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Susceptibility to hypnosis is a very pervasive psychophysiological trait characterized by different attentional abilities, information processing, and cardiovascular control. Since near infrared spectroscopy is a good index of neurovascular coupling, we used it during mental computation (MC) and trail making task (TMT) in 13 healthy low-to-medium (med-lows) and 10 healthy medium-to-high (med-highs) hypnotizable participants classified according to the Stanford Hypnotic Susceptibility Scale, form A, and characterized for the level of proneness to be deeply absorbed in related experiences by the Tellegen Absorption Scale. The med-highs reported greater absorption than med-lows. The tissue hemoglobin index (THI) and the tissue oxygenation index (TOI) increased across the tasks only in med-highs who displayed also different time courses of THI and TOI during MC and TMT, which indicates different tasks processing despite the two groups' similar performance. The findings suggest that med-highs' tissue oxygenation is more finely adjusted to metabolic demands than med-lows'., Competing Interests: Declaration of Competing Interest The authors declare no conflict of interest., (Copyright © 2022 Elsevier Inc. All rights reserved.)

The aim of the study was to investigate the effects of pleasant and unpleasant interoceptive imagery on postural control in participants with different hypnotizability, interoceptive sensibility and ability of imagery. Forty-one healthy individuals classified as high (highs), medium (mediums) and low hypnotizables (lows) according to the Stanford Hypnotic Susceptibility Scale, form A (SHSS, A) were characterized for Interoceptive Sensitivity (IS) through the Multisensory Assessment of Interoceptive Awareness (MAIA) and for organic mental imagery (ORG) through Betts' questionnaire. The experimental session included baseline closed eyes conditions preceding tasks of pleasant (P) and unpleasant imagery (U) and a neutral cognitive task (NT) while standing on a stabilometric platform. Subjective reports of vividness and pleasantness/unpleasantness of mental images were collected. Postural variables, ECG and pneumogram were acquired. Highs exhibited greater vividness of imagery than mediums/lows and larger Area of the Centre of Pressure (CoP), while mediums and lows decreased it during all tasks with respect to baseline conditions. Significant differences moderated by IS and ORG were found between highs and lows in the CoP Area. In all groups significant task related differences in the CoP Area were moderated only by IS. Cardiovascular variables were similar in the three groups, but differed among tasks and were influenced by IS and ORG. Our findings extend earlier observations on the role of hypnotisability in the postural correlates of sensorimotor imagery to interoceptive imagery, support the hypothesis that interoceptive sensibility moderates postural control and cardiorespiratory variables during interoceptive imagery, and confirm earlier reports of the absence of hypnotisability-related modulation of cardiorespiratory variables during emotional tasks., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Hypnotizability is a psychophysiological trait associated with morphofunctional brain peculiarities and with several cognitive, sensorimotor and cardiovascular correlates. Behavioral and EEG studies indicate stronger functional equivalence (FE) between motor imagery and action in the individuals with high hypnotizability scores (Highs). We hypothesized that stronger FE leading to greater proneness to ideomotor behavior could be due to greater cortical excitability of the motor cortex. The aim of the study was to evaluate the motor cortical excitability through measurements of the muscle potentials (MEPs) evoked in the left abductor pollicis brevis by transcranial magnetic stimulation (TMS) of the right motor cortex in 10 Highs, 10 medium (Mediums) and 10 low hypnotizable individuals (Lows) classified according to the Stanford Hypnotic Susceptibility Scale, form A (SHSS). They were studied in basal conditions (B) and during motor imagery (MI). Results showed significant, negative correlations (i) between hypnotizability and MEPs Resting Motor Threshold (RMT) in basal conditions, and (ii) between hypnotizability and both MEPs RMT and suprathreshold (I 1mv ) stimulation intensities during MI. ANOVA revealed significantly lower stimulation intensities in Highs than in Lows, with Mediums exhibiting intermediate values. Thus, the Highs' greater cortical excitability could sustain their greater FE and proneness to ideomotor behavior. In cognitive neuroscience these findings are relevant to the physiological interpretation of the response to sensorimotor suggestions by participants in the ordinary state of consciousness. In the clinical field they can predict the efficacy of mental training based on motor imagery and, possibly, the degree of imagery-induced cortical plasticity., (Copyright © 2020 IBRO. Published by Elsevier Ltd. All rights reserved.)

