Hypnosis and top-down regulation of consciousness

Trait responsiveness to verbal suggestions predicts nocebo responding: A meta-analysis

BACKGROUND

Nocebo responding involves the experience of adverse health outcomes in response to contextual cues. These deleterious responses impact numerous features of mental and physical health but are characterized by pronounced heterogeneity. Suggestion is widely recognized as a contributing factor to nocebo responding but the moderating role of trait responsiveness to verbal suggestions (suggestibility) in nocebo responding remains poorly understood.

OBJECTIVE

We conducted a pre-registered meta-analysis (PROSPERO registration number CRD42023425605) to quantitatively synthesize available research on the relationship between suggestibility and nocebo responding.

METHODS

Four electronic databases were searched for original studies involving both the assessment of suggestibility and symptom reports in response to an inactive stimulus.

RESULTS

Of 7729 search results, 10 articles presenting 13 correlations between suggestibility and nocebo responding were analysed. A random-effects meta-analysis revealed a significant, albeit weak, positive correlation, r = .21 [95% CI: .04, .37], between suggestibility and nocebo responses, such that more highly suggestible individuals displayed larger responses. Sensitivity and meta-regression analyses demonstrated that studies of higher methodological quality, including those that maintained experimenter blinding, exhibited stronger effect sizes.

CONCLUSION

These results corroborate proposals that trait responsiveness to verbal suggestions confers greater response to nocebos and warrants renewed attention to the role of suggestibility in symptom induction and perception.

A neurocognitive pathway for engineering artificial touch

Artificial haptics has the potential to revolutionize the way we integrate physical and virtual technologies in our daily lives, with implications for teleoperation, motor skill acquisition, rehabilitation, gaming, interpersonal communication, and beyond. Here, we delve into the intricate interplay between the somatosensory system and engineered haptic inputs for perception and action. We critically examine the sensory feedback's fidelity and the cognitive demands of interfacing with these systems. We examine how artificial touch interfaces could be redesigned to better align with human sensory, motor, and cognitive systems, emphasizing the dynamic and context-dependent nature of sensory integration. We consider the various learning processes involved in adapting to artificial haptics, highlighting the need for interfaces that support both explicit and implicit learning mechanisms. We emphasize the need for technologies that are not only physiologically biomimetic but also behaviorally and cognitively congruent with the user, affording a range of alternative solutions to users' needs.

Ongoing Dynamics of Peak Alpha Frequency Characterize Hypnotic Induction in Highly Hypnotic-Susceptible Individuals

Hypnotic phenomena exhibit significant inter-individual variability, with some individuals consistently demonstrating efficient responses to hypnotic suggestions, while others show limited susceptibility. Recent neurophysiological studies have added to a growing body of research that shows variability in hypnotic susceptibility is linked to distinct neural characteristics. Building on this foundation, our previous work identified that individuals with high and low hypnotic susceptibility can be differentiated based on the arrhythmic activity observed in resting-state electrophysiology (rs-EEG) outside of hypnosis. However, because previous work has largely focused on mean spectral characteristics, our understanding of the variability over time of these features, and how they relate to hypnotic susceptibility, is still limited. Here we address this gap using a time-resolved assessment of rhythmic alpha peaks and arrhythmic components of the EEG spectrum both prior to and following hypnotic induction. Using multivariate pattern classification, we investigated whether these neural features differ between individuals with high and low susceptibility to hypnosis. Specifically, we used multivariate pattern classification to investigate whether these non-stationary neural features could distinguish between individuals with high and low susceptibility to hypnosis before and after a hypnotic induction. Our analytical approach focused on time-resolved spectral decomposition to capture the intricate dynamics of neural oscillations and their non-oscillatory counterpart, as well as Lempel-Ziv complexity. Our results show that variations in the alpha center frequency are indicative of hypnotic susceptibility, but this discrimination is only evident during hypnosis. Highly hypnotic-susceptible individuals exhibit higher variability in alpha peak center frequency. These findings underscore how dynamic changes in neural states related to alpha peak frequency represent a central neurophysiological feature of hypnosis and hypnotic susceptibility.

How hypnotic suggestions work - A systematic review of prominent theories of hypnosis

In recent decades, hypnosis has increasingly moved into the mainstream of scientific inquiry. Hypnotic suggestions are frequently implemented in behavioral, neurocognitive, and clinical investigations and interventions. Despite abundant reports about the effectiveness of suggestions in altering behavior, perception, cognition, and agency, no consensus exists regarding the mechanisms driving these changes. This article reviews competing theoretical accounts that address the genesis of subjective, behavioral, and neurophysiological responses to hypnotic suggestions. We systematically analyze the broad landscape of hypnosis theories that best represent our estimation of the current status and future avenues of scientific thinking. We start with procedural descriptions of hypnosis, suggestions, and hypnotizability, followed by a comparative analysis of systematically selected theories. Considering that prominent theoretical perspectives emphasize different aspects of hypnosis, our review reveals that each perspective possesses salient strengths, limitations, and heuristic values. We highlight the necessity of revisiting extant theories and formulating novel evidence-based accounts of hypnosis.

An interhemispheric frontoparietal network supports hypnotic states

Understanding the neural substrate of altered conscious states is an important cultural, scientific, and clinical endeavour. Although hypnosis causes strong shifts in conscious perception and cognition, it remains largely unclear how hypnosis affects information processing in cortical networks. Here we manipulated the depth of hypnotic states to study information processing between cortical regions involved in attention and awareness. We used high-density Electroencephalography (EEG) to record resting-state cortical activity from 30 hypnosis experts during two hypnotic states with different depth. Each participant entered a light and a deep hypnotic state as well as two well-matched control states. Bridging top-down and lateralisation models of hypnosis, we found that interhemispheric frontoparietal connectivity distinguished hypnosis and control conditions, while no difference was found between the two hypnotic states. Using a graph-theoretic measure, we revealed that the amount of information passing through individual nodes (measured via betweenness centrality) is reduced during hypnosis relative to control states. Finally, we found that theta power was enhanced during hypnosis. Our result contributes to the current discussion around a role for theta power in bringing about hypnotic states, as well as other altered conscious states. Overall, our findings support the notion that altered top-down control in frontoparietal regions facilitates hypnosis by integrating information between cortical hemispheres.

French Norms for a Shortened Online Adaptation of the Harvard Group Scale of Hypnotic Susceptibility, Form A

This study presents the norms and psychometric properties for a shortened online adaptation of a French version of the Harvard Group Scale of Hypnotic Susceptibility, Form A (HGSHS:A). Assessment of involuntariness and subjective intensity was added to the traditional scoring. A total of 373 individuals completed an online hypnotizability screening test on their own computer. Participants received the HGSHS:A script through an audio recording lasting about 30 minutes. The results showed that the item difficulty and reliability of the short online HGSHS:A were consistent with the offline version of the scale and with the reference samples. Involuntariness and subjective intensity corrections improved significantly the accuracy in the measurement of the scale and helped to dissociate between different phenomenologies in hypnotic responding. These findings indicate that the short online HGSHS:A is a reliable tool for measuring hypnotizability. Moreover, we suggest that using complementary measures of involuntariness and subjective intensity helps to shed more light on hypnotizability as part of a multi-componential approach to hypnotic response.

