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Transcranial magnetic stimulation can influence the selection of motor programmes
1Department of Clinical Neurophysiology, Prince Henry Hospital, Sydney, Australia.
Journal of Neurology, Neurosurgery, and Psychiatry
|August 1, 1990
Summary
Transcranial magnetic stimulation (TMS) can influence hand preference even without causing movement. The direction of induced current and coil placement over frontal cortex determined the effect on motor planning.
Area of Science:
- Neuroscience
- Cognitive Science
- Motor Control
Background:
- Transcranial magnetic stimulation (TMS) is widely used to investigate motor cortex output.
- The impact of non-movement-inducing TMS on higher-level cortical functions remains largely unexplored.
Purpose of the Study:
- To investigate the effects of subthreshold TMS on motor planning.
- To determine if TMS can influence hand selection in a task.
Main Methods:
- Single magnetic stimuli were applied, subthreshold for movement.
- A forced-choice task was used to assess hand preference.
- Coil position (frontal vs. occipital) and current direction were varied.
- Comparison with weak direct current (DC) stimulation was performed.
Main Results:
- Subthreshold TMS significantly altered hand preference in the forced-choice task.
- Hand preference was dependent on the direction of the induced current.
- The effect was observed with frontal cortex stimulation but not occipital.
- Weak DC stimulation did not replicate these findings.
Conclusions:
- Non-movement-evoking TMS can modulate high-level motor planning.
- TMS offers a tool to probe the neural mechanisms underlying motor selection.
- Cortical excitability, modulated by TMS, plays a role in decision-making processes related to motor output.