Effects of monocular deprivation on the structure-function relationship of individual neurons in the cat's lateral geniculate nucleus

The retino-geniculo-cortical pathways of the cat composed of at least three parallel channels. The neurons in these channels (W-, X-, and Y- cells) have different physiological properties. In earlier studies, we used a direct structure-function for analysis for individual geniculate neurons in normal cats. This was accomplished by electrophysiological characterization of the neuron followed by intracellular iontophoresis of horseradish peroxidase into the same neuron. By this technique, we demonstrated that W-, X-, and Y-cells have distinctive morphological features in the lateral geniculate nucleus of the act. We have extended this analysis in cats reared with monocular eyelid suture to 24 geniculate neurons innervated by the sutured eye in lamina A or A1. Ten of the 24 neurons (42%) had abnormal structure-function relationships. All but 1 of the normal cells were X-cells. Abnormalities included: (1) Y-cells with normal physiology but abnormally small somata; (2) Y-cells with abnormal physiology and morphology, including poor responsiveness and unusually thin, tortuous, and beaded dendrites; (3) visually unresponsive cells with morphology similar to that of the physiologically abnormal Y-cells; and (4) cells with the physiology of normal X-cells but the morphology of normal Y-cells. Furthermore, soma size measurements indicate that the abnormally small somata found in deprived geniculate laminae result from a selective effect on Y-cells.