Single-cell responses to three-dimensional structure in a functionally defined patch in macaque area TEO.

Area of Science:

• Neuroscience
• Visual Perception
• Computational Neuroscience

Background:

• The dorsal and ventral visual pathways process binocular disparity, crucial for 3D vision.
• While early visual areas (V1-V3) and end-stage areas (TE, AIP) are well-studied for disparity, midlevel area TEO remains less understood.
• Higher-order disparity, sensitive to disparity gradients, is key for complex shape perception.

Purpose of the Study:

• To investigate the role of macaque area TEO in processing higher-order disparity.
• To characterize single-unit responses to disparity-defined curved stimuli in an fMRI-identified TEO region.
• To determine if TEO neurons preserve 3D structure selectivity across depth.

Main Methods:

• Single-unit recordings were performed in macaque area TEO, guided by fMRI activation for curved vs. flat surfaces.
• Neurons were tested with disparity-defined curved stimuli at varying depths.
• A linear support vector machine (SVM) was used to classify stimulus properties from neural responses.

Main Results:

• The fMRI-defined TEO region contained a small proportion of disparity-selective neurons, with few showing second-order disparity selectivity.
• TEO neurons did not consistently preserve 3D structure selectivity across depth, indicating limited higher-order disparity processing.
• SVM analysis revealed that TEO neurons reliably encode the sign of curvature and stimulus position in depth.

Conclusions:

• Macaque area TEO exhibits limited higher-order disparity selectivity, unlike some other visual areas.
• Despite this, TEO neurons contain significant information about stimulus curvature and depth.
• This suggests TEO plays a role in representing 3D shape features, potentially contributing to downstream processing.