Cognitive simulation along with neural adaptation explain effects of suggestions: a novel theoretical framework

Hypnosis is an effective intervention with proven efficacy that is employed in clinical settings and for investigating various cognitive processes. Despite their practical success, no consensus exists regarding the mechanisms underlying well-established hypnotic phenomena. Here, we suggest a new framework called the Simulation-Adaptation Theory of Hypnosis (SATH). SATH expands the predictive coding framework by focusing on (a) redundancy elimination in generative models using intrinsically generated prediction errors, (b) adaptation due to amplified or prolonged neural activity, and (c) using internally generated predictions as a venue for learning new associations. The core of our treatise is that simulating proprioceptive, interoceptive, and exteroceptive signals, along with the top-down attenuation of the precision of sensory prediction errors due to neural adaptation, can explain objective and subjective hypnotic phenomena. Based on these postulations, we offer mechanistic explanations for critical categories of direct verbal suggestions, including (1) direct-ideomotor, (2) challenge-ideomotor, (3) perceptual, and (4) cognitive suggestions. Notably, we argue that besides explaining objective responses, SATH accounts for the subjective effects of suggestions, i.e., the change in the sense of agency and reality. Finally, we discuss individual differences in hypnotizability and how SATH accommodates them. We believe that SATH is exhaustive and parsimonious in its scope, can explain a wide range of hypnotic phenomena without contradiction, and provides a host of testable predictions for future research.

Inhibition in the emotional Hayling task: can hypnotic suggestion enhance cognitive control on a prepotent negative word?

Recent studies suggest that instrumental hypnosis is a useful experimental tool to investigate emotional and language processing effects. However, the capacity of hypnotic suggestions to intervene during the response inhibition of emotional words remains elusive. This study investigated whether hypnotic suggestion can improve the inhibition of prepotent negative word responses in an emotional Hayling sentence completion task. High-suggestible participants performed a computerised emotional Hayling task. They were first asked to select the appropriate words ending highly predictable sentences among two propositions (initiation part), and then to select the filler words that did not end the sentences correctly (inhibition part). Half of the expected final words had a negative emotional valence, while the other half was neutral. The task was performed in a control condition (without suggestion) and with a hypnotic suggestion to decrease emotional reactivity. The results revealed that hypnotic suggestion (compared to the control condition) hastened response times on negative final words in the inhibition part, showing that hypnotic suggestion can enhance cognitive control over prepotent negative word responses in a sentence completion task. We suggest that this modulation stems from a reduction in the emotional relevance of the final words caused by the hypnotic suggestion.

Comparing Neural Correlates of Consciousness: From Psychedelics to Hypnosis and Meditation

BACKGROUND

Pharmacological and nonpharmacological methods of inducing altered states of consciousness (ASCs) are becoming increasingly relevant in the treatment of psychiatric disorders. While comparisons between them are often drawn, to date no study has directly compared their neural correlates.

METHODS

To address this knowledge gap, we directly compared 2 pharmacological methods (psilocybin 0.2 mg/kg orally [n = 23] and lysergic acid diethylamide [LSD] 100 μg orally [n = 25]) and 2 nonpharmacological methods (hypnosis [n = 30] and meditation [n = 29]) using resting-state functional connectivity magnetic resonance imaging and assessed the predictive value of the data using a machine learning approach.

RESULTS

We found that 1) no network reached significance in all 4 ASC methods; 2) pharmacological and nonpharmacological interventions of inducing ASCs showed distinct connectivity patterns that were predictive at the individual level; 3) hypnosis and meditation showed differences in functional connectivity when compared directly and also drove distinct differences when jointly compared with the pharmacological ASC interventions; and 4) psilocybin and LSD showed no differences in functional connectivity when directly compared with each other, but they did show distinct behavioral-neural relationships.

CONCLUSIONS

Overall, these results extend our understanding of the mechanisms of action of ASCs and highlight the importance of exploring how these effects can be leveraged in the treatment of psychiatric disorders.

Hypnosis in psychotherapy, psychosomatics and medicine. A brief overview

Aspects of hypnosis and its application in psychotherapy, psychosomatics and medicine are examined and contextualized in the 250-year history of hypnosis. Imagination as an essential element of hypnotic treatments appeared as early as 1784 as an argument rejecting the theory of animal magnetism of Franz Anton Mesmer. In somnambulism of German romanticism, another proto-form of hypnosis after 1800, concepts of the mind-body problem were dealt with, which still characterize the understanding of unconscious mental processes today. Hypnosis was at the beginning of psychoanalysis, but was not pursued further by Sigmund Freud from 1900 onwards. Nevertheless, there were some hypnoanalytical approaches in the 20th century, as well as attempts to integrate hypnosis into behavior therapy. Techniques of imagination and relaxation combine both; in particular findings from cognitive psychology explain processes of both hypnosis and cognitive behavioral therapy. The influence of social psychology brought a new perspective to the debate about the nature of hypnosis, which continues to this day: is hypnosis to be understood as a special state of consciousness or is it a completely normal, mundane interaction? The experiments that were carried out to support one side or the other were also dependent on the hypnotizability of the subjects involved, as the more difficult hypnotic phenomena such as paralysis, hallucinations or identity delusions can only be demonstrated by highly hypnotizable subjects. The fact that these are not mere compliance reactions has now been proven by many studies using imaging techniques. But even those who are moderately hypnotizable benefit from hypnosis rituals. Variables postulated by socio-cognitive hypnosis researchers, such as motivation and expectation, are relevant, as is a good "hypnotic rapport." Practical application of hypnotherapy today is characterized by the innovative techniques and strategies developed by Milton H. Erickson. Research into the effectiveness of hypnosis in the field of psychotherapy and psychosomatics still leaves much to be done. The situation is different in the field of medical hypnosis, where there are considerably more studies with a satisfactory design and verifiable effects. However, the impact in practical application in everyday medical practice is still low. Newer developments such as virtual reality and artificial intelligence are being looked at with critical interest.

Gamma power and beta envelope correlation are potential neural predictors of deep hypnosis

Hypnosis is a psychological intervention that is commonly used to enhance the effectiveness of therapeutic suggestions. Despite extensive fascination and study, the neural mechanisms behind hypnosis remain elusive. In the current study, we undertook a systematic exploration of these neural correlates. We first extracted well-studied neurophysiological features from EEG sensors and source-localized data using spectral analysis and two measures of functional connectivity: weighted phase lag index (wPLI) and power envelope correlation (PEC). Next, we developed classification models that predicted self-rated hypnotic experience based on the extracted feature sets. Our findings reveal that gamma power computed on sensor-level data and beta PEC computed between source-localized brain networks are the top predictors of hypnosis depth. Further, a SHapley Additive exPlanations (SHAP) analysis suggested reduced gamma power in the midline frontal area and increased beta PEC between interhemispheric Dorsal Attention Networks (DAN) contribute to the hypnotic experience. These results broaden our understanding of the neural correlates of deep hypnosis, highlighting potential targets for future research. Moreover, this study demonstrates the potential of using predictive models in understanding the neural underpinnings of self-reported hypnotic depth, offering a template for future investigations.

