title: Effects of transcranial direct current stimulation of primary somatosensory cortex on vibrotactile detection and discrimination.
abstract: Anodal transcranial direct current stimulation (a-tDCS) of primary somatosensory cortex (S1) has been shown to enhance tactile spatial acuity, but there is little information as to the underlying neuronal mechanisms. We examined vibrotactile perception on the distal phalanx of the middle finger before, during, and after contralateral S1 tDCS [a-, cathodal (c)-, and sham (s)-tDCS]. The experiments tested our shift-gain hypothesis, which predicted that a-tDCS would decrease vibrotactile detection and discrimination thresholds (leftward shift of the stimulus-response function with increased gain/slope) relative to s-tDCS, whereas c-tDCS would have the opposite effects (relative to s-tDCS). The results showed that weak a-tDCS (1 mA, 20 min) led to a reduction in both vibrotactile detection and discrimination thresholds to 73-76% of baseline during the application of the stimulation in subjects categorized as responders. These effects persisted after the end of a-tDCS but were absent 30 min later. Most, but not all, subjects showed a decrease in threshold (8/12 for detection; 9/12 for discrimination). Intersubject variability was explained by a ceiling effect in the discrimination task. c-tDCS had no significant effect on either detection or discrimination threshold. Taken together, our results supported our shift-gain hypothesis for a-tDCS but not c-tDCS.
authors: Département de Neurosciences, Faculté de Médecine, Université de Montréal, Montréal, Quebec, Canada; and.
authors: Sara
authors: S
authors: Labbé
authors: Département de Neurosciences, Faculté de Médecine, Université de Montréal, Montréal, Quebec, Canada; and.
authors: El-Mehdi
authors: el-M
authors: Meftah
authors: Département de Neurosciences, Faculté de Médecine, Université de Montréal, Montréal, Quebec, Canada; and Groupe de Recherche sur le Système Nerveux Central, Faculté de Médecine, Université de Montréal, Montréal, Quebec, Canada c.elaine.chapman@umontreal.ca.
authors: C Elaine
authors: CE
authors: Chapman
mesh_terms: D000293:Adolescent; D004192:Discrimination, Psychological; D005260:Female; D006801:Humans; D008297:Male; D012684:Sensory Thresholds; D013003:Somatosensory Cortex / Q000502:physiology*; D055698:Touch Perception; D065908:Transcranial Direct Current Stimulation; D014732:Vibration; D055815:Young Adult
keywords: cortical plasticity; psychophysics; somatosensory cortex; tactile; transcranial direct current stimulation; vibration