Title: "Form Perception during Natural Vision: Salience Maps in V4"

Jamie Mazer

University of California, Berkeley

Abstract:

Natural exploration of complex visual scenes depends on saccadic eye movements that direct the fovea toward key points in each scene. Saccade targeting is thought to be mediated by a retinotopic map (a salience map) that encodes the locations of visually salient or behaviorally relevant features in the visual scene. It is likely that fine spatial resolution is required to compute salience effectively during natural vision. Such information is processed primarily in the ventral form processing pathway. I will present data demonstrating that an extrastriate ventral stream area, V4, provides visual input for salience computation during free viewing visual search based on single neuron recordings from V4 during performance of an attentionally demanding, free viewing search task that requires both accurate oculomotor planning and fine visual discrimination. In more than half of recorded cells, visually driven activity was enhanced prior to saccades that moved the fovea toward the location previously occupied by a neuron's spatial receptive field. In addition, I will present evidence of attentionally-driven changes in spatiotemporal tuning contingent on search target identity. These results suggest that area V4 provides key visual input to a network of brain areas that cooperate to compute salience and direct eye movements during natural vision.