Synthetic surprise as the foundation of the psychedelic experience

Psychedelic agents, such as LSD and psilocybin, induce marked alterations in consciousness via activation of the 5-HT2A receptor (5-HT2ARs). We hypothesize that psychedelics enforce a state of synthetic surprise through the biased activation of the 5-HTRs system. This idea is informed by recent insights into the role of 5-HT in signaling surprise. The effects on consciousness, explained by the cognitive penetrability of perception, can be described within the predictive coding framework where surprise corresponds to prediction error, the mismatch between predictions and actual sensory input. Crucially, the precision afforded to the prediction error determines its effect on priors, enabling a dynamic interaction between top-down expectations and incoming sensory data. By integrating recent findings on predictive coding circuitry and 5-HT2ARs transcriptomic data, we propose a biological implementation with emphasis on the role of inhibitory interneurons. Implications arise for the clinical use of psychedelics, which may rely primarily on their inherent capacity to induce surprise in order to disrupt maladaptive patterns.

Redefining hypnosis: A narrative review of theories to move towards an integrative model

Hypnosis is an ancient mind-body intervention that has regained interest with the surge of research in the last decade documenting its clinical validity. Yet, theoretical controversies and misconceptions prevail among theorists, clinicians, and the general public, impeding the understanding, acceptance, replication, and use of hypnosis. Providing adequate information, which dispels misconceptions and promotes more balanced views, is warranted to facilitate the implementation and adoption of hypnosis in clinical and research settings. This review re-examines the conceptualisation of hypnosis throughout history and the theoretical controversies surrounding it while highlighting their meeting points and clinical implications. Despite dichotomies, a broad agreement appears across theoretical approaches regarding hypnotic analgesia effects, key components, and vocabulary. Further, theories highlight key factors of hypnotic responding. For instance, social theories highlight social and contextual variables, whereas state theories highlight biopsychosocial mechanisms and individual factors. Based on theories, the terms hypnotherapy or clinical hypnosis are recommended to refer to the therapeutic use of hypnosis in psychotherapeutic and medical contexts, respectively. This review concludes with a model that integrates various theories and evidence and presents hypnosis as a complex multifaceted intervention encompassing multiple procedures, phenomena, and influencing factors. This review intends to deepen our understanding of hypnosis, and promote its more rapid adoption and adequate implementation in research and clinical contexts, in addition to steering research towards evidence-based hypnotic practice. The review can have important research and clinical implications by contributing to advancing knowledge regarding hypnotic procedures, phenomena, and influencing factors.

Brain Functional Correlates of Resting Hypnosis and Hypnotizability: A Review

This comprehensive review delves into the cognitive neuroscience of hypnosis and variations in hypnotizability by examining research employing functional magnetic resonance imaging (fMRI), positron emission tomography (PET), and electroencephalography (EEG) methods. Key focus areas include functional brain imaging correlations in hypnosis, EEG band oscillations as indicators of hypnotic states, alterations in EEG functional connectivity during hypnosis and wakefulness, drawing critical conclusions, and suggesting future research directions. The reviewed functional connectivity findings support the notion that disruptions in the available integration between different components of the executive control network during hypnosis may correspond to altered subjective appraisals of the agency during the hypnotic response, as per dissociated and cold control theories of hypnosis. A promising exploration avenue involves investigating how frontal lobes' neurochemical and aperiodic components of the EEG activity at waking-rest are linked to individual differences in hypnotizability. Future studies investigating the effects of hypnosis on brain function should prioritize examining distinctive activation patterns across various neural networks.

What is the Source of Hypnotic Responses?

The author proposes that hypnosis is a culture-bound concept that has misattributed - to suggestion and hypnosis - the functioning of a natural, freestanding, human ability to alter personal experience. The 18th-century attribution of these phenomena (to the suggestions of a magnetizer) continues today because science and Western culture still do not explicitly acknowledge that humans possess a natural capacity to intentionally alter their own experiences. Like every other human ability (e.g. athletic, artistic, musical, mathematical, etc.), utilization of the natural human ability to intentionally alter one's personal experience does not require suggestion, trance, or hypnotic induction. This ability has been studied for over 200 years under the conceptual aegis of suggestibility and hypnosis. As a consequence, the phenomena of this freestanding ability have been veiled and conflated with hypnosis, suggestion, suggestibility, and hypnotizability. One serious consequence of this conflation is an underdeveloped, nomological network of hypnosis-centric concepts that has impeded the integration of hypnosis with the rest of science.

Spiritual healing in palliative care with clinical hypnosis: neuroscience and therapy

THIS PAPER REVIEWS

The neuroscientific features of inner consciousness, including its role in suffering and in accessing states of mind that relieve suffering; details salient meditative and hypnotic approaches appropriate for palliative settings of care; discusses core principles and orientations shared by effective approaches; and proposes early integration of hypnotic training as a coping skill and a platform for spiritual exploration, as desired.

Investigating functional brain connectivity patterns associated with two hypnotic states

While there's been clinical success and growing research interest in hypnosis, neurobiological underpinnings induced by hypnosis remain unclear. In this fMRI study (which is part of a larger hypnosis project) with 50 hypnosis-experienced participants, we analyzed neural and physiological responses during two hypnosis states, comparing them to non-hypnotic control conditions and to each other. An unbiased whole-brain analysis (multi-voxel- pattern analysis, MVPA), pinpointed key neural hubs in parieto-occipital-temporal areas, cuneal/precuneal and occipital cortices, lingual gyri, and the occipital pole. Comparing directly both hypnotic states revealed depth-dependent connectivity changes, notably in left superior temporal/supramarginal gyri, cuneus, planum temporale, and lingual gyri. Multi-voxel- pattern analysis (MVPA) based seeds were implemented in a seed-to-voxel analysis unveiling region-specific increases and decreases in functional connectivity patterns. Physiologically, the respiration rate significantly slowed during hypnosis. Summarized, these findings foster fresh insights into hypnosis-induced functional connectivity changes and illuminate further knowledge related with the neurobiology of altered consciousness.

Creating critical palliative hypnotic adjustments: temporality, hope, and meaning

When cure is not possible, suffering often takes form as pain and distressing symptoms, death anxiety, existential distress, and meaninglessness. This paper describes important elements connecting palliative care principles with hypnotic approaches designed to provide support, palliate symptoms, foster hope, and address existential and spiritual distress. We offer a developmental process for and examples of hypnotic suggestions customized to simultaneously ameliorate physical symptoms and address profound distress arising from physical, social, psychological, existential, and spiritual challenges commonly encountered in terminal illness. This process necessarily requires use of the patient's vernacular to hypnotically deepen inwardly focused attention in order to explore and access internal resources, reframe negative automatic thoughts, and create positive meanings for experiences that disinvite suffering. Effective delivery utilizes cognitive tools such as clinical and scientific principles, artistic forms such as poetry and haiku, and a thorough assessment of needs. This approach strategically addresses an overarching dimension of temporality through suggestions that sequentially address multiple sources of suffering that are layered throughout the various dimensions of self. This requires focus and presence in the present moment; it ultimately fosters a therapeutic relationship that can safely hold past painful experience as helpful new meanings emerge that build resiliency for that experience. This work benefits from inwardly focused concentration and a holding environment to identify and access helpful inner resources, which include an increasingly malleable relationship with temporal memories.

