Human cortical and behavioral sensitivity to patterns of complex motion at eccentricity.

Area of Science:

• Neuroscience
• Visual Perception
• Computational Neuroscience

Background:

• Complex motion patterns (expanding, contracting, rotating, spiraling) are crucial for visually guided behaviors.
• While specialized motion detectors exist in monkey visual cortex, their representation in human visual cortex is not well understood.

Purpose of the Study:

• To investigate the sensitivity of human visual cortex regions to complex motion trajectories using fMRI.
• To compare neural responses with psychophysical sensitivity to complex motion patterns.
• To explore potential anisotropies in human visual motion processing.

Main Methods:

• Functional magnetic resonance imaging (fMRI) was employed to measure brain activity in human participants.
• A novel stimulus design presented parametrically modulated complex motion fields in the periphery, distinguishing them from foveal local motion.
• Psychophysical testing complemented fMRI to assess behavioral sensitivity to the same motion stimuli.

Main Results:

• Anisotropies in fMRI signals were observed, with significantly enhanced responses to expanding motion fields compared to contracting fields, evident even in early visual cortex.
• Psychophysical sensitivity measures showed a similar anisotropic pattern.
• These behavioral anisotropies correlated with neural activity in specific visual areas, including hV4, V5/MT, and MST.

Conclusions:

• This study provides the first systematic behavioral and neural examination of complex motion perception in humans.
• A characteristic processing anisotropy, favoring expanding over contracting motion, was revealed in both neural and behavioral data.
• These findings inform models of complex motion processing, particularly concerning computations in early visual cortex.