Purpose: Primates frequently make saccadic eye movements to receive acute visual information, which causes blur and displacement of visual inputs on retina. However, despite the instable visual inputs our visual perception remains stable. One possible neural mechanism underlying the visual stabilization is so called perisaccadic receptive field (RF) remapping, i.e., around the time of saccade, visual neurons in many cortical areas become sensitive to spatial locations that will be covered by the neurons’ classical retinotopic RF after a saccade. This theory, however, is charged recently by findings that, just before saccade, neurons' RF in monkey’s frontal eye field converged to the location of saccadic target instead of future RF. To understand neural mechanisms of visual stability further, we systematically studied the dynamic change of visual RF in macaque posterior parietal cortex.
Methods: We recorded extracellular activity of single neurons while monkeys were performing a visually-guided delay saccade task, and mapped neuron’s visual RF at four periods ( fixation, delay, just before saccade and long after saccade) to get current RF, delay RF, perisaccadic RF and future RF. Then, we compared the spatial properties of them to analyze the dynamic change of a neuron’s visual RF.
Results: We recorded 119 visual neurons in total from the posterior parietal cortex of two monkeys. Among them, some (41/119) show constant retinotopic RF throughout the four task epochs, but another show significant change of receptive field just before saccade (37/119) or during delay period (19/119). Remarkably, the change of receptive field for most neurons tend toward the location of the future rather than saccadic target.
Conclusion: These results indicate that, inconsistent with frontal eye field, posterior parietal cortex integrates pre and post saccadic visual information through a mechanism of receptive field remapping rather than receptive field convergence.