Illness-Promoting Psychological Processes in Children and Adolescents with Functional Neurological Disorder

Previous studies suggest that subjective distress in children with functional neurological disorder (FND) is associated with stress-system dysregulation and modulates aberrant changes in neural networks. The current study documents illness-promoting psychological processes in 76 children with FND (60 girls and 16 boys, aged 10.00-17.08 years) admitted to the Mind-Body Program. The children completed a comprehensive family assessment and self-report measures, and they worked with the clinical team to identify psychological processes during their inpatient admission. A total of 47 healthy controls (35 girls and 12 boys, aged 8.58-17.92 years) also completed self-report measures, but were not assessed for illness-promoting psychological processes. Children with FND (vs. controls) reported higher levels of subjective distress (total DASS score, t(104.24) = 12.18; p ˂ 0.001) and more adverse childhood experiences across their lifespans (total ELSQ score, t(88.57) = 9.38; p ˂ 0.001). Illness-promoting psychological processes were identified in all children with FND. Most common were the following: chronic worries about schoolwork, friendships, or parental wellbeing (n = 64; 84.2%); attention to symptoms (n = 61; 80.3%); feeling sad (n = 58; 76.3%); experiencing a low sense of control (helplessness) in relation to symptoms (n = 44; 57.9%); pushing difficult thoughts out of mind (n = 44; 57.9%); self-critical rumination (n = 42; 55.3%); negative/catastrophic-symptom expectations (n = 40; 52.6%); avoidance of activities (n = 38; 50%); intrusive thoughts/feelings/memories associated with adverse events (n = 38, 50%); and pushing difficult feelings out of mind (n = 37; 48.7%). In children with FND-disabled enough to be admitted for inpatient treatment-illness-promoting psychological processes are part of the clinical presentation. They contribute to the child's ongoing sense of subjective distress, and if not addressed can maintain the illness process. A range of clinical interventions used to address illness-promoting psychological processes are discussed, along with illustrative vignettes.

Hypnotic suggestion modulates visual recognition of negative words depending on word arousal

This study examined whether and how emotional hypnotic suggestions modulate the visual recognition of negative words. We investigated the influence of hypnotic suggestions aimed at modifying emotional reactivity on the arousal effect in negative words. High and low suggestible individuals performed a go/no-go lexical decision task in three intra-individual conditions: with a suggestion to increase emotional reactivity, with a suggestion to decrease emotional reactivity and without hypnotic suggestion. Results showed that hypnotic suggestions modulated the arousal facilitation effect differently depending on the level of suggestibility of the participants. In high suggestible individuals, response times for low-arousal negative words varied oppositely according to the suggestion administered, while no modulations were retrieved for high-arousal ones. In contrast, no suggestion effects were found for low suggestible participants. Altogether, these findings suggest a higher influence of hypnotic suggestions on emotional words that require longer processing times in high suggestible individuals.

Reassessing referral of touch following peripheral deafferentation: The role of contextual bias

Some amputees have been famously reported to perceive facial touch as arising from their phantom hand. These referred sensations have since been replicated across multiple neurological disorders and were classically interpreted as a perceptual correlate of cortical plasticity. Common to all these and related studies is that participants might have been influenced in their self-reports by the experimental design or related contextual biases. Here, we investigated whether referred sensations reports might be confounded by demand characteristics (e.g., compliance, expectation, suggestion). Unilateral upper-limb amputees (N = 18), congenital one-handers (N = 19), and two-handers (N = 22) were repeatedly stimulated with computer-controlled vibrations on 10 body-parts and asked to report the occurrence of any concurrent sensations on their hand(s). To further manipulate expectations, we gave participants the suggestion that some of these vibrations had a higher probability to evoke referred sensations. We also assessed similarity between (phantom) hand and face representation in primary somatosensory cortex (S1), using functional Magnetic Resonance Imaging (fMRI) multivariate representational similarity analysis. We replicated robust reports of referred sensations in amputees towards their phantom hand; however, the frequency and distribution of reported referred sensations were similar across groups. Moreover, referred sensations were evoked by stimulation of multiple body-parts and similarly reported on both the intact and phantom hand in amputees. Face-to-phantom-hand representational similarity was not different in amputees' missing hand region, compared with controls. These findings weaken the interpretation of referred sensations as a perceptual correlate of S1 plasticity and reveal the need to account for contextual biases when evaluating anomalous perceptual phenomena.

Hypnotic suggestion versus sensory modulation of bodily awareness

Bodily awareness arises from somatosensory, vestibular, and visual inputs but cannot be reduced to these incoming sensory signals. Cognitive factors are known to also impact bodily awareness, though their specific influence is poorly understood. Here we systematically compared the effects of sensory (bottom-up) and cognitive (top-down) manipulations on the estimated size of body parts. Toward this end, in a repeated-measures design, we sought to induce the illusion that the right index finger was elongating by vibrating the biceps tendon of the left arm whilst participants grasped the tip of their right index finger (Lackner illusion; bottom-up) and separately by hypnotic suggestion (top-down), with a sham version of the Lackner illusion as an active control condition. The effects of these manipulations were assessed with perceptual and motor tasks to capture different components of the representation of body size. We found that hypnotic suggestion significantly induced the illusion in both tasks relative to the sham condition. The magnitudes of these effects were stronger than those in the Lackner illusion condition, which only produced a significantly stronger illusion than the sham condition in the perceptual task. We further observed that illusion magnitude significantly correlated across tasks and conditions, suggesting partly shared mechanisms. These results are in line with theories of separate but interacting representational processes for perception and action and highlight the influence of cognitive factors on low-level body representations.

A Qualitative Exploration of Weight Loss Experiences through Hypnotherapy

Hypnotherapy has been gaining recognition as an alternative treatment for excess weight problems. This qualitative study aims to explore individuals' experiences of losing weight through hypnotherapy and their perceived barriers and facilitators for healthy lifestyle changes. Semistructured interviews were conducted with 15 participants (11 women and 4 men; mean age of 23 years) who recorded having lost ≥5% weight after undergoing 3 hypnotherapy sessions previously at a public university in Terengganu, Malaysia. Each interview was audiotaped, transcribed, and analyzed using thematic analysis. The themes that emerged were the usefulness of hypnotherapy, barriers, and facilitators of healthy lifestyle changes. All participants contended that hypnotherapy played a role in their weight-loss journey through increased mindful eating and enhanced motivation to make lifestyle modifications. Barriers to healthy lifestyle changes included high costs of healthy foods and lack of support for healthy food sources in social and family settings. Hypnotherapy is essential as an adjunct tool in assisting weight loss. However, additional efforts are needed to improve support in the weight management journey.

The nature and persistence of the effects of posthypnotic suggestions on food preferences: The final report of an online study

The persistence of food preferences, which are crucial for diet-related decisions, is a significant obstacle to changing unhealthy eating behavior. To overcome this obstacle, the current study investigates whether posthypnotic suggestions (PHSs) can enhance food-related decisions by measuring food choices and subjective ratings. After assessing hypnotic susceptibility in Session 1, at the beginning of Session 2, a PHS was delivered aiming to increase the desirability of healthy food items (e.g., vegetables and fruit). After the termination of hypnosis, a set of two tasks was administrated twice, once when the PHS was activated and once deactivated in counterbalanced order. The task set consisted of rating 170 pictures of food items, followed by an online supermarket where participants were instructed to select enough food from the same item pool for a fictitious week of quarantine. After 1 week, Session 3 mimicked Session 2 without renewed hypnosis induction to assess the persistence of the PHS effects. The Bayesian hierarchical modeling results indicate that the PHS increased preferences and choices of healthy food items without altering the influence of preferences in choices. In contrast, for unhealthy food items, not only both preferences and choices were decreased due to the PHS, but also their relationship was modified. That is, although choices became negatively biased against unhealthy items, preferences played a more dominant role in unhealthy choices when the PHS was activated. Importantly, all effects persisted over 1 week, qualitatively and quantitatively. Our results indicate that although the PHS affected healthy choices through resolve, i.e., preferred more and chosen more, unhealthy items were probably chosen less impulsively through effortful suppression. Together, besides the translational importance of the current results for helping the obesity epidemic in modern societies, our results contribute theoretically to the understanding of hypnosis and food choices.

