# Cognitive Psychology and Cognitive Neuroscience/Neuroscience of Text Comprehension


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|                               | olog |                               |
|                               | y_an |                               |
|                               | d_Co |                               |
|                               | gnit |                               |
|                               | ive_ |                               |
|                               | Neur |                               |
|                               | osci |                               |
|                               | ence |                               |
|                               |  "wi |                               |
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## Introduction

What is happening inside my head when I listen to a sentence? How do I
process written words? This chapter will take a closer look on brain
processes concerned with language comprehension. Dealing with natural
language understanding, we distinguish between the neuroscientific and
the psycholinguistic approach. As text understanding spreads through the
broad field of cognitive psychology, linguistics, and neurosciences, our
main focus will lay on the intersection of two latter, which is known as
neurolinguistics.

Different brain areas need to be examined in order to find out how words
and sentences are being processed. For long time scientist were
restricted to draw conclusions from certain brain lesions to the
functions of corresponding brain areas. During the last 40 years
techniques for brain imaging and ERP-measurement have been established
which allow for a more accurate identification of brain parts involved
in language processing.

Scientific studies on these phenomena are generally divided into
research on auditory and visual language comprehension; we will discuss
both. Not to forget is that it is not enough to examine English: To
understand language processing in general, we have to look at
non-Indo-European and other language systems like sign language. But
first of all we will be concerned with a rough localization of language
in the brain.

## Lateralization of language

Although functional lateralization studies and analyses find individual
differences in personality or cognitive style don\'t favor one
hemisphere or the other, some brain functions occur in one or the other
side of the brain. Language tends to be on the left and attention on the
right (Nielson, Zielinski, Ferguson, Lainhart & Anderson,
2013).
There is a lot of evidence that each brain hemisphere has its own
distinct functions in language comprehension. Most often, the right
hemisphere is referred to as the non-dominant hemisphere and the left is
seen as the dominant hemisphere. This distinction is called
lateralization (from the Latin word lateral, meaning sidewise) and
reason for it first was raised by experiments with split-brain patients.
Following a top-down approach we will then discuss the right hemisphere
which might have the mayor role in higher level comprehension, but is
not quite well understood. Much research has been done on the left
hemisphere and we will discuss why it might be dominant before the
following sections discuss the fairly well understood fundamental
processing of language in this hemisphere of the brain.

### Functional asymmetry

**Anatomical differences between left and right hemisphere**

Initially we will consider the most apparent part of a differentiation
between left and right hemisphere: Their differences in shape and
structure. As visible to the naked eye there exists a clear asymmetry
between the two halves of the human brain: The right hemisphere
typically has a bigger, wider and farther extended frontal region than
the left hemisphere, whereas the left hemisphere is bigger, wider and
extends farther in it's occipital region (M. T.
Banich,\"Neuropsychology\", ch.3, pg.92). Significantly larger on the
left side in most human brains is a certain part of the temporal lobe's
surface, which is called the planum temporale. It is localized near
Wernicke's area and other auditory association areas, wherefore we can
already speculate that the left hemisphere might be stronger involved in
processes of language and speech treatment.

In fact such a left laterality of language functions is evident in 97%
of the population (D. Purves, \"Neuroscience\", ch.26, pg.649). But
actually the percentage of human brains, in which a \"left-dominance\"
of the planum temporale is traceable, is only 67% (D. Purves,
\"Neuroscience\", ch.26, pg.648). Which other factors play aunsolved
yet.

**Evidence for functional asymmetry from \"split brain\" patients**

In hard cases of epilepsy a rarely performed but popular surgical method
to reduce the frequency of epileptic seizures is the so-called corpus
callosotomy. Here a radical cut through the connecting \"communication
bridge\" between right and left hemisphere, the corpus callosum, is
done; the result is a \"split-brain\". For patients whose corpus
callosum is cut, the risk of accidental physical injury is mitigated,
but the side-effect is striking: Due to this eradicative transection of
left and right half of the brain these two are not longer able to
communicate adequately. This situation provides the opportunity to study
differentiation of functionality between the hemispheres. First
experiments with split-brain patients were performed by Roger Sperry and
his colleagues at the California Institute of Technology in 1960 and
1970 (D. Purves, \"Neuroscience\", ch.26, pg.646). They lead researchers
to sweeping conclusions about laterality of speech and the organization
of the human brain in general.

```{=html}
<center>
```
  -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
  **A digression on the laterality of the visual system**
  !Visual systemA visual stimulus, located within the left visual field, projects onto the nasal (inner) part of the left eye's retina and onto the temporal (outer) part of the right eye's retina. Images on the temporal retinal region are processed in the visual cortex of the same side of the brain (ipsilateral), whereas nasal retinal information is mapped onto the opposite half of the brain (contralateral). The stimulus within the left visual field will completely arrive in the right visual cortex to be processed and worked up. In \"healthy\" brains this information furthermore attains the left hemisphere via the corpus callosum and can be integrated there. In split-brain patients this current of signals is interrupted; the stimulus remains \"invisible\" for the left hemisphere.
  -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

```{=html}
</center>
```
!Split Brain
Experiments{width="300"}The
experiment we consider now is based on the laterality of the visual
system: What is seen in the left half of the visual field will be
processed in the right hemisphere and vice versa. Aware of this
principle a test operator presents the picture of an object to one half
of the visual field while the participant is instructed to name the seen
object, and to blindly pick it out of an amount of concrete objects with
the contralateral hand. It can be shown that a picture, for example the
drawing of a die, which has only been presented to the left hemisphere,
can be named by the participant (\"I saw a die\"), but is not selectable
with the right hand (no idea which object to choose from the table).
Contrarily the participant is unable to name the die, if it was
recognized in the right hemisphere, but easily picks it out of the heap
of objects on the table with the help of the left hand.

These outcomes are clear evidence of the human brain's functional
asymmetry. The left hemisphere seems to dominate functions of speech and
language processing, but is unable to handle spatial tasks like
vision-independent object recognition. The right hemisphere seems to
dominate spatial functions, but is unable to process words and meaning
independently. In a second experiment evidence arose that a split-brain
patient can only follow a written command (like \"get up now!\"), if it
is presented to the left hemisphere. The right hemisphere can only
\"understand\" pictorial instructions.

