The brain as a dependent variable.

The mainstream of neuropsychological research and practice has been devoted to the impact of the brain as an independent variable on behavior as a dependent variable. Evidence is currently available to make clear that the order of causation may be reversed: Behavioral changes can have a durable impact on the brain. The results of extensive research indicate that a large number of neuroanatomical, neurophysiological, neurochemical, and neuropsychological parameters of the animal brain can be modified through environmental manipulation, sensory experience, and systematic training. Some evidence is available to show that psychological stimulation has certain effects on the physiology of the human brain. For instance, hemisphere-specific stimulation through the presentation of words flashed in a visual hemifield appears to modify the electrophysiological activity of the contralateral hemisphere in dyslexic children and to affect their subsequent reading performance. Neuropsychology may profit from paying more attention to the ecology of the human brain.