title: Transcranial direct current stimulation (tDCS) and the cardiovascular responses to acute pain in humans.
abstract: OBJECTIVE
  To determine if transcranial direct current stimulation (tDCS) reduces both acute pain perception and the resultant cardiovascular responses.
  
  
  METHODS
  Data were acquired on 15 healthy subjects at rest and in response to three cold pressor tests: 0, 7, and 14 °C. Subsequently, single sessions of sham and active anodal tDCS (2.0 mA for 40 min) were delivered to the left primary motor cortex (M1).
  
  
  RESULTS
  Perceived pain was reduced only after active tDCS with the 14 °C cold pressor test. This was accompanied by tendency for lesser increases in heart rate (~2 beats/min, p=0.09) and blood pressure (~3 mmHg, p=0.06). The effect size of tDCS on peak heart rate and blood pressure responses at 14 °C 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.
  
  
  CONCLUSIONS
  Our 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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Physical Medicine and Rehabilitation, Harvard Medical School and Spaulding Rehabilitation Hospital, Boston, MA, United States.
authors.forename: J W
authors.initials: JW
authors.lastname: Hamner
authors.affiliation: Department of Physical Medicine and Rehabilitation, Harvard Medical School and Spaulding Rehabilitation Hospital, Boston, MA, United States.
authors.forename: Mauricio F
authors.initials: MF
authors.lastname: Villamar
authors.affiliation: Department of Physical Medicine and Rehabilitation, Harvard Medical School and Spaulding Rehabilitation Hospital, Boston, MA, United States.
authors.forename: Felipe
authors.initials: F
authors.lastname: Fregni
authors.affiliation: Department of Physical Medicine and Rehabilitation, Harvard Medical School and Spaulding Rehabilitation Hospital, Boston, MA, United States. Electronic address: jandrew_taylor@hms.harvard.edu.
authors.forename: J Andrew
authors.initials: JA
authors.lastname: Taylor
mesh_terms: D059787:Acute Pain / Q000503:physiopathology*; D000328:Adult; D001794:Blood Pressure; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D009044:Motor Cortex / Q000502:physiology; D058748:Pain Perception; D017288:Pain Threshold; D065908:Transcranial Direct Current Stimulation
keywords: Acute pain; Autonomic; Brain stimulation; Cardiovascular; Sympathetic; tDCS