Decreased peripheral and central responses to acupuncture stimulation following modification of body ownership

Cognitive and affective interaction with somatosensory afference in acupuncture-a specific brain response to compound stimulus

Introduction

Acupuncture is a clinical intervention consisting of multiple stimulus components, including somatosensory stimulation and manipulation of therapeutic context. Existing findings in neuroscience consolidated cognitive modulation to somatosensory afferent process, which could differ from placebo mechanism in brain. Here, we aimed to identify intrinsic process of brain interactions induced by compound stimulus of acupuncture treatment.

Methods

To separately and comprehensively investigate somatosensory afferent and cognitive/affective processes in brain, we implemented a novel experimental protocol of contextual manipulation with somatosensory stimulation (real acupuncture: REAL) and only contextual manipulation (phantom acupuncture: PHNT) for fMRI scan, and conducted independent component (IC)-wise assessment with the concatenated fMRI data.

Results

By our double (experimentally and analytically) dissociation, two ICs (CA1: executive control, CA2: goal-directed sensory process) for cognitive/affective modulation (associated with both REAL and PHNT) and other two ICs (SA1: interoceptive attention and motor-reaction, SA2: somatosensory representation) for somatosensory afference (associated with only REAL) were identified. Moreover, coupling between SA1 and SA2 was associated with a decreased heart rate during stimulation, whereas CA1 was associated with a delayed heart rate decrease post-stimulation. Furthermore, partial correlation network for these components demonstrated a bi-directional interaction between CA1 and SA1/SA2, suggesting the cognitive modulation to somatosensory process. The expectation for the treatment negatively affected CA1 but positively affected SA1 in REAL, whereas the expectation positively affected CA1 in PHNT.

Discussion

These specific cognitive-somatosensory interaction in REAL were differed from vicarious sensation mechanism in PHNT; and might be associated with a characteristic of acupuncture, which induces voluntary attention for interoception. Our findings on brain interactions in acupuncture treatment elucidated the underlying brain mechanisms for compound stimulus of somatosensory afferent and therapeutic contextual manipulation, which might be a specific response to acupuncture.

The role of visual expectations in acupuncture analgesia: A quantitative electroencephalography study

Acupuncture is a complex treatment comprising multisensory stimulation, including visual and tactile sensations and experiences of body ownership. The purpose of this study was to investigate the role of these three components of acupuncture stimulation in acupuncture analgesia. 40 healthy volunteers participated in the study and received acupuncture treatment under three different conditions (real-hand, rubber-hand synchronous, and rubber-hand asynchronous). The tolerance for heat pain stimuli was measured before and after treatment. Brain oscillation changes were also measured using electroencephalography (EEG). The pain tolerance was significantly increased after acupuncture treatment under all three conditions. Noticeable deqi (needle) sensations in response to acupuncture stimulation of the rubber hand were found under both rubber-hand synchronous and rubber-hand asynchronous conditions. Deqi sensations were significantly correlated with acupuncture analgesia only under the rubber-hand synchronous condition. Increased delta and decreased theta, alpha, beta, and gamma waves were observed after acupuncture treatment under all three conditions. Our findings clarified the role of cognitive components of acupuncture treatment in acupuncture analgesia through the rubber-hand illusion. This study is a first step toward separating various components of acupuncture analgesia, i.e. visual, tactile, and body ownership, and utilizing those components to maximize analgesic effects.

Embodying an artificial hand increases blood flow to the investigated limb [version 3; peer review: 2 approved]

Background

The autonomic nervous system is the main determinant of the blood flow directed towards a body part, and it is tightly connected to the representation of the body in the brain; would the experimental modulation of the sense of limb ownership affect its blood perfusion?

Methods

In healthy participants, we employed the rubber hand illusion paradigm to modulate limb ownership while we monitored the brachial artery blood flow and resistance index within the investigated limb.

Results

In all conditions with brush-stroking, we found an initial drop in the blood flow due to tactile stimulation. Subsequently, in the illusion condition (where both the rubber and real hand synchronous brush-stroking were present), the blood flow rose significantly faster and reached significantly higher values. Moreover, the increase in blood flow correlated with the extent of embodiment as measured by questionnaires and correlated negatively with the change of peripherical vascular resistance.

Conclusions

These findings suggest that modulating the representation of a body part impacts its blood perfusion.

