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PubMed1993

Hypnotic hypo- and hyperalgesia: divergent effects on pain ratings and pain-related cerebral potentials.

Pain ratings and pain-related cerebral potentials in response to noxious stimuli were investigated under hypnotic hypo- or hyperalgesia. Out of a sample of 50 subjects the 10 most highly hypnotizable were selected using the Stanford Hypnotic Susceptibility Scale. Phasic pain was induced by brief electrical stimuli intracutaneously applied to the subject's left middle finger. The subjects took part in three experimental sessions. The first session was without hypnosis for familiarization with the experimental surroundings. In the two other sessions, the subjects were hypnotized and given a suggestion of analgesia or hyperalgesia with respect to pain sensation in the left hand. The sequence of hypnosis was matched within and between sessions. Pain ratings and late cerebral somatosensory evoked potentials (SEP) were used to quantify pain reactions. In addition, auditory evoked potentials (AEP) and spontaneous EEG were evaluated to differentiate between pain-specific and unspecific effects of hypnosis. Only the subjects' verbal reports of pain were drastically influenced by hypnosis: suggestion of analgesia diminished the mean pain ratings, suggestion of hyperalgesia enhanced them (P < 0.001). In contrast, the amplitudes of the late somatosensory potentials evoked by the pain-inducing stimuli were not modified in either of the suggestive states. Furthermore, no effects of hypnosis were found on AEPs and on the power spectra of the spontaneous EEG. The results are discussed on the basis of a dissociation of sensory and affective components of pain under hypnosis.

Adult↗
PubMed2005

Changes in mismatch negativity across pre-hypnosis, hypnosis and post-hypnosis conditions distinguish high from low hypnotic susceptibility groups.

The role of alterations in mismatch negativity (MMN) in hypnosis was examined by recording MMN of the auditory ERP at frontal (F3, Fz, and F4) and mastoid (M1 and M2) placements. Frontal MMN is believed to reflect activity in right anterior cortical generators, whereas MMN at mastoid leads reflects generators located bilaterally in the temporal auditory cortex. MMN recordings were obtained in 11 low and 12 high hypnotically susceptible participants in three successive blocks; pre-hypnosis, hypnosis and post-hypnosis. Frontal (but not temporal) MMN showed a significant quadratic trend across testing conditions. It increased during hypnosis and then dropped post-hypnosis for both susceptibility groups. Linear trends for frontal and temporal MMN showed directly opposite patterns of change in the interaction between hypnotic susceptibility and testing blocks. Frontal MMN built up linearly over the test blocks in high relative to low susceptibility participants. Temporal MMN showed the reverse pattern and increased linearly across test conditions in those with low relative to high hypnotic susceptibility.

Acoustic Stimulation↗
PubMed2005

Hypnotic susceptibility, baseline attentional functioning, and the Stroop task.

According to the theoretical framework relating hypnosis to attention, baseline attentional functioning in highly hypnotizable individuals should be more efficient than in low hypnotizable individuals. However, previous studies did not find differences in Stroop-like tasks in which the measure indicative of the Stroop interference effect was based on response latencies. This study was designed to determine whether subjects with different levels of hypnotic susceptibility show differences in baseline attentional functioning. To assess this hypothesis, high, medium, and low hypnotizable subjects performed a Stroop task designed to evaluate accuracy performance, before being subjected to hypnotic induction. Results showed that the Stroop interference effect was smaller in high hypnotizable subjects than in low hypnotizable subjects, whereas it was not different between high, and medium hypnotizable subjects. This outcome supports the notion that baseline attentional functioning is related to hypnotic susceptibility.

Attention↗
PubMed2006

Local and systemic vasodilation following hypnotic suggestion of warm tub bathing.

