Generalized Representation of Stereoscopic Surface Shape and Orientation in the Human Visual Cortex

Area of Science:

• Neuroscience
• Visual Perception
• Cognitive Science

Background:

• Stereoscopic 3D surface perception is crucial for daily life and relies on binocular disparity.
• While neurons selective to binocular disparity exist across visual areas, their specific roles in 3D surface representation remain unclear.

Purpose of the Study:

• To investigate how different visual cortical areas represent 3D shape and orientation from binocular disparity.
• To determine if specific areas are involved in generalized representations of curvature and orientation.

Main Methods:

• Participants viewed random dot stereograms (RDS) of curved surfaces defined by shear or compression disparity using functional magnetic resonance imaging (fMRI).
• Multi-voxel pattern analysis (MVPA) was used to classify shape and orientation selectivity within visual areas.
• Transfer classification assessed generalized shape and orientation representations across different stimulus types.

Main Results:

• Most visual areas analyzed showed selectivity for both shape and orientation of disparity-defined 3D surfaces.
• The dorsal visual area V3A demonstrated generalized shape representation, with higher classification accuracies for surface curvature.
• Higher dorsal areas (V3A, V7), the ventral lateral occipital complex (LOC), and parts of the intraparietal sulcus (IPS) showed generalized 3D surface orientation representation.

Conclusions:

• Visual cortical areas exhibit distinct and overlapping roles in processing 3D surface shape and orientation from binocular disparity.
• Area V3A plays a significant role in generalized shape perception, while V3A, V7, LOC, and IPS contribute to generalized orientation representation.