Activity in the primary somatosensory cortex induced by reflexological stimulation is unaffected by pseudo-information: a functional magnetic resonance imaging study.

Naoki Miura,Ryuta Kawashima,Yuko Akitsuki,Atsushi Sekiguchi

doi:10.1186/1472-6882-13-114

Abstract

BackgroundReflexology 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.MethodsThirty-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.ResultsOur 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.ConclusionThese 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.

Highlights

Reflexology is an alternative medical practice that produces beneficial effects by applying pressure to specific reflex areas
The results suggest that a robust relationship exists between tactile stimulation of the eye reflex area and neural activity representing the somatosensory percept of the reflexological stimulation of the corresponding body part
Several neuroimaging studies of acupuncture have suggested that stimulation of different acupoints on upper and lower limbs led to activation in somatotopically different locations [8,24]

Summary

Introduction

Reflexology is an alternative medical practice that produces beneficial effects by applying pressure to specific reflex areas. Reflexology is an alternative medical practice that produces beneficial effects on the human body by applying pressure to specific points or areas on the feet, hands, and ears called “reflex areas.”. It is a kind of massage therapy that is performed without using any special instruments (i.e., uses hands only). The modern concept of reflexology was introduced in both the U.S and Europe in the early 20th century [1], and it is believed to help eliminate stress, improve blood circulation, and restore the psychological balance of the body [2] It is practiced throughout the world and several clinical studies have shown positive effects of this practice, the precise mechanisms underpinning its clinical effectiveness have not been elucidated [3,4,5]. As for touch massage, including reflexology, a relaxing effect of reflexology was observed using electroencephalography (EEG) [11], pleasant touch massage induced activation of the pregenual anterior cingulate cortex [12], and reflexological treatments affected resting-state neural activity in the retrosplenial/posterior cingulated cortex [13]

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Conclusion