Comparative effects of hypnotic suggestion and imagery instruction on bodily awareness

Bodily awareness is informed by both sensory data and prior knowledge. Although misleading sensory signals have been repeatedly shown to affect bodily awareness, only scant attention has been given to the influence of cognitive variables. Hypnotic suggestion has recently been shown to impact visuospatial and sensorimotor representations of body-part size although the mechanisms subserving this effect are yet to be identified. Mental imagery might play a causal or facilitative role in this effect, as it has been shown to influence body awareness in previous studies. Nonetheless, current views ascribe only an epiphenomenal role to imagery in the implementation of hypnotic suggestions. This study compared the effects of hypnotic suggestion and imagery instruction for influencing the visuospatial and sensorimotor aspects of body-size representation. Both experimental manipulations produced significant increases (elongation) in both representations compared to baseline, although the effects were larger in the hypnotic suggestion condition. The effects of both manipulations were highly correlated across participants, suggesting overlapping mechanisms. Self-reports suggested that the use of voluntary imagery did not significantly contribute to the efficacy of either manipulation. Rather, top-down effects on body representations seem to be partly driven by response expectancies, spontaneous imagery, and hypnotic suggestibility in both conditions. These results are in line with current theories of suggestion and raise fundamental questions regarding the mechanisms driving the influence of cognition on body representations.

A neurophenomenological approach to non-ordinary states of consciousness: hypnosis, meditation, and psychedelics

No contemporary unifying framework has been provided for the study of non-ordinary states of consciousness (NSCs) despite increased interest in hypnosis, meditation, and psychedelics. NSCs induce shifts in experiential contents (what appears to the experiencer) and/or structure (how it appears). This can allow the investigation of the plastic and dynamic nature of experience from a multiscale perspective that includes mind, brain, body, and context. We propose a neurophenomenological (NP) approach to the study of NSCs which highlights their role as catalysts of transformation in clinical practice by refining our understanding of the relationships between experiential (subjective) and neural dynamics. We outline the ethical implications of the NP approach for standard conceptions of health and pathology as well as the crucial role of experience-based know-how in NSC-related research and application.

Modulation of attentional bias by hypnotic suggestion: experimental evidence from an emotional Stroop task

Hypnosis is considered a unique tool capable of modulating cognitive processes. The extent to which hypnotic suggestions intervenes is still under debate. This study was designed to provide a new insight into this issue, by focusing on an unintentional emotional process: attentional bias. In Experiment 1, highly suggestible participants performed three sessions of an emotional Stroop task where hypnotic suggestions aiming to increase and decrease emotional reactivity towards emotional stimuli were administered within an intra-individual design. Compared to a baseline condition (without hypnotic suggestion), a significant increase in attentional bias was found when a hypnotic suggestion to increase emotional reactivity was administered. In contrast, the bias was eliminated when a suggestion to decrease emotional reactivity was administered. Experiment 2 investigated the effect of session repetition on attentional bias across three successive experimental sessions without hypnosis, and showed that the emotional Stroop effect did not vary across sessions. Hence, session repetition could not account for part of the modulation of attentional bias in Experiment 1. Taken together, the results suggest that specific hypnotic suggestions can influence elicitation of unintentional emotional processing. The implications are discussed regarding the locus of intervention of hypnotic suggestion in cognitive and emotional processes.

The response set theory of hypnosis reconsidered: toward an integrative model

Irving Kirsch is a leading figure in the field of psychological science who has advanced our understanding of hypnosis in key respects that have withstood the tests of time and replication. We honor his prodigious contributions over his distinguished career and extend his response expectancy theory in an integrative model that encompasses predictive coding. We review the construct of expectancies that he articulated and championed for decades and extended in response set theory. We propose novel hypotheses to align his innovative contributions with the most current findings in psychological science and to acknowledge the heuristic value of his work. We especially focus on (I) how the response set theory can be conceptualized in terms of the predictive coding model and (II) psycho-social constructs that need to be considered to better understand the effects of expectancies on hypnotic phenomena in an open and evidence-based integrative model of hypnosis.

The use of audio self-hypnosis to promote weight loss using the transtheoretical model of change: a randomized clinical pilot trial

Background

Few studies suggest the use of hypnosis in weight loss may be beneficial, especially when in conjunction with other lifestyle modifications or cognitive behavioral therapy. The primary aim of this study was to determine the ability of self-hypnosis audiotape to promote weight loss by measuring its effects on the Transtheoretical Model (TTM) of change stages and processes.

Methods

This study is a 3-week randomized double-blinded parallel controlled trial among adults who have overweight or obesity. The intervention group listened to a self-hypnosis audio file while the control group listened to a placebo audio file.

Results

Forty-six participants completed the 3-week follow-up visit. There was no association between progression across stages of change and self-hypnosis (X2(2, 46) = 1.909, p-value = 0.580). Gender, baseline BMD, and baseline S-weight had no effect on the association between stage change progression and self-hypnosis. The mean difference in weight at 3 weeks was -0.63 ± 0.43 kg in the hypnosis group and 0.0 ± 1.5 kg in the control group, independent t-test, p = 0.148.

Conclusion

Self-hypnosis was not associated with a progression in the TTM's stages of change or with weight loss after 3 weeks. As this pilot study was underpowered, further research with larger sample size and an examination of the effect of various self-hypnosis content and duration is recommended.

Neurophysiology of hypnosis in chronic pain: A review of recent literature

Chronic pain is a complex phenomenon which includes biological, psychological, and socio-professional factors that undermine patients' everyday life. Currently, only few patients significantly benefit from pharmacological treatments and many have to stop them because of negative side effects. Moreover, no medication or treatment addresses all aspects of chronic pain at once (i.e., sensations, emotions, behaviors, and cognitions), positioning chronic pain as an important public health issue and thus contributing to high health-care costs. Consequently, patients and health-care providers are increasingly turning to complementary non-pharmacological techniques such as hypnosis. Clinical research has demonstrated a decrease of pain perception, pain interference, depression and anxiety, and an increase in global quality of life when patients with chronic pain have benefited from hypnosis learning. Neuroimaging studies offer a possible explanation of these results by focusing on neural processes of pain modulation in chronic pain patients' brain. Studies conducted with chronic pain patients showed a modulation of pain matrix activity during hypnosis with a specific involvement of the anterior cingulate cortex (related to emotional and cognitive processing of pain). Therefore, hypnosis seems to act upon regions underlying emotion and cognition, with an influence on pain perception and emotional regulation. In this review, we propose to carry out a review of the recent literature on hypnosis in chronic pain management. A better understanding of the beneficial effects of hypnosis on chronic pain and its neurophysiology should enable more systematic use of this technique in the management of this complex health problem.

