title: Double-Cone Coil TMS Stimulation of the Medial Cortex Inhibits Central Pain Habituation.
abstract: OBJECTIVE
  The aim of this study was to investigate whether Transcranial Magnetic Stimulation (TMS) applied over the medial line of the scalp affects the subjective perception of continuous pain induced by means of electric stimulation. In addition, we wanted to identify the point of stimulation where this effect was maximum.
  
  
  METHODS
  Superficial electrical stimulation was used to induce continuous pain on the dominant hand. At the beginning of the experiment we reached a pain rating of 5 on an 11-point numeric rating scale (NRS; 0 = no pain and 10 = maximum tolerable pain) for each subject by setting individually the current intensity. The TMS (five pulses at increasing intensities) was applied on 5 equidistant points (one per session) over the medial line of the scalp in 13 healthy volunteers using a double-cone coil to stimulate underlying parts of the brain cortex. In every experimental session the painful stimulation lasted 45 minutes, during which pain and distress intensities NRS were recorded continuously. We calculated the effect of adaptation and the immediate effect of the TMS stimulation for all locations. Additionally, an ALE (Activation Likelihood Estimation) meta-analysis was performed to compare our results with the neuroimaging literature on subjective pain rating.
  
  
  RESULTS
  TMS stimulation temporarily decreased the pain ratings, and pain adaptation was suppressed when applying the TMS over the FCz site on the scalp. No effect was found for distress ratings.
  
  
  CONCLUSIONS
  The present data suggest that the medial cortex in proximity of the cingulated gyrus has a causal role in adaptation mechanisms and in processing ongoing pain and subjective sensation of pain intensity.
authors.affiliation: LabNI, University of Turin, Turin, Italy; Neuroscience Department, University of Turin, Turin, Italy.
authors.forename: Federico
authors.initials: F
authors.lastname: D'Agata
authors.affiliation: LabNI, University of Turin, Turin, Italy; Neuroscience Department, University of Turin, Turin, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Cicerale
authors.affiliation: LabNI, University of Turin, Turin, Italy.
authors.forename: Arianna
authors.initials: A
authors.lastname: Mingolla
authors.affiliation: Institut du Cerveau et de la Moelle épinière, ICM, Hôpital Pitié Salpêtrière, Paris, France.
authors.forename: Paola
authors.initials: P
authors.lastname: Caroppo
authors.affiliation: Neuroscience Department, AOU Citta della Salute e della Scienza (Presidio Molinette), Turin, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Orsi
authors.affiliation: Neuroscience Department, University of Turin, Turin, Italy; Neuroscience Department, AOU Citta della Salute e della Scienza (Presidio Molinette), Turin, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Mortara
authors.affiliation: Neuroscience Department, University of Turin, Turin, Italy.
authors.forename: Walter
authors.initials: W
authors.lastname: Troni
authors.affiliation: Neuroscience Department, University of Turin, Turin, Italy; Neuroscience Department, AOU Citta della Salute e della Scienza (Presidio Molinette), Turin, Italy.
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Pinessi
mesh_terms: D000222:Adaptation, Physiological; D000328:Adult; D001931:Brain Mapping; D004558:Electric Stimulation / Q000295:instrumentation; D005260:Female; D006801:Humans; D016013:Likelihood Functions; D008297:Male; D010146:Pain / Q000503:physiopathology*; D010147:Pain Measurement; D017288:Pain Threshold / Q000502:physiology*; D017397:Prefrontal Cortex / Q000033:anatomy & histology / Q000502:physiology / Q000503:physiopathology*; D050781:Transcranial Magnetic Stimulation