Macaque inferior temporal neurons are selective for three-dimensional boundaries and surfaces

Area of Science:

• Neuroscience
• Computational Neuroscience
• Visual Perception

Background:

• The inferior temporal cortex, specifically the superior temporal sulcus (TEs), contains neurons crucial for processing visual information.
• Previous research indicates TEs neurons are selective for three-dimensional (3-D) shapes defined by binocular disparity.
• A significant portion of these neurons exhibit higher-order disparity selectivity, responding to spatial variations in disparity.

Purpose of the Study:

• To investigate whether curved boundaries or surfaces alone are sufficient to elicit 3-D shape selectivity in TEs neurons.
• To determine if TEs neurons can represent second-order disparities along the horizontal axis and code curvature direction.

Main Methods:

• Single-unit recordings were performed on higher-order disparity-selective TEs neurons.
• Neurons were presented with concave and convex 3-D shapes with disparity variations along boundaries or surfaces.
• Stimuli included shapes with horizontal and vertical curvature to assess directional selectivity.

Main Results:

• A majority of TEs neurons showed 3-D shape selectivity based on curved boundaries.
• A comparable number of neurons responded selectively to 3-D surfaces.
• Some neurons exhibited selectivity for both surface and boundary information, and TEs neurons were found to be selective for horizontal 3-D shapes, coding curvature direction.

Conclusions:

• TEs neurons utilize both boundary and surface information to encode 3-D shape properties.
• These neurons are capable of representing curved boundaries and surfaces in depth.
• TEs neurons can signal the direction of curvature, contributing to the brain's 3-D shape representation.