We have reared neonatal monkeys under many different visual conditions and tested their VEP asymmetry to determine what conditions lead to abnormalities. Our emphasis has been on binocularity and its influence on the asymmetry. As one aspect of this search, it has been found that normal neonates, and many adults after abnormal visual development, have directional preferences for visual stimulus motions; i.e., they give better responses for optokinetic nystagmus (OKN) and visually evoked potentials (VEP) in one direction when compared with the opposite direction. We tested whether the asymmetrical VEP responses were because of abnormal eye movements. Our results show that the neonate and abnormally reared monkeys continued to have asymmetrical responses even after their eyes were paralyzed. Therefore, eye movements cannot be the source of the asymmetrical amplitudes of the VEPs, and the visual cortex is at least one possible source controlling asymmetries observed in neona tes and adults reared under abnormal visual inputs.
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