons in the underlying brain tissue, the recordings made by the electrodes on the surface of the scalp vary in accordance with their orientation and distance to the source of the activity. Furthermore the value recorded is distorted by intermediary tissues and bone which act in a manner akin to resistors and capacitors in an electrical circuit. This means not all neurons will contribute equally to an EEG signal with an EEG predominately reflecting the activity of cortical neurons near to the electrodes on the scalp. Deep structures within the brain further away from the electrodes will not contribute directly to an EEG, these include the base of the cortical gyrus, mesial walls of the major lobes, hippocampus, thalamus and brain stem.


title: Electroencephalography

text: A healthy human EEG will show certain patterns of activity which correlate with how awake a person is. The range of frequencies one observes are between 1 to 30 Hz and amplitudes will vary between 20 to 100 μV. The observed frequencies are subdivided in various groups, these are alpha (8-13 Hz), beta (13-30 Hz), delta (0.5-4 Hz) and theta (4-7 Hz). Alpha waves are observed when a person is in a state of relaxed wakefulness and are mostly prominent over parietal and occipital sites. During intense mental activity beta waves are more prominent in frontal areas as well as other regions. If a relaxed person is told to open their eyes one observes alpha activity decreasing and an increase in beta activity. Theta and delta waves are not seen in wakefulness and if they are it is a sign of brain dysfunction.


title: Electroencephalography

text: EEG can detect abnormal electrical discharges such as sharp waves, spikes or spike-and-wave complexes that are seen in people with epilepsy, thus it is often used to inform the medical diagnosis. EEG can detect the onset and spatio-temporal (location and time) evolution of seizures and the presence of status epilepticus. It is also used to help diagnose sleep disorders, depth of anesthesia, coma, encephalopathies, cerebral hypoxia after cardiac arrest, and brain death. EEG used to be a first-line method of diagnosis for tumors, stroke and other focal brain disorders, but this use has decreased with the advent of high-resolution anatomical imaging techniques such as magnetic resonance imaging (MRI) and computed tomography (CT). Despite limited spatial resolution, EEG continues to be a valuable tool for research and diagnosis. It is one of the few mobile techniques available and offers millisecond-range temporal resolution which is not possible with CT, PET or MRI.


title: Electroencephalography

text: Derivatives of the EEG technique include evoked potentials (EP), which involves averaging the EEG activity time-locked to the presentation of a stimulus of some sort (visual, somatosensory, or auditory). Event-related potentials (ERPs) refer to averaged EEG responses that are time-locked to more complex processing of stimuli; this technique is used in cognitive science, cognitive psychology, and psychophysiological research.


title: Electroencephalography

text: In 1875, Richard Caton (1842–1926), a physician practicing in Liverpool, presented his findings about electrical phenomena of the exposed cerebral hemispheres of rabbits and monkeys in the "British Medical Journal". In 1890, Polish physiologist Adolf Beck published an investigation of spontaneous electrical activity of the brain of rabbits and dogs that included rhythmic oscillations altered by light. Beck started experiments on the electrical brain activity of animals. Beck placed electrodes directly on the surface of the brain to test for sensory stimulation. His observation of fluctuating brain activity led to the conclusion of brain waves.


title: Electroencephalography

text: In 1912, Ukrainian physiologist Vladimir Vladimirovich Pravdich-Neminsky published the first animal EEG and the evoked potential of the mammalian (dog). In 1914, Napoleon Cybulski and Jelenska-Macieszyna photographed EEG recordings of experimentally induced seizures.


title: Electroencephalography

text: German physiologist and psychiatrist Hans Berger (1873–1941) recorded the first human EEG in 1924. Expanding on work previously conducted on animals by Richard Caton and others, Berger also invented the electroencephalogram (giving the device its name), an invention described "as one of the most surprising, remarkable, and momentous developments in the history of clinical neurology". His discoveries were first confirmed by British scientists Edgar Douglas Adrian and B. H. C. Matthews in 1934 and developed by them.


title: Electroencephalography

text: In 1934, Fisher and Lowenbach first demonstrated epileptiform spikes. In 1935, Gibbs, Davis and Lennox described interictal spike waves and the three cycles/s pattern of clinical absence seizures, which began the field of clinical electroencephalography. Subsequently, in 1936 Gibbs and Jasper reported the interictal spike as the focal signature of epilepsy. The same year, the first EEG laboratory opened at Massachusetts General Hospital.