Direct comparisons between hypnosis and meditation: A mini-review

Hypnosis and meditation share phenomenological and neurophysiological features, and their comparison is a topic of growing interest in the scientific literature. In this article, we review a classification of these two kinds of non-ordinary states of consciousness, and discuss the studies that directly compare them. Some findings seem to suggest that hypnosis and meditation are distinct phenomena, while others underline their similarities, but experiments that directly contrast them are still scarce and no consensus has been reached yet. While this comparison could give us fundamental insights into central issues concerning the role of attention, metacognition and executive control in the study of consciousness, it is clear that we are still at the early stages of this research.

Occupational Health and Safety Receptivity towards Clinical Innovations That Can Benefit Workplace Mental Health Programs: Anxiety and Hypnotherapy Trends

Anxiety is one of the most common mental health conditions experienced by people in Australia during their working years according to the Australian Bureau of Statistics (ABS) and employers recognising that mental health impacts their organisation’s bottom line are increasingly interested in programs to promote better mental health, well-being, and productivity. Beyond management concern for productivity, statutory protection is necessary to safeguard mental health, under the Australian Occupational Health and Safety (OHS) Act, organisations have a duty to eliminate or minimise risks to psychological (mental) health by designing effective workplace systems and Occupational Health and Safety (OHS) practitioners are central to the design and responsibility in managing these systems. Despite literature indicating the benefits of OHS workplace mental health initiatives, such as improved overall health, reduced absenteeism, increased job satisfaction and morale, there remains a lack of empirical research around program measurement, and their effectiveness in this area has been brought into question. The OHS function is interested in improving research around the relationship and connection between work performance and mental health but: there are few studies regarding performance outcomes of mental health OHS services within management journals and insufficient information around the prevalence of psychological morbidity in the workplace and its impact. The purpose of this study was to assess OHS perception regarding anxiety and reveal perceptions and receptivity towards alternative therapies and solutions being used in clinical practice to deal with anxiety such as cognitive behavioural therapy (CBT) with a focus on Hypnotherapy.

Hypnotic suggestibility in dissociative and related disorders: A meta-analysis

Elevated responsiveness to verbal suggestions is hypothesized to represent a predisposing factor for dissociative disorders (DDs) and related conditions. However, the magnitude of this effect has not been estimated in these populations nor has the potential moderating influence of methodological limitations on effect size variability across studies. This study assessed whether patients with DDs, trauma- and stressor-related disorders (TSDs), and functional neurological disorder (FND) display elevated hypnotic suggestibility. A systematic literature search identified 20 datasets. A random-effects meta-analysis revealed that patients displayed greater hypnotic suggestibility than controls, Hedges's g=0.92 [0.66, 1.18]. This effect was observed in all subgroups but was most pronounced in the DDs. Although there was some evidence for publication bias, a bias-corrected estimate of the group effect remained significant, g=0.57 [0.30, 0.85]. Moderation analyses did not yield evidence for a link between effect sizes and methodological limitations. These results demonstrate that DDs and related conditions are characterized by elevated hypnotic suggestibility and have implications for the mechanisms, risk factors, and treatment of dissociative psychopathology.

Anxiety and Depression in Chronic Obstructive Pulmonary Disease: Perspectives on the Use of Hypnosis

Chronic Obstructive Pulmonary Disease (COPD) is a highly prevalent and debilitating respiratory condition, characterized by chronic airflow limitation, breathlessness, and other persistent respiratory symptoms. Critically, patients suffering from COPD often find themselves trapped in a vicious comorbidity cycle: while breathlessness and increased respiratory rate are known inducers of anxiety, the latter have been shown in turn to exacerbate breathlessness and chest discomfort. Hypnosis holds great potential for the simultaneous complementary management of anxiety and breathlessness in COPD. It is an inexpensive psychological intervention tailored to the patient's own experience, convenient in terms of logistics and implementation. In this short qualitative review, we present hypnosis' structural, cognitive, and neural fundamentals, and assess existing instances of hypnosis use in the treatment of anxiety, depression, and respiratory disease. We then discuss its potential as a tool for improving health-related quality of life and the self-management of COPD within (and beyond) pulmonary rehabilitation.

Hypnotic Induction of Deafness to Elementary Sounds: An Electroencephalography Case-Study and a Proposed Cognitive and Neural Scenario

Hypnosis can be conceived as a unique opportunity to explore how top-down effects can influence various conscious and non-conscious processes. In the field of perception, such modulatory effects have been described in distinct sensory modalities. In the present study we focused on the auditory channel and aimed at creating a radical deafness to elementary sounds by a specific hypnotic suggestion. We report here a single case-study in a highly suggestible healthy volunteer who reported a total hypnotically suggested deafness. We recorded high-density scalp EEG during an auditory odd-ball paradigm before and after hypnotic deafness suggestion. While both early auditory event-related potentials to sounds (P1) and mismatch negativity component were not affected by hypnotic deafness, we observed a total disappearance of the late P3 complex component when the subject reported being deaf. Moreover, a centro-mesial positivity was present exclusively during the hypnotic condition prior to the P3 complex. Interestingly, source localization suggested an anterior cingulate cortex (ACC) origin of this neural event. Multivariate decoding analyses confirmed and specified these findings. Resting state analyses confirmed a similar level of conscious state in both conditions, and suggested a functional disconnection between auditory areas and other cortical areas. Taken together these results suggest the following plausible scenario: (i) preserved early processing of auditory information unaffected by hypnotic suggestion, (ii) conscious setting of an inhibitory process (ACC) preventing conscious access to sounds, (iii) functional disconnection between the modular and unconscious representations of sounds and global neuronal workspace. This single subject study presents several limits that are discussed and remains open to alternative interpretations. This original proof-of-concept paves the way to a larger study that will test the predictions stemming from our theoretical model and from this first report.

Hypnotherapy for procedural pain, itch, and state anxiety in children with acute burns: a feasibility and acceptability study protocol

Background

Burns and related procedures are painful and distressing for children, exposing them to acute and chronic sequelae that can negatively affect their physiological, psychological, and social functions. Non-pharmacological interventions such as distraction techniques are beneficial adjuncts to pharmacological agents for procedural pain, state anxiety, and itch in children with burns but have limitations (e.g. lack of research on burn-related itch, tailoring, and consensus on optimal treatment). Hypnotherapy is a non-pharmacological intervention that can be tailored for varied settings and populations with evidence of benefit for itch and superior effectiveness in comparison to other non-pharmacological interventions for children’s procedural pain and state anxiety. Thus, children with burns can benefit from hypnotherapy as an adjunct to pharmacological agents. Yet, in paediatric burns, rigorous studies of effectiveness are limited and no studies have been identified that screen for hypnotic suggestibility, an important predictor of hypnotherapy outcomes. Considering potential barriers to the delivery of hypnotherapy in paediatric burns, the proposed study will examine the feasibility and acceptability of hypnotic suggestibility screening followed by hypnotherapy for procedural pain, state anxiety, and itch in children with acute burns.

Methods

An observational mixed-methods feasibility and acceptability study will be conducted over 15 weeks. Eligible children (N = 30) aged 4 to 16 years presenting to a paediatric burns outpatient centre in a metropolitan children’s hospital in Australia with acute burns requiring dressing changes will be included. Eligible parents of children (N = up to 30) and clinicians who perform dressing changes (N = up to 20) will also be included. Child participants screened as having medium to high suggestibility as assessed by behavioural measures will receive hypnotherapy during dressing changes. A process evaluation will target feasibility and acceptability as primary outcomes and implementation (i.e. fidelity in delivery), reach, potential effectiveness, and adoption of evaluation procedures and intervention as secondary outcomes.

