title: Activity in the primary somatosensory cortex induced by reflexological stimulation is unaffected by pseudo-information: a functional magnetic resonance imaging study.
abstract: BACKGROUND
  Reflexology is an alternative medical practice that produces beneficial effects by applying pressure to specific reflex areas. Our previous study suggested that reflexological stimulation induced cortical activation in somatosensory cortex corresponding to the stimulated reflex area; however, we could not rule out the possibility of a placebo effect resulting from instructions given during the experimental task. We used functional magnetic resonance imaging (fMRI) to investigate how reflexological stimulation of the reflex area is processed in the primary somatosensory cortex when correct and pseudo-information about the reflex area is provided. Furthermore, the laterality of activation to the reflexological stimulation was investigated.
  
  
  METHODS
  Thirty-two healthy Japanese volunteers participated. The experiment followed a double-blind design. Half of the subjects received correct information, that the base of the second toe was the eye reflex area, and pseudo-information, that the base of the third toe was the shoulder reflex area. The other half of the subjects received the opposite information. fMRI time series data were acquired during reflexological stimulation to both feet. The experimenter stimulated each reflex area in accordance with an auditory cue. The fMRI data were analyzed using a conventional two-stage approach. The hemodynamic responses produced by the stimulation of each reflex area were assessed using a general linear model on an intra-subject basis, and a two-way repeated-measures analysis of variance was performed on an intersubject basis to determine the effect of reflex area laterality and information accuracy.
  
  
  RESULTS
  Our results indicated that stimulation of the eye reflex area in either foot induced activity in the left middle postcentral gyrus, the area to which tactile sensation to the face projects, as well as in the postcentral gyrus contralateral foot representation area. This activity was not affected by pseudo information. The results also indicate that the relationship between the reflex area and the projection to the primary somatosensory cortex has a lateral pattern that differs from that of the actual somatotopical representation of the body.
  
  
  CONCLUSIONS
  These findings suggest that a robust relationship exists between neural processing of somatosensory percepts for reflexological stimulation and the tactile sensation of a specific reflex area.
authors.affiliation: Department of Information and Communication Engineering, Faculty of Engineering, Tohoku Institute of Technology, Yagiyama kasumicho 35-1 Taihaku-ku, Sendai 982-8577, Japan. miura.naoki@tohtech.ac.jp
authors.forename: Naoki
authors.initials: N
authors.lastname: Miura
authors.forename: Yuko
authors.initials: Y
authors.lastname: Akitsuki
authors.forename: Atsushi
authors.initials: A
authors.lastname: Sekiguchi
authors.forename: Ryuta
authors.initials: R
authors.lastname: Kawashima
mesh_terms: D000328:Adult; D001931:Brain Mapping; D005260:Female; D005528:Foot / Q000502:physiology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008405:Massage; D011859:Radiography; D013003:Somatosensory Cortex / Q000000981:diagnostic imaging* / Q000502:physiology*; D055815:Young Adult