Related Experiment Videos
Interhemispheric inhibition of the human motor cortex
A Ferbert1, A Priori, J C Rothwell
1MRC Human Movement and Balance Unit, National Hospital for Neurology and Neurosurgery, London.
The Journal of Physiology
|January 1, 1992
Summary
This study shows that a magnetic stimulus to one brain hemisphere inhibits responses in the opposite hemisphere's first dorsal interosseous (FDI) muscle. This interhemispheric inhibition occurs at the cerebral cortex and depends on stimulus timing and location.
Area of Science:
- Neuroscience
- Motor Control
- Cerebral Cortex Function
Background:
- Investigating interhemispheric communication is crucial for understanding motor control.
- Previous research has explored neural pathways between cerebral hemispheres, but precise mechanisms remain under investigation.
Purpose of the Study:
- To examine the effect of a conditioning magnetic stimulus on one motor cortex hemisphere on EMG responses in the contralateral first dorsal interosseous (FDI) muscle.
- To characterize the nature and cortical basis of interhemispheric inhibition.
Main Methods:
- Utilized two magnetic stimulators to deliver conditioning and test stimuli to the motor cortex.
- Measured electromyography (EMG) responses in the first dorsal interosseous (FDI) muscle.
- Varied conditioning-test intervals, stimulus intensities, and coil placements.
Main Results:
- A conditioning stimulus to one hemisphere inhibited EMG responses in the contralateral FDI muscle when the conditioning-test interval was 5-6 ms or longer (interhemispheric inhibition).
- Inhibition duration increased with conditioning stimulus intensity, while depth decreased with test stimulus intensity.
- The inhibitory effect was maximal when the conditioning coil targeted the hand area of the motor cortex and occurred at the cortical level.
Conclusions:
- Magnetic brain stimulation can induce interhemispheric inhibition of motor responses, likely acting at the cerebral cortex.
- The findings highlight the role of intracortical circuits in modulating motor output between hemispheres.
- Interhemispheric inhibition is dependent on precise timing and cortical localization of stimuli.