The following table (D. Purves, \"Neuroscience\", ch.26, pg.647) gives a
rough distinction of functions:

```{=html}
<center>
```
+------------------------------------+-----------------------------------+
| **Left Hemisphere**                | **Right Hemisphere**              |
+------------------------------------+-----------------------------------+
| -   analysis of right visual field | -   analysis of left visual field |
| -   language processing            | -   spatial tasks                 |
|     -   writing                    | -   visuospatial tasks            |
|     -   speech                     | -   object and face recognition   |
+------------------------------------+-----------------------------------+

```{=html}
</center>
```
First it is important to keep in mind that these distinctions comprise
only functional dominances, no exclusive competences. In cases of
unilateral brain damage, often one half of the brain takes over tasks of
the other one. Furthermore it should be mentioned that this experiment
works only for stimuli presented for less than a second. This is because
not only the corpus callosum, but as well some subcortical commissures
serve for interhemispheric transfer. In general both can simultaneously
contribute to performance, since they use complement roles in
processing.

```{=html}
<center>
```
+----------------------------------------------------------------------+
| **A digression on handedness**                                       |
+----------------------------------------------------------------------+
| An important issue, when exploring the different brain organization, |
| is handedness, which is the tendency to use the left or the right    |
| hand to perform activities. Throughout history, left-handers, which  |
| only comprise about 10% of the population, have often been           |
| considered being something abnormal. They were said to be evil,      |
| stubborn, defiant and were, even until the mid 20th century, forced  |
| to write with their right hand.                                      |
|                                                                      |
| One most commonly accepted idea, as to how handedness affects the    |
| hemispheres, is the brain hemisphere division of labour. Since both  |
| speaking and handiwork require fine motor skills, the presumption    |
| here is that it would be more efficient to have one brain hemisphere |
| do both, rather than having it divided up. Since in most people, the |
| left side of the brain controls speaking, right-handedness           |
| predominates. The theory also predicts that left-handed people have  |
| a reversed brain division of labour.                                 |
|                                                                      |
| In right handers, verbal processing is mostly done in the left       |
| hemisphere, whereas visuospatial processing is mostly done in the    |
| opposite hemisphere. Therefore, 95% of speech output is controlled   |
| by the left brain hemisphere, whereas only 5% of individuals control |
| speech output in their right hemisphere. Left-handers, on the other  |
| hand, have a heterogeneous brain organization. Their brain           |
| hemisphere is either organized in the same way as right handers, the |
| opposite way, or even such that both hemispheres are used for verbal |
| processing. But usually, in 70% of the cases, speech is controlled   |
| by the left-hemisphere, 15% by the right and 15% by either           |
| hemisphere. When the average is taken across all types of            |
| left-handedness, it appears that left-handers are less lateralized.  |
|                                                                      |
| After, for example, damage occurs to the left hemisphere, it follows |
| that there is a visuospatial deficit, which is usually more severe   |
| in left-handers than in right-handers. Dissimilarities may derive,   |
| in part, from differences in brain morphology, which concludes from  |
| asymmetries in the planum temporale. Still, it can be assumed that   |
| left-handers have less division of labour between their two          |
| hemispheres than right-handers do and are more likely to lack        |
| neuroanatomical asymmetries.                                         |
|                                                                      |
| There have been many theories as to find out why people are          |
| left-handed and what its consequences may be. Some people say that   |
| left-handers have a shorter life span or higher accident rates or    |
| autoimmune disorders. According to the theory of Geschwind and       |
| Galaburda, there is a relation to sex hormones, the immune system,   |
| and profiles of cognitive abilities that determine, whether a person |
| is left-handed or not. Concludingly, many genetic models have been   |
| proposed, yet the causes and consequences still remain a mystery     |
| (M.T.Banich, \"Neuropsychology\", ch.3, pg. 119).                    |
+----------------------------------------------------------------------+

```{=html}
</center>
```
### The right hemisphere

**The role of the right hemisphere in text comprehension**

The experiments with \"split-brain\" patients and evidence that will be
discussed soon suggest that the right hemisphere is usually not (but in
some cases, e.g. 15% of left handed people) dominant in language
comprehension. What is most often ascribed to the right hemisphere is
cognitive functioning. When damage is done to this part of the brain or
when temporal regions of the right hemisphere are removed, this can lead
to cognitive-communication problems, such as impaired memory, attention
problems, and poor reasoning (L. Cherney, 2001). Investigations lead to
the conclusion that the right hemisphere processes information in a
gestalt and holistic fashion, with a special emphasis on spatial
relationships. Here, an advantage arises for differentiating two
distinct faces because it examines things in a global manner and it also
reacts to lower spatial, and also auditory, frequency. The former point
can be undermined with the fact that the right hemisphere is capable of
reading most concrete words and can make simple grammatical comparisons
(M. T. Banich,"Neuropsychology", ch.3, pg.97). But in order to function
in such a way, there must be some sort of communication between the
brain halves.

**Prosody - the sound envelope around words**

Consider how different the simple statement \"She did it again\" could
be interpreted in the following context taken from Banich: LYNN: Alice
is way into this mountain-biking thing. After breaking her arm, you\'d
think she\'d be a little more cautious. But then yesterday, she went out
and rode Captain Jack\'s. That trail is gnarly - narrow with lots of
tree roots and rocks. And last night, I heard that she took a bad tumble
on her way down. SARA: *She did it again* Does Sara say that with rising
pitch or emphatically and with falling intonation? In the first case she
would ask whether Alice has injured herself again. In the other case she
asserts something she knows or imagines: That Alice managed to hurt
herself a second time. Obviously the sound envelope around words -
prosody - does matter.

Reason to belief that recognition of prosodic patterns appears in the
right hemisphere arises when you take into account patients that have
damage to an anterior region of the right hemisphere. They suffer from
**aprosodic** speech, that is, their utterances are all at the same
pitch. They might sound like a robot from the 80ties. There is another
phenomena appearing from brain damage: **dysprosodic** speech. In that
case the patient speaks with disordered intonation. This is not due to a
right hemisphere lesion, but arises when damage to the left hemisphere
is suffered. The explanation is that the left hemisphere gives ill-timed
prosodic cues to the right hemisphere, thus proper intonation is
affected.

**Beyond words: Inference from a neurological point of view**

On the word level, the current studies are mostly consistent with each
other and with findings from brain lesion studies. But when it comes to
the more complex understanding of whole sentences, texts and storylines,
the findings are split. According to E. C. Ferstl's review "The
Neuroanatomy of Text Comprehension. What's the story so far?" (2004),
there is evidence for and against right hemisphere regions playing the
key role in pragmatics and text comprehension. On the current state of
knowledge, we cannot exactly say how and where cognitive functions like
building situation models and inferencing work together with "pure"
language processes.

As this chapter is concerned with the neurology of language, it should
be remarked that patients with right hemisphere damage have difficulties
with inferencing. Take into account the following sentence:

*With mosquitoes, gnats, and grasshoppers flying all about, she came
across a small black bug that was being used to eavesdrop on her
conversation.*

You might have to reinterpret the sentence until you realize that
\"small black bug\" does not refer to an animal but rather to a spy
device. People with damage in the right hemisphere have problems to do
so. They have difficulty to follow the thread of a story and to make
inferences about what has been said. Furthermore they have a hard time
understanding non-literal aspects of sentences like metaphors, so they
might be really horrified when they hear that someone was \"Crying her
eyes out\".

