Pharmacological and morphological differences between X- and Y-type ganglion cells in the cat's retina

Pharmacological and morphological differences between X- and Y-cells of the cat's retina were studied using extracellular as well as intracellular recordings of the ganglion cells in the perfused eye-cup preparations. First, the effects of strychnine and bicuculline on the center and the surround responses were investigated. Strychnine blocked the surround inhibition of on-center X-cells, whereas bicuculline blocked that of on-center Y-cells, suggesting that these two-types of cells have different inhibitory interneurons which employ different neurotransmitters. In contrast, the center and the surround responses of off-center cells were reduced by bicuculline, leaving brief transient excitations, irrespective of whether the cells were X- or Y-type. Second, cells whose responses were studied intracellularly and classified as X- or Y-type, were stained with Lucifer yellow CH and observed in whole-mount preparations. It was found that X-cells have morphological characteristics of beta-cells, and Y-cells those of alpha-cells.