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.

Sex moderates the association between the COMT Val158Met single-nucleotide polymorphism and disorderliness facet of novelty seeking.

Previous studies have shown inconsistent results regarding the effect of the Val158Met polymorphism of the catechol-O-methyltransferase (COMT) gene on personality and cognition. Here, nonclinical Caucasian university students of Italian origin were administered the Temperament and Character Inventory-Revised, Tellegen Absorption Scale, Differential Attentional Processes Inventory, and Waterloo-Stanford Group Scale of Hypnotic Susceptibility. We found that the COMT Val158Met polymorphism was significantly associated with the disorderliness facet of novelty seeking (NS4) and that sex was a moderator of this association. Females with the Met/Met genotype showed higher NS4 scores compared to those with the Val/Met and Val/Val genotypes. No significant genotype effect was found for males. Additionally, we failed to find a significant effect of the COMT gene on attention and hypnotic suggestibility measures. These results provide further evidence for a sex-specific influence on the gene-behaviour associations.

Effects of Prehypnotic Instructions on Hypnotizability and Relationships Between Hypnotizability, Absorption, and Empathy.

Although hypnotizability exhibits high across-time and across-test consistencies, it is not clear (a) how different preambles to a hypnotic procedure (metasuggestions) influence responsiveness to suggestions and the strength of the association between two hypnotizability scales and (b) how hypnotizability relates to absorption and empathy. In Experiment 1, nonclinical participants (N = 152 women) were administered the Modified Tellegen Absorption Scale (MODTAS), Interpersonal Reactivity Index (IRI), Hypnotic Induction Profile (HIP), and Stanford Hypnotic Susceptibility Scale, Form C (SHSS:C). In Experiment 2, nonclinical participants (N = 188; 105 women and 83 men) were administered the MODTAS, IRI, and Harvard Group Scale of Hypnotic Susceptibility, Form A (HGSHS:A). The induction scores of the HIP (HIP-IND) and the SHSS:C scores showed a significantly stronger correlation when the HIP was introduced to the participants after hypnosis metasuggestion (HIP-H-IND) than after imagination metasuggestion (HIP-I-IND). Metasuggestion was a moderator of the association between HIP-IND and SHSS:C scores. Participants with low and medium, but not with high, hypnotizability levels on the SHSS:C showed significantly higher scores on the HIP-I-IND than on the HIP-H-IND. The strong correlations between the SHSS:C, HIP-H-IND, and HIP eye-roll (HIP-ER) scores indicate that both the HIP-H-IND and HIP-ER are robust measures of hypnotizability. Absorption and empathy were not significantly associated with hypnotizability. Women were more hypnotizable than men, as assessed by the HGSHS:A. The clinical relevance of metasuggestions, intended to increase responsiveness to suggestions, is discussed as a strategy to improve treatment outcomes.

Psychopathy traits and reinforcement sensitivity theory: Prepulse inhibition and ERP responses.

This study examined the associations between Reinforcement Sensitivity Theory (RST-PQ, Corr & Cooper, 2016) and psychopathy traits (LSRPS, Levenson et al., 1995) in university students. The aim was to identify psychopathy and RST traits associated with prepulse inhibition (PPI) of acoustic startle and ERP responses by using two prepulse-stimulus intensities (70 and 85 dB) combined with a 105 dB startle pulse (200 ms prepulse-plus-pulse interval). The higher intensity prepulse produced a larger PPI, although both prepulse stimuli reliably activated the startle system. Higher Primary Psychopathy was associated with a higher Defensive-Fight trait and both measures were associated with larger PPI. A principal components factor analysis disclosed an N1-startle factor that was a significant predictor of both reward reactivity and Goal-Drive Persistence scores. Results appear in line with Newman's response modulation hypothesis emphasizing the engagement of attention and recognition of stimulus salience, which may be disrupted in psychopathy.

Changes of EEG band oscillations to tonic cold pain and the behavioral inhibition and fight-flight-freeze systems.

Using electroencephalography (EEG) power measures within conventional delta, theta, alpha, beta, and gamma bands, the aims of the current study were to highlight cortical correlates of subjective perception of cold pain (CP) and the associations of these measures with behavioral inhibition system (BIS), fight-flight-freeze system (FFFS), and behavioral approach system personality traits. EEG was recorded in 55 healthy right-handed women under (i) a white noise interruption detection condition (Baseline); (ii) enduring CP induced by the cold cup test. CP and Baseline EEG band power scores within conventional frequency bands served for covariance analyses. We found that: (1) higher Pain scorers had higher EEG beta power changes at left frontal, midline central, posterior temporal leads; (2) higher BIS was associated with greater EEG delta activity changes at parietal scalp regions; (3) higher FFFS was associated with higher EEG delta activity changes at temporal and left-parietal regions, and with lower EEG gamma activity changes at right parietal regions. High FFFS, compared to Low FFFS scorers, also showed a lower gamma power across the midline, posterior temporal, and parietal regions. Results suggest a functional role of higher EEG beta activity in the subjective perception of tonic pain. EEG delta activity underpins conflict resolution system responsible for passive avoidance control of pain, while higher EEG delta and lower EEG gamma activity changes, taken together, underpin active avoidance system responsible for pain escape behavior.

