Neurophysiological correlates of hypnotic analgesia
Steven Laureys2009, Contemporary Hypnosis
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Abstract
This short review describes recent advances in understanding hypnotic modulation of pain. Our current understanding of pain perception is followed by a critical review of the hypnotic analgesia studies using EEG, evoked potential and functional imaging methodologies.
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Neurophysiology of hypnosis
Neurophysiologie Clinique/Clinical Neurophysiology, 2013
We here review behavioral, neuroimaging and electrophysiological studies of hypnosis as a state, as well as hypnosis as a tool to modulate brain responses to painful stimulations. Studies have shown that hypnotic processes modify internal (self awareness) as well as external (environmental awareness) brain networks. Brain mechanisms underlying the modulation of pain perception under hypnotic conditions involve cortical as well as subcortical areas including anterior cingulate and prefrontal cortices, basal ganglia and thalami. Combined with local anesthesia and conscious sedation in patients undergoing surgery, hypnosis is associated with improved periand postoperative comfort of patients and surgeons. Finally, hypnosis can be considered as a useful analogue for simulating conversion and dissociation symptoms in healthy subjects, permitting better characterization of these challenging disorders by producing clinically similar experiences.
Neural Mechanisms of Hypnotic Analgesia
OBM Integrative and Complementary Medicine
There is increasing evidence demonstrating that hypnosis could be effective in the downmodulation of pain sensation in both acute and chronic pain states. In the neurophysiological context, recent evidence has deciphered, to a certain extent, the mystery of pain relief upon hypnosis. It is probable that hypnotic suggestions of analgesia are able to modulate pain processing at multiple levels and sites within the central nervous system (CNS). At the peripheral level, hypnosis may modulate the nociceptive input through the down-regulation of the stimulation of A delta and C fibers and reduction of sympathetic arousal. At the spinal level, sensory analgesia occurring during hypnosis has been demonstrated to be linearly associated with the reduction in the nociceptive flexion (RIII) reflex, a polysynaptic spinal reflex. At the supraspinal cortical level, neuro-imaging and electrophysiological studies have demonstrated that hypnotic suggestions of analgesia could directly modulate both sensory and affective dimensions of pain perception, and the affective dimensions exhibit more significant reduction compared to the sensory ones. Moreover, highly hypnotizable subjects possess stronger attentional filtering abilities in comparison to the low hypnotizable subjects; this greater cognitive flexibility of the former might result in better focusing and diverting the attention from the nociceptive stimulus as well as in better ignoring of the irrelevant stimuli in the environment. Cognitive control processes are associated with a "supervisory attentional system" which involves fronto-temporal limbic cortices.
Shedding light on the fundamental mechanism underlying hypnotic analgesia
Annals of Palliative Medicine, 2018
Owing to the increasing importance of clinical hypnosis in pain therapy and palliative care, there is a growing interest in uncovering the mechanism underlying hypnotic analgesia. The neurophysiological findings suggest that the hypnotic state is associated with an altered operating mode of the brain that is clearly different from the normal operating mode. While in the normal operating mode a dolorogenic stimulus induces a highly synchronized large-scale activity pattern that leads to the experience of pain, the altered operating mode inhibits the synchronization of spatially divided brain regions. As a consequence, the conscious experience of pain cannot arise. In order to gain a deeper understanding of the mechanism, a novel theoretical framework is made use of. It accepts consciousness as a fundamental property of the universe and is based on the hypothesis that the whole range of phenomenal qualities is built into the frequency spectrum of a ubiquitous background field. The body of evidence supports the view that in the normal operating mode our brains act as filters that extract the plethora of phenomenal nuances selectively from this field. In the altered operating mode, which establishes under hypnotic conditions, the extraction of phenomenal qualities is partially prevented. From this perspective, hypnotic analgesia is due to an impairment of the fundamental mechanism underlying conscious perception.
Bursting the hypnotic bubble: does hypnotic analgesia work and if yes how?
