Year, Volume, Issue, Page(s):15, 126, 5, 1039-1046
Study examined whether transcranial direct current stimulation (tDCS) reduces both acute pain perception and the resultant cardiovascular responses and if it impacts basal hemodynamics. Data were acquired on 15 healthy subjects at rest and in response to three cold pressor tests: 0, 7, and 14 degrees centigrade. Subsequently, single sessions of sham and active anodal tDCS (2.0 mA for 40 minutes) were delivered to the left primary motor cortex (M1). Perceived pain was reduced only after active tDCS with the 14 degrees centigrade cold pressor test. This was accompanied by tendency for lesser increases in heart rate and blood pressure. The effect size of tDCS on peak heart rate and blood pressure responses at 14 degrees centigrade was 0.47 and 0.54, respectively. On the other hand, baseline heart rate, blood pressure, leg blood flow, and leg vascular resistance were unaffected by tDCS. No other responses were affected. Results demonstrate that M1 anodal tDCS has no effect on basal hemodynamics or cardiovascular autonomic outflow and has only modest effects on the responses to acute pain in healthy humans. The findings suggest that application of tDCS shifts the pain perception threshold in healthy individuals but does not significantly modulate efferent cardiovascular control at rest or in response to pain. Only with the least painful stimulus, tDCS modestly reduced perceived pain and the peak cardiovascular and autonomic responses.