The reader is referred to the next chapter for a detailed discussion of
Situation
Models

### The left hemisphere

**Further evidence for left hemisphere dominance: The Wada technique**

Before concerning concrete functionality of the left hemisphere, further
evidence for the dominance of the left hemisphere is provided. Of
relevance is the so-called Wada technique, allowing testing which
hemisphere is responsible for speech output and usually being used in
epilepsy patients during surgery. It is not a brain imaging technique,
but simulates a brain lesion. One of the hemispheres is anesthetized by
injecting a barbiturate (sodium amobarbital) in one of the patient's
carotid arteries. Then he is asked to name a number of items on cards.
When he is not able to do that, despite the fact that he could do it an
hour earlier, the concerned hemisphere is said to be the one responsible
for speech output. This test must be done twice, for there is a chance
that the patient produces speech bilaterally. The probability for that
is not very high, in fact, according to Rasmussen & Milner 1997a (as
referred to in Banich, p. 293) it occurs only in 15% of the left-handers
and none of the right-handers. (It is still unclear where these
differences in left-handers' brains come from.)

That means that in most people, only one hemisphere "produces" speech
output -- and in 96% of right-handers and 70% of left-handers, it is the
left one. The findings of the brain lesion studies about asymmetry were
confirmed here: Normally (in healthy right-handers), the left hemisphere
controls speech output.

**Explanations of left hemisphere dominance**

Two theories why the left hemisphere might have special language
capacities are still discussed. The first states that dominance of the
left hemisphere is due to a specialization for **precise temporal
control of oral and manual articulators**. Here the main argument is
that gestures related to a story line are most often made with the right
and therefore by the left hemisphere controlled hand whilst other hand
movements appear equally often with both hands. The other theory says
that the left hemisphere is dominant because it is specialized for
**linguistic processing** and is due to a single patient - a speaker of
American Sign Language with a left hemisphere lesion. He could neither
produce nor comprehend ASL, but could still communicate by using
gestures in non-linguistic domains.

**How innate is the organisational structure of the brain?**

Not only cases of left-handers but also brain imaging techniques have
shown examples of bilateral language processing: According to ERP
studies (by Bellugi et al. 1994 and Neville et al. 1993 as cited in E.
Dabrowska, \"Language, Mind an Brain\" 2004, p. 57), people with the
Williams' syndrome (WS) also have no dominant hemisphere for language.
WS patients have a lot of physical and mental disorders, but show,
compared to their other (poor) cognitive abilities, very good linguistic
skills. And these skills do not rely on one dominant hemisphere, but
both of them contribute equally. So, whilst the majority of the
population has a dominant left hemisphere for language processing there
are a variety of exceptions to that dominance. That there are different
"organisation possibilities" in individual brains Dabrowska (p. 57)
suggests that the organisational structure in the brain could be less
innate and fixed as it is commonly thought.

## Auditory Language Processing

This section will explain where and how language is processed. To avoid
intersections with visual processes we will firstly concentrate on
spoken language. Scientists have developed three approaches of
conceiving information about this issue. The first two approaches are
based upon brain lesions, namely aphasia, whereas the recent approach
relies on results of on modern brain-image techniques.

### Neurological Perspective

The Neurological Perspective describes which pathways language follows
in order to be comprehended. Scientists revealed that there are concrete
areas inside the brain where concrete tasks of language processing are
taking place. The most known areas are the Broca and the Wernicke Area.

**Broca's aphasia**

!Broca\'s and Wernicke\'s
area One of the most
well-known aphasias is Broca's aphasia that causes patients to be unable
to speak fluently. Moreover they have a great difficulty producing
words. Comprehension, however, is relatively intact in those patients.
Because these symptoms do not result from motoric problems of the vocal
musculature, a region in the brain that is responsible for linguistic
output must be lesioned. Broca discovered that the brain region causing
fluent speech is responsible for linguistic output, must be located
ventrally in the frontal lobe, anterior to the motor strip. Recent
research suggested that Broca\`s aphasia results also from subcortical
tissue and white matter and not only cortical tissue.

```{=html}
<center>
```
  Example of spontaneous Speech - Task: What do you see on this picture?
  ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
  „O, yea. Det's a boy an' girl\... an' \... a \... car \... house\... light po' (pole). Dog an' a \... boat. ‚N det's a \... mm \... a \... coffee, an' reading. Det's a \... mm \... a \... det's a boy \... fishin'." (Adapted from „Principles of Neuroscience" 4th edition, 2000, p 1178)

```{=html}
</center>
```
**Wernicke's aphasia**

Another very famous aphasia, known as Wernicke\`s aphasia, causes
opposite syndromes. Patients suffering from Wernicke\`s aphasia usually
speak very fluently, words are pronounced correctly, but they are
combined senselessly -- "word salad" is the way it is most often
described. Understanding what patients of Wernicke\`s aphasia say is
especially difficult, because they use paraphasias (substitution of a
word in verbal paraphasia, of word with similar meaning in semantic
paraphasia, and of a phoneme in phonemic paraphasia) and neologisms.
With Wernicke\`s aphasia the comprehension of simple sentences is a very
difficult task. Moreover their ability to process auditory language
input and also written language is impaired. With some knowledge about
the brainstructure and their tasks one is able to conclude that the area
that causes Wernicke\`s aphasia, is situated at the joint of temporal,
parietal and occipital regions, near Heschl\`s gyrus (primary auditory
area), because all the areas receiving and interpreting sensory
information (posterior cortex), and those connecting the sensory
information to meaning (parietal lobe) are likely to be involved.

```{=html}
<center>
```
  Example of spontaneous Speech - Task: What do you see on this picture?
  -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
  „Ah, yes, it's ah \... several things. It's a girl \... uncurl \... on a boat. A dog \... 'S is another dog \... uh-oh \... long's \... on a boat. The lady, it's a young lady. An' a man a They were eatin'. 'S be place there. This \... a tree! A boat. No, this is a \... It's a house. Over in here \... a cake. An' it's, it's a lot of water. Ah, all right. I think I mentioned about that boat. I noticed a boat being there. I did mention that before \... Several things down, different things down \... a bat \... a cake \... you have a \..." (adapted from „Principles of Neuroscience" 4th edition, 2000, p 1178)

```{=html}
</center>
```
**Conduction aphasia**

Wernicke supposed that an aphasia between Broca's area and Wernicke's
area, namely conduction aphasia, would lead to severe problems to repeat
just heard sentences rather than having problems with the comprehension
and production of speech. Indeed patients suffering from this kind of
aphasia show an inability to reproduce sentences since they often make
phonemic paraphasias, may substitute or leave out words, or might say
nothing. Investigations determined that the \"connection cable\", namely
the arcuate fasciculus between Wernicke's and Broca's area is almost
invariably damaged in case of a conduction aphasia. That is why
conduction aphasia is also regarded as a disconnection syndrome (the
behavioural dysfunction because of a damage to the connection of two
connected brain regions).

```{=html}
<center>
```
  Example of the repetition of the sentence „The pastry-cook was elated":
  ------------------------------------------------------------------------------------------------------------------
  „The baker-er was /vaskerin/ \... uh \..." (adapted from „Principles of Neuroscience" 4th edition, 2000, p 1178)

```{=html}
</center>
```
**Transcortical motor aphasia and global aphasia**