Contemporary Hypnosis, 2009
Somatosensory event-related potential and autonomic activity to varying pain reduction cognitive strategies in hypnosis
Clinical Neurophysiology, 2001
Objectives: The issues of differential effects among cognitive strategies during hypnosis in the control of human pain are under active debate. This study, which employs measures of pain perception, electrocortical and autonomic responses, was aimed at determining these pain-related modulations. Methods: Somatosensory event-related potentials (SERPs) to noxious stimuli under an odd-ball paradigm were recorded at the frontal, temporal and parietal regions in 10 high, 9 mid, and 10 low hypnotizable right-handed young women, at waking baseline, varying cognitive strategies (deep relaxation, dissociative imagery, focused analgesia) in hypnosis and placebo conditions. The phasic heart rate (HR) and skin conductance response were also recorded. The analysis was focused on the frequent standard trials of the odd-ball SERPs. Repeated measures analysis of variance was conducted to examine the experimental effects. Results: Focused analgesia induced the largest reduction in pain rating, more in the high than low hypnotizable subjects. In high hypnotizable subjects, the N2 amplitude was greater over frontal and temporal scalp sites than over parietal and central sites, whereas in moderately and low hypnotizable subjects, N2 was greater over temporal sites than over frontal, parietal, and central sites. These subjects also displayed a larger N2 peak over temporal sites during focused analgesia than in the other conditions. The P3 amplitude was smaller under deep relaxation, dissociative imagery and focused analgesia in the high hypnotizable subjects. For these subjects, the smallest P3 peaks were obtained for dissociated imagery and focused analgesia over frontal and temporal sites. In contrast, for the P3 peak, low hypnotizable subjects failed to show signi®cant condition effects. In all of the subjects, the skin conductance and HR were smaller during hypnotic suggestions than in the waking state. Conclusions: The effect of pain modulation is limited to high hypnotizable subjects rather than low hypnotizable ones. Higher frontal± temporal N2 and smaller posterior parietal P3 may indicate active inhibitory processes during cognitive strategies in hypnotic analgesia. These inhibitory processes also regulate the autonomic activities in pain perception.
Pain-Reduction Strategies in Hypnotic Context and Hypnosis: ERPs and SCRs During a Secondary Auditory Task
International Journal of Clinical and Experimental Hypnosis, 2004
Pain-rating scores were obtained from 10 high, 10 medium, and 10 low hypnotizable subjects who were holding a painful cold bottle in their left hands and were exposed to pain reduction treatments while they were performing a secondary oddball task. All subjects received suggestions of dissociative imagery and focused analgesia as cognitive strategies for pain reduction. The following measures were obtained for tone targets of the auditory oddball task: (a) reaction time; (b) P300 peak amplitude of the event-related potentials (ERPs); (c) skin conductance levels and skin conductance responses. Focused analgesia produced the most pain reduction in high, but not medium or low, hypnotizable subjects who showed shorter reaction times, higher central and parietal P300 peaks, and higher skin conductance responses. These findings were discussed vis-a `-vis the dissociated-control model assuming that capacity demands of hypnotic suggestion are low.
Different strategies of modulation can be operative during hypnotic analgesia: a neurophysiological study
Pain, 1998
Nociceptive electrical stimuli were applied to the sural nerve during hypnotically-suggested analgesia in the left lower limb of 18 highly susceptible subjects. During this procedure, the verbally reported pain threshold, the nociceptive flexion (RIII) reflex and late somatosensory evoked potentials were investigated in parallel with autonomic responses and the spontaneous electroencephalogram (EEG). The hypnotic suggestion of analgesia induced a significant increase in pain threshold in all the selected subjects. All the subjects showed large changes (i.e., by 20% or more) in the amplitudes of their RIII reflexes during hypnotic analgesia by comparison with control conditions. Although the extent of the increase in pain threshold was similar in all the subjects, two distinct patterns of modulation of the RIII reflex were observed during the hypnotic analgesia: in 11 subjects (subgroup 1), a strong inhibition of the reflex was observed whereas in the other seven subjects (subgroup 2) there was a strong facilitation of the reflex. All the subjects in both subgroups displayed similar decreases in the amplitude of late somatosensory evoked cerebral potentials during the hypnotic analgesia. No modification in the autonomic parameters or the EEG was observed. These data suggest that different strategies of modulation can be operative during effective hypnotic analgesia and that these are subject-dependent. Although all subjects may shift their attention away from the painful stimulus (which could explain the decrease of the late somatosensory evoked potentials), some of them inhibit their motor reaction to the stimulus at the spinal level, while in others, in contrast, this reaction is facilitated.
Hypnotic Approaches for Chronic Pain Management Clinical Implications of Recent Research Findings
The empirical support for hypnosis for chronic pain management has flourished over the past two decades. Clinical trials show that hypnosis is effective for reducing chronic pain, although outcomes vary between individuals. The findings from these clinical trials also show that hypnotic treatments have a number of positive effects beyond pain control. Neurophysiological studies reveal that hypnotic analgesia has clear effects on brain and spinal-cord functioning that differ as a function of the specific hypnotic suggestions made, providing further evidence for the specific effects of hypnosis. The research results have important implications for how clinicians can help their clients experience maximum benefits from hypnosis and treatments that include hypnotic components.