Embodying an artificial hand increases blood flow to the investigated limb

Background: The autonomic nervous system is the main determinant of the blood flow directed towards a body part, and it is tightly connected to the representation of the body in the brain; would the experimental modulation of the sense of ownership of the limb affect its blood perfusion? Methods: In healthy participants, we employed the rubber hand illusion paradigm to modulate limb ownership while we monitored the brachial artery blood flow and resistance of the investigated limb. Results: In all conditions with brush-stroking, we found an initial drop in the blood flow due to tactile stimulation. Subsequently, in the illusion condition where both the rubber and real hand experience synchronous brush-stroking, the blood flow rose significantly faster and reached significantly higher values. Moreover, the increase in blood flow correlated to the embodiment level measured by questionnaires and, negatively, to the change of peripherical vascular resistance. Conclusions: These findings demonstrate that modulating the representation of a body part impacts its blood perfusion.

Treatment of Rosacea using acupuncture for improving the local skin microcirculation: A case report

RATIONALE

Rosacea is an irritating disease that affects patients' health and life quality. The current treatments for rosacea have limited efficacy and are generally not satisfying most patients. This report presents a patient diagnosed with rosacea who was treated with acupuncture to a satisfactory effect. Laser Doppler was used to measure the local blood perfusion of the nose before, during, and after acupuncture treatment. The Dermatology Life Quality Index (DLQI) was used to measure the impact of rosacea on the quality of the patient's life.

PATIENT CONCERNS

A 52-year-old woman had been diagnosed with rosacea 18 months before this study. She had tried medical treatments in other hospitals with metronidazole cream, antifungal drugs, and steroidal ointments, but the effect was poor and limited.

DIAGNOSES

In this study, the diagnosis of rosacea (stage I, subtype Erythematotelangiectatic) was made by a dermatologist according to physical examination).

INTERVENTIONS

The patient's treatment included a half-hour of acupuncture 3 times per week.

OUTCOMES

The patient experienced significant improvements in the region around the nose after 3 sessions of acupuncture treatment within the first week and reported that there was no relapse for 6 months after acupuncture treatment. The perfusion of blood flow was redistributed during and after acupuncture treatment according to laser Doppler measurements. The patient's DLQI score substantially improved. The patient was generally satisfied with the acupuncture treatment.

LESSONS

The results suggested that acupuncture might be an alternative therapy for facial localized rosacea. As well, acupuncture may be effective in treating rosacea through redistributing micro-circulation of blood at the localized area of effect. The overall costs of the rosacea treatment may be reduced, provided that this therapy is demonstrated to be effective in future controlled studies.

Brain activation during the expectations of sensory experience for cutaneous electrical stimulation

The brain actively interprets sensory inputs by integrating top-down and bottom-up information. Humans can make inferences on somatosensation based on prior experiences and expectations even without the actual stimulation. We used functional magnetic resonance imaging to investigate the neural substrates of the expectations of the sensory experience of cutaneous electrical stimulation on acupoint without actual stimuli. This study included 22 participants who wore sticker-type electrodes attached on three different acupoints on different body regions: CV17 (chest), CV23 (chin), and left PC6 (arm). Participants evaluated de qi sensations after they expected electrical stimulation on those points in random order without actual stimulation. All stimuli were presented with corresponding visual information of the stimulation sites. The control condition included the same visual information but outside the body. The expectations of cutaneous electrical stimuli without actual stimulation on three acupoints resulted in greater de qi sensation compared to the control condition. Cognitive components of cutaneous electrical stimulation exhibited greater brain activation in the anterior insula, pre-supplementary motor area, and secondary somatosensory area. The expectations of acupuncture stimulation exhibited a distinct experience of somatosensation as well as brain activations in insula and pre-supplementary motor area. Our findings suggest that the sensory experience of the pseudo-cutaneous stimulation may be derived from the predictive role of the salience network in monitoring internal and external body states.

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The pseudo-cutaneous stimulation can elicit remarkable somatic sensations.

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Insula and pre-SMA are involved in the expectations of sensory experience.

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Somatic sensation from pseudo-stimulation is influenced by top-down information.

Investigation of the Phenomenon of Propagated Sensation along the Channels in the Upper Limb Following Administration of Acupuncture and Mock Laser

BACKGROUND

Similar to De Qi psychophysical responses, propagated sensation along the channels (PSC) is considered an important phenomenon in traditional Chinese acupuncture. In acupuncture clinical trials, different acupuncture manipulation techniques are used to enhance the propagation of sensation along the channels to facilitate an optimum therapeutic result.

AIM

To examine and compare the PSC reported by participants in a clinical trial following the administration of acupuncture and inactive mock laser.

