Volitional hand activation intensifies cortical proprioceptive processing in the primary sensorimotor cortex.

Area of Science:

• Neuroscience
• Human sensorimotor cortex research
• Proprioception studies

Background:

• Proprioception, the sense of body position and movement, is crucial for skilled motor control.
• The sensorimotor cortex (SM1) processes finger movements, but its proprioceptive representations are not fully understood.
• Previous studies explored finger representations via tactile stimulation and active movements.

Purpose of the Study:

• To investigate cortical representations of the index and ring fingers in the SM1 cortex.
• To compare brain responses to proprioceptive stimulation during passive versus active finger movements.
• To understand how volitional activation influences proprioceptive processing in SM1.

Main Methods:

• Used 3T fMRI and an MRI-compatible proprioceptive stimulator.
• Investigated index and ring finger representations.
• Employed kinematically matched passive and active finger movements.

Main Results:

• Both active and passive conditions activated the SM1 cortex.
• Active finger movements produced stronger and more extensive SM1 activations than passive movements.
• Volitional activation intensifies cortical proprioceptive processing in SM1.

Conclusions:

• Active finger movements enhance proprioceptive processing in the sensorimotor cortex.
• This enhancement may stem from the SM1 cortex's active state and heightened peripheral proprioceptor sensitivity.
• Somatotopic organization of proprioceptive finger representations was observed at the group level but varied individually.