MECHANISMS OF HYPNOTIC ANALGESIA EXPLAINED BY FUNCTIONAL MAGNETIC RESONANCE (fMRI)
International Journal of Clinical and Experimental Hypnosis, 2020
Hypnotic-focused analgesia (HFA) was produced in 20 highly hypnotizable subjects receiving nociceptive stimulations while undergoing functional magnetic resonance imaging (fMRI). The fMRI pattern in brain cortex activation while receiving a painful stimulus was recorded both during nonhypnosis and during HFA. The scanning protocol included the acquisition of a T1-weighted structural scan, 4 functional scans, a T2-weighted axial scan, and a fluid attenuated inversion recovery (FLAIR) scan. Total imaging time, including localization and structural image acquisitions, was approximately 60 minutes. Without HFA, the subjects reported subjective presence of pain, and the cortex primary sensory areas S1, S2, and S3 were activated. During HFA, the subjects reported complete absence of subjective pain and S1, S2, and S3 were deactivated. The findings suggest that HFA may prevent painful stimuli from reaching the sensory brain cortex, possibly through a gate-control mechanism.
Is hypnotic assessment relevant to neurology?
Neurological Sciences, 2022
Studies conducted in healthy subjects have clearly shown that different hypnotic susceptibility, which is measured by scales, is associated with different functional equivalence between imagery and perception/action (FE), cortical excitability, and information processing. Of note, physiological differences among individuals with high (highs), medium (mediums), and low hypnotizability scores (lows) have been observed in the ordinary state of consciousness, thus independently from the induction of the hypnotic state, and in the absence of specific suggestions. The potential role of hypnotic assessment and its relevance to neurological diseases have not been fully explored. While current knowledge and therapies allow a better survival rate, there is a constant need to optimize rehabilitation treatments and quality of life. The aim of this paper is to provide an overview of hypnotizability-related features and, specifically, to discuss the hypothesis that the stronger FE, the different mode of information processing, and the greater proneness to control pain and the activity of the immune system observed in individuals with medium-to-high hypnotizability scores have potential applications to neurology. Current evidence of the outcome of treatments based on hypnotic induction and suggestions administration is not consistent, mainly owing to the small sample size in clinical trials and inadequate control groups. We propose that hypnotic assessment may be feasible in clinical routine and give additional cues into the treatment and rehabilitation of neurological diseases.
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Functional neuroanatomy of the hypnotic state
Journal of Physiology-paris, 2006
The neural mechanisms underlying hypnosis and especially the modulation of pain perception by hypnosis remain obscure. Using PET we first described the distribution of regional cerebral blood flow during the hypnotic state. Hypnosis relied on revivification of pleasant autobiographical memories and was compared to imaging autobiographical material in ''normal alertness''. The hypnotic state was related to the activation of a widespread set of cortical areas involving occipital, parietal, precentral, premotor, and ventrolateral prefrontal and anterior cingulate cortices. This pattern of activation shares some similarities with mental imagery, from which it mainly differs by the relative deactivation of precuneus. Second, we looked at the anti-nociceptive effects of hypnosis. Compared to the resting state, hypnosis reduced pain perception by approximately 50%. The hypnosis-induced reduction of affective and sensory responses to noxious thermal stimulation were modulated by the activity in the midcingulate cortex (area 24a 0 ). Finally, we assessed changes in cerebral functional connectivity related to hypnosis. Compared to normal alertness (i.e., rest and mental imagery), the hypnotic state, significantly enhanced the functional modulation between midcingulate cortex and a large neural network involved in sensory, affective, cognitive and behavioral aspects of nociception. These findings show that not only pharmacological but also psychological strategies for pain control can modulate the cerebral network involved in noxious perception.
