Gongchen Yu¹, Leor Katz¹, Richard Krauzlis¹; ¹Laboratory of Sensorimotor Research, National Eye Institute, NIH

We recently reported that neurons in the macaque superior colliculus (SC) exhibit a preference for face stimuli at extremely short latencies. This finding raises the question of whether and how SC contributes to the well-established selectivity for faces in temporal cortex. To address this question, we used multichannel probes to record activity from face-selective neurons in the middle fundus face patch (MF) of the temporal cortex, both before and during SC inactivation. Visual object stimuli—including faces, bodies, and human-made objects—were presented either within the visual field location affected by SC inactivation (5° away from fixation, contralateral to the recorded hemisphere) or outside it (5° ipsilateral). Our results show that SC inactivation significantly reduced the selectivity of face-selective neurons in MF. This effect was predominantly observed for faces presented in the visual field affected by SC inactivation, and was primarily centered on the initial visual response period following stimulus onset (~70–140ms). In addition to face-selective neurons, our dataset included a population of neurons selective for bodies. Preliminary analyses indicate that SC inactivation reduced the selectivity of body-selective neurons as well, albeit not as strongly as observed for face-selective neurons. Our findings demonstrate that the SC causally contributes to face processing in the temporal cortex, particularly at short visual latencies. Thus, SC activity might be critical for prioritizing the processing of objects—especially faces—and for facilitating subsequent higher-order processing in cortex.