Transcortical motor aphasia, another brain lesion caused by a connection
disruption, is very similar to Broca\`s aphasia, with the difference
that the ability to repeat is kept. In fact people with a transcortical
motor aphasia often suffer from echolalia, the need to repeat what they
just heard. Usually patients\` brain is damaged outside Broca\`s area,
sometimes more anterior and sometimes more superior. Individuals with
transcortical sensory aphasia have similar symptoms as those suffering
from Wernicke\`s aphasia, except that they show signs of echolalia.
Lesions in great parts of the left hemisphere lead to global aphasia,
and thus to an inability of both comprehending and producing language,
because not only Broca\`s or Wenicke\`s area is damaged. (Barnich, 1997,
pp. 276--282)

```{=html}
<center>
```
+----------+----------+----------+----------+----------+----------+
| **Type   | **Spo    | **Para   | *        | **Repe   | **       |
| of       | ntaneous | phasia** | *Compreh | tition** | Naming** |
| A        | Speech** |          | ension** |          |          |
| phasia** |          |          |          |          |          |
+----------+----------+----------+----------+----------+----------+
| -        | -   N    | -        | -   Good | -   Poor | -   Poor |
| Broca\`s | onfluent | Uncommon | -   Poor | -   Poor | -   Poor |
| -   Wer  | -        | -        | -   Good | -   Poor | -   Poor |
| nicke\`s |   Fluent |   Common | -   Good | -   Good | -   Poor |
| -   Co   | -        |          | -   Poor |     (ec  | -   Poor |
| nduction |   Fluent | (verbal) | -   Poor | holalia) | -   Poor |
| -        | -   N    | -        |          | -   Good |          |
|    Trans | onfluent |   Common |          |     (ec  |          |
| cortical | -        |     (    |          | holalia) |          |
|          |   Fluent | literal) |          | -   Poor |          |
|    motor | -   N    | -        |          |          |          |
| -        | onfluent | Uncommon |          |          |          |
|    Trans |          | -        |          |          |          |
| cortical |          |   Common |          |          |          |
|          |          | -        |          |          |          |
|  sensory |          | Variable |          |          |          |
| -        |          |          |          |          |          |
|   Global |          |          |          |          |          |
+----------+----------+----------+----------+----------+----------+

`<small>`{=html}Overview of the effects of aphasia from the neurological
perspective`</small>`{=html}

```{=html}
</center>
```
(Adapted from Benson, 1985,p. 32 as cited in Barnich, 1997, p. 287)

### Psychological Perspective

Since the 1960's psychologists and psycholinguists tried to resolve how
language is organised and represented inside the brain. Patients with
aphasias gave good evidence for location and discrimination of the three
main parts of language comprehension and production, namely phonology,
syntax and semantics.

**Phonology**

Phonology deals with the processing of meaningful parts of speech
resulting from the mere sound. More over there exists a differentiation
between a phonemic representation of a speech sound which are the
smallest units of sounds that leads to different meanings (e.g. the /b/
and /p/ in bet and pat) and phonetic representation. The latter means
that a speech sound may be produced in a different manner at different
situations. For instance the /p/ in pill sounds different than the /p/
in spill since the former /p/ is aspirated and the latter is not.

Examining which parts are responsible for phonetic representation,
patients with Broca\`s or Wernicke\`s aphasia can be compared. As the
speech characteristic for patients with Broca\`s aphasia is non-fluent,
i.e. they have problems producing the correct phonetic and phonemic
representation of a sound, and people with Wernicke\`s aphasia do not
show any problems speaking fluently, but also have problems producing
the right phoneme. This indicates that Broca\`s area is mainly involved
in phonological production and also, that phonemic and phonetic
representation do not take place in the same part of the brain.
Scientists examined on a more precise level the speech production, on
the level of the distinctive features of phonemes, to see in which
features patients with aphasia made mistakes.

A distinctive feature describes the different manners and places of
articulation. /t/ (like in touch) and /s/ (like in such) for example are
created at the same place but produced in different manner. /t/ and /d/
are created at the same place and in the same manner but they differ in
voicing.

Results show that in fluent as well as in non-fluent aphasia patients
usually mix up only one distinctive feature, not two. In general it can
be said that errors connected to the place of articulation are more
common than those linked to voicing. Interestingly some aphasia patients
are well aware of the different features of two phonemes, yet they are
unable to produce the right sound. This suggests that though patients
have great difficulty pronouncing words correctly, their comprehension
of words is still quite good. This is characteristic for patients with
Broca\`s aphasia, while those with Wernicke\`s aphasia show contrary
symptoms: they are able to pronounce words correctly, but cannot
understand what the words mean. That is why they often utter
phonologically correct words (neologisms) that are not real words with a
meaning.

**Syntax**

Syntax describes the rules of how words must be arranged to result in
meaningful sentences. Humans in general usually know the syntax of their
mother tongue and thus slip their tongue if a word happens to be out of
order in a sentence. People with aphasia, however, often have problems
with parsing of sentences, not only with respect to the production of
language but also with respect to comprehension of sentences. Patients
showing an inability of comprehension and production of sentences
usually have some kind of anterior aphasia, also called agrammatical
aphasia. This can be revealed in tests with sentences. These patients
cannot distinguish between active and passive voice easily if both agent
and object could play an active part. For example patients do not see a
difference between "The boy chased the girl" and "The boy was chased by
the girl", but they do understand both "The boy saw the apple" and "The
apple was seen by the boy", because they can seek help of semantics and
do not have to rely on syntax alone. Patients with posterior aphasia,
like for example Wernicke\`s aphasia, do not show these symptoms, as
their speech is fluent. Comprehension by mere syntactic means would be
possible as well, but the semantic aspect must be considered as well.
This will be discussed in the next part.

**Semantics**

Semantics deals with the meaning of words and sentences. It has been
shown that patients suffering from posterior aphasia have severe
problems understanding simple texts, although their knowledge of syntax
is intact. The semantic shortcoming is often examined by a Token Test, a
test in which patients have to point to objects referred to in simple
sentences. As might have been guessed, people with anterior aphasia have
no problems with semantics, yet they might not be able to understand
longer sentences because the knowledge of syntax then is involved as
well.

```{=html}
<center>
```
  --------------- ----------------------------------------------- ---------------------------------------
                  **anterior Aphasia (e.g. Broca)**               **posterior Aphasia (e.g. Wernicke)**
  **Phonology**   phonetic and phonemic representation affected   phonemic representation affected
  **Syntax**      affected                                        no effect
  **Syntax**      no effect                                       affected
  --------------- ----------------------------------------------- ---------------------------------------

`<small>`{=html}Overview of the effects of aphasia from the
psychological perspective`</small>`{=html}

```{=html}
</center>
```
In general studies with lesioned people have shown that anterior areas
are needed for speech output and posterior regions for speech
comprehension. As mentioned above anterior regions are also more
important for syntactic processing, while posterior regions are involved
in semantic processing. But such a strict division of the parts of the
brain and their responsibilities is not possible, because posterior
regions must be important for more than just sentence comprehension, as
patients with lesions in this area can neither comprehend nor produce
any speech. (Barnich, 1997, pp. 283--293)

### Evidence from Advanced Neuroscience Methods

Measuring the functions of both normal and damaged brains has been
possible since the 1970s, when the first brain imaging techniques were
developed. With them, we are able to "watch the brain working" while the
subject is e.g. listening to a joke. These methods (further described in
chapter 4) show whether the earlier findings are correct and precise.

