Reversible inactivation of different millimeter-scale regions of primate IT results in different patterns of core object recognition deficits

Abstract

Extensive research suggests that the inferior temporal (IT) population supports visual object recognition behavior. However, causal evidence for this hypothesis has been equivocal, particularly beyond the specific case of face-selective sub-regions of IT. Here, we directly tested this hypothesis by pharmacologically inactivating individual, millimeter-scale sub-regions of IT while monkeys performed several object discrimination tasks, interleaved trial-by-trial. First, we observed that IT inactivation resulted in reliable contralateral-biased task-selective behavioral deficits. Moreover, inactivating different IT sub-regions resulted in different patterns of task deficits, each predicted by that sub-region’s neuronal object discriminability. Finally, the similarity between different inactivation effects was tightly related to the anatomical distance between corresponding inactivation sites. Taken together, these results provide direct evidence that IT cortex causally supports general core object recognition, and that the underlying IT codes are topographically organized.