title: Electroencephalography

text: Franklin Offner (1911–1999), professor of biophysics at Northwestern University developed a prototype of the EEG that incorporated a piezoelectric inkwriter called a Crystograph (the whole device was typically known as the Offner Dynograph).


title: Electroencephalography

text: In 1947, The American EEG Society was founded and the first International EEG congress was held. In 1953 Aserinsky and Kleitman described REM sleep.


title: Electroencephalography

text: In the 1950s, William Grey Walter developed an adjunct to EEG called EEG topography, which allowed for the mapping of electrical activity across the surface of the brain. This enjoyed a brief period of popularity in the 1980s and seemed especially promising for psychiatry. It was never accepted by neurologists and remains primarily a research tool.


title: Electroencephalography

text: An electroencephalograph system manufactured by Beckman Instruments was used on at least one of the Project Gemini manned spaceflights (1965-1966) to monitor the brain waves of astronauts on the flight. It was one of many Beckman Instruments specialized for and used by NASA.


title: Electroencephalography

text: In 1988, report was given by Stevo Bozinovski, Mihail Sestakov, and Liljana Bozinovska on EEG control of a physical object, a robot.


title: Electroencephalography

text: In October 2018, scientists connected the brains of three people to experiment with the process of thoughts sharing. Five groups of three people participated in the experiment using EEG. The success rate of the experiment was 81%.


title: Electroencephalography

text: EEG is the gold standard diagnostic procedure to confirm epilepsy. The sensitivity of a routine EEG to detect interictal epileptiform discharges at epilepsy centers has been reported to be in the range of 29-55%. Given the low to moderate sensitivity, a routine EEG (typically with a duration of 20–30 minutes) can be normal in people that have epilepsy. When an EEG shows interictal epileptiform discharges (e.g. sharp waves, spikes, spike-and-wave, etc.) it is confirmatory of epilepsy in nearly all cases (high specificity), however up to 3.5% of the general population may have epileptiform abnormalities in an EEG without ever having had a seizure (low false positive rate) or with a very low risk of developing epilepsy in the future.


title: Electroencephalography

text: When a routine EEG is normal and there is a high suspicion or need to confirm epilepsy, it may be repeated or performed with a longer duration in the epilepsy monitoring unit (EMU) or at home with an ambulatory EEG. In addition, there are activating maneuvers such as photic stimulation, hyperventilation and sleep deprivation that can increase the diagnostic yield of the EEG.


title: Electroencephalography

text: At times, a routine EEG is not sufficient to establish the diagnosis or to determine the best course of action in terms of treatment. In this case, attempts may be made to record an EEG while a seizure is occurring. This is known as an ictal recording, as opposed to an interictal recording which refers to the EEG recording between seizures. To obtain an ictal recording, a prolonged EEG is typically performed accompanied by a time-synchronized video and audio recording. This can be done either as an outpatient (at home) or during a hospital admission, preferably to an Epilepsy Monitoring Unit (EMU) with nurses and other personnel trained in the care of patients with seizures. Outpatient ambulatory video EEGs typically last one to three days. An admission to an Epilepsy Monitoring Unit typically lasts several days but may last for a week or longer. While in the hospital, seizure medications are usually withdrawn to increase the odds that a seizure will occur during admission. For reasons of safety, medications are not withdrawn during an EEG outside of the hospital. Ambulatory video EEGs, therefore, have the advantage of convenience and are less expensive than a hospital admission, but the disadvantage of a decreased probability of recording a clinical event.


title: Electroencephalography

text: Epilepsy monitoring is often considered when patients continue having events despite being on antiseizure medications or if there is concern that the patient's events have an alternate diagnosis, eg: psychogenic non-epileptic seizures, syncope (fainting), sub-cortical movement disorders, migraine variants, stroke etc. In cases of epileptic seizures, continuous EEG monitoring helps to characterize seizures and localize/lateralize the region of brain from which a seizure originates. This can help identify appropriate non-medication treatment options. In clinical use, EEG traces are visually analyzed by neurologists to look at various features. Increasingly, quantitative analysis of EEG is being used in conjunction with visual analysis. Quantitative analysis displays like power spectrum analysis, alpha-delta ratio, amplitude integrated EEG, spike detection can help quickly identify segments of EEG that need close visual analysis or in some cases be used as surrogates for quick identification of seizures in long term recordings.


