2022 Volume 25 Issue 1 Pages 27-34
Purpose: The purpose of this study was to use transcranial magnetic stimulation (TMS) to estimate the time period during which the supplementary motor area is active to generate anticipatory postural adjustments (APA).
Methods: Electromyograms (EMG) were recorded from the deltoid and biceps femoris muscles of eleven healthy subjects, and a reaction time task was performed by raising the right upper limb in a standing position. During the task, TMS was applied to the supplementary motor area at 0 ms, 30 ms, 50 ms, and 70 ms after the reaction sound. The trials were classified into two groups: trials in which TMS was administered in the 100-ms time period before the onset of deltoid muscle activity (APA-window) and trials with a earlier interval (APA-out). The EMG activities of the deltoid and biceps femoris muscles were also integrated to compare the muscle activities.
Results: TMS administered in the APA-window period significantly delayed the onset time of muscle activity of the biceps femoris compared to control.
Conclusion: In a standing arm raising task, the time at which the supplementary motor cortex is active to generate APAs was estimated to be within 100 ms before the onset of deltoid muscle activity.