The aim of the present study was to compare the effects of explicit suggestions of analgesia and of the activation of the Diffuse Noxious Inhibitory Control (DNIC) by cold pressor test on pain perception and heart rate in healthy participants with high (highs, N=18), low (lows, N=18) and intermediate scores of hypnotizability (mediums, N=15) out of hypnosis. Pain reports and the stimulus-locked heart rate changes induced by electrical nociceptive stimulation of the left hand were studied in the absence of concomitant stimuli (Control), during suggestions of analgesia (SUGG, glove analgesia) and during cold pressor test used as a conditioning stimulus to the right hand (DNIC, water temperature=10-12°C) in the REAL session. Participants were submitted also to a SHAM session in which the DNIC water temperature was 30°C and the suggestions for analgesia were substituted with weather forecast information. Both suggestions and DNIC reduced pain significantly in all subjects; however, the percentage of reduction was significantly larger in highs (pain intensity=55% of the control condition) than in mediums (70%) and lows (80%) independently of the REAL/SHAM session and of the specific pain manipulation. Heart rate was not modulated consistently with pain experience. Findings indicate that both suggestions and DNIC influence pain experience as a function of hypnotizability and suggest that both sensory and cognitive mechanisms co-operate in DNIC induced analgesia., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Hypnotizability is associated with attentional characteristics whose neurophysiological bases are still under debate. Aim of the study was the assessment of possible hypnotizability-related differences in blink reflex (BR) which has a nociceptive component, is sensitive to attentional-emotional traits and states and is modulated by the brain dopamine content. In 10 high (highs) and 10 low hypnotizable participants (lows) BR was induced by electrical nociceptive stimulation of the right supraorbital nerve in the absence (noW) and in the presence of a visual cue preceding the electrical stimulation by 0.1ms (W01) and by 1ms (W1). The studied variables were: the amplitude of BR components (R1, R2, R3), the amplitude of the quick change (TO) of heart rate ("turbulence") induced by stimulation and its recovery slope (TS), the role of the Behavioral Inhibition/Activation System (BIS/BAS) in the variability BR and cardiac turbulence. Repeated measures ANOVA did not show any significant difference between highs and lows in blink reflex. TO indicated stimulation related HR increase in highs and decrease in lows, TS was larger in highs. BIS and BAS accounted for the warning effects on the BR amplitude and modulated the hypnotizability and warning effects on TO and TS. Findings do not support dopamine based hypnotizability-related attentional abilities. In contrast, they indicate that hypnotizability modulates the short-lasting cardiac response to electrical nociceptive stimulation., (Copyright © 2016 Elsevier Inc. All rights reserved.)

We report novel findings concerning the role of hypnotizability, suggestions of analgesia and the activity of the Behavioral Inhibition/Activation System (BIS/BAS) in the modulation of the subjective experience of pain and of the associated EEG dynamics. The EEG of high (highs) and low hypnotizable participants (lows) who completed the BIS/BAS questionnaire was recorded during basal conditions, tonic nociceptive stimulation without (PAIN) and with suggestions for analgesia (AN). Participants scored the perceived pain intensity at the end of PAIN and AN. The EEG midline dynamics was characterized by indices indicating the signal predictability (Determinism) and complexity (Entropy) obtained through the Recurrence Quantification Analysis. The reduced pain intensity reported by highs during AN was partially accounted for by the activity of the Behavioral Activation System. The decreased midline cortical Determinism observed during nociceptive stimulation in both groups independently of suggestions remained significantly reduced only in lows after controlling for the activity of the Behavioral Activation System. Finally, controlling for the activity of the Behavioral Inhibition System abolished stimulation, suggestions and hypnotizability-related differences. Results indicate that the BIS/BAS activity may be more important than hypnotizability itself in pain modulation and in the associated EEG dynamics., (Copyright © 2015. Published by Elsevier Inc.)

Hypnotizability is a cognitive trait modulating some physiological responses to cognitive and physical stimulation also in the normal awake state and in the absence of specific suggestions. Aim of the study was the characterization of the cardiovascular correlates of deep pain induced by nociceptive pressor stimulation without (PAIN) and with (AN) suggestions for analgesia, pain imagery/perception (IM) and mental computation (MC) in not hypnotized highly (Highs) and low (Lows) hypnotizable healthy subjects of both genders. The subjective experience of pain intensity, relaxation and task related fatigue were measured through a structured interview. Heart rate, blood pressure, skin blood flow and respiratory activity were monitored throughout the experimental session. Only Highs perceived lower pain intensity during AN with respect to PAIN and were able to perceive pain during IM. Heart rate decreased during PAIN, increased during MC and did not change during AN and IM in both groups. On the whole, the haemodynamic response consisted of decreased systolic/mean blood pressure and maximum skin blood flow together with increased diastolic blood pressure/minimum skin blood flow in both groups during all conditions. Scarce differences were observed between Highs and Lows (in systolic blood pressure during IM and in respiratory amplitude during PAIN, AN and IM, modulated by gender). The results indicate that in not hypnotized subjects hypnotizability is not associated with relevant differences in the autonomic responses to deep pain, suggestions for analgesia, pain imagery/perception and cognitive load., (Copyright 2010 Elsevier Inc. All rights reserved.)

