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E-37 Free Communication/Poster - Neuromotor Control Friday, May 29, 2015, 7: 30 AM - 12: 30 PM Room: Exhibit Hall F

Motor Cortex Excitability And Inhibition During A Cognitive Task

2441 Board #188 May 29, 11

00 AM - 12

30 PM

Edwards, Eli K.; Holste, Katherine G.; Yasen, Alia L.; Hill, Matthew J.; Christie, Anita D.

Author Information
Medicine & Science in Sports & Exercise: May 2015 - Volume 47 - Issue 5S - p 659
doi: 10.1249/01.mss.0000478515.23370.50
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It is well understood that the addition of a secondary cognitively demanding task to an ongoing motor task results in a decrement in motor function. However, the effect of such a cognitive task on motor cortex function is not well understood.

PURPOSE: To assess the effect of a cognitive task on motor cortex excitability and inhibition.

METHODS: Transcranial magnetic stimulation of the motor cortex was performed on 20 healthy individuals (18-24 years; 9 females) to measure motor evoked potentials (MEPs) and cortical silent periods (CSPs) of the first dorsal interosseous at baseline, during, and following a cognitive task.

RESULTS: The MEP amplitude increased from 0.50±0.09 to 0.87±0.50 mV during the cognitive task (p=0.04), and returned to baseline (0.48±0.31 mV; p=0.90) post-task. The CSP duration also increased from 93.48±28.76 to 113.6 ± 33.68 ms (p=0.001) during the cognitive task, and returned to baseline post-task (89.0 ± 6.9 ms; p=0.88). Further, variability in force production during CSP trials increased during the cognitive task, as the standard deviation in relative force increased from 1.08±0.11 to 1.54±0.20 (p=0.05), and returned to baseline post-task (0.97±0.12; p=0.83).

CONCLUSION: The increase in intracortical inhibition and variability in force may help to explain the motor deficits experienced during a secondary cognitive task, while the increased corticomotor excitability may act as a compensatory mechanism.

© 2015 American College of Sports Medicine