title: Electroencephalography

text: EEG may be used to monitor the depth of anesthesia, as an indirect indicator of cerebral perfusion in carotid endarterectomy, or to monitor amobarbital effect during the Wada test.


title: Electroencephalography

text: EEG can also be used in intensive care units for brain function monitoring to monitor for non-convulsive seizures/non-convulsive status epilepticus, to monitor the effect of sedative/anesthesia in patients in medically induced coma (for treatment of refractory seizures or increased intracranial pressure), and to monitor for secondary brain damage in conditions such as subarachnoid hemorrhage (currently a research method).


title: Electroencephalography

text: In cases where significant brain injury is suspected, eg after cardiac arrest, EEG can provide some prognostic information.


title: Electroencephalography

text: If a patient with epilepsy is being considered for resective surgery, it is often necessary to localize the focus (source) of the epileptic brain activity with a resolution greater than what is provided by scalp EEG. In these cases, neurosurgeons typically implant strips and grids of electrodes or penetrating depth electrodes under the dura mater, through either a craniotomy or a burr hole. The recording of these signals is referred to as electrocorticography (ECoG), subdural EEG (sdEEG), intracranial EEG (icEEG), or stereotactic EEG (sEEG). The signal recorded from ECoG is on a different scale of activity than the brain activity recorded from scalp EEG. Low voltage, high frequency components that cannot be seen easily (or at all) in scalp EEG can be seen clearly in ECoG. Further, smaller electrodes (which cover a smaller parcel of brain surface) allow for better spatial resolution to narrow down the areas critical for seizure onset and propagation. Some clinical sites record from penetrating microelectrodes.


title: Electroencephalography

text: EEG is not indicated for diagnosing headache. Recurring headache is a common pain problem, and this procedure is sometimes used in a search for a diagnosis, but it has no advantage over routine clinical evaluation.


title: Electroencephalography

text: Sometimes it is more convenient or clinically necessary to perform ambulatory EEG recordings in the home of the patient. These studies typically have a duration of 24–72 hours.


title: Electroencephalography

text: EEG, and the related study of ERPs are used extensively in neuroscience, cognitive science, cognitive psychology, neurolinguistics and psychophysiological research, but also to study human functions such as swallowing. any EEG techniques used in research are not standardised sufficiently for clinical use, and many ERP studies fail to report all of the necessary processing steps for data collection and reduction, limiting the reproducibility and replicability of many studies. But research on mental disabilities, such as auditory processing disorder (APD), ADD, or ADHD, is becoming more widely known and EEGs are used as research and treatment.


title: Electroencephalography

text: Several other methods to study brain function exist, including functional magnetic resonance imaging (fMRI), positron emission tomography (PET), magnetoencephalography (MEG), nuclear magnetic resonance spectroscopy (NMR or MRS), electrocorticography (ECoG), single-photon emission computed tomography (SPECT), near-infrared spectroscopy (NIRS), and event-related optical signal (EROS). Despite the relatively poor spatial sensitivity of EEG, the "one-dimensional signals from localised peripheral regions on the head make it attractive for its simplistic fidelity and has allowed high clinical and basic research throughput". Thus, EEG possesses some advantages over some of those other techniques:


title: Electroencephalography

text: Simultaneous EEG recordings and fMRI scans have been obtained successfully, though recording both at the same time effectively requires that several technical difficulties be overcome, such as the presence of ballistocardiographic artifact, MRI pulse artifact and the induction of electrical currents in EEG wires that move within the strong magnetic fields of the MRI. While challenging, these have been successfully overcome in a number of studies.


title: Electroencephalography

text: MRI's produce detailed images created by generating strong magnetic fields that may induce potentially harmful displacement force and torque. These fields produce potentially harmful radio frequency heating and create image artifacts rendering images useless. Due to these potential risks, only certain medical devices can be used in an MR environment.


title: Electroencephalography

text: Similarly, simultaneous recordings with MEG and EEG have also been conducted, which has several advantages over using either technique alone:


title: Electroencephalography

text: Recently, a combined EEG/MEG (EMEG) approach has been investigated for the purpose of source reconstruction in epilepsy diagnosis.


title: Electroencephalography

text: EEG has also been combined with positron emission tomography. This provides the advantage of allowing researchers to see what EEG signals are associated with different drug actions in the brain.


