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Stimulating the Lip Motor Cortex with Transcranial Magnetic Stimulation
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Time in the motor cortex: Motor evoked potentials track foreperiod duration without concurrent movement
Jordan J Wehrman1, Paul Sowman1
1Macquarie University Cognitive Science Department, Sydney, Australia.
Neuroscience Letters
|January 11, 2019
Summary
Transcranial magnetic stimulation (TMS) reveals motor evoked potentials (MEPs) decrease over time during trials, independent of response preparation. This suggests motor cortex involvement in broader timing functions.
Area of Science:
- Neuroscience
- Motor Control
- Cognitive Science
Background:
- Transcranial magnetic stimulation (TMS) monitors motor cortex activity.
- Motor evoked potentials (MEPs) typically decrease before a required response.
Purpose of the Study:
- To investigate motor cortex dynamics using TMS without requiring a participant response.
- To examine how MEPs change over trial duration and with muscle contraction/relaxation.
Main Methods:
- Applied TMS to participants at varying times during a trial.
- Participants either relaxed or contracted their first dorsal interosseous muscle.
- No participant response was required during TMS application.
Main Results:
- MEPs systematically decreased as trial duration increased.
- This MEP decrease was not mirrored by changes in neural inhibition.
- Evidence suggests MEPs are inversely proportional to prior trial duration.
Conclusions:
- Motor cortex activity, specifically MEPs, declines with trial duration independent of response preparation.
- Findings indicate a broader role for the motor cortex in timing.
- Implications for TMS research using variable trial timings.
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