Visual Sensitivity of Frontal Eye Field Neurons During the Preparation of Saccadic Eye Movements
56.501, Tuesday, May 14, 2:45 - 6:45 pm, Vista Ballroom
Rebecca Krock1, Tirin Moore1,2; 1Department of Neurobiology, Stanford University School of Medicine, 2Howard Hughes Medical Institute, Stanford University School of Medicine
Saccadic suppression is a well-characterized psychophysical phenomenon in which visual sensitivity decreases profoundly just before and during saccades. It could play a role in minimizing the perception of self-generated motion signals. The visual responses of neurons before and during saccades have been investigated at numerous stages of the primate visual system, but the relationship between saccadic modulations of visual responses and suppression of psychophysical contrast sensitivity remains unclear. Furthermore, no evidence of a correlate has been observed in the frontal eye field (FEF), which in addition to representing visual information also plays a role in generating saccadic eye movements. To obtain a more direct comparison with psychophysical measurements of saccadic suppression and determine whether a correlate is present in the FEF, we measured not just visual responses but also the contrast sensitivity of neurons in the FEF during the preparation of saccades. We functionally characterized neurons as having visual, visuomovement, or movement activity using a memory-guided saccade task. For cells with visual or visuomovement activity, we recorded responses to brief visual probes (8 ms, full-field, 0.1 cycles/degree sinusoidal gratings ranging from 2% to 32% Michelson contrast). To quantify suppression, we compared the contrast sensitivities measured from contrast-response functions for probes presented long (>100ms) and immediately (<100ms) before saccades. Our results suggest a means by which the representation of visual stimuli in the FEF might account in part for the changes in visual sensitivity that precede saccades.