Interactions between two different inhibitory systems in the human motor cortex

• DOI: 10.1111/j.1469-7793.2001.0307l.x
• Publication Date: 2004-08-05T11:34:09Z
• Authors: Terence D. Sanger; Rami R. Garg; Robert Chen
• Keywords: Stimulus (psychology)

1 Intracortical inhibition in the human motor cortex has been previously demonstrated using paired-pulse transcranial magnetic stimulation (TMS) protocols at short intervals (1-6 ms; interval intracortical inhibition, SICI) with a subthreshold conditioning pulse preceding suprathreshold test pulse, and long (50-200 LICI) pulses. 2 We investigated whether different circuits mediate these inhibitory phenomena how they interact. In nine healthy volunteers, we applied TMS to recorded evoked potentials from first dorsal interosseous muscle. 3 With increasing strength, LICI decreases but SICI tends increase. There was no correlation between degree of LICI. 4 tested interactions reduced or eliminated presence Loss seen even stimulus too weak induce significant 5 Our findings demonstrate that cell populations The results are consistent hypothesis inhibits through presynaptic GABAB receptors. Testing may be non-invasive way evaluating cortex.