Generally, imaging shows that certain functional brain regions are much
smaller than estimated in brain lesion studies, and that their
boundaries are more distinct (cf. Banich p. 294). The exact location
varies individually, therefore bringing the results of many brain lesion
studies together caused too big estimated functional regions before. For
example, stimulating brain tissue electrically (during epilepsy surgery)
and observing the outcome (e.g. errors in naming tasks) led to a much
better knowledge where language processing areas are located.

PET studies (Fiez & Petersen, 1993, as cited in Banich, p. 295) have
shown that in fact both anterior and posterior regions were activated in
language comprehension and processing, but with different strengths --
in agreement with the lesion studies. The more active speech production
is required in experiments, the more frontal is the main activation: For
example, when the presented words must be repeated.

Another result (Raichle et al. 1994, as referred to in Banich, p. 295)
was that the familiarity of the stimuli plays a big role. When the
subjects were presented well-known stimuli sets in well-known
experimental tasks and had to repeat them, anterior regions were
activated. Those regions were known to cause conduction aphasia when
damaged. But when the words were new ones, and/or the subjects never had
to do a task like this before, the activation was recorded more
posterior. That means, when you repeat an unexpected word, the heaviest
working brain tissue is about somewhere under your upper left earlap,
but when you knew this word that would be the next to repeat before, it
is a bit nearer to your left eye.

## Visual Language Processing

The processing of written language is performed when we are reading or
writing and is thought to happen in a distinct neural processing unit
than auditory language processing. Reading and writing respectively rely
on vision whereas spoken language is first mediated by the auditory
system. Language systems responsible for written language processing
have to interact with a sensory system different from the one involved
in spoken language processing.

Visual language processing in general begins when the visual forms of
letters ("c" or "C" or "c") are mapped onto abstract letter identities.
These are then mapped onto a word form and the corresponding semantic
representation (the "meaning" of the word, i.e. the concept behind it).
Observations of patients that lost a language ability due to a brain
damage led to different disease patterns that indicated a difference
between perception (reading) and production (writing) of visual language
just like it is found in non-visual language processing.

Alexic patients possess the ability to write while not being able to
read whereas patients with agraphia are able to read but cannot write.
Though alexia and agraphia often occur together as a result of damage to
the angular gyrus, there were patients found having alexia without
agraphia (e.g. Greenblatt 1973, as cited in M. T. Banich,
"Neuropsychology", p. 296) or having agraphia without alexia (e.g.
Hécaen & Kremin, 1976, as cited in M. T. Banich, "Neuropsychology",
p. 296). This is a double dissociation that suggests separate neural
control systems for reading and writing.

Since double dissociations are also found in phonological and surface
dyslexia, experimental results support the theory that language
production and perception respectively are subdivided into separate
neural circuits. The two route model shows how these two neural circuits
are believed to provide pathways from written words to thoughts and from
thoughts to written words.

### Two routes model

!1.1. Each route derives the meaning of a word or the word of a meaning
in a different
way{width="395"}In
essence, the two routes model contains two routes. Each of them derives
the meaning of a word or the word of a meaning in a different way,
depending on how familiar we are with the word.

Using the **phonological route** means having an intermediate step
between perceiving and comprehending of written language. This
intermediate step takes places when we are making use of
grapheme-to-phoneme rules. Grapheme-to-phoneme rules are a way of
determining the phonological representation for a given grapheme. A
grapheme is the smallest written unit of a word (e.g. "sh" in "shore")
that represents a phoneme. A phoneme on the other hand is the smallest
phonological unit of a word distinguishing it from another word that
otherwise sounds the same (e.g. "bat" and "cat"). People learning to
read or are encountering new words often use the phonological route to
arrive at a meaning representation. They construct phonemes for each
grapheme and then combine the individual phonemes to a sound pattern
that is associated with a certain meaning (see 1.1).

The **direct route** is supposed to work without an intermediate
phonological representation, so that print is directly associated with
word-meaning. A situation in which the direct route has to be taken is
when reading an irregular word like "colonel". Application of
grapheme-to-phoneme rules would lead to an incorrect phonological
representation.

According to Taft (1982, as referred to in M. T.
Banich,"Neuropsychology", p. 297) and others the direct route is
supposed to be faster than the phonological route since it does not make
use of a "phonological detour" and is therefore said to be used for
known words ( see 1.1). However, this is just one point of view and
others, like Chastain (1987, as referred to in M. T. Banich,
"Neuropsychology", p. 297), postulate a reliance on the phonological
route even in skilled readers.

### The processing of written language in reading

!1.2. Regularity effects are common in cases of surface
alexia{width="353"}Several
kinds of alexia could be differentiated, often depending on whether the
phonological or the direct route was impaired. Patients with brain
lesions participated in experiments where they had to read out words and
non-words as well as irregular words. Reading of non-words for example
requires access to the phonological route since there cannot be a
"stored" meaning or a sound representation for this combination of
letters. Patients with a lesion in temporal structures of the left
hemisphere (the exact location varies) suffer from so called **surface
alexia**. They show the following characteristic symptoms that suggest a
strong reliance on the phonological route: Very common are regularity
effects, that is a mispronunciation of words in which the spelling is
irregular like \"colonel\" or \"yacht\" (see 1.2). These words are
pronounced according to grapheme-to-phoneme rules, although
high-frequency irregularly spelled words may be preserved in some cases,
the pronunciation according to the phonological route is just wrong.

Furthermore, the would-be pronunciation of a word is reflected in
reading-comprehension errors. When asked to describe the meaning of the
word "bear", people suffering from surface alexia would answer something
like "a beverage" because the resulting sound pattern of "bear" was the
same for these people as that for "beer". This characteristic goes along
with a tendency to confuse homophones (words that sound the same but are
spelled differently and have different meanings associated). However,
these people are still able to read non-words with a regular spelling
since they can apply grapheme-to-phoneme rules to them.

!1.3. Patients with phonological alexia have to rely on the direct
route{width="353"}In
contrast, **phonological alexia** is characterised by a disruption in
the phonological route due to lesions in more posterior temporal
structures of the left hemisphere. Patients can read familiar regular
and irregular words by making use of stored information about the
meaning associated with that particular visual form (so there is no
regularity effect like in surface alexia). However, they are unable to
process unknown words or non-words, since they have to rely on the
direct route (see 1.3).