Brain Responses to Hypnotic Verbal Suggestions Predict Pain Modulation
Frontiers in pain research, 2021
Background: The effectiveness of hypnosis in reducing pain is well supported by the scientific literature. Hypnosis typically involves verbal suggestions but the mechanisms by which verbal contents are transformed into predictive signals to modulate perceptual processes remain unclear. We hypothesized that brain activity during verbal suggestions would predict the modulation of responses to acute nociceptive stimuli. Methods: Brain activity was measured using BOLD-fMRI in healthy participants while they listened to verbal suggestions of HYPERALGESIA, HYPOALGESIA, or NORMAL sensation (control) following a standardized hypnosis induction. Immediately after the suggestions, series of noxious electrical stimuli were administered to assess pain-related responses. Brain responses measured during the suggestions were then used to predict changes in pain-related responses using delayed regression analyses. Results: Listening to suggestions of HYPERALGESIA and HYPOALGESIA produced BOLD decreases (vs. control) in the parietal operculum (PO) and in the anterior midcingulate cortex (aMCC), and increases in the left parahippocampal gyrus (lPHG). Changes in activity in PO, aMCC and PHG during the suggestions predicted larger pain-evoked responses following the HYPERALGESIA suggestions in the anterior cingulate cortex (ACC) and the anterior insula (aINS), and smaller pain-evoked responses following the HYPOALGESIA suggestions in the ACC, aMCC, posterior insula (pINS) and thalamus. These changes in pain-evoked brain responses are consistent with the changes in pain perception reported by the participants in HYPERALGESIA and HYPOALGESIA, respectively. Conclusions: The fronto-parietal network (supracallosal ACC and PO) has been associated with self-regulation and perceived self-agency. Deactivation of these regions during suggestions is predictive of the modulation of brain responses to noxious stimuli in areas previously associated with pain perception and pain modulation. The response of the hippocampal complex may reflect its role in contextual learning, memory and pain anticipation/expectations induced by verbal suggestions of pain modulation. This study provides a basis to further explore the transformation of verbal suggestions into perceptual modulatory processes fundamental to hypnosis neurophenomenology. These findings are discussed in relation to predictive coding models.
Pain Modulation in Waking and Hypnosis in Women: Event-Related Potentials and Sources of Cortical Activity
PLOS ONE, 2015
Using a strict subject selection procedure, we tested in High and Low Hypnotizable subjects (HHs and LHs) whether treatments of hypoalgesia and hyperalgesia, as compared to a relaxation-control, differentially affected subjective pain ratings and somatosensory event-related potentials (SERPs) during painful electric stimulation. Treatments were administered in waking and hypnosis conditions. LHs showed little differentiation in pain and distress ratings between hypoalgesia and hyperalgesia treatments, whereas HHs showed a greater spread in the instructed direction. HHs had larger prefrontal N140 and P200 waves of the SERPs during hypnotic hyperalgesia as compared to relaxation-control treatment. Importantly, HHs showed significant smaller frontocentral N140 and frontotemporal P200 waves during hypnotic hypoalgesia. LHs did not show significant differences for these SERP waves among treatments in both waking and hypnosis conditions. Source localization (sLORETA) method revealed significant activations of the bilateral primary somatosensory (BA3), middle frontal gyrus (BA6) and anterior cingulate cortices (BA24). Activity of these contralateral regions significantly correlated with subjective numerical pain scores for control treatment in waking condition. Moreover, multivariate regression analyses distinguished the contralateral BA3 as the only region reflecting a stable pattern of pain coding changes across all treatments in waking and hypnosis conditions. More direct testing showed that hypnosis reduced the strength of the association of pain modulation and brain activity changes at BA3. sLORETA in HHs revealed, for the N140 wave, that during hypnotic hyperalgesia, there was an increased activity within medial, supramarginal and superior frontal gyri, and cingulated gyrus (BA32), while for the P200 wave, activity was increased in the superior (BA22), middle (BA37), inferior temporal (BA19) gyri and superior parietal lobule (BA7). Hypnotic hypoalgesia in HHs, for N140 wave, showed reduced activity within medial and superior frontal gyri (BA9,8), paraippocampal gyrus (BA34), and postcentral gyrus (BA1), while for the P200, activity was reduced within middle and superior frontal gyri (BA9 and BA10), anterior cingulate (BA33), cuneus (BA19) and sub-lobar insula (BA13). These findings demonstrate that hypnotic suggestions can exert a top-down modulatory effect on attention/preconscious brain processes involved in pain perception.
High resolution EEG indicators of pain responses in relation to hypnotic susceptibility and suggestion
Biological Psychology, 2002
In this report we use a dense array (129 electrodes) EEG procedure to examine the effects of hypnotic susceptibility and hypnotic suggestions on electrocortical and self-report measures of painful stimuli. Self-report and event-related potential measures of six high and six low hypnotic susceptible individuals in response to pain were examined during an initial baseline condition and following a standard hypnotic induction under suggestions to either increase (hyperalgesia) or decrease (hypoalgesia) the painful stimulation. Our results show that high and low hypnotically susceptible individuals: (1) show few self-report or psychophysiological differences in response to baseline pain stimuli; (2) report differential pain experiences depending on hypnotic suggestions and (3) display differential psychophysiological indicators following an hypnotic induction with a suggestion of hypoalgesia. Overall, the findings suggest that hypnotic suggestions with high susceptible individuals modulate the later components of the evoked potential in a global manner and point up the importance of using both high and low hypnotically susceptible individuals preceding and following an hypnotic induction.
