ABSTRACT
The left and right hemispheres not only have a physiological equivalency, but a functional one as wellin the early years of life. This equivalency in cognitive functions, referred to as equipotentiality, Allows either hemisphere to assumethe skills associated with the other, upon injury to one cortical side. Lenneberg, Krashen also postulated that the hemispheres shared equipotentiality in functions starting at the organism's birth. Many reviews have indicated that the incidence of aphasia after damage to the right hemisphere in infancy is significantly higher than after similar damage to the same side in later years. Other clinical studies have focused on the effects obtained by more extensive types of brain damage. These operations, referred to as hemispherectomies, involve removal of the entire cortex of the brain. Some initial observations in favor of this lateralization by age zero approach, a label coined by Krashen, have dealt with the behavioral measures of head turning and the onset of handedness in infancy.
