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.
Brain only fully 'matures' in middle age, claims neuroscientist. You might think that you become fully matur when you turn 21 but new research suggests that your brain does not stop developing until your late 40s. Scientists used to believe that your brain stopped physically evolving in early childhood but new research has shown that keeps changing well into middle age. Brain scans have shown that prefrontal cortex â the area just behind your forehead â continues to change shape in your 30s and 40s.