Effects of Ethanol on Visual Unit Activity in the Thalamus,

The investigator studied the effects of ethanol on the spontaneous activity of single neurons in functionally differentiated subnuclei of a posterior thalamic visual projection area, nucleus rotundus, in the anesthetized pigeon. Low doses of ethanol, 0.05 - 0.10 mlkg producing blood levels of about 0.005 - 0.010 , inhibited activity in anterior rotundus but had complex excitatory-inhibitory effects on posterior rotundal cells. Nonvisual dorsal thalamic cells, and lateral geniculate neurons were inhibited by ethanol but threshold doses 0.25 - 0.40 mlkg were far higher than those for the rotundal cells 0.05 mlkg. These differing dose-response curves for visual and nonvisual thalamic neurons suggest 1 low doses of ethanol may seriously impair peripheral visual functions 2 The behavioral effects of ethanol are highly dose-dependent 3 Effects of low doses of ethanol may not be extrapolated from high-dose effects since high-dose effects may mask effects dominant at low doses 4 The effects of a given dose of ethanol may vary widely and unpredictably among individuals. Thus, the notorious unpredictability of ethanol-induced changes in behavior or task performance may be the inevitable consequence of the reported differential dose-response effects on single neurons.