Effects of early monocular lid suture on spatial and temporal sensitivity of neurons in dorsal lateral geniculate nucleus of the cat.

1. We measured spatial and temporal contrast thresholds for 70 Xand 40 Y-cells in the lateral geniculate nucleus of cats raised with monocular eyelid closure. Of these cells, 52 X-cells and 30 Y-cells were located in the deprived laminae (i.e., the laminae of the lateral geniculate receiving input from the previously lid-sutured eye). The stimulus display employed to measure contrast thresholds was a vertically oriented counter-phased sine-wave grating (see Ref. 21). 2. The spatial contrast sensitivity functions were measured at a temporal frequency of 2 cycles/s. These functions for deprived X-cells revealed a sensitivity loss to higher spatial frequencies. At lower spatial frequencies, these deprived X-cells exhibited normal sensitivity. The spatial resolution of deprived X-cells, which was the highest spatial frequency to which a cell responded at 0.6 contrast, was approximately one-half of that measured for nondeprived X-cells at all retinal eccentricities; this included cells located in the monocular segment. The few deprived Y-cells that were studied in the binocular segment and all in the monocular segment exhibited normal spatial sensitivity. 3. The temporal contrast sensitivity functions were measured with the spatial frequency at which each cell exhibited the lowest contrast threshold. The temporal contrast sensitivity functions for deprived X-cells revealed no effects of deprivation. Consequently, temporal resolution, which was the highest temporal frequency to which the cell responded at 0.6 contrast, was roughly equivalent for deprived and nondeprived X-cells at all retinal eccentricities. The few temporal functions measured for deprived Y-cells were also within the range observed for nondeprived Y-cells. 4. Receptive-field center sizes for deprived X-cells were not different from those of nondeprived X-cells. This was true for estimates of center size based on hand plotting, as well as those based on area-response functions. The area-response functions indicated that the major receptive field property of X-cells that was altered by lid-suture deprivation was the sensitivity of the center to small stimuli. 5. We conclude in monocularly sutured cats that the development of Y-cells is primarily governed by binocular competition, whereas the development of X-cells is mainly influenced by a mechanism that does not involve binocular competition.