Hypnotic_modulation_of_pain
Laser-evoked potentials (LEPs) Nociception Posterior parietal cortex a b s t r a c t Introduction: Neuroimaging studies indicate that hypnotic suggestions of increased and decreased pain intensity and unpleasantness may modulate somatosensory and cingulate cortex activity, respectively.
Increased cerebral functional connectivity underlying the antinociceptive effects of hypnosis
Cognitive Brain Research, 2003
Focused analgesia in waking and hypnosis: Effects on pain, memory, and somatosensory event-related potentials
Acute Pain, 2008
Somatosensory event-related potentials (SERPs) to painful electric standard stimuli under an odd-ball paradigm were analyzed in 12 high hypnotizable (HH), 12 medium hypnotizable (MH), and 12 low hypnotizable (LH) subjects during waking, hypnosis, and a cued eyes-open posthypnotic condition. In each of these conditions subjects were suggested to produce an obstructive imagery of stimulus perception as a treatment for pain reduction. A No-Analgesia treatment served as a control in waking and hypnosis conditions. The subjects were required to count the number of delivered target stimuli. HH subjects experienced significant pain and distress reductions during posthypnotic analgesia as compared to hypnotic analgesia and between these two analgesic conditions as compared to the two control conditions. Outside of hypnosis, these subjects remembered less pain and distress levels than they reported during hypnotic and posthypnotic analgesia treatments. In contrast, for waking-analgesia treatment, HH subjects remembered similar pain and distress levels to those they reported concurrently with the stimulation. HH subjects, during hypnotic and posthypnotic analgesia treatments, detected a smaller number of target stimuli and displayed a significant amplitude reduction of the midline frontal and central N140 and P200 SERP components. No significant SERP differences were observed for these subjects between treatments in waking condition and between hypnotic and posthypnotic analgesic treatments. For the MH and LH subjects no significant N140 and P200 amplitude changes were observed among analgesic conditions as compared to control conditions. These amplitude findings are seen as indicating that hypnotic analgesia can affect earlier and later stages of stimulus processing.
New directions in hypnosis research: strategies for advancing the cognitive and clinical neuroscience of hypnosis
Neuroscience of Consciousness
This article summarizes key advances in hypnosis research during the past two decades, including (i) clinical research supporting the efficacy of hypnosis for managing a number of clinical symptoms and conditions, (ii) research supporting the role of various divisions in the anterior cingulate and prefrontal cortices in hypnotic responding, and (iii) an emerging finding that high hypnotic suggestibility is associated with atypical brain connectivity profiles. Key recommendations for a research agenda for the next decade include the recommendations that (i) laboratory hypnosis researchers should strongly consider how they assess hypnotic suggestibility in their studies, (ii) inclusion of study participants who score in the middle range of hypnotic suggestibility, and (iii) use of expanding research designs that more clearly delineate the roles of inductions and specific suggestions. Finally, we make two specific suggestions for helping to move the field forward including (i) the use of data sharing and (ii) redirecting resources away from contrasting state and nonstate positions toward studying (a) the efficacy of hypnotic treatments for clinical conditions influenced by central nervous system processes and (b) the neurophysiological underpinnings of
Effects of hypnosis on regional cerebral blood flow during ischemic pain with and without suggested hypnotic analgesia
International Journal of Psychophysiology, 1993
Cerebral Mechanisms of Hypnotic Induction and Suggestion
Journal of Cognitive Neuroscience, 1999
The neural mechanisms underlying hypnotic states and responses to hypnotic suggestions remain largely unknown and, to date, have been studied only with indirect methods. Here, the effects of hypnosis and suggestions to alter pain perception were investigated in hypnotizable subjects by using positron emission tomography (PET) measures of regional cerebral blood flow (rCBF) and electroencephalographic (EEG) measures of brain electrical activity. The experimental conditions included a restful state (Baseline) followed by hypnotic relaxation alone (Hypnosis) and by hypnotic relaxation with suggestions for altered pain unpleasantness (Hypnosis-with-Suggestion). During each scan, the left hand was immersed in neutral (35°C) or painfully hot (47°C) water in the first two conditions and in painfully hot water in the last condition. Hypnosis was accompanied by significant increases in both occipital rCBF and delta EEG activity, which were highly correlated with each other (r = 0.70, p < ...
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