Resting Frontal Asymmetry and Reward Sensitivity Theory Motivational Traits.

The revised reinforcement sensitivity theory (rRST) of personality has conceptualized three main systems: the behavioural approach system (BAS), behavioural inhibition system (BIS), and fight-flight-freeze system (FFFS). Research links greater relative left-frontal activity with BAS-related tendencies and impulsivity and greater relative right-frontal activity with "withdrawal" motivation that included both BIS and FFFS. Although rRST has addressed the separation of FFFS and BIS, much of personality neuroscience research does not indicate which system is related to right frontal activity. We administered the Reinforcement Sensitivity Theory of Personality Questionnaire (RST-PQ) to measure the BAS and its facets (goal-drive persistence, reward interest, reward reactivity, and impulsivity), BIS, and the withdrawal FFFS. We examined the association of RST-PQ traits with resting electroencephalogram (EEG) alpha-asymmetry in female participants (N = 162) by considering the influence of experimenter's gender. In the total group, that included two subgroups with experimenters of different gender, BAS-impulsivity was related to greater left- than right-frontal activity, and FFFS, but not BIS, was related to greater relative right-frontocentral activity. These associations remained significant for the subgroup with a young same-sex experimenter, but not with opposite-sex experimenter.

Extraversion and behavioural approach system in stimulus analysis and motor response initiation.

In this study, we attempt to validate previous findings on extraversion-related differences in speed of sensorimotor processing and to extend them into Behavioural Approach System (BAS) subtraits within the framework of the revised Reinforcement Sensitivity Theory (rRST) of personality. Here, we assessed psychological traits of extraversion (E), four BAS facets (Goal-Drive Persistence, BAS-GDP; Reward Interest, BAS-RI; Reward Reactivity, BAS-RR; Impulsivity, BAS-I), Behavioural Inhibition System (BIS), and Fight-Flight-Freeze System (FFFS) in 51 volunteers (28 women). Stimulus-locked lateralized readiness potential (S-LRP), response-locked LRP (R-LRP), stimulus-locked and response-locked forearm electromyogram (S-EMG and R-EMG), and P3 components of the event-related potentials (ERPs), were recorded during the performance of a two-choice Go/NoGo visual letter-digit discrimination task varying in task difficulty. High extraverts, relative to introverts and individuals high relative to low on BAS-RI, were more likely to exhibit shorter S-LRP latencies and stimulus- and response-locked EMG latencies. Additionally, high BAS-I had a shorter R-RLP latency than low BAS-I participants for the difficult task. High FFFS levels were associated with longer S-LRP and S-EMG latencies, while high BIS levels had larger response accuracy. Extraverts, relative to introverts, along with those high relative to low on BAS-RR and BAS-I, exhibited smaller P3 amplitudes. The faster cortical premotor initiation, found in individuals high on extraversion, BAS-RI and low on FFFS, may account for their faster peripheral motor response initiation and execution. Smaller P3 amplitudes in extraverts and individuals high on BAS-RR and BAS-I may indicate reduced perceptual processing capacity in these individuals.

Hypnotizability and Placebo Analgesia in Waking and Hypnosis as Modulators of Auditory Startle Responses in Healthy Women: An ERP Study.

We evaluated the influence of hypnotizability, pain expectation, placebo analgesia in waking and hypnosis on tonic pain relief. We also investigated how placebo analgesia affects somatic responses (eye blink) and N100 and P200 waves of event-related potentials (ERPs) elicited by auditory startle probes. Although expectation plays an important role in placebo and hypnotic analgesia, the neural mechanisms underlying these treatments are still poorly understood. We used the cold cup test (CCT) to induce tonic pain in 53 healthy women. Placebo analgesia was initially produced by manipulation, in which the intensity of pain induced by the CCT was surreptitiously reduced after the administration of a sham analgesic cream. Participants were then tested in waking and hypnosis under three treatments: (1) resting (Baseline); (2) CCT-alone (Pain); and (3) CCT plus placebo cream for pain relief (Placebo). For each painful treatment, we assessed pain and distress ratings, eye blink responses, N100 and P200 amplitudes. We used LORETA analysis of N100 and P200 waves, as elicited by auditory startle, to identify cortical regions sensitive to pain reduction through placebo and hypnotic analgesia. Higher pain expectation was associated with higher pain reductions. In highly hypnotizable participants placebo treatment produced significant reductions of pain and distress perception in both waking and hypnosis condition. P200 wave, during placebo analgesia, was larger in the frontal left hemisphere while placebo analgesia, during hypnosis, involved the activity of the left hemisphere including the occipital region. These findings demonstrate that hypnosis and placebo analgesia are different processes of top-down regulation. Pain reduction was associated with larger EMG startle amplitudes, N100 and P200 responses, and enhanced activity within the frontal, parietal, and anterior and posterior cingulate gyres. LORETA results showed that placebo analgesia modulated pain-responsive areas known to reflect the ongoing pain experience.