Some effects of chronic monocular paralysis in adult cats rapidly reversed by paralyzing the second eye

Disruptions in binocular stimulation induced by two or more weeks of monocular paralysis (ChMP), reduce the encounter rates for Xrelative to Y-type LGN cells (a reduction in the X/Y ratio) during semichronic recordings from adult cats. Less than four days of monocular paralysis (AcMP) has no impact upon the X/Y ratio. The processes underlying ChMP'.s impact upon the X/Y ratio are not passive or degenerative, and are therefore active processes such as 1) excitability changes in X-cells, in Y-cells, or in both cell types; or 2) change in the functional characteristics of X-cells such that they are systematically reclassified as Y-cells. These alternatives were explored using standard extracellular unit recording procedures, including classification of cells as X- or Y-type with a common battery of receptive field and physiological measures. Preliminary experiments indicated that nitrous oxide anesthesia reverses the impact of ChMP, rendering the X/Y ratio of ChMP equivalent to that of AcMP (which is unaffected by anesthesia), and that this effect is so robust that it is evident in single electrode penetrations