rTMS over the human medial parietal cortex impairs online reaching corrections

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Motor Control

Background:

• The posteromedial parietal cortex, specifically area hV6A, is indirectly linked to reaching corrections.
• Understanding the precise role of hV6A in real-time motor adjustments is essential for explaining sensorimotor integration.

Purpose of the Study:

• To investigate the causal role of human area hV6A in reaching movement adjustments.
• To determine the specific functions of hV6A during action reprogramming in response to sudden environmental changes.

Main Methods:

• Utilized repetitive transcranial magnetic stimulation (rTMS) to temporarily interfere with hV6A function in healthy participants.
• Monitored reaching movements and in-flight hand trajectory adjustments during unexpected target shifts.

Main Results:

• rTMS over hV6A significantly disrupted action reprogramming, leading to trajectory deviations.
• Deviations were particularly pronounced along the vertical dimension (distance), indicating a role in state estimation for reaching.
• Findings align with lesion data implicating the dorsal posterior parietal cortex in distance-related action impairments.

Conclusions:

• Area hV6A is functionally relevant for action reprogramming when sudden events necessitate performance changes.
• hV6A plays a significant role in online state estimation during reaching movements.
• This research provides direct evidence for hV6A's involvement in sensorimotor control and error correction.