Visually evoked potentials from occipital and precentral cortex in visually deprived humans.

The visually evoked potential (VEP) was recorded from the scalp overlying precentral and occipital cortex in three monocularly deprived humans. The subjects had defects of the globe from birth that effectively created a condition of diffuse light rearing in one eye. In subject, BER, a 19-year-old with a recently removed congenital cataract, the occipital response evoked from the deprived eye was reduced by 53% compared with the response evoked from the good eye. In subject GUZ, age 20 with a congenital cataract, the occipital response evoked from the deprived eye was actually larger by 20% than was the response evoked from the good eye. For UTZ, age 5 with whitish cellular debri in the anterior vitreous of the eye, the occipital response evoked from the deprived eye was only 4% smaller than the response evoked from his good eye. In all three subjects, the precentral response evoked from the deprived eye was reduced in amplitude compared with the precentral response evoked from the good eye. In terms of relative effect of the deprivation upon the VEP from the two recording sites, the precentral VEP was altered to a greater extent than was the occipital VEP. These findings indicate that diffuse light rearing can affect the pathways projecting to precentral cortex independently of the specific visual pathways.