During hypnosis it is easy to induce hallucinations having, for the hypnotized subject, the characteristics and the concreteness of reality. This study was performed to put in evidence the physical effects of hypnotic suggestion of warm tub bathing. 18 volunteers screened for high hypnotizability were studied. They underwent suggestion of forearm in warm water (30 min), suggestion of body in warm water (30 min), and hypnosis without any thermal suggestion (30 min), while blood pressure, heart rate, body temperature, forearm flow and resistance, stroke volume, cardiac index and total peripheral resistance were monitored. During suggestion of forearm in warm water, local vasodilation was recorded, with decrease of forearm resistance (-18%, P<0.01) and increase of forearm blood flow (+43%, P<0.01) like in real local passive warming. During suggestion of whole-body in a warm water tub, there was a systemic vasodilation with decrease of total peripheral resistance (-29%, P<0.01) and increase of cardiac index (+54%, P<0.01), like in real total-body passive warming. Body temperature, arterial blood pressure and heart rate were unchanged. During simple hypnosis (sham procedure) no haemodynamic variations were observed. These results are in keeping with the possibility to induce through hypnotic suggestion of heat a physical pattern that is typical of hyperthermia, even without increase in body temperature.

Adult↗
PubMed2006

Functional neuroanatomy of the hypnotic state.

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'). 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↗
PubMed2000

Changes in autonomic and EEG patterns induced by hypnotic imagination of aversive stimuli in man.

Autonomic and electroencephalographic (EEG) responses to aversive stimuli presented by means of hypnotic suggestion have been studied in man.Healthy volunteers with simple phobia were screened for susceptibility to hypnosis. The experimental paradigm included periods of rest during which the hypnotized subjects were asked to produce an emotionally neutral mental image and periods of emotional activation in which they were asked to image a phobic object. Heart rate (HR), respiratory frequency (RF) and EEG were processed to obtain the HR-related indexes of sympatho-vagal balance and the EEG spectral components. The results showed a significant increase in HR and RF with a shift of the sympatho-vagal indexes towards a sympathetic predominance during the hypnotic emotional activation. EEG activity showed a significant increase in the gamma band with a left fronto-central prevalence. There was also a less pronounced increase in the beta band. In conclusion, by means of hypnosis, autonomic and behavioral responses to fear-like stimuli can be induced in man in a reproducible and controlled manner. Such a paradigm could be applied in human neuroimaging studies to identify central nervous structures that modulate stress and fear-related reactions.

Adult↗
PubMed2003

Hypnotic control of attention in the Stroop task: a historical footnote.

Raz, Shapiro, Fan, and Posner (2002) have recently provided a compelling demonstration of enhanced attentional control under post-hypnotic suggestion. Using the classic color-word interference paradigm, in which the task is to ignore a word and to name the color in which it is printed (e.g., RED in green, say "green"), they gave a post-hypnotic instruction to participants that they would be unable to read. This eliminated Stroop interference in high suggestibility participants but did not alter interference in low suggestibility participants. replicated this pattern and further demonstrated that it is not due to a visual strategy (such as blurring or looking at a different location). As a historical footnote, we describe a "case study" from 18 years ago in which we observed the same result using a hypnotic instruction to a single highly suggestible individual that he could not read. The elimination of Stroop interference has important implications for both the study of attention and the study of hypnosis.

Attention↗
PubMed1991

Effects of active alert and relaxation hypnotic inductions on cold pressor pain.

We contrasted relaxation and active alert hypnotic inductions with or without a specific suggestion for cold pressor pain analgesia. Groups of high (n = 38) and low (n = 27) hypnotizable subjects were tested; hypnotizability had been determined from results of the Stanford Hypnotic Susceptibility Scale, Form C. Cold pressor pain data were obtained after counterbalanced exposure to relaxation and active alert inductions. Highly hypnotizable subjects demonstrated lower pain scores than did low hypnotizable ones. Pain reports did not differ between induction conditions. Highly hypnotizable subjects given an analgesic suggestion showed lower pain scores than did those exposed only to hypnosis. The findings, conceptualized within E.R. Hilgard's (1977a) neodissociation theory, show that relaxation is not necessary for hypnotic analgesia.

Analgesia↗
PubMed1996

Hypnotic amnesia and the paradox of intentional forgetting.

