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Cerebral mechanisms of hypnotic hypoesthesia. An ERP investigation on the expectancy stage of perception
Abstract
The present study aims at identifying reliable markers of neural preparatory processes during hypnosis. To this goal, we recorded the electroencephalographic activity of 23 volunteers regardless of their hypnotizability score. Somatosensory evoked potentials (SEPs) were elicited while participants received non‐painful electrical stimuli on the left median nerve in the conditions of relaxation and hypnosis with suggestions of reduced sensation. SEPs analysis was focused on the pre‐stimulus activity and revealed two main components: the prefrontal negativity (pN) and the somatosensory negativity (sN) over the frontal and parietal areas of the scalp, respectively. Results showed reduced amplitudes for both components under hypnosis, mostly for the pN, suggesting a change of top‐down control of parietal and prefrontal areas. Furthermore, the sLORETA source imaging showed a deactivation of the lateral and anterior portions of the prefrontal cortex (PFC) during the hypnotic state. The present study highlights the downregulation of the PFC as a core aspect of the adopted hypnotic task and confirms the ability of hypnosis to modulate the activity of frontal executive functions. Further, since the majority of participants fell into the medium range of hypnotizability, the present findings could reflect the hypnosis effects in most of the population. This is the first ERP study that recruited participants with a medium level of hypnotizability to identify the neurocognitive effects of the hypnotic hypoestesia. Results reported reduced subjective experience of the electrical stimulation, along with reduced activity of the prefrontal and somatosensory cortex during the preparation stage. This investigation confirms the ability of hypnosis to modulate the executive functions, even in the medium hypnotizables.
... One of the main findings concerns the role of the DLPFC in producing the hypnotic responses and appraising the subjective feeling of agency during hypnosis. This evidence was also corroborated by the neurocognitive models of hypnosis (e.g., [57]) as well as by recent electrophysiological studies describing the flexibility of the DLPFC as a core aspect of the hypnotic experience [49,51,58,59]. In fact, changes in the DLPFC activity during hypnosis were associated with altered executive control, leading to reduction of feedback to the monitoring system and resulting in the experience of involuntariness (for review see [60,61]). ...
... In fact, changes in the DLPFC activity during hypnosis were associated with altered executive control, leading to reduction of feedback to the monitoring system and resulting in the experience of involuntariness (for review see [60,61]). For these reasons, we provided inhibitory tDCS bilaterally over the DLPFC, with the active electrode over the left hemisphere as its deactivation seems to best reflect the reduced peripheral awareness [29,58] featuring the neutral hypnosis [62]. Our hypothesis was that the cathodal stimulation of the DLPFC could increase hypnotic depth and response to hypnotic suggestions. ...
... This study followed the findings addressing the contribution of the DLPFC in hypnotic phenomena [58,[79][80][81] such as the inhibition of its neural activity to alter the response to hypnotic suggestions [28,29]. In particular, we aimed to reduce cortical excitability through electric neurostimulation, while the hypnotic experience was assessed from a quantifiable, phenomenological perspective, thus considering the fluid variation of consciousness. ...
Hypnotizability refers to the individual responsiveness to hypnosis, and literature shows that the greater the hypnotizability, the more effective the hypnotic suggestions. So far, few studies attempted to enhance hypnotizability, and only two adopted brain stimulation with magnetic pulses. In the present study, we aimed to boost hypnotizability through transcranial direct current stimulation (tDCS). To this aim, bilateral tDCS was applied over the dorsolateral prefrontal cortex (DLPFC) with the target electrode providing negative current (cathodal stimulation) over the left hemisphere. Twenty-nine subjects participated in the study and they were randomly assigned to the sham or the active group in a double-blind design. The hypnotic experience was assessed before and after the stimulation through a phenomenological measure of consciousness (the PCI-HAP). The main findings revealed that a single tDCS session enhanced the hypnotic depth by 11% and reduced the volitional control by 30%, while no differences emerged in the sham group. This is the first study adopting the electrical neurostimulation to produce an alteration of hypnotizability and sense of agency, and confirmed the key-role of the DLPFC and executive control in the hypnotic phenomena. If confirmed, these findings could have relevant implications as enhanced hypnotizability could be translated into better outcomes for many hypnotic interventions.
