Medial temporal cortex supports object perception by integrating over visuospatial sequences

Abstract

Perception unfolds across multiple timescales. For humans and other primates, many object-centric visual attributes can be inferred ‘at a glance’ (i.e., given $<$200 ms of visual information), an ability supported by ventral temporal cortex (VTC). Other perceptual inferences require more time; to determine a novel object’s identity, we might need to represent its unique configuration of visual features, requiring multiple ‘glances.’ Here we evaluate whether medial temporal cortex (MTC), downstream from VTC, supports object perception by integrating over such visuospatial sequences. We first compare human visual inferences directly to electrophysiological recordings from macaque VTC. While human performance ‘at a glance’ is approximated by a linear readout of VTC, participants radically outperform VTC given longer viewing times (i.e., $>$200 ms). Next, we leverage a stimulus set that enables us to characterize MTC involvement in these temporally extended visual inferences. We find that human visual inferences ‘at a glance’ resemble the deficits observed in MTC-lesioned human participants. By measuring gaze behaviors during these temporally extended viewing periods, we find that participants sequentially sample task-relevant features via multiple saccades/fixations. These patterns of visuospatial attention are both reliable across participants and necessary for MTC-dependent visual inferences. These data reveal complementary neural systems that support visual object perception: VTC provides a rich set of visual features ‘at a glance’, while MTC is able to integrate over the sequential outputs of VTC to support object-level inferences.