METHODS

The study was embedded in a two-arm parallel design multicenter, randomized clinical trial, the Tennis Elbow Acupuncture-International Study-China, Hong Kong, Australia, Italy (TEA IS CHAI). Needle sensations were measured using a validated instrument, the Massachusetts General Hospital Acupuncture Sensation Spreading Scale. Ninety-six participants with lateral elbow pain were randomly allocated into two groups in a 1:1 ratio; the acupuncture treatment group (n = 47) and the mock laser control group (n = 49). Participants in both groups received the intervention at two acupoints, LI10 and LI11, consisting of 2 minutes of either standardized needle manipulation or mock laser at each acupoint with a rest period between each intervention period. Data were collected immediately following the interventions at the first and the ninth session within the clinical trial.

RESULTS

Although participants in both groups perceived PSC radiating to similar sites along the upper limb, the frequency of the reported radiation sites among the two intervention groups for both radiation up the limb (p < 0.05) and radiation down the limb (p < 0.001) were statistically significantly different. Among the radiating sensation sites recorded within the two study groups, the sensations were reported as radiating a greater distance down the forearm to the wrist compared to up the arm. Evaluation of PSC across the four study sites revealed a statistically significant difference in frequency of the reported radiation down the limb sites in each study group and radiation up the limb sites only in control group only (p < 0.001).

CONCLUSION

The findings of the study demonstrated that the PSC phenomenon is not just associated with needling but can be perceived when using a mock laser.

TRIAL REGISTRATION

Australian and New Zealand Clinical Trial Registry reference: ACTRN12613001138774 on 11th of October 2013.

Psychophysical responses in patients receiving a mock laser within context of an acupuncture clinical trial: an interoceptive perspective

Background

The psychophysical responses induced by verum acupuncture are characterized by a constellation of unique subjective sensory responses commonly termed De Qi. Furthermore, a variety of sham interventions have been used as a control for acupuncture clinical trials. Indeed, one such control has been mock laser which has been used as control intervention in several acupuncture clinical controlled trials. The current study aim was to examine the De Qi sensory responses and its related characteristics elicited from acupuncture and compare them to those reported following sham laser in participants enrolled in a clinical trial.

Methods

The study was embedded in a multi-center, two-arm randomised clinical trial, which evaluated the effect of acupuncture on lateral elbow pain. De Qi was assessed using the Massachusetts General Hospital Acupuncture Sensation Scale (MASS). Ninety-six participants were randomly allocated to receive either acupuncture (n = 47) or mock laser (n = 49) at the acupoints LI 10 and LI 11.

Results

Participants in both intervention groups reported similar De Qi psychophysical characteristics; however, both intensity and frequency of the individually perceived De Qi characteristics were significantly higher in the acupuncture group. ‘Soreness’, ‘deep pressure’, and ‘fullness-distension’ in the acupuncture group and ‘tingling’, and ‘sharp pain’ in mock laser group, were identified as the leading characteristics. Similar level of MASS De Qi Index (MDI) scores were reported for ‘Hong Kong-China’ and ‘Australia-Italy’ with a significantly higher level of De Qi reported by ‘Hong Kong-China’. Furthermore, two distinct De Qi categories were identified, namely De Qi (in line with classical sensory responses of Suan, Ma, Zhang, and Zhong) and pain.

Conclusions

Subjective ‘somatic or interoceptive awareness’ should be taken into account when De Qi psychophysical responses are examined. The study accentuates the necessity and the significance of further research into interoception phenomenon which may contribute to a better understanding of the placebo effect and De Qi psychophysical responses.

Trial registration

Australian and New Zealand Clinical Trial Registry reference: ACTRN12613001138774 on 11th of October 2013.

Placebo Analgesia From a Rubber Hand

Placebo analgesia, reductions in pain after administration of an inert treatment, is a well documented phenomenon. We report, to our knowledge, the first demonstration that placebo analgesia can be experienced when a sham analgesic is applied onto a rubber hand. The effect was obtained by exploiting the rubber hand illusion, in which ownership is felt over a rubber arm that is unattached to the body. Under conditions of synchronous as well as asynchronous visuotactile stimulation, a thermal pain stimulus was delivered on the real arm of 20 participants and seemingly also on the rubber arm, before and after applying a sham analgesic and a control cream only to the rubber arm. During synchronous visuotactile stimulation, pain was experienced on the rubber arm, and the application of the sham analgesic to the rubber arm significantly decreased the severity of reported pain. This shows that experience of the body can modulate expectations and the induction of placebo analgesia.