Hypnotic amnesia is often interpreted as a deliberate effort to avoid thinking of ideas or thoughts targeted for amnesia. However, as D.M. Wegner (1989) showed, nonhypnotized individuals who deliberately attempt to suppress certain thoughts or images paradoxically suffer intrusions of the prescribed material. The authors replicated Wegner's findings in 2 separate investigations. However, they also found that hypnotic amnesia did not have such paradoxical effects. Indeed, the great majority of high-hypnotizable individuals administered suggestions for amnesia showed no such intrusions whatsoever, indicating that thought suppression and hypnotic amnesia represent quite different processes.

Adult↗
PubMed1984

Hypnotic susceptibility and performance on various attention-specific cognitive tasks.

We conducted two experiments to investigate cognitive performance as related to level of hypnotic susceptibility. In Experiment 1 time-to-location of a target in a visual search task was assessed. For this task the letter Z was embedded either within straight-form or round-form letters. Results indicated that high-hypnotic-susceptibility subjects (highs) were significantly faster than low-susceptibility-subjects (lows) in locating the embedded letter. Experiment 2 investigated performance on single- and double-digit arithmetic (addition) problems as a function of hypnotic susceptibility level. Subjects were presented with arithmetic problems and were asked to complete them within a 60-s time period. Highs completed a significantly greater number of double-digit problems but not single-digit problems within this time frame than did lows. The results of the two experiments are explained in terms of the application of differing strategies or operations by highs and lows in the performance of cognitive tasks.

Attention↗
PubMed1986

A social-cognitive skills approach to the successful modification of hypnotic susceptibility.

Subjects low and medium in hypnotic susceptibility were administered cognitive strategy and instructional set information and also practiced responding to test suggestions in order to enhance susceptibility. Those in one modification treatment received this information both from the experimenter and by observing a videotaped female model who responded successfully to suggestions and reported on the cognitive strategies she used to do so. Those in a second modification treatment received the information and practice but were not exposed to the model. Low and medium susceptibles in a third condition (practice alone) received a hypnotic induction procedure and practice suggestions but neither modification information nor modeling. No-treatment controls performed a filler task. All subjects were posttested on two different susceptibility scales. Information plus modeling produced significantly greater increments on all objective and subjective indices of susceptibility on both posttests than did practice-alone or control treatments. Susceptibility increments in the information without model treatment always fell between those of the model and practice-alone treatments. In the modeling treatment, over half of the initial low susceptibles and over two thirds of the initial medium susceptibles scored as high susceptibles on both posttests. These findings provide strong support for a social-cognitive skill formulation of hypnotic susceptibility.

Adolescent↗
PubMed1988

Modifying hypnotic suggestibility with the Carleton Skills Training program.

The Carleton Skills Training (CST) program was used to investigate (a) whether increases in hypnotic responsiveness obtained at Carleton University could be replicated at a different laboratory, (b) the influence of demand characteristics on suggestibility gains, and (c) whether initial gains are maintained over time. After two screening sessions, a replication and experimental group received the CST program, while a control group was allowed to practice hypnotic responding. All groups were then tested twice. Whereas the replication group was told that training and testing were part of the same experiment, the experimental group was told that training and testing were unrelated. Trained subjects returned after 4 months for a final session. Results indicated that (a) the CST program does increase hypnotic responsiveness, (b) suggestibility gains found in this study were relatively modest, (c) demand characteristics may influence suggestibility gains, and (d) suggestibility gains were not maintained at follow-up.

Adolescent↗
PubMed1990

Imagery vividness, hypnotic susceptibility, and the perception of fragmented stimuli.

Two experiments were conducted to determine the role of hypnotic susceptibility level (high or low) and imaging ability (vivid or poor) in the performance of gestalt closure tasks. In Experiment 1, subjects were required to identify fragmented stimuli in the Closure Speed Test and in the Street Test. In Experiment 2, subjects reported on fragmented stimuli that were projected to the right eye and subsequently produced an afterimage. Individuals were asked to identify the composite if possible and to report on the duration of the afterimage. In both experiments, hypnotic susceptibility level and imaging ability affected reports of gestalt closure. The greatest number of correct closures was reported by those who were both high in hypnotic susceptibility and vivid in imaging ability. In addition, in the second experiment, this group also reported the longest enduring afterimage. These results are discussed in terms of the processes required to perform in a gestalt closure task.