title: Electroencephalography

text: Recent studies using machine learning techniques such as neural networks with statistical temporal features extracted from frontal lobe EEG brainwave data has shown high levels of success in classifying mental states (Relaxed, Neutral, Concentrating), mental emotional states (Negative, Neutral, Positive) and thalamocortical dysrhythmia.


title: Electroencephalography

text: The brain's electrical charge is maintained by billions of neurons. Neurons are electrically charged (or "polarized") by membrane transport proteins that pump ions across their membranes. Neurons are constantly exchanging ions with the extracellular milieu, for example to maintain resting potential and to propagate action potentials. Ions of similar charge repel each other, and when many ions are pushed out of many neurons at the same time, they can push their neighbours, who push their neighbours, and so on, in a wave. This process is known as volume conduction. When the wave of ions reaches the electrodes on the scalp, they can push or pull electrons on the metal in the electrodes. Since metal conducts the push and pull of electrons easily, the difference in push or pull voltages between any two electrodes can be measured by a voltmeter. Recording these voltages over time gives us the EEG.


title: Electroencephalography

text: The electric potential generated by an individual neuron is far too small to be picked up by EEG or MEG. EEG activity therefore always reflects the summation of the synchronous activity of thousands or millions of neurons that have similar spatial orientation. If the cells do not have similar spatial orientation, their ions do not line up and create waves to be detected. Pyramidal neurons of the cortex are thought to produce the most EEG signal because they are well-aligned and fire together. Because voltage field gradients fall off with the square of distance, activity from deep sources is more difficult to detect than currents near the skull.


title: Electroencephalography

text: Scalp EEG activity shows oscillations at a variety of frequencies. Several of these oscillations have characteristic frequency ranges, spatial distributions and are associated with different states of brain functioning (e.g., waking and the various sleep stages). These oscillations represent synchronized activity over a network of neurons. The neuronal networks underlying some of these oscillations are understood (e.g., the thalamocortical resonance underlying sleep spindles), while many others are not (e.g., the system that generates the posterior basic rhythm). Research that measures both EEG and neuron spiking finds the relationship between the two is complex, with a combination of EEG power in the gamma band and phase in the delta band relating most strongly to neuron spike activity.


title: Electroencephalography

text: In conventional scalp EEG, the recording is obtained by placing electrodes on the scalp with a conductive gel or paste, usually after preparing the scalp area by light abrasion to reduce impedance due to dead skin cells. Many systems typically use electrodes, each of which is attached to an individual wire. Some systems use caps or nets into which electrodes are embedded; this is particularly common when high-density arrays of electrodes are needed.


title: Electroencephalography

text: Electrode locations and names are specified by the International 10–20 system for most clinical and research applications (except when high-density arrays are used). This system ensures that the naming of electrodes is consistent across laboratories. In most clinical applications, 19 recording electrodes (plus ground and system reference) are used. A smaller number of electrodes are typically used when recording EEG from neonates. Additional electrodes can be added to the standard set-up when a clinical or research application demands increased spatial resolution for a particular area of the brain. High-density arrays (typically via cap or net) can contain up to 256 electrodes more-or-less evenly spaced around the scalp.


title: Electroencephalography

text: Each electrode is connected to one input of a differential amplifier (one amplifier per pair of electrodes); a common system reference electrode is connected to the other input of each differential amplifier. These amplifiers amplify the voltage between the active electrode and the reference (typically 1,000–100,000 times, or 60–100 dB of voltage gain). In analog EEG, the signal is then filtered (next paragraph), and the EEG signal is output as the deflection of pens as paper passes underneath. Most EEG systems these days, however, are digital, and the amplified signal is digitized via an analog-to-digital converter, after being passed through an anti-aliasing filter. Analog-to-digital sampling typically occurs at 256–512 Hz in clinical scalp EEG; sampling rates of up to 20 kHz are used in some research applications.


title: Electroencephalography

text: During the recording, a series of activation procedures may be used. These procedures may induce normal or abnormal EEG activity that might not otherwise be seen. These procedures include hyperventilation, photic stimulation (with a strobe light), eye closure, mental activity, sleep and sleep deprivation. During (inpatient) epilepsy monitoring, a patient's typical seizure medications may be withdrawn.