Word class effects and morphological errors are common, too. Nouns, for
example, are read better than function words and sometimes even better
than verbs. Affixes which do not change the grammatical class or meaning
of a word (inflectional affixes) are often substituted (e.g. "farmer"
instead of "farming"). Furthermore, concrete words are read with a lower
error rate than abstract ones like "freedom" (concreteness effect).

**Deep Alexia** shares many symptomatic features with phonological
alexia such as an inability to read out non-words. Just as in
phonological alexia, patients make mistakes on word inflections as well
as function words and show visually based errors on abstract words
("desire" → "desert"). In addition to that, people with deep alexia
misread words as different words with a strongly related meaning
("woods" instead of "forest"), a phenomenon referred to as semantic
paralexia. Coltheart (as referred to in the "Handbook of
Neurolinguistics", ch.41-3, p. 563) postulates that reading in deep
dyslexia is mediated by the right hemisphere. He suggests that when
large lesions affecting language abilities other than reading prevent
access to the left hemisphere, the right-hemispheric language store is
used. Lexical entries stored there are accessed and used as input to
left-hemisphere output systems.

!Overview alexia{width="622"}

### The processing of written language in spelling

!The phonological route is supposed to make use of phoneme-to-grapheme
rules while the direct route links thought to writing without an
intermediary phonetic
representation{width="365"}Just
like in reading, two separate routes --a phonological and a direct
route- are thought to exist. The phonological route is supposed to make
use of phoneme-to-grapheme rules while the direct route links thought to
writing without an intermediary phonetic representation (see 1.4).

It should be noted here that there is a difference between
phoneme-to-grapheme rules (used for spelling) and grapheme-to-phoneme
rules in that one is not simply the reverse of the other. In case of the
grapheme "k" the most common phoneme for it is /k/. The most common
grapheme for the phoneme /k/, however, is "c". Phonological agraphia is
caused by a lesion in the left supramarginal gyrus, which is located in
the parietal lobe above the posterior section of the Sylvian fissure (M.
T. Banich, "Neuropsychology", p. 299). The ability to write regular and
irregular words is preserved while the ability to write non-words is
not. This, together with a poor retrieval of affixes (which are not
stored lexically), indicates an inability to associate spoken words with
their orthographic form via phoneme-to-grapheme rules. Patients rely on
the direct route, which means that they use orthographic word-form
representations that are stored in lexical memory. Lesions at the
conjunction of the posterior parietal lobe and the parieto-occipital
junction cause so called lexical agraphia that is sometimes also
referred to as surface agraphia. As the name already indicates, it
parallels surface alexia in that patients have difficulty to access
lexical-orthographic representations of words. Lexical agraphia is
characterised by a poor spelling of irregular words but good spelling
for regular and non-words. When asked to spell irregular words, patients
often commit regularization errors, so that the word is spelled
phonologically correct (for example, "whisk" would be written as
"wisque"). The BEST to CONNECT is to CAPITALISE the WORDS you WANT TO
COMMUNICATE for readers to COMPREHEND.

!Overview
agraphia{width="581"}

### Evidence from Advanced Neuroscience Methods

How can we find evidence for the theory of the two routes. Until now
neuroscientific research is not able to ascertain that there are neural
circuits representing a system like the one described above. The problem
of finding evidence for visual language processing on two routes in
contrast to one route ( as stated by e.g. from Seidenberg & McClelland
as referred to in M. T. Banich,"Neuropsychology", p. 308) is that it is
not clear what characteristic brain activation would indicate that it is
either happening on two or one routes. To investigate whether there are
one or two systems, neuroimaging studies examine correlations between
the activations of the angular gyrus, which is thought to be a crucial
brain area in written language processing and other brain regions. It
was found out that during reading of non- words ( which would strongly
engage the phonological route) the activation is mostly correlated with
brain regions which are involved in phonological processing e.g.
superior temporal regions (BA 22) and Boca's area. During reading of
normal words (which would strongly engage the direct route) the highest
activation was found in occipital and ventral cortex. That at least can
imply that there are two distinct routes. However, these are conclusions
drawn from highest correlations which do not ensure this suggestion.
What neuroimaging studies do ascertain is that the usage of a
phonological and a direct route strongly overlap, which is rather
unspectacular since it is quiet reasonable that fluent speaker mix both
of the routes. Other studies additionally provide data in which the
activated brain regions during reading of non-words and reading of
normal words differ. ERP studies suggest that the left hemisphere
possesses some sort mechanism which response to combinations of letters
in a string, or to its orthography and / or to the phonological
representation of the string. ERP waves differ, during early analysis of
the visual form of the string, if the string represents a correct word
or just pronounceable nonsense (Posner & McCandliss, 1993 as referred in
M.T. Banich, „Neuropsychology"p. 307-308). That indicates that this
mechanism is sensitive to correct or incorrect words.

The opposite hemisphere, the right hemisphere, is in contrast to the
left hemisphere, not involved in abstract mapping of word meaning but is
rather responsible for encoding word specific visual forms. ERP and PET
studies provides evidence that the right hemisphere responds in a
stronger manner than the left hemisphere to letter like strings.
Moreover divided visual field studies reveal that the right hemisphere
can better distinguish between different shapes of the same letter (e.g.
in different handwritings) than the left hemisphere. The contribution of
visual language processing on both hemispheres is that the right
hemisphere first recognizes a written word as letter sequences, no
matter how exactly they look like, then the language network in the left
hemisphere builds up an abstract representation of the word, which is
the comprehension of the word.

## Other symbolic systems

Most neurolinguistic research is concerned with production and
comprehension of English language, either written or spoken. However,
looking at different language systems from a neuroscientific perspective
can substantiate as well as differentiate acknowledged theories of
language processing. The following section shows how neurological
research of three symbolic systems, each different from English in some
aspect, has made it possible to distinguish - at least to some extent -
between brain regions that deal with the modality of the language (and
therefore may vary from language to language, depending on whether the
language in question is e.g. spoken or signed) from brain regions that
seem to be necessary to language processing in general - regardless
whether we are dealing with signed, spoken, or even musical language.

### Kana and Kanji

Kana and Kanji are the two writing systems used parallel in the Japanese
language. Since different approaches are used in them to represent
words, studying Japanese patients with alexia is a great possibility to
test the hypothesis about the existence of two different routes to
meaning, explicated in the previous section.

