Changes in cortical excitability during and just before motor imagery

Area of Science:

• Neuroscience
• Motor Control
• Human Physiology

Background:

• Cortical excitability refers to the responsiveness of neurons in the cerebral cortex.
• Motor imagery involves mentally rehearsing a movement without physical execution.
• Hand dominance influences neural processing and motor performance.

Purpose of the Study:

• To investigate changes in cortical excitability during motor imagery.
• To determine the effect of hand dominance on cortical excitability.
• To explore the neural mechanisms underlying motor imagery.

Main Methods:

• Transcranial magnetic stimulation (TMS) was used to measure motor evoked potentials (MEPs).
• MEPs were recorded from the first dorsal interosseous (FDI) muscle of both dominant and non-dominant hands.
• Participants performed three motor imagery tasks: dominant hand grasping, non-dominant hand grasping, and ankle dorsiflexion.

Main Results:

• MEPs significantly increased in the dominant hand during and just before motor imagery tasks.
• Cortical excitability was higher in the dominant hand's FDI muscle compared to the non-dominant hand during motor imagery, though not statistically significant.
• Increased cortical excitability was observed prior to contralateral hand and leg muscle imagery.

Conclusions:

• The left primary motor cortex (M1) exhibits greater excitability during motor imagery of hand muscles.
• Cortical excitability changes precede the initiation of imagined movements, indicating preparatory neural activity.
• Hand dominance plays a role in modulating cortical excitability during motor imagery.