Bicuculline reversal of deprivation amblyopia in the cat.

Abstract

CATS deprived of visual experience in one eye during a critical period of early life develop marked changes in the functional organisation of their visual system1–3. Useful vision seems to be lost in the deprived eye, and neurophysiological studies reveal a loss of binocular input to neurones in the visual cortex. Most neurones fail to respond to stimuli presented to the deprived eye; whereas almost all respond to stimulation of the normal eye. In normal neonatal kittens without visual experience, most cortical neurones respond to stimulation of either eye. Moreover, this binocular neuronal input persists when subsequent visual experience is prevented by binocular lid suture. Thus, asymmetrical visual experience seems necessary to produce a loss of binocular input. This loss of functional input from the deprived eye could result from a loss of the normal excitatory synaptic connections or from inhibitory suppression of afferent input. We postulate that asymmetrical visual experience causes synaptic inhibition of input from the deprived eye and that reduction of such inhibition might restore binocularity.