Modifying Bodily Self-Awareness during Acupuncture Needle Stimulation Using the Rubber Hand Illusion

Abstract

Background. The rubber hand illusion (RHI) is an experimental paradigm that manipulates important aspects of body self-awareness. Objectives. We were interested in whether modifying bodily self-awareness by manipulation of body ownership and visual expectations using the RHI would change the subjective perception of pain as well as the autonomic response to acupuncture needle stimulation. Methods. Acupuncture needle stimulation was applied to the real hand during the RHI with (experiment 1) or without (experiment 2) visual expectation while measuring concurrent autonomic changes such as the skin conductance response (SCR). Subjective responses such as perception of the RHI and perceived pain were measured by questionnaires. Results. In experiment 1, the amplitude of the increase in SCR was visibly higher during the synchronous session compared with that of the asynchronous session. In experiment 2, the amplitude of the increase of SCR was lower for the synchronous session compared with that for the asynchronous session. Comparing these two experiments, the visual expectation of needle stimulation produced a greater autonomic response to acupuncture stimulation. Conclusions. Our findings suggest that the sympathetic response to acupuncture needle stimulation is primarily influenced by visual expectation rather than by modifications of body ownership.

Decreased Peripheral and Central Responses to Acupuncture Stimulation following Modification of Body Ownership

“…In the current study, we found no significant differences of subjective DeQi ratings between the two sessions. Even though there were two different characteristics of acupuncture sensations, such as the pain domain and DeQi domain [41] , our findings are partially supporting the previous findings that there were no differences of pain ratings during the RHI [36] , [49] . Although we did not find significant differences of subjective DeQi ratings between the two sessions, differences of brain activations to acupuncture stimulation in the posterior insula was associated with the difference of DeQi sensation between the two sessions in the current study.…”

“…Mohan et al have failed to demonstrate that the RHI modulate pain threshold or pain evoked by individually calibrated high and low painful stimuli delivered on the real arm [49] . Our previous study also found no significant differences in self-reported pain rating to acupuncture stimulation between the asynchronous and the synchronous session [36] . In the current study, we found no significant differences of subjective DeQi ratings between the two sessions.…”

“…In order to minimize visual differences between the rubber hand and the real hand, on the other hand, we performed experiment 2 with the acupuncture needle inserted into the real hand as well as in the rubber hand. In our previous study, the sympathetic activations to acupuncture stimulation in the real hand were markedly higher during the synchronous session compared to that of the asynchronous session only when a visual expectation of the acupuncture needle stimulation existed in the rubber hand [36] . In this case, it is assumed that the participants seemed to have already allowed the incorporation of the artificial body part into their self-representation, and can experience an additional “visual capture” of the acupuncture needling.…”

“…From the perspective of cognitive neuroscience, acupuncture is not only seen as a ‘simple needling’ but also as a complex treatment comprised of multimodal sensory stimulation that interacts with various factors, including bodily self-awareness [36] , [37] . The role of psychosocial and contextual factors, including body image and body schema, are thought to exert an important influence on the clinical effects of acupuncture [38] .…”

Multisensory Integration in the Virtual Hand Illusion with Active Movement

“…We also expect that our study can improve the sense of immersion in VR based clinical applications, such as treatment for phantom limb pain [33] and pain relief during acupuncture [34]. A network of multisensory and homeostatic brain areas was reported to be responsible for maintaining a “body-matrix” [35].…”