Area MSTd neurons encode visual stimuli in eye coordinates during fixation and pursuit.

Area of Science:

• Neuroscience
• Visual System
• Computational Neuroscience

Background:

• Self-motion visual cues are initially processed in retinal coordinates.
• Transformation into body or world coordinates is crucial for navigation.
• The dorsal medial superior temporal area (MSTd) contains neurons tuned to the focus of expansion (FOE).

Purpose of the Study:

• To determine if MSTd neurons represent FOE tuning curves in eye-centered or screen-centered coordinates.
• To investigate the coordinate frame of MSTd neurons during both stationary and moving eye conditions.

Main Methods:

• Extracellular recordings from 80 MSTd neurons in two rhesus monkeys.
• Experiments conducted under fixed gaze, real pursuit, and simulated pursuit conditions.
• Analysis of FOE tuning curves to identify the coordinate frame.

Main Results:

• The vast majority of MSTd neurons (96%) showed FOE tuning curves aligned in an eye-centered coordinate frame across all conditions.
• This eye-centered representation was consistent during fixed gaze, real pursuit, and simulated pursuit.
• MSTd neurons exhibited significant eye position gain modulation, similar to neighboring areas.

Conclusions:

• MSTd neurons represent heading information in an eye-centered coordinate frame, regardless of eye movement.
• This finding is critical for understanding how the brain integrates visual self-motion cues for navigation.
• Area MSTd plays a key role in processing heading information within a stable, eye-centered reference frame.