title: Electroencephalography

text: The digital EEG signal is stored electronically and can be filtered for display. Typical settings for the high-pass filter and a low-pass filter are 0.5–1 Hz and 35–70 Hz respectively. The high-pass filter typically filters out slow artifact, such as electrogalvanic signals and movement artifact, whereas the low-pass filter filters out high-frequency artifacts, such as electromyographic signals. An additional notch filter is typically used to remove artifact caused by electrical power lines (60 Hz in the United States and 50 Hz in many other countries).


title: Electroencephalography

text: The EEG signals can be captured with opensource hardware such as OpenBCI and the signal can be processed by freely available EEG software such as EEGLAB or the Neurophysiological Biomarker Toolbox.


title: Electroencephalography

text: As part of an evaluation for epilepsy surgery, it may be necessary to insert electrodes near the surface of the brain, under the surface of the dura mater. This is accomplished via burr hole or craniotomy. This is referred to variously as "electrocorticography (ECoG)", "intracranial EEG (I-EEG)" or "subdural EEG (SD-EEG)". Depth electrodes may also be placed into brain structures, such as the amygdala or hippocampus, structures, which are common epileptic foci and may not be "seen" clearly by scalp EEG. The electrocorticographic signal is processed in the same manner as digital scalp EEG (above), with a couple of caveats. ECoG is typically recorded at higher sampling rates than scalp EEG because of the requirements of Nyquist theorem – the subdural signal is composed of a higher predominance of higher frequency components. Also, many of the artifacts that affect scalp EEG do not impact ECoG, and therefore display filtering is often not needed.


title: Electroencephalography

text: Since an EEG voltage signal represents a difference between the voltages at two electrodes, the display of the EEG for the reading encephalographer may be set up in one of several ways. The representation of the EEG channels is referred to as a "montage."


title: Electroencephalography

text: When analog (paper) EEGs are used, the technologist switches between montages during the recording in order to highlight or better characterize certain features of the EEG. With digital EEG, all signals are typically digitized and stored in a particular (usually referential) montage; since any montage can be constructed mathematically from any other, the EEG can be viewed by the electroencephalographer in any display montage that is desired.


title: Electroencephalography

text: The EEG is read by a clinical neurophysiologist or neurologist (depending on local custom and law regarding medical specialities), optimally one who has specific training in the interpretation of EEGs for clinical purposes. This is done by visual inspection of the waveforms, called graphoelements. The use of computer signal processing of the EEG – so-called quantitative electroencephalography – is somewhat controversial when used for clinical purposes (although there are many research uses).


title: Electroencephalography

text: In the early 1990s Babak Taheri, at University of California, Davis demonstrated the first single and also multichannel dry active electrode arrays using micro-machining. The single channel dry EEG electrode construction and results were published in 1994. The arrayed electrode was also demonstrated to perform well compared to silver/silver chloride electrodes. The device consisted of four sites of sensors with integrated electronics to reduce noise by impedance matching. The advantages of such electrodes are: (1) no electrolyte used, (2) no skin preparation, (3) significantly reduced sensor size, and (4) compatibility with EEG monitoring systems. The active electrode array is an integrated system made of an array of capacitive sensors with local integrated circuitry housed in a package with batteries to power the circuitry. This level of integration was required to achieve the functional performance obtained by the electrode. The electrode was tested on an electrical test bench and on human subjects in four modalities of EEG activity, namely: (1) spontaneous EEG, (2) sensory event-related potentials, (3) brain stem potentials, and (4) cognitive event-related potentials. The performance of the dry electrode compared favorably with that of the standard wet electrodes in terms of skin preparation, no gel requirements (dry), and higher signal-to-noise ratio.


title: Electroencephalography

text: In 1999 researchers at Case Western Reserve University, in Cleveland, Ohio, led by Hunter Peckham, used 64-electrode EEG skullcap to return limited hand movements to quadriplegic Jim Jatich. As Jatich concentrated on simple but opposite concepts like up and down, his beta-rhythm EEG output was analysed using software to identify patterns in the noise. A basic pattern was identified and used to control a switch: Above average activity was set to on, below average off. As well as enabling Jatich to control a computer cursor the signals were also used to drive the nerve controllers embedded in his hands, restoring some movement.


