Cortical recovery from effects of monocular deprivation: acceleration with norepinephrine and suppression with 6-hydroxydopamine.

Abstract

The effects of continuous microperfusion of the visual cortex with either norepinephrine (NE) or 6-hydroxydopamine (6-OHDA) were studied in young kittens that were monocularly deprived first at 4 wk of age for a week and then allowed to use both eyes for various times (1-30 days) after reopening of the closed eyelid. The time course of recovery of the normal ocular dominance distribution in these 2 experimental conditions was compared with that of control kittens that had similar visual experience. The recovery of binocular cortical cells from the effects of the brief monocular deprivation was acclerated by concomitant, continuous perfusion of NE, and largely delayed in the visual cortex that had been depleted of its catecholamine terminals by perfusion of 6-OHDA. There was a correlation between an increase in synaptic plasticity and loss of binocularity in NE-perfused and monocularly deprived visual cortex that was pretreated with 6-OHDA. Independent of whether the synaptic change involves an increase or a decrease in binocularity, local availability of NE appears to enhance the process of synaptic modification that follows altered patterns of activity in kitten visual cortex.