Ipsilateral finger representations in the sensorimotor cortex are driven by active movement processes, not passive...

Area of Science:

• Neuroscience
• Motor Control
• Brain Imaging

Background:

• Hand and finger movements are primarily controlled by the contralateral hemisphere via corticospinal pathways.
• Ipsilateral brain activity during unimanual movements, though suppressed, can still represent movement parameters, but its origin is unclear.
• Understanding the role of ipsilateral activity is crucial for a complete picture of motor control.

Purpose of the Study:

• To investigate whether ipsilateral neural representations of finger movements originate from active motor commands or passive sensory input.
• To compare the neural representations of active versus passive finger movements in both hemispheres.
• To elucidate the functional relevance and origin of ipsilateral cortical activity during hand movements.

Main Methods:

• High-field (7T) functional imaging was used to record brain activity.
• Participants alternated between performing active finger presses and receiving passive finger stimulation.
• Brain activity patterns were analyzed in sensorimotor areas of both ipsilateral and contralateral hemispheres.

Main Results:

• Contralateral hemisphere finger representations were equally strong for both active and passive conditions, indicating sensory feedback importance.
• Ipsilateral sensorimotor cortex representations were significantly stronger during active finger presses compared to passive stimulation.
• Distinct spatial distributions of finger representations were observed: contralateral in Brodmann areas 3a/3b, ipsilateral in premotor/parietal areas.

Conclusions:

• Contralateral hemisphere representations are driven by both active movement and sensory input.
• Ipsilateral hemisphere representations are primarily associated with active movement execution, not direct sensory input.
• This suggests different functional origins for neural representations in the contralateral versus ipsilateral hemispheres during hand actions.