title: Electroencephalography

text: In 2018, a functional dry electrode composed of a polydimethylsiloxane elastomer filled with conductive carbon nanofibers was reported. This research was conducted at the U.S. Army Research Laboratory. EEG technology often involves applying a gel to the scalp which facilitates strong signal-to-noise ratio. This results in more reproducible and reliable experimental results. Since patients dislike having their hair filled with gel, and the lengthy setup requires trained staff on hand, utilizing EEG outside the laboratory setting can be difficult. Additionally, it has been observed that wet electrode sensors' performance reduces after a span of hours. Therefore, research has been directed to developing dry and semi-dry EEG bioelectronic interfaces.


title: Electroencephalography

text: Dry electrode signals depend upon mechanical contact. Therefore, it can be difficult getting a usable signal because of impedance between the skin and the electrode. Some EEG systems attempt to circumvent this issue by applying a saline solution. Others have a semi dry nature and release small amounts of the gel upon contact with the scalp. Another solution uses spring loaded pin setups. These may be uncomfortable. They may also be dangerous if they were used in a situation where a patient could bump their head since they could become lodged after an impact trauma incident.


title: Electroencephalography

text: ARL also developed a visualization tool, Customizable Lighting Interface for the Visualization of EEGs or CLIVE, which showed how well two brains are synchronized.


title: Electroencephalography

text: Currently, headsets are available incorporating dry electrodes with up to 30 channels. Such designs are able to compensate for some of the signal quality degradation related to high impedances by optimizing pre-amplification, shielding and supporting mechanics.


title: Electroencephalography

text: EEG has several limitations. Most important is its poor spatial resolution. EEG is most sensitive to a particular set of post-synaptic potentials: those generated in superficial layers of the cortex, on the crests of gyri directly abutting the skull and radial to the skull. Dendrites, which are deeper in the cortex, inside sulci, in midline or deep structures (such as the cingulate gyrus or hippocampus), or producing currents that are tangential to the skull, have far less contribution to the EEG signal.


title: Electroencephalography

text: EEG recordings do not directly capture axonal action potentials. An action potential can be accurately represented as a current quadrupole, meaning that the resulting field decreases more rapidly than the ones produced by the current dipole of post-synaptic potentials. In addition, since EEGs represent averages of thousands of neurons, a large population of cells in synchronous activity is necessary to cause a significant deflection on the recordings. Action potentials are very fast and, as a consequence, the chances of field summation are slim. However, neural backpropagation, as a typically longer dendritic current dipole, can be picked up by EEG electrodes and is a reliable indication of the occurrence of neural output.


title: Electroencephalography

text: Not only do EEGs capture dendritic currents almost exclusively as opposed to axonal currents, they also show a preference for activity on populations of parallel dendrites and transmitting current in the same direction at the same time. Pyramidal neurons of cortical layers II/III and V extend apical dendrites to layer I. Currents moving up or down these processes underlie most of the signals produced by electroencephalography.


title: Electroencephalography

text: Therefore, EEG provides information with a large bias to select neuron types, and generally should not be used to make claims about global brain activity. The meninges, cerebrospinal fluid and skull "smear" the EEG signal, obscuring its intracranial source.


title: Electroencephalography

text: It is mathematically impossible to reconstruct a unique intracranial current source for a given EEG signal, as some currents produce potentials that cancel each other out. This is referred to as the inverse problem. However, much work has been done to produce remarkably good estimates of, at least, a localized electric dipole that represents the recorded currents.


title: Electroencephalography

text: EEG has several strong points as a tool for exploring brain activity. EEGs can detect changes over milliseconds, which is excellent considering an action potential takes approximately 0.5–130 milliseconds to propagate across a single neuron, depending on the type of neuron. Other methods of looking at brain activity, such as PET, fMRI or fUS have time resolution between seconds and minutes. EEG measures the brain's electrical activity directly, while other methods record changes in blood flow (e.g., SPECT, fMRI, fUS) or metabolic activity (e.g., PET, NIRS), which are indirect markers of brain electrical activity.


title: Electroencephalography

text: EEG can be used simultaneously with fMRI or fUS so that high-temporal-resolution data can be recorded at the same time as high-spatial-resolution data, however, since the data derived from each occurs over a different time course, the data sets do not necessarily represent exactly the same brain activity.


title: Electroencephalography

text: There are technical difficulties associated with combining EEG and fMRI including the need to remove the "MRI gradient artifact" present during MRI acquisition. Furthermore, currents can be induced in moving EEG electrode wires due to the magnetic field of the MRI.