Subjects with high (Highs) and low (Lows) susceptibility to hypnosis show differences in the sensory-motor integration for postural control and in the cardiovascular response to stress and experimental pain. Aim of the experiment was to assess whether the cardiac response to gravity-related stimulation depending on changes in the body position were different in the two groups. Thus, heart rate (HR) and heart rate variability (HRV) were evaluated in sitting and upright position in Highs and Lows. Position-related HRV changes were studied in the time (statistical indexes, Poincaré Plot) and frequency (spectral analysis) domain. Results indicated that upright stance was associated with similar changes in heart rate and different modulation of HRV in the two groups. The association of time and frequency domain analyses allowed hypothesizing different control mechanisms as responsible for the cardiac response to upright stance in Highs and Lows, likely due to a different role of the Very Low Frequency (VLF) spectral component of HRV in the two groups. The results are in line with previous findings indicating a natural protection of Highs against cardiovascular events and suggest that the Highs' cardiac function might be less impaired by microgravity than the Lows' one.

In a previous study we showed that healthy highly hypnotizable subjects, during the suggestion of a moderately unpleasant situation administered in awake conditions, exhibited a sympathetic response greatly attenuated with respect to non-hypnotizable individuals. This was interpreted as a natural protection of hypnotizable subjects against the cardiovascular effects of cognitive stress. Aim of the present study was to investigate whether the hypnotic trait is able to modulate the autonomic and cerebral activities also in specific phobic awake hypnotizable (Highs) and non-hypnotizable (Lows) subjects. Electroencephalogram, electrooculogram, electromiogram of corrugator muscle, electrocardiogram, respirogram and tonic electrodermal activity were recorded during a guided mental imagery of an animal phobic object. Phobic stimulation induced in both groups the rise of heart and respiratory frequency and the lowering of skin resistance. These changes are less pronounced in Highs than in Lows and are sustained by a different modulation of the sympatho-vagal balance. During phobic stimulation both groups exhibited a similar significant increase of EEG gamma relative power. At variance, significant stimulation-related decrements of alpha1, theta1 and theta2 activities were found only in Highs that exhibited similar changes during the control and phobic stimulation. Results suggest that hypnotizability is able to modulate cerebral and autonomic responses also in specific phobic subjects. However, the presence of a specific phobia attenuates the effectiveness of hypnotizability as a protective factor against possible stress-related cardiac illness.

Previous studies suggest that hypnotizability represents a protective factor against the cardiac effects of cognitive stress and that hypnosis prevents vascular stress-induced modifications in highly hypnotizable individuals. The aim of the experiment was to investigate whether a similar effect at vascular level is present in awake subjects with a high (Highs) and a low (Lows) hypnotic susceptibility. Thus, brachial artery post-ischaemic flow-mediated vascular dilation (FMD) was evaluated non-invasively by ultrasound methodology during cognitive stress (mental computation) in Highs and Lows. Results showed that Highs, similarly to that previously observed in hypnotized Highs and in contrast with Lows, did not exhibit any stress-related endothelial dysfunction (FMD decrement). Thus, hypnotizability should be considered a protective factor against vascular disease.

The autonomic and EEG correlates of the response to a cognitive unpleasant stimulation (US) verbally administered to awake hypnotizable and non hypnotizable subjects were studied. They were compared with the values obtained during a resting condition immediately preceding the stimulus and with those produced by a cognitive neutral stimulation (NS), also administered after a basal resting period. Results showed hypnotic trait effects on skin resistance, heart and respiratory rate as well as on EEG theta, alpha, beta and gamma relative power changes. The autonomic and EEG patterns observed indicated different strategies in the task execution for hypnotizable and non hypnotizable subjects and a discrepancy between the autonomic and EEG changes associated to the US in susceptible subjects. Results support dissociation theories of hypnosis and suggest for hypnotizable persons an active mechanism of protection against cardiac hazard.