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Updated: May 16, 2026
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Measuring and Manipulating Functionally Specific Neural Pathways in the Human Motor System with Transcranial Magnetic Stimulation
Published on: February 23, 2020
Dynamic and Context-Dependent Modulation of Somatosensory Input in the Primate Primary Motor Cortex
Junichiro Yoshida1,2, Satomi Kikuta1, Woranan Hasegawa1
1Department of Neurophysiology, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo 187-8502, Japan.
Summary
Proprioceptive input to the primary motor cortex (M1) is generally suppressed during voluntary movement. However, specific signals from antagonist muscles and skin are preserved during static holds for posture control.
Area of Science:
- Neuroscience
- Motor Control
- Somatosensation
Background:
- Voluntary movement involves sensory gating, attenuating somatosensory input to prevent the central nervous system (CNS) from being overwhelmed.
- Sensory gating is observed in sensory cortical areas, but its occurrence and purpose in the primary motor cortex (M1) remain unclear.
- Proprioceptive feedback is vital for shaping motor output from M1.
Purpose of the Study:
- To investigate whether proprioceptive signals to M1 are attenuated during movement.
- To determine the functional purpose of sensory gating in M1 regarding proprioception.
- To provide direct evidence for sensory gating of proprioceptive input in M1.
Main Methods:
- Recorded somatosensory-evoked potentials (SEPs) in M1 of monkeys performing a wrist task.
- Electrically stimulated muscle and cutaneous afferents in forearm extensors.
- Utilized local field potential and single-neuron recordings.
Main Results:
- Muscle-evoked SEPs in M1 were significantly suppressed during active movement and static hold phases.
- This provides direct evidence that proprioceptive input to M1 is generally gated during motor execution.
- A subset of M1 neurons preserved SEPs during static hold, particularly those evoked by afferents from antagonistic muscles and stretched skin.
Conclusions:
- Proprioceptive muscle and cutaneous inputs to M1 are broadly suppressed during motor output.
- Specific afferent signals are selectively maintained in a context-dependent manner to support posture control.
- Cortical somatosensory gating is an adaptable principle, allowing preservation of task-relevant signals for functions like postural stabilization.
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