title: Electroencephalography

text: EEG can be used simultaneously with NIRS or fUS without major technical difficulties. There is no influence of these modalities on each other and a combined measurement can give useful information about electrical activity as well as hemodynamics at medium spatial resolution.


title: Electroencephalography

text: EEG reflects correlated synaptic activity caused by post-synaptic potentials of cortical neurons. The ionic currents involved in the generation of fast action potentials may not contribute greatly to the averaged field potentials representing the EEG. More specifically, the scalp electrical potentials that produce EEG are generally thought to be caused by the extracellular ionic currents caused by dendritic electrical activity, whereas the fields producing magnetoencephalographic signals are associated with intracellular ionic currents.


title: Electroencephalography

text: The EEG is typically described in terms of (1) rhythmic activity and (2) transients. The rhythmic activity is divided into bands by frequency. To some degree, these frequency bands are a matter of nomenclature (i.e., any rhythmic activity between 8–12 Hz can be described as "alpha"), but these designations arose because rhythmic activity within a certain frequency range was noted to have a certain distribution over the scalp or a certain biological significance. Frequency bands are usually extracted using spectral methods (for instance Welch) as implemented for instance in freely available EEG software such as EEGLAB or the Neurophysiological Biomarker Toolbox.


title: Electroencephalography

text: Most of the cerebral signal observed in the scalp EEG falls in the range of 1–20 Hz (activity below or above this range is likely to be artifactual, under standard clinical recording techniques). Waveforms are subdivided into bandwidths known as alpha, beta, theta, and delta to signify the majority of the EEG used in clinical practice.


title: Electroencephalography

text: The practice of using only whole numbers in the definitions comes from practical considerations in the days when only whole cycles could be counted on paper records. This leads to gaps in the definitions, as seen elsewhere on this page. The theoretical definitions have always been more carefully defined to include all frequencies. Unfortunately there is no agreement in standard reference works on what these ranges should be – values for the upper end of alpha and lower end of beta include 12, 13, 14 and 15. If the threshold is taken as 14 Hz, then the slowest beta wave has about the same duration as the longest spike (70 ms), which makes this the most useful value.


title: Electroencephalography

text: "Ultra-slow" or "near-DC" activity is recorded using DC amplifiers in some research contexts. It is not typically recorded in a clinical context because the signal at these frequencies is susceptible to a number of artifacts.


title: Electroencephalography

text: Some features of the EEG are transient rather than rhythmic. Spikes and sharp waves may represent seizure activity or interictal activity in individuals with epilepsy or a predisposition toward epilepsy. Other transient features are normal: vertex waves and sleep spindles are seen in normal sleep.


title: Electroencephalography

text: Note that there are types of activity that are statistically uncommon, but not associated with dysfunction or disease. These are often referred to as "normal variants". The mu rhythm is an example of a normal variant.


title: Electroencephalography

text: The normal electroencephalogram (EEG) varies by age. The prenatal EEG and neonatal EEG is quite different from the adult EEG. Fetuses in the third trimester and newborns display two common brain activity patterns: "discontinuous" and "trace alternant." "Discontinuous" electrical activity refers to sharp bursts of electrical activity followed by low frequency waves. "Trace alternant" electrical activity describes sharp bursts followed by short high amplitude intervals and usually indicates quiet sleep in newborns. The EEG in childhood generally has slower frequency oscillations than the adult EEG.


title: Electroencephalography

text: The normal EEG also varies depending on state. The EEG is used along with other measurements (EOG, EMG) to define sleep stages in polysomnography. Stage I sleep (equivalent to drowsiness in some systems) appears on the EEG as drop-out of the posterior basic rhythm. There can be an increase in theta frequencies. Santamaria and Chiappa cataloged a number of the variety of patterns associated with drowsiness. Stage II sleep is characterized by sleep spindles – transient runs of rhythmic activity in the 12–14 Hz range (sometimes referred to as the "sigma" band) that have a frontal-central maximum. Most of the activity in Stage II is in the 3–6 Hz range. Stage III and IV sleep are defined by the presence of delta frequencies and are often referred to collectively as "slow-wave sleep". Stages I–IV comprise non-REM (or "NREM") sleep. The EEG in REM (rapid eye movement) sleep appears somewhat similar to the awake EEG.


