Using Transcranial Magnetic Stimulation (TMS) to Compare Cortical Excitability Among Depressed Patients, Sleep-Deprived Controls, and Rested Controls

Objective: To compare cortical excitability among sleep-deprived and rested controls, and depressed subjects. Methods: 3 controls and 4 depressed patients (average HAM-D 19) wererecruited. Sleep-deprived controls were instructed to sleep \u3c=4 hours the previous night. TMS-produced motor evoked potentials (MEPs) were measured before and after subjects engaged in sets of non-fatiguing manual exercise. Results: Post-exercise MEP increased 71+1-19% for rested controls, 28+1-32% for sleep deprived controls, and 8+1-15% for depressed patients. This increase, facilitation, was significantly greater in rested controls than in depressed patients (p=0.011). No significant difference in facilitation was found between sleep-deprived controls and depressed patients. Conclusion: Sleep-deprivation may partially account for reduced cortical excitability in depressed patients