@article {KalfasENEURO.0113-17.2017, author = {Ioannis Kalfas and Satwant Kumar and Rufin Vogels}, title = {Shape Selectivity of Middle Superior Temporal Sulcus Body Patch Neurons}, elocation-id = {ENEURO.0113-17.2017}, year = {2017}, doi = {10.1523/ENEURO.0113-17.2017}, publisher = {Society for Neuroscience}, abstract = {fMRI studies in primates demonstrated cortical regions that are strongly activated by visual images of bodies. The presence of such body patches in macaques allows characterization of the stimulus selectivity of their single neurons. Middle Superior Temporal Sulcus body (MSB) patch neurons showed similar stimulus selectivity for natural, shaded and textured images compared with their silhouettes, suggesting that shape is an important determinant of MSB responses. Here, we examined and modeled the shape selectivity of single MSB neurons. We measured the responses of single MSB neurons to a variety of shapes producing a wide range of responses. We employed an adaptive stimulus sampling procedure, selecting and modifying shapes based on the responses of the neuron. Forty percent of shapes that produced the maximal response were rated by humans as animal-like, but the top shape of many MSB neurons was not judged as resembling a body. We fitted the shape selectivity of MSB neurons with a model that parameterizes shapes in terms of curvature and orientation of contour segments, with a pixel-based model, and with layers of units of convolutional neural networks (CNNs). The deep convolutional layers of CNNs provided the best goodness-of-fit, with a median explained explainable variance of the neurons{\textquoteright} responses of 77\%. The goodness-of-fit increased along the convolutional layers{\textquoteright} hierarchy, but was lower for the fully-connected layers. Together with demonstrating the successful modeling of single unit shape selectivity with deep CNNs, the data suggest that semantic or category knowledge determines only slightly the single MSB neuron{\textquoteright}s shape selectivity.Significance Statement fMRI studies showed regions in the temporal cortex that are selectively activated by bodies. In agreement with the fact that animals can be identified from their silhouette, recording studies showed that the stimulus selectivity of single units of the middle Superior Temporal Sulcus body patch (MSB) is strongly determined by shape. We examined for the first time the shape selectivity of single MSB neurons, employing adaptive stimulus sampling which produced a wide range of responses to a variety of shapes. Deeper layers of deep convolutional neural networks provided excellent models of the observed shape selectivity of single neurons in the fMRI-defined MSB. Overall, the data suggest that semantic or category knowledge determines only slightly the single MSB neuron{\textquoteright}s shape selectivity.}, URL = {https://www.eneuro.org/content/early/2017/06/16/ENEURO.0113-17.2017}, eprint = {https://www.eneuro.org/content/early/2017/06/16/ENEURO.0113-17.2017.full.pdf}, journal = {eNeuro} }