Discussion

Ethical approval was obtained from the Queensland Children’s Hospital and Health Service ethics committee. Results will be published in peer-reviewed publications and conference proceedings.

The findings will guide the design of future trials on the effectiveness of hypnotherapy and inform the development of child-centred hypnotic interventions in children with burns.

Trial registration

Australian New Zealand Clinical Trials Registry ACTRN12620000988954

Supplementary Information

The online version contains supplementary material available at 10.1186/s40814-022-01017-z.

Strategies that reduce Stroop interference

A remarkable example of reducing Stroop interference is provided by the word blindness post-hypnotic suggestion (a suggestion to see words as meaningless during the Stroop task). This suggestion has been repeatedly demonstrated to halve Stroop interference when it is given to highly hypnotizable people. In order to explore how highly hypnotizable individuals manage to reduce Stroop interference when they respond to the word blindness suggestion, we tested four candidate strategies in two experiments outside of the hypnotic context. A strategy of looking away from the target words and a strategy of visual blurring demonstrated compelling evidence for substantially reducing Stroop interference in both experiments. However, the pattern of results produced by these strategies did not match those of the word blindness suggestion. Crucially, neither looking away nor visual blurring managed to speed up incongruent responses, suggesting that neither of these strategies is the likely underlying mechanism of the word blindness suggestion. Although the current results did not unravel the mystery of the word blindness suggestion, they showed that there are multiple voluntary ways through which participants can dramatically reduce Stroop interference.

Hypnosis for the Management of COPD-related anxiety and dyspnea in Pulmonary Rehabilitation - rationale and design for a cluster-randomised, active-control trial [HYPNOBPCO_2]

Complementary psychological care is recommended for COPD, as it significantly reduces anxiety and boosts the pulmonary rehabilitation efficacy. In a precedent trial (HYPNOBPCO_1, ISRCTN10029862), administering a single hypnosis session was linked to reduced anxiety and improved breathing mechanics in intermediate and advanced COPD patients. However, whether hypnosis could improve self-management of anxiety and dyspnoea in COPD during pulmonary rehabilitation is yet to be investigated.

This is the protocol for HYPNOBPCO_2, a 2-arm, cluster-randomised, statistician-blinded superiority monocentre trial (NCT04868357). Its aim is to assess the efficacy of hypnosis as a tool to manage anxiety and dyspnoea during a pulmonary rehabilitation programme (PRP). Clusters of COPD patients eligible for the conventional hospital-based PRP at the Centre Hospitalier de Bligny (CHB) will be randomised and evenly allocated into two parallel arms: “Hypnosis” (treatment) and “Relaxation” (active control). “Hypnosis” will consist of the CHB's conventional 4-week group PRP, supplemented by two educational sessions for teaching self-hypnosis. “Relaxation” will be identical, except standard relaxation exercises will be taught instead. Primary end-point will consist of assessing weekly changes in anxiety throughout the PRP, additional to total anxiety change after treatment completion. Anxiety will be determined by the six-item version of the State-Trait Anxiety Inventory (STAI-6). Secondary outcomes will include change in the 6-min walk test and the COPD assessment test (CAT). Further follow-up outcomes will include CAT and STAI-6 retests, re-hospitalisation rate, action plan use and persistence in self-hypnosis use, throughout the 12 weeks ensuing PRP completion.

Rationale for HYPNOBPCO_2 (NCT04868357), a trial investigating whether self-hypnosis (fast, low-cost, effortless) reliably improves breathlessness-related anxiety and breathing mechanics, during and after pulmonary rehabilitation in COPDhttps://bit.ly/3JF2vCW

Direct Verbal Suggestibility as a Predictor of Placebo Hypoalgesia Responsiveness

OBJECTIVE

Reliably identifying good placebo responders has pronounced implications for basic research on, and clinical applications of, the placebo response. Multiple studies point to direct verbal suggestibility as a potentially valuable predictor of individual differences in placebo responsiveness, but previous research has produced conflicting results on this association.

METHODS

In two double-blind studies, we examined whether behavioral direct verbal suggestibility measures involving a correction for compliance would be associated with individual differences in responsiveness to conditioned and unconditioned placebo hypoalgesia using an established placebo analgesia paradigm. In study 1 (n = 57; mean [standard deviation] age = 23.7 [8.1] years; 77% women), we used behavioral hypnotic suggestibility as a predictor of placebo hypoalgesia induced through conditioning and verbal suggestion, whereas in study 2 (n = 78; mean [standard deviation] = 26.1 [7.4] years; 65% women), we measured nonhypnotic suggestibility and placebo hypoalgesia induced through verbal suggestion without conditioning.

RESULTS

In study 1, the placebo hypoalgesia procedure yielded a moderate placebo response (g = 0.63 [95% confidence interval = 0.32 to 0.97]), but the response magnitude did not significantly correlate with hypnotic suggestibility (rs = 0.11 [-0.17 to 0.37]). In study 2, the placebo procedure did not yield a significant placebo response across the full sample (g = 0.11 [-0.11 to 0.33]), but the magnitude of individual placebo responsiveness significantly correlated with nonhypnotic suggestibility (rs = 0.27 [0.03 to 0.48]).

CONCLUSIONS

These results suggest that the extent to which direct verbal suggestibility captures variability in placebo responsiveness depends on the use of conditioning and highlights the utility of suggestibility as a potential contributing factor to placebo responding when placebo hypoalgesia is induced through verbal suggestions.

Suggested visual blockade during hypnosis: Top-down modulation of stimulus processing in a visual oddball task

Several theories of hypnosis assume that responses to hypnotic suggestions are implemented through top-down modulations via a frontoparietal network that is involved in monitoring and cognitive control. The current study addressed this issue re-analyzing previously published event-related-potentials (ERP) (N1, P2, and P3b amplitudes) and combined it with source reconstruction and connectivity analysis methods. ERP data were obtained from participants engaged in a visual oddball paradigm composed of target, standard, and distractor stimuli during a hypnosis (HYP) and a control (CON) condition. In both conditions, participants were asked to count the rare targets presented on a video screen. During HYP participants received suggestions that a wooden board in front of their eyes would obstruct their view of the screen. The results showed that participants’ counting accuracy was significantly impaired during HYP compared to CON. ERP components in the N1 and P2 window revealed no amplitude differences between CON and HYP at sensor-level. In contrast, P3b amplitudes in response to target stimuli were significantly reduced during HYP compared to CON. Source analysis of the P3b amplitudes in response to targets indicated that HYP was associated with reduced source activities in occipital and parietal brain areas related to stimulus categorization and attention. We further explored how these brain sources interacted by computing time-frequency effective connectivity between electrodes that best represented frontal, parietal, and occipital sources. This analysis revealed reduced directed information flow from parietal attentional to frontal executive sources during processing of target stimuli. These results provide preliminary evidence that hypnotic suggestions of a visual blockade are associated with a disruption of the coupling within the frontoparietal network implicated in top-down control.

