Where is language located in the brain? There are two sides to this story

Simple facts about the brain are rare, but one of them is that for most people language function is located mainly in their left brain hemisphere. The stats vary according to the measures used, but this is the situation for around 95 per cent of right-handers and approximately 75 per cent of left-handers. When it comes to the brain though, few things are straight-forward.If we dig deeper, as Byron Bernal and Alfredo Ardila have done for a new review paper, we find a more complex, two-sided story. The extent to which language is dominated by the left hemisphere is not fixed. It increases through childhood and adolescence, and then this trend reverses in old age, with signs of greater sharing of language function across the brain hemispheres in later life. Moreover, by characterising people in binary fashion as having their language abilities housed either in their left or right hemisphere, we ignore those people for whom language is a genuinely "bilateral function," meaning that both brain hemispheres are substantially involved.As Bernal and Ardila point out, a dramatic demonstration of this comes from the Wada test, named after  Japanese neurologist Juhn Atsushi Wada. With the patient awake, anaesthetic is injected into the neck or head on one side to effectively shut down function in that side of the brain. Speech and language comprehension tests are conducted first with one hemisphere silenced, then the other. Looking at the results from 1,799 Wada tests, most of which...
Source: BPS RESEARCH DIGEST - Category: Psychiatrists and Psychologists Authors: Source Type: blogs