Enhanced neural plasticity in monkey TE compared to TEO during learning of a feature-ambiguous visual categorization task.

Primates can rapidly categorize images by visual feature similarity. We previously showed that inferior temporal cortex (IT) subregions TEO and TE contribute to visual categorization to differing extents. To investigate the neural plasticity underlying visual categorization, we recorded simultaneously from both areas while two male monkeys learned a visual categorization task. Category specificity and generalization are initially stronger in TEO than in TE but increase with learning only in the TE neuronal population, whose neural representations correlate with behavioral performance. TE and TEO can contribute complementary, partially independent category information. However, TEO does not add learning-relevant variance across days. TE exhibits greater categorical enhancement for correct than error trials compared with TEO. Single-neuron analyses revealed that TE category selectivity strengthens with learning, primarily through enhanced encoding of one category. Combined with lesion evidence, our results suggest that TE plasticity likely plays a more fundamental role in supporting visual category learning.