The human middle temporal cortex responds to both active leg movements and egomotion-compatible visual motion

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Visual Perception

Background:

• The human middle-temporal area (MT+) is recognized for visual motion processing.
• Emerging evidence suggests MT+ is modulated by extraretinal signals, hinting at cross-modal motion processing capabilities.

Purpose of the Study:

• To investigate the influence of retinal and extraretinal signals on MT+ using functional MRI.
• To explore the functional connectivity of MT+ subdivisions (MST, FST, MT, V4t) using resting-state fMRI.

Main Methods:

• Functional MRI (fMRI) was employed to compare brain responses to coherent versus random visual motion.
• Resting-state fMRI was used to analyze functional connectivity patterns within MT+ subdivisions and with other brain regions.
• Regional analyses examined responses to visual motion and limb movements (arm vs. leg).

Main Results:

• The MST and FST subregions of MT+ showed positive activation to coherent visual motion.
• MST and FST were activated by leg movements but not arm movements, while MT and V4t were deactivated by arm movements.
• Distinct functional connectivity patterns emerged: visuomotor regions (MST, FST) connected with somatosensory and motor areas, particularly those for the lower limbs.

Conclusions:

• The anterior areas MST and FST exhibit a visuomotor role, integrating visual motion with lower-limb movements.
• The MT and V4t areas demonstrate a pure visual role in motion processing.
• These findings suggest MST and FST are crucial for integrating sensory and motor information, potentially supporting locomotion.