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Updated: Aug 8, 2026
Corticospinal Excitability Modulation During Action Observation
Published on: December 31, 2013
Alteration of motor cortex excitability in response to intermittent photic stimulation
1Department of Neurology, University of Utah, 50 North Medical Drive, Salt Lake City, UT 84132, USA. me.taher@m.cc.utah.edu
Objective:
To measure the duration of cortical silent period (C-SP) in response to different frequencies of intermittent photic stimulation (IPS).
Methods:
Ten normal volunteers without a history of seizures were studied. First, using a magnetic stimulator we determined the resting motor threshold (RMT). The C-SP produced by a single magnetic shock at 120% of RMT was measured in the maximally contracted abductor pollicis brevis. C-SP was then measured while subjects were exposed to IPS at 5, 10, 15, 20, 30, 50, and 60 Hz with closed eyes.
Results:
The average duration of C-SP was 135+/-33. 2 ms with no photic stimulation. This did not change significantly when subjects were exposed to IPS at 5, 10, 15, 20, and 30 Hz. The duration of C-SP, however, decreased significantly at higher frequencies. At 50 Hz it was 116.2+/-43 ms (P=0.003) and at 60 Hz it was 112.7+/-44.6 ms (P<0.001).
Conclusion:
Our findings suggest that motor cortex inhibition is altered in response to IPS at 50 and 60 Hz.
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