The English writing system is phonological -- each grapheme in written
English roughly represents one speech sound -- a consonant or a vowel.
There are, however, other possible approaches to writing down a spoken
language. In syllabic systems like the Japanese kana, one grapheme
stands for one syllable. If written English were syllabic, it could e.g.
include a symbol for the syllable "nut", appearing both in the words
"donut" and "peanut". Syllabic systems are sound-based -- since the
graphemes represent units of spoken words rather than meaning directly,
an auditory representation of the word has to be created in order to
arrive at the meaning. Therefore, reading of syllabic systems should
require an intact phonological route. In addition to kana, Japanese also
use a logographic writing system called kanji, in which one grapheme
represents a whole word or a concept. Different from phonological and
syllabic systems, logographic systems don't comprise systematical
relationships between visual forms and the way they're pronounced --
instead, visual form is directly associated with the pronunciation and
meaning of the corresponding word. Reading kanji should therefore
require the direct route to meaning to be intact.

The hypothesis about the existence of two different routes to meaning
has been confirmed by the fact that after brain damage, there can be a
double dissociation between kana and kanji. Some Japanese patients can
thus read kana but not kanji (surface alexia), whereas other can read
kanji but not kana (phonological alexia). In addition, there is evidence
that different brain regions of Japanese native speakers are active
while reading kana and kanji, although like in the case of English
native speakers, these regions also overlap.

Since the distinction between direct and phonological route also makes
sense in case of Japanese, it may be a general principle common to all
written languages that reading them relies on two independent (at least
partially) systems, both using different strategies to catch the meaning
of a written word -- either associating the visual form directly with
the meaning (the direct route), or using the auditory representation as
an intermediary between the visual form and the meaning of the word (the
phonological route).

```{=html}
<center>
```
  ----------------------------------------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
  !The Japanese Kana sign for the syllable \"mu\"   !The Japanese Kanji sign for the concept \"Book\", \"writing\", or \"calligraphy
  ----------------------------------------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

```{=html}
</center>
```
### Sign Language

From a linguistic perspective, sign languages share many features of
spoken languages -- there are many regionally bounded sign languages,
each with a distinct grammar and lexicon. Since at the same time, sign
languages differ from spoken languages in the way the words are
"uttered", i.e. in the modality, neuroscientific research in them can
yield valuable insights into the question whether there are general
neural mechanisms dealing with language, regardless of its modality.

**Structure of SL**

Sign languages are phonological languages - every meaningful sign
consists of several phonemes (phonemes used to be called cheremes (Greek
χερι: hand) until their cognitive equivalence to phonemes in spoken
languages was realized) that carry no meaning as such, but are
nevertheless important to distinguish the meaning of the sign. One
distinctive feature of SL phonemes is the place of articulation -- one
hand shape can have different meanings depending on whether it's
produced at the eye-, nose-, or chin-level. Other features determining
the meaning of a sign are hand shape, palm orientation, movement, and
non-manual markers (e.g. facial expressions).

To express syntactic relationships, Sign Languages exploit the
advantages of the visuo-spatial medium in which the signs are produced
-- the syntactic structure of sign languages therefore often differs
from that of spoken languages. Two important features of most sign
language\'s grammars (including American Sign Language (ASL), Deutsche
Gebärdensprache (DGS) and several other major sign languages) are
directionality and simultaneous encoding of elements of information:

-   Directionality

The direction in which the sign is made often determines the subject and
the object of a sentence. Nouns in SL can be \'linked\' to a particular
point in space, and later in the discourse they can be referred to by
pointing to that same spot again (this is functionally related to
pronouns in English). The object and the subject can then be switched by
changing the direction in which the sign for a transitive verb is made.

-   Simultaneous encoding of elements of information

The visual medium also makes it possible to encode several pieces of
information simultaneously. Consider e.g. the sentence \"The flight was
long and I didn\'t enjoy it\". In English, the information about the
duration and unpleasantness of the flight have to be encoded
sequentially by adding more words to the sentence. To enrich the
utterance \"The flight was long" with the information about the
unpleasantness of the flight, another sentence ("I did not enjoy it\")
has to be added to the original one. So, in order to convey more
information, the length of the original sentence must grow. In sign
language, however, the increase of information in an utterance doesn't
necessarily increase the length of the utterance. To convey information
about the unpleasantness of a long flight experienced in the past, one
can just use the single sign for \"flight\" with the past tense marker,
moved in a way that represents the attribute \"long\", combined with the
facial expression of disaffection. Since all these features are signed
simultaneously, no additional time is needed to utter \"The flight was
long\" as compared to \"The flight was long and I didn\'t enjoy it\".

**Neurology of SL**

Since sentences in SL are encoded visually, and since its grammar is
often based on visual rather than sequential relationships among
different signs, it could be suggested that the processing of SL mainly
depends on the right hemisphere, which is mainly concerned with the
performance on visual and spatial tasks. However, there is evidence
suggesting that processing of SL and spoken language might be equally
dependant on the left hemisphere, i.e. that the same basic neural
mechanism may be responsible for all language functioning, regardless of
its modality (i.e. whether the language is spoken or signed).

The importance of the left hemisphere in SL processing indicated e.g. by
the fact that signers with a damaged right hemisphere may not be
aphasiacs, whereas as in case of hearing subjects, lesions in the left
hemisphere of signers can result in subtle linguistic difficulties
(Gordon, 2003). Furthermore, studies of aphasic native signers have
shown that damage to anterior portions of the left hemisphere (Broca's
area) result in a syndrome similar to Broca's aphasia -- the patients
lose fluency of communication, they aren't able to correctly use
syntactic markers and inflect verbs, although the words they sign are
semantically appropriate. In contrast, patients with damages to
posterior portions of the superior temporal gyrus (Wernicke's area) can
still properly inflect verbs, set up and retrieve nouns from a discourse
locus, but the sequences they sign have no meaning (Poizner, Klima &
Bellugi, 1987). So, like in the case of spoken languages, anterior and
posterior portions of the left hemisphere seem to be responsible for the
syntax and semantics of the language respectively. Hence, it's not
essential for the \"syntax processing mechanisms\" of the brain whether
the syntax is conveyed simultaneously through spatial markers or
successively through word order and morphemes added to words - the same
underlying mechanisms might be responsible for syntax in both cases.

Further evidence for the same underlying mechanisms for spoken and
signed languages comes from studies in which fMRI has been used to
compare the language processing of:

-   1\. congenitally deaf native signers of British Sign Language,
-   2\. hearing native signers of BSL (usually hearing children of deaf
    parents)
-   3\. hearing signers who have learned BSL after puberty
-   4\. non-signing subjects

Investigating language processing in these different groups allows
making some distinctions between different factors influencing language
organization in the brain - e.g. to what amount does deafness influences
the organization of language in the brain as compared to just having SL
as a first language(1 vs. 2), or to what amount does learning of SL as a
first language differ from learning SL as native language(1,2 vs.3), or
to what amount is language organized in speakers as compared to
signers(1,2,3 vs.4).

These studies have shown that typical areas in the left hemisphere are
activated in both native English speakers given written stimuli and
native signers given signs as stimuli. Moreover, there are also areas
that are equally activated both in case of deaf subjects processing sign
language and hearing subjects processing spoken language -- a finding
which suggests that these areas constitute the core language system
regardless of the language modality(Gordon, 2003).