title: Electroencephalography

text: EEG under general anesthesia depends on the type of anesthetic employed. With halogenated anesthetics, such as halothane or intravenous agents, such as propofol, a rapid (alpha or low beta), nonreactive EEG pattern is seen over most of the scalp, especially anteriorly; in some older terminology this was known as a WAR (widespread anterior rapid) pattern, contrasted with a WAIS (widespread slow) pattern associated with high doses of opiates. Anesthetic effects on EEG signals are beginning to be understood at the level of drug actions on different kinds of synapses and the circuits that allow synchronized neuronal activity.


title: Electroencephalography

text: EEG is an extremely useful technique for studying brain activity, but the signal measured is always contaminated by artifacts which can impact the analysis of the data. An artifact is any measured signal that does not originate within the brain. Although multiple algorithms exist for the removal of artifacts, the problem of how to deal with them remains an open question. The source of artifacts can be from issues relating to the instrument, such as faulty electrodes, line noise or high electrode impedance, or they may be from the physiology of the subject being recorded. This can include, eye blinks and movement, cardiac activity and muscle activity and these types of artifacts are more complicated to remove. Artifacts may bias the visual interpretation of EEG data as some may mimic cognitive activity that could affect diagnoses of problems such as Alzheimer’s disease or sleep disorders. As such the removal of such artifacts in EEG data used for practical applications is of the upmost importance.


title: Electroencephalography

text: It is important to be able to distinguish artifacts from genuine brain activity in order to prevent incorrect interpretations of EEG data. General approaches for the removal of artifacts from the data are, prevention, rejection and cancellation. The goal of any approach is to develop methodology capable of identifying and removing artifacts without affecting the quality of the EEG signal. As artifact sources are quite different the majority of researchers focus on developing algorithms that will identify and remove a single type of noise in the signal. Simple filtering using a notch filter is commonly employed to reject components with a 50/60 Hz frequency. However such simple filters are not an appropriate choice for dealing with all artifacts, as for some, their frequencies will overlap with the EEG frequencies. Regression algorithms have a moderate computation cost and are simple. They represented the most popular correction method up until the mid 1990's when they were replaced by "blind source separation" type methods. Regression algorithms work on the premise that all artifacts are comprised by one or more reference channels. Subtracting these reference channels from the other contaminated channels, in either the time or frequency domain, by estimating the impact of the reference channels on the other channels, would correct the channels for the artifact. Although the requirement of reference channels ultimately lead to this class of algorithm being replaced, they still represent the benchmark to which modern algorithms are evaluated against.


title: Electroencephalography

text: Blind source separation (BSS) algorithms employed to remove artifacts include principle component analysis (PCA) and independent component analysis (ICA) and several algorithms in the this class have been successful at tackling most physiological artifacts.


title: Electroencephalography

text: Ocular artifacts affect the EEG signal significantly. This is due to eye movements involving a change in electric fields surrounding the eyes, distorting the electric field over the scalp, and as EEG is recorded on the scalp, it therefore distorts the recorded signal. A difference of opinion exists among researchers, with some arguing ocular artifacts are, or may be reasonably described as a single generator, whilst others argue it is important to understand the potentially complicated mechanisms. Three potential mechanisms have been proposed to explain the ocular artifact.


title: Electroencephalography

text: The first is corneal retinal dipole movement which argues that an electric dipole is formed between the cornea and retina, as the former is positively and the latter negatively charged. When the eye moves, so does this dipole which impacts the electrical field over the scalp, this is the most standard view. The second mechanism is retinal dipole movement, which is similar to the first but differing in that it argues there is a potential difference, hence dipole across the retina with the cornea having little effect. The third mechanism is eyelid movement. It is known that there is a change in voltage around the eyes when the eyelid moves, even if the eyeball does not. It is thought that the eyelid can be described as a sliding potential source and that the impacting of blinking is different to eye movement on the recorded EEG.


title: Electroencephalography

text: Eyelid fluttering artifacts of a characteristic type were previously called Kappa rhythm (or Kappa waves). It is usually seen in the prefrontal leads, that is, just over the eyes. Sometimes they are seen with mental activity. They are usually in the Theta (4–7 Hz) or Alpha (7–14 Hz) range. They were named because they were believed to originate from the brain. Later study revealed they were generated by rapid fluttering of the eyelids, sometimes so minute that it was difficult to see. They are in fact noise in the EEG reading, and should not technically be called a rhythm or wave. Therefore, current usage in electroencephalography refers to the phenomenon as an eyelid fluttering artifact, rather than a Kappa rhythm (or wave).