ABSTRACT
The brain has developed over a period of millions of years, with the first primate brain appearing some 20 million years ago. As with any other part of the body, the brain may develop abnormally in a small minority of individuals, even to the extent of lacking one of the hemispheres. Connected to the brain stem is the cerebellum, or little brain, which handles signals between the main part of the brain and the various parts of the body to control posture, walking, and coordinated movements. Above the brain stem and cerebellum, the brain divides into the two cerebral hemispheres. As scientists continue to investigate the workings of the brain there is constant tension between two factors: increased accuracy in pinpointing brain processes and the inherent flexibility of the brain. Improvements in brain imaging enable us to pinpoint with increasing accuracy areas of the brain performing particular tasks.
