Effects of short-term IOP elevation on receptive field properties of cat LGN cells

To investigate the effects of short-term intra- ocular pressure (IOP) elevation on the receptive field proper- ties of lateral geniculate nucleus (LGN) cells, responses of the LGN cells to annulus, disc and drifting gratings with high or low spatial frequencies have been recorded extracellularly in the cat with the retinal perfusion pressure kept stable (30 mmHg). Our results indicated that the responses of the X and Y type LGN cells were significantly weakened during IOP elevation. And the responses varied with the different mechanisms of receptive fields. Specifically, while using an- nulus and disc as stimuli, the responses of Y cells were more tolerant than X cells to IOP elevation. The surround area of the receptive field was more sensitive to IOP elevation than the center. The mean responses during IOP elevation de- creased more than the peak responses did. IOP elevation has more influence on the responses of X cells than on the re- sponse of Y cells to the drifting gratings with high spatial frequency. These results may reflect different degrees of ischemia on corresponding retinal structures caused by IOP elevation.