Face-hand sensorimotor interactions revealed by afferent inhibition

Area of Science:

• Neuroscience
• Sensorimotor Cortex Plasticity
• Somatosensory Integration

Background:

• Sensorimotor cortex reorganization occurs after hand deafferentation, showing plasticity between hand and face representations.
• The underlying physiological mechanisms of this sensorimotor reorganization are not well understood.

Purpose of the Study:

• To investigate sensorimotor interactions between the face and hand using afferent inhibition transcranial magnetic stimulation.
• To test the hypothesis that face and hand sensorimotor cortex representations are functionally coupled.

Main Methods:

• Used an afferent inhibition transcranial magnetic stimulation protocol.
• Applied electrocutaneous stimulation to the face (upper lip/cheek) and recorded motor evoked potentials from the hand (first dorsal interosseous).
• Compared face stimulation effects with stimulation of the forearm and upper arm.

Main Results:

• ElectrocANEOUS stimulation of the face (lip and cheek) significantly inhibited hand muscle motor evoked potentials.
• Stimulation of the forearm and upper arm also inhibited motor evoked potentials, but to a lesser extent than face stimulation.
• These findings demonstrate face-to-hand afferent inhibition.

Conclusions:

• The study provides the first evidence for face-to-hand afferent inhibition.
• Functional coupling exists between face and hand representations in the sensorimotor cortex.
• This supports the understanding of sensorimotor plasticity and integration.