PERSPECTIVE

This article presents an experiment suggesting that a placebo treatment applied to a rubber hand during the rubber hand illusion can produce placebo analgesia. This finding indicates that embodiment may influence the placebo effect, a previously unexamined factor in the treatment process with potential applications to treatment administration.

The role of touch in acupuncture treatment

Acupuncture is a therapeutic treatment that is characterised by the insertion of a needle at a particular location on the body. Acupuncture stimulation includes sensory-discriminative and affective-social touch dimensions. In this review, we discuss the role of touch during acupuncture stimulation with an emphasis on the therapeutic, sensory-discriminative and affective-social aspects. In the discriminative dimension, de qi, which is associated with needling, includes a combination of various sensations, such as heaviness, numbness, soreness and distension. Achieving the appropriate de qi sensation appears to be fundamental to the therapeutic outcome following acupuncture treatment. In the affective dimension, the acupuncture procedure typically includes gentle manual touch stimulation, which induces feelings of calm and well-being, perhaps by activating C tactile fibres. Enhanced activity of C tactile afferents may induce a 'limbic touch' response, resulting in emotional and hormonal reactions. Because acupuncture is a 'therapist intensive' and complex intervention, it is necessary to understand the role of social touch between the practitioner and patient. Both sensory-discriminative and affective-social touch aspects play an important role in the therapeutic effect of acupuncture treatment in clinical practice.

Neural Network Underlying Recovery from Disowned Bodily States Induced by the Rubber Hand Illusion

We used functional magnetic resonance imaging to investigate how causal influences between brain regions during the rubber hand illusion (RHI) are modulated by tactile and visual stimuli. We applied needle rotations during the RHI in two different ways: one was with the real hand (reinstantiation by tactile stimuli, R-TS) and the other was with the rubber hand (reinstantiation by visual stimuli, R-VS). We used dynamic causal modeling to investigate interactions among four relevant brain regions: the ventral premotor cortex (PMv), the intraparietal sulcus (IPS), the secondary somatosensory cortex (SII), and the lateral occipitotemporal cortex (LOC). The tactile aspects of needle rotations changed the effective connectivity by directly influencing activity in the SII, whereas visual aspects of needle rotation changed the effective connectivity by influencing both the SII and the LOC. The endogenous connectivity parameters between the IPS and the PMv were reduced significantly in the R-TS condition. The modulatory parameters between the IPS and the PMv were enhanced significantly in the R-TS condition. The connectivity patterns driven by disowned bodily states could be differentially modulated by tactile and visual afferent inputs. Effective connectivity between the parietal and frontal multimodal areas may play important roles in the reinstantiation of body ownership.

Cortical Activation Patterns of Bodily Attention triggered by Acupuncture Stimulation

We investigated commonalities and differences in brain responses to enhanced bodily attention around acupuncture points with and without stimulation. Fourteen participants received acupuncture needles at both PC6 and HT7 acupoints in the left hand. To enhance bodily attention to acupoints, participants responded to the locations of stimulations in a two-alternative forced choice task. Two fMRI scans were taken in a block design: session 1 labeled with manual stimulation (genuine stimulation) and session 2 labeled with electro-acupuncture (pseudo-stimulation). To compare cortical activation patterns, data were analyzed using the Freesurfer software package. Both genuine-and pseudo-stimulation resulted in brain activations in the insula, anterior cingulate cortex, secondary somatosensory cortex, superior parietal cortex, and brain deactivation in the medial prefrontal cortex, posterior cingulate cortex, inferior parietal cortex, and the parahippocampus. Genuine acupuncture stimulation exhibited greater brain activation in the posterior insula, posterior operculum and the caudal part of the anterior cingulate cortex, compared with pseudo-stimulation. We demonstrated that enhanced bodily attention triggered by genuine acupuncture stimulation can activate the salience network and deactivate the default mode network regardless of the type of stimulation. The component of enhanced attention to a certain part of the body is significant in the brain response to acupuncture stimulation.

Brain responses to acupuncture stimulation in the prosthetic hand of an amputee patient

This report describes the brain responses to acupuncture in an upper limb amputee patient. A 62-year-old male had previously undergone a lower left arm amputation following an electrical accident. Using functional MRI, we investigated brain responses to acupuncture stimulation in the aforementioned amputee under three conditions: (a) intact hand, (b) prosthetic hand (used by the patient), and (c) fake fabric hand. The patient described greater de qi sensation when he received acupuncture stimulation in his prosthetic hand compared to a fake hand, with both stimulations performed in a similar manner. We found enhanced brain activation in the insula and sensorimotor cortex in response to acupuncture stimulation in the amputee's prosthetic hand, while there was only minimal activation in the visual cortex in response to acupuncture stimulation in a fake hand. The enhanced brain responses to acupuncture stimulation of the patient's prosthetic hand might be derived from cortical reorganisation, as he has been using his prosthetic hand for over 40 years. Our findings suggest the possible use of acupuncture stimulation in a prosthetic hand as an enhanced sensory feedback mechanism, which may represent a new treatment approach for phantom limb pain.

