Bilingual Brain

There has been studies on how language is organized in the “bilingual brain” and how this organization differs from that of the monolingual.  Language processing usually occurs mainly in the left hemisphere of the brain or in both hemispheres. Based on some early case studies and experiments of bilingual some researchers believed that bilinguals use the right hemisphere in language processing more than monolinguals. However, more recent and better controlled studies found clear evidence that monolinguals and bilinguals do not differ at all in hemispheric involvement during language processing. (Zatorre, 1989)

From most experiments, researchers believe that the bilingual languages are not stored in completely different locations. Monolingual and bilingual use similar neural region for language processing. In addition, there are research that found that bilinguals have two subsets of neural connections, one for each language . Each can be activated or inhibited independently. (Paradis, 1989).

The brain consist of white matter and grey matter. Grey matter is the major component of the brain that consist of cell bodies, dendrites and synapses.  The gray matter is mostly found on the surface around the brain but also inside such as the thalamus, hypothalamus and cerebrum. The white matter consist of glial cells and myelinated axon and it mainly serves as transmitting nerve signals.  White matter serves like a supporting role for the grey matter of the brain.  A recent study found that earlier bilingual speaker had a higher density of grey matter in the left inferior parietal cortex than monolingual speakers (Mechelli et al., 2004) The left inferior parietal cortex is concerned with language and mathematical operations.

This video explains how an experiment found a switch in the brain for changing between two languages.  There was a increase in activity in the left caudate which is a specific region in the brain when speakers shifted from one language to the other.  This would explain why bilinguals with damaged left caudates involuntarily switch languages when speaking.

There is still many unknown about the bilingual brain and many future research are still required.