Different from speakers, however, signers also show a strong activation
of the right hemisphere. This is partly due to the necessity to process
visuo-spatial information. Some of those areas, however (e.g. the
angular gyrus) are only activated in native signers and not in hearing
subjects that learned SL after puberty. This suggests that the way of
learning sign languages (and languages in general) changes with time:
Late learner\'s brains are unable to recruit certain brain regions
specialized for processing this language (Newman et al., 1998).\]

We have seen that evidence from aphasias as well as from neuroimaging
suggest the same underlying neural mechanisms to be responsible for sign
and spoken languages. It 's natural to ask whether these neural
mechanisms are even more general, i.e. whether they are able to process
any type of symbolic system underlying some syntax and semantics. One
example of this kind of more general symbolic system is music.

### Music

Like language, music is a human universal involving some combinatorial
principles that govern the organizing of discrete elements (tones) into
structures (phrases) that convey some meaning -- music is a symbolic
system with a special kind of syntax and semantics. It's therefore
interesting to ask whether music and natural language share some neural
mechanisms: whether processing of music is dependent on processing of
language or the other way round, or whether the underlying mechanisms
underlying them are completely separate. By investigating the neural
mechanisms underlying music we might find out whether the neural
processes behind language are unique to the domain of natural language,
i.e. whether language is modular. Up to now, research in the
neurobiology of music has yielded contradicting evidence regarding these
questions.

On the one hand, there is evidence that there is a double dissociation
of language and music abilities. People suffering from amusia are unable
to perceive harmony, to remember and to recognize even very simple
melodies; at the same time they have no problems in comprehending or
producing speech. There is even a case of a patient who developed amusia
without aprosodia, i.e. although she couldn\'t recognize tone in musical
sequences, she nevertheless could still make use of pitch, loudness,
rate, or rhythm to convey meanings in spoken language (Pearce, 2005).
This highly selective problem in processing music (amusia) can occur as
a result of brain damage, or be inborn; in some cases it runs on
families, suggesting a genetic component. The complement syndrome of
amusia also exists -- after suffering a brain damage in the left
hemisphere, the Russian composer Shebalin lost his speech functions, but
his musical abilities remained intact (Zatorre, McGill, 2005).

On the other hand, neuroimaging data suggest that language and music
have a common mechanism for processing syntactical structures. The P600
ERP\`s in the Broca area, measured as a response to ungrammatical
sentences, is also elicited in subjects listening to musical chord
sequences lacking harmony (Patel, 2003) -- the expectation of typical
sequences in music could therefore be mediated by the same neural
mechanisms as the expectation of grammatical sequences in language.

A possible solution to this apparent contradiction is the dual system
approach (Patel, 2003) according to which music and language share some
procedural mechanisms (frontal brain areas) responsible for processing
the general aspects of syntax, but in both cases these mechanisms
operate on different representations (posterior brain areas) -- notes in
case of music and words in case of language.

## Outlook

Many questions are to be answered, for it is e.g. still unclear whether
there is a distinct language module (that you could cut out without
causing anything in other brain functions) or not. As Evely C. Ferstl
points out in her review, the next step after exploring distinct small
regions responsible for subtasks of language processing will be to find
out how they work together and build up the language network.

## References & Further Reading

`        `

*Books - english*

-   Brigitte Stemmer, Harry A. Whitaker. Handbook of Neurolinguistics.
    Academic Press (1998). 
-   Marie T. Banich: Neuropsychology. The neural bases of mental
    function (1997).
-   Ewa Dąbrowska: Language, Mind and Brain. Edinburgh University press
    Ltd.(2004)
-   *a review:* Evelyn C. Ferstl, The functional neuroanatomy of text
    comprehension. What\'s the story so far?\" from: Schmalhofer, F. &
    Perfetti, C. A. (Eds.), Higher Level Language Processes in the
    Brain:Inference and Comprehension Processes. Lawrence Erlbaum.
    (2004)

*Books - german*

-   Müller,H.M.& Rickert,G. (Hrsg.): Neurokognition der Sprache.
    Stauffenberg Verlag (2003)
-   Poizner, Klima & Bellugi: What the hands reveal about the brain. MIT
    Press (1987)
-   N. Chomsky: Aspects of the Theory of Syntax. MIT Press (1965).
    
-   Neville & Bavelier: Variability in the effects of experience on the
    development of cerebral specializations: Insights from the study of
    deaf individuals. Washington, D.C.: US Government Printing Office
    (1998)
-   Newman et al.: Effects of Age of Acquisition on Cortical
    Organization for American Sign Language: an fMRI Study. NeuroImage,
    7(4), part 2 (1998)

*Links - english*

-   Robert A. Mason and Marcel Adam Just: How the Brain Processes
    Causal Inferences in
    Text
-   Neal J. Pearlmutter and Aurora Alma Mendelsohn: Serial versus
    Parallel Sentence
    Comprehension
-   Brain Processes of Relating a Statement to a Previously Read Text:
    Memory Resonance and Situational
    Constructions
-   Clahsen, Harald: Lexical Entries and Rules of Language: A
    Multidisciplinary Study of German
    Inflection.
-   Cherney, Leora (2001): Right Hemisphere Brain
    Damage
-   Grodzinsky, Yosef (2000): The neurology of syntax: Language use
    without Broca\'s
    area.
-   Müller, H.M. & Kutas, M. (1996). What\'s in a name?
    Electrophysiological differences between spoken nouns, proper names
    and one\'s own
    name.
    NeuroReport 8:221-225.
-   Müller, H. M., King, J. W. & Kutas, M. (1997). Event-related
    potentials elicited by spoken relative
    clauses
    Cognitive Brain Research 4:193-203.

*Links - german*

-   University of Bielefeld:
    -   Müller, H. M., Weiss, S. & Rickheit, G. (1997). Experimentelle
        Neurolinguistik: Der Zusammenhang von Sprache und
        Gehirn
        In: Bielefelder Linguistik (Hrsg.) Aisthesis-Verlag,
        pp. 125--128.
    -   Müller, H.M. & Kutas, M. (1997). Die Verarbeitung von
        Eigennamen und Gattungsbezeichnungen: Eine elektrophysiologische
        Studie.
        In: G. Rickheit (Hrsg.). Studien zur Klinischen Linguistik -
        Methoden, Modelle, Intervention. Opladen: Westdeutscher Verlag,
        pp. 147--169.
    -   Müller, H.M., King, J.W. & Kutas, M. (1998).
        Elektrophysiologische Analyse der Verarbeitung
        natürlichsprachlicher Sätze mit unterschiedlicher Belastung des
        Arbeitsgedächtnisses.
        Klinische Neurophysiologie 29: 321-330.

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-   Michael Schecker (1998): Neuronale \"Kodierung\" zentraler
    Sprachverarbeitungsprozesse
    \--\> Debates (only a criticism)

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