Acupuncture-brain interactions as hypothesized by mood scale recordings

Mood expressions encompassing positive scales like "activity, elation, contemplation, calmness" and negative scales like "anger, excitement, depression, fatigue" were applied for introducing a new tool to assess the effects of acupuncture on brain structures. Traditional acupuncture points defined in the literature for their effects on task negative and task positive brain structures were applied to chronic disease patients supposed to have dominant negative mood scales. Burn-out syndrome (n=10) and female chronic pain patients (n=22) showed a significant improvement on positive mood scales and a decline in negative mood scales after 10 acupuncture sessions. We observed a direct effect of acupuncture on brain structures in 5 burn-out syndrome patients showing an immediate, fast suppression of unusual slow high amplitude EEG waves in response to acupuncture needle rotation. These EEG waves described here for the first time in awake patients disappeared after 10 sessions but gradually returned after 1-1.5 years without acupuncture. This was accompanied with deterioration of positive mood scales and a return to negative mood scales. Both male (n=16) and female chronic pain patients reported a significant decrease of pain intensity after 10 sessions. Female patients only, however, showed a linear correlation between initial pain intensity and pain relief as well as a linear correlation between changes in pain intensity and mood scales accompanied by a drop of their heart rate during the acupuncture sessions. We hypothesized that mood scale recordings are a sensitive and specific new tool to reveal individual acupuncture-brain interaction.

Psychophysical and neurophysiological responses to acupuncture stimulation to incorporated rubber hand

From a neuroscientific perspective, the sensations induced by acupuncture are not only the product of the bottom-up modulation of simple needling at somatosensory receptors, but also of the reciprocal interaction of top-down modulation from the brain. The present study investigated whether acupuncture stimulation to incorporated body parts produces brain responses that are similar to the responses observed following acupuncture stimulation to the real hand. The present study included 17 participants who watched a rubber hand being synchronously stroked with their unseen left hand to induce incorporation of the rubber hand into their body. After the experimental modification of body ownership, acupuncture needle stimulation was applied to the LI4 acupoint on the incorporated rubber hand while brain activity was measured with functional magnetic resonance imaging (fMRI). When the rubber hand was fully incorporated with the real body, acupuncture stimulation to the rubber hand resulted in the experience of the DeQi sensation as well as brain activations in the dorsolateral prefrontal cortex (DLPFC), insula, secondary somatosensory cortex (SII), and medial temporal (MT) visual area. The insular activation was associated with the DeQi sensation from the rubber hand. The psychophysical and neurophysiological responses associated with acupuncture stimulation to the incorporated rubber hand were influenced by an enhanced bodily awareness of the hand, which was likely due to top-down modulation from the interoceptive system in the brain.

When pain is not only pain: inserting needles into the body evokes distinct reward-related brain responses in the context of a treatment

The aim of this study was to compare behavioral and functional brain responses to the act of inserting needles into the body in two different contexts, treatment and stimulation, and to determine whether the behavioral and functional brain responses to a subsequent pain stimulus were also context dependent. Twenty-four participants were randomly divided into two groups: an acupuncture treatment (AT) group and an acupuncture stimulation (AS) group. Each participant received three different types of stimuli, consisting of tactile, acupuncture, and pain stimuli, and was given behavioral assessments during fMRI scanning. Although the applied stimuli were physically identical in both groups, the verbal instructions differed: participants in the AS group were primed to consider the acupuncture as a painful stimulus, whereas the participants in the AT group were told that the acupuncture was part of therapeutic treatment. Acupuncture yielded greater brain activation in reward-related brain areas (ventral striatum) of the brain in the AT group when compared to the AS group. Brain activation in response to pain stimuli was significantly attenuated in the bilateral secondary somatosensory cortex and the right dorsolateral prefrontal cortex after prior acupuncture needle stimulation in the AT group but not in the AS group. Inserting needles into the body in the context of treatment activated reward circuitries in the brain and modulated pain responses in the pain matrix. Our findings suggest that pain induced by therapeutic tools in the context of a treatment is modulated differently in the brain, demonstrating the power of context in medical practice.