Brain Lateralization

The human brain is divided into two hemispheres: the left and the right.  Each of these hemispheres specializes in specific functional capability.  For example, the textbook outlines the well-known research of Paul Broca and his findings on Broca's area in the left temporal lobe as the site of articulate speech.  Without this contribution to science, we might have been far behind in our understanding of the functional lateralization of the human brain.

It was interesting to learn about Dr. Jill Taylor's experience on the stroke that occurred in the left hemisphere of her brain.  Many of her descriptions resembled the descriptions of people under the influence of psychotropic drugs, and I found this odd.  There is a rather disappointingly small body of research on the effects of psychotropic drugs on speech, and because of this I can't make a scientific statement on this subject, but what I can say is that there may be a relationship between psychotropic drugs and speech.  What that relationship is, I'm not sure, but many people who have used psychotropics report similar experiences to Dr. Taylor's experience, and I find this fascinating.  There definitely needs to be more research that uses neuroimaging techniques to study the effects of psychotropics on different brain sites.

It's also important to consider the evolutionary pathways that have led to the lateralization of the human brain.  There are many other species that demonstrate brain lateralization as well, and understanding the function of brain lateralization in less complex organisms may give rise to a greater insight in our understanding of functional lateralization in our own brains.  This review over several research articles is highly informative on numerous pieces of evidence that support the hypothesis that brain lateralization and asymmetry has evolved across many terrestrial and marine species.