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Abstract:
The responses of cells in the temporal lobe to faces and objects has been the topic of extensive research; however, the eye movement constraints during these experiments varies considerably. Some require central eye fixation during image presentation, whereas others allow unconstrained viewing of stimuli. Here, we explore the influence of saccadic eye movements on neural responses in the temporal lobe. Awake macaques were presented with a set of objects or faces while we recorded simultaneously from neurons in the upper-bank of the superior temporal sulcus (STS) and in the auditory cortex. Responses during three categories of saccades were evaluated: 1) those occurring prior to fixation onset (spontaneous saccades), 2) those made at the time of central cue fixation (visually-guided saccades) and 3) saccades made during scanning of an image (image-guided saccades). Saccade modulation was observed for all categories of saccades, though not always in the same cells, and irrespective of a cell’s image selectivity. Single unit responses typically occurred during negative components of the local field potential (LFP). Whereas broad peri-saccadic modulation was seen in both STS and auditory cortex, only cells in STS showed precise, short-latency responses at the termination of a saccade. The results of our study demonstrate that even those cells that respond to face and object stimuli can show modulation to eye movements. In addition, saccade modulation is not limited to classically-defined image-responsive regions of the brain: broad peri-saccadic modulation was also observed in auditory cortex. The observation that actions can influence sensory responses will be considered within the framework of embodied cognition.