Hypnosis

Clinical hypnosis is an important therapeutic tool with an increasingly understood cognitive and neurobiological basis, and evidence for efficacy. Hypnosis involves controlled modulation of components of cognition-such as awareness, volition, perception and belief-by an external agent (the hypnotist) or by oneself (self-hypnosis) employing suggestion. In this article, we describe what hypnosis is, how it can be used in clinical settings, and how it is done.

Hypnosis as sole anesthesia for oral surgery: The egg of Columbus

BACKGROUND AND OVERVIEW

Hypnosis, despite its effectiveness, has been neglected. The aim of this study is to show the effectiveness and manageability of hypnosis as a stand-alone technique in dentistry.

CASE DESCRIPTION

Three patients underwent 6 oral surgery procedures (surgical third-molar removal, implant surgery, maxillary bone augmentation, and mucogingival surgery) with hypnosis as the only anesthetic. Two of the 3 patients had difficulties: 1 was sensitive to multiple chemicals, had Addison disease, and had previously experienced anaphylactic reactions to local anesthetics; the other was allergic to lidocaine and had undergone a paradoxical reaction to pharmacologic sedation in the past. All 3 patients had 2 preoperative sessions each to assess their perioperative risk, level of anxiety, hypnotic susceptibility, and capacity to develop full hypnotic analgesia. On a surgery day, hypnosis was induced and hypnotic analgesia was obtained according to a standard protocol, a procedure taking no more than 9 minutes in each case. Each surgical procedure was then completed successfully with the patient in a painless condition of full relaxation and sense of well-being, with stable cardiovascular parameters. None of the patients required postoperative analgesics, which were prescribed for use as needed.

CONCLUSIONS AND PRACTICAL IMPLICATIONS

Hypnosis is a valuable tool in dentistry, enabling the safe and rapid relief of anxiety and phobia and raising patient pain thresholds to the level of surgical analgesia. Unlike drugs and equipment, it is always readily available, cost-free, and has no adverse effects when administered by competent professionals. Hypnosis can be used for sedation in most patients and as a stand-alone technique in those with appropriate hypnotic susceptibility, improving the well-being and safety of patients.

Beyond imagination: Hypnotic visual hallucination induces greater lateralised brain activity than visual mental imagery

Hypnotic suggestions can produce a broad range of perceptual experiences, including hallucinations. Visual hypnotic hallucinations differ in many ways from regular mental images. For example, they are usually experienced as automatic, vivid, and real images, typically compromising the sense of reality. While both hypnotic hallucination and mental imagery are believed to mainly rely on the activation of the visual cortex via top-down mechanisms, it is unknown how they differ in the neural processes they engage. Here we used an adaptation paradigm to test and compare top-down processing between hypnotic hallucination, mental imagery, and visual perception in very highly hypnotisable individuals whose ability to hallucinate was assessed. By measuring the N170/VPP event-related complex and using multivariate decoding analysis, we found that hypnotic hallucination of faces involves greater top-down activation of sensory processing through lateralised neural mechanisms in the right hemisphere compared to mental imagery. Our findings suggest that the neural signatures that distinguish hypnotically hallucinated faces from imagined faces lie in the right brain hemisphere.

No evidence for theta power as a marker of hypnotic state in highly hypnotizable subjects

EEG spectral-power density was analyzed in a group of nine highly hypnotizable subjects via ten frontal, central, parietal, and occipital electrodes under four conditions: 1) wake state, 2) neutral hypnosis, 3) hypnotic suggestion for altering perception of tones, and 4) post-hypnosis. Results indicate no theta-power changes between conditions, challenging previous findings that increased theta power is a marker of hypnosis. A decrease in gamma power under hypnotic suggestion and an almost significant decrease under neutral hypnosis were observed, compared to post-hypnosis. Anteroposterior power distribution remained stable over all conditions. The results are discussed and compared to earlier studies, which report heterogenous findings.

The neural mechanisms of immediate and follow-up of the treatment effect of hypnosis on smoking craving

Hypnosis has a therapeutic effect on substance dependence. However, its neural basis remains unclear, which impedes its further clinical applications. This study investigated the mechanisms of smoking treatment based on hypnosis from two perspectives: immediate and follow-up effects. Twenty-four smokers screened from 132 volunteers underwent hypnosis suggestion and performed a smoking-related cue task twice during functional magnetic resonance imaging (fMRI) scanning (in normal and hypnotic states). The number of cigarettes smoked per day was recorded at follow-up visits. The smokers reported decreased craving after hypnosis. The activations in the right dorsal lateral prefrontal cortex (rDLPFC), the left insula and the right middle frontal gyrus (rMFG), and the functional connectivity between the rDLPFC and the left insula were increased in the hypnotic state. The reduced craving was related to the DLPFC-insula network, which reflected the immediate mechanism of hypnosis on smoking. The number of cigarette use at the 1-week and 1 month follow-up was correlated with the rMFG activation which reflecting hypnotic depth, suggesting the follow-up effect of hypnosis on smoking depended on the trait of smokers. We identified two different mechanisms of hypnosis effect on smoking, which have important implications for design and optimization of hypnotic treatments on mental disorders.

The neurochemistry of hypnotic suggestion

A diverse array of studies has been devoted to understanding the neurochemical systems supporting responsiveness to hypnotic suggestions, with implications for experimental and clinical applications of hypnosis. However, this body of research has only rarely been integrated and critically evaluated and the prospects for the reliable pharmacological manipulation of hypnotic suggestibility remain poorly understood. Here we draw on pharmacological, genotyping, neuroimaging, and electrophysiological research to synthesize current knowledge regarding the potential role of multiple widely-studied neurochemicals in response to suggestion. Although we reveal multiple limitations with this body of evidence, we identify converging results implicating different neurochemical systems in response to hypnotic suggestion. We conclude by assessing the extent to which different results align or diverge and outline multiple avenues for future research. Elucidating the neurochemical systems underlying response to suggestion has the potential to significantly advance our understanding of suggestion.

Influences of hypnotic suggestibility, contextual factors, and EEG alpha on placebo analgesia

We tested the role of hypnotic suggestibility, involuntariness, pain expectation, and subjective hypnotic depth in the prediction of placebo analgesia (PA) responsiveness. We also tested the link of lower and upper alpha sub-band (i.e., 'alpha1' and 'alpha2') power changes with tonic PA responding during waking and hypnosis conditions. Following an initial PA manipulation condition, we recorded EEG activity during waking and hypnosis under two treatments: (1) painful stimulation (Pain); (2) painful stimulation after application of a PA cream. Alpha1 and alpha2 power were derived using the individual alpha frequency method. We found that (1) PA in both waking and hypnosis conditions significantly reduced relative pain perception; (2) during waking, all the above mentioned contextual measures were associated with pain reduction, while involuntariness alone was associated with pain reduction within hypnosis. Enhanced alpha2 power at the left-parietal lead was solely associated with pain reduction in waking, but not in hypnosis condition. Using multiple regression and mediation analyses we found that: (i) during waking, the enhancement of relative left-parietal alpha2 power, directly influenced the enhancement in pain reduction, and, indirectly, through the mediating positive effect of involuntariness; (j) during hypnosis, the enhancement of left-temporoparietal alpha2 power, through the mediation of involuntariness, influenced pain reduction. Current findings obtained during waking suggest that enhanced alpha2 power may serve as a direct-objective measure of the subjective reduction of tonic pain in response to PA treatment. Overall, our findings suggest that placebo analgesia during waking and hypnosis involves different processes of top-down regulation.