Body-part tuning in the macaque superior temporal sulcus

Area of Science:

• Neuroscience
• Primate Vision
• Computational Neuroscience

Background:

• Neurons in the macaque superior temporal sulcus (STS) are known to respond to faces and headless bodies.
• However, their selectivity for individual body parts remains less understood.

Purpose of the Study:

• To investigate the tuning of neurons in the middle and anterior STS for various body parts, including heads.
• To understand the role of internal structure and body context in body part representation.

Main Methods:

• Electrophysiological recordings were conducted in the middle and anterior STS of macaques viewing body parts.
• Experiments manipulated visual features such as color, achromatic stimuli, and scrambled internal features.
• Convolutional neural network (CNN) modeling was used to analyze feature reliance.

Main Results:

• Faces were represented distinctly from other body parts in both STS regions.
• Genitalia, rumps, and torso formed distinct subclusters, with hands appearing variably in the anterior STS.
• CNN modeling indicated that mid- to high-level features are crucial for body part tuning.
• Internal features contribute to, but do not solely determine, body part representations.
• Non-head-preferring neurons showed greater response suppression within a body context compared to head-preferring neurons.

Conclusions:

• There is a clear distinction between face and other body part representations in the STS.
• Body part selectivity relies on complex visual features and is modulated by contextual information.
• Non-face body part representations are more sensitive to body context than face representations.