EVIDENCE FOR GREATER SIGHT IN BLINDSIGHT FOLLOWING DAMAGE OF PRIMARY VISUAL-CORTEX EARLY IN LIFE

This review compares the behavioral, physiological and anatomical repe rcussions of lesions of primary visual cortex incurred by developing a nd mature humans, monkey and cats. Comparison of the data on the reper cussions following lesions incurred earlier or later in life suggests that earlier, but not later, damage unmasks a latent flexibility of th e brain to compensate partially for functions normally attributed to t he damaged cortex. The compensations are best documented in the cat an d they can be linked to system-wide repercussions that include selecte d pathway expansions and neuron degenerations, and functional adjustme nts in neuronal activity. Even though evidence from humans and monkeys is extremely limited, it is argued on the basis of known repercussion s and similarity of visual system organization and developmental seque nce, that broadly equivalent repercussions most likely occur in humans and monkeys following early lesions of primary visual cortex. The ext ant data suggest potentially useful directions for future investigatio ns on functional anatomical aspects of visual capacities spared in hum an patients and monkeys following early damage of primary visual corte x. Such research is likely to have a substantial impact on increasing our understanding of the repercussions that result from damage elsewhe re in the developing cerebral cortex and it is likely to contribute to our understanding of the remarkable ability of the human brain to ada pt to insults. Copyright (C) 1996 Elsevier Science Ltd.