By some reports, the word samurai first appeared in the 12th century. For a long time, the samurai provided the main military force used against emishi and other clans. In the 1100s, two powerful clans served the emperor of Japan: the Taira clan, and the Minamoto clan. These two families became bitter rivals, and in 1192, Minamoto Yoritomo led his clan to victory over the Taira.
EEG measures brain activity and must demonstrate regular wave patterns to be considered valid. Therefore, by this rule the onset of life would be the time when fetal brain activity begins to exhibit regular wave patterns, which occurs fairly consistently around week 25. Previous to that time, the EEG only shows small bursts of activity without sustained firing of neurons.
According to experts, thereâs a lot you can do to boost babyâs brainpower even before birth. The human brain begins developing between the first and second week of fetal development. Exercising throughout your pregnancy is a good idea, but avoid overheating â especially during the first trimester. Relax. 2  While low levels of stress during pregnancy are nothing to worry about, numerous studies have shown high levels (particularly in cases of mental or physical abuse) can have serious, long-lasting effects on the babyâs brain development.