Clustered functional domains for curves and corners in cortical area V4

The ventral visual pathway is crucially involved in integrating low-level visual features into complex representations for objects and scenes. At an intermediate stage of the ventral visual pathway, V4 plays a crucial role in supporting this transformation. Many V4 neurons are selective for shape segments like curves and corners; however, it remains unclear whether these neurons are organized into clustered functional domains, a structural motif common across other visual cortices. Using two-photon calcium imaging in awake macaques, we confirmed and localized cortical domains selective for curves or corners in V4. Single-cell resolution imaging confirmed that curveor corner-selective neurons were spatially clustered into such domains. When tested with hexagonal-segment stimuli, we find that stimulus smoothness is the cardinal difference between curve and corner selectivity in V4. Combining cortical population responses with single-neuron analysis, our results reveal that curves and corners are encoded by neurons clustered into functional domains in V4. This functionally specific population architecture bridges the gap between the early and late cortices of the ventral pathway and may serve to facilitate complex object recognition.

Automated summary

The ventral visual pathway, specifically the V4 area, plays a crucial role in integrating low-level visual features for complex object and scene representations. Neurons in V4 are organized into clustered functional domains selective for shape segments like curves and corners. Stimulus smoothness is identified as the key difference between curve and corner selectivity in V4, indicating the specific population architecture facilitates complex object recognition.