Adult↗
PubMed1992

Interpretive sets, expectancy, fantasy proneness, and dissociation as predictors of hypnotic response.

College students with no prior experience of hypnosis were assessed for fantasy proneness and dissociation. In a totally separate context, they were subsequently tested for their interpretations of hypnotic suggestions, hypnotic response expectancies, and hypnotizability. Contrary to Spanos and Gorassini's (1984) hypothesis, strategic enactment of suggested responses was rarely reported, and its endorsement was not correlated with hypnotic responsiveness. Suggestibility was significantly predicted by fantasy proneness and response expectancy, but not by dissociation. A path analysis suggested that the relation between fantasy proneness and hypnotizability was partially mediated by expectancy.

Adult↗
PubMed1975

Involvement in everyday imaginative activities, attitudes toward hypnosis, and hypnotic suggestibility.

One hundred male and 83 female subjects were assessed on absorption (i.e., involvement in everyday imaginative activities), attitudes toward hypnosis, and hypnotic suggestibility. Significant positive correlations were obtained for both sexes between absorption and attitudes and between each of these variables and hypnotic suggestibility. Multiple regression analyses indicated that most of the predicted variance in hypnotic suggestibility scores was accounted for in both sexes by the absorption variable.

Activities of Daily Living↗
PubMed1999

Functional anatomy of hypnotic analgesia: a PET study of patients with fibromyalgia.

Hypnosis is a powerful tool in pain therapy. Attempting to elucidate cerebral mechanisms behind hypnotic analgesia, we measured regional cerebral blood flow with positron emission tomography in patients with fibromyalgia, during hypnotically-induced analgesia and resting wakefulness. The patients experienced less pain during hypnosis than at rest. The cerebral blood-flow was bilaterally increased in the orbitofrontal and subcallosial cingulate cortices, the right thalamus, and the left inferior parietal cortex, and was decreased bilaterally in the cingulate cortex. The observed blood-flow pattern supports notions of a multifactorial nature of hypnotic analgesia, with an interplay between cortical and subcortical brain dynamics. Copyright 1999 European Federation of Chapters of the International Association for the Study of Pain.

Journal Article↗
PubMed2000

Hypnotic medication in the treatment of chronic insomnia: non nocere! Doesn't anyone care?

Chronic primary insomnia is a recurrent condition that negatively effects the daily functioning of patients, diminishing the quality of their lives. It is associated with, and in some situations, is a risk factor in both psychiatric (depression) and physical (cardiovascular) illness. Treatment effectiveness has been shown in the short term for both drug (benzodiazepine and benzodiazepine agonists) and behavioral treatment. Expert opinion has strongly advised against long-term drug treatment because of concerns about residual sedative effects, memory impairment, falls, respiratory depression, rebound insomnia, medication abuse, dose escalation, dependency and withdrawal difficulties, and an increased risk of death possibly associated with the current hypnotic medications. Many of these concerns could be made against using these agents at all. Worries about these potential problems are challenged by the widespread clinical practice of using hypnotic drugs long-term without any of these difficulties developing and with patients who feel their sleep and daily function function is improved with the nightly use of their sleeping pill. The ability to mount a randomized, placebo-controlled, parallel group, double-blind trial of hypnotic medication in primary insomnia may not be possible. We may have to develop large systematic clinical databases, a number of case series in effect, to monitor both emergent symptoms and possible clinical effectiveness. There is the additional concern that there is a reluctance to examine the long-term drug treatment of insomnia. This reluctance may reflect a negative moral judgement about treating primary insomnia with drugs, a sort of <<< >>>, rather than just a data based judiciousness.

Journal Article↗
PubMed1975

Failure of the opiate antagonist naloxone to modify hypnotic analgesia.

Hypnotic analgesia in some respects resembles opiate analgesia. We tested the hypothesis that some features of hypnotic analgesia are mediated through neuronal pathways activating specific opiate receptors in brain. The opiate antagonist naloxone had no effect on hypnotic analgesia in three subjects. Thus, the hypothesis was not confirmed.

Female↗