... While this prediction can be partially effective for the extreme categories of very high and very low hypnotizables, greater difficulties emerge for mediums, and this is likely due to the scoring issues discussed above. As an indirect confirmation, in a few recent studies mediums showed neither subjective nor neurophysiological differences with highs during hypnotic tasks to reduce sensory perception (Perri et al., 2020a;Perri, Rossani, & Di Russo, 2019) and cognitive conflict (Perri et al., 2020b). ...
Most of the experimental investigations on hypnosis used to compare small samples of individuals with low or high responsiveness to hypnosis by systematically excluding medium responders. The present article underlines the limitations of this methodological approach that may have partially weakened the scientific impact of hypnosis research. In fact, the mediums-neglecting bias might be one of the reasons why some investigations suffer from low replicability and generalizability. Themes such as hypnotizability scales, suggestibility, statistical power, and research design are critically reviewed with the aim of proposing a more rigorous approach that boost up impact and reliability of hypnosis research. In particular, the recruitment of medium hypnotizables and the adoption of a within-instead of a between-subjects design currently seem to be some of the best recommendations for strengthening hypnosis research, as well as to renew the dialogue between clinical and experimental hypnosis.
... A common example of positive hallucinations is a color hallucination, for example, when hypnotized participants see a gray scale in different colors when suggested to do so . An example of negative hallucinations is the hypnosis-induced elimination or reduction of pain, inflicted by noxious stimuli (e.g., Perri et al., 2020; 2019; for review please see Thompson et al., 2019). Noteworthy, we categorized these responses as objective, as these suggestion-induced changes in perceptions can be objectively measured, for instance by implicit tasks or neuroimaging. ...
Exekutive Funktionen (EF) sind eine Gruppe von Top-Down-Prozessen, die in neuartigen Situationen eingesetzt werden, um neue Trigger-Response-Assoziationen herzustellen oder vorhandene Handlungsoptionen an neue Situationen anzupassen. Obwohl EF erschöpfend untersucht wurden, bleiben wichtige Fragen offen. Beispiele dafür sind (a) Sind Exekutivfunktionen vollständig trennbar oder beruhen sie auf einem gemeinsamen neurokognitiven System? (b) Was messen verschiedene Versionen der Stroop-Aufgabe, einer der meist-verwendeten Aufgaben zur Prüfung der Inhibitionsfunktion? (c) Muss Inhibition immer Ressourcen-fordernd sein, oder gibt es eine Form der Inhibition, die mühelos implementiert werden kann? Zur Beantwortung dieser Fragen, habe ich neurokognitive Korrelate von EF und ihrer Verbesserung mithilfe posthypnotischer Suggestionen (PHS) und Ereigniskorrelierter Hirnpotentiale (EKP) untersucht. Zusammenfassend ergaben sich folgende Antworten: (a) Psychometrische und EKP-Daten aus den Studien zur Gedächtnisaktualisierung und Inhibition sowie deren Verbesserung anhand PHS zeigten sowohl funktionsspezifische als auch gemeinsame neurokognitive Prozesse der Inhibition und Aktualisierung. (b) Obwohl sowohl die vokale als auch die manuelle Version der Stroop-Aufgabe Inhibitionsfunktionen erfordern, ist die vokale Version Ressourcen-fordernder, da sie mindestens einen zusätzlichen Lokus der Interferenz im Antwort-Produktionsprozess aufweist, der nicht mit PHS beeinflussbar ist und der in der manuellen Version fehlt. (c) Unter Verwendung PHS zur Erhöhung der Präferenzen für kalorienarme Lebensmittel untersuchte ich die Auflösung von Konflikten. Die EKP-Ergebnisse zeigten, dass auch Konflikt-Auflösung, ähnlich wie Inhibition, Ressourcen konsumiert. Insgesamt zeigt dieses Projekt, dass die Verwendung Aufgaben-bezogener PHS in Kombination mit Neuroimaging-Techniken einen fruchtbaren Ansatz für die Untersuchung ungeklärter Fragen über Exekutivfunktionen darstellt.
... Interestingly, the suggestions for analgesia have been found effective also in healthy mediums undergoing nociceptive stimulation (Fidanza et al., 2017) and in chronic pain patients independently from hypnotizability (Elkins et al., 2007;Jensen, 2011;Jensen and Patterson, 2014;Mazzola et al., 2017;Facco et al., 2018;Sandvik et al., 2020). This can be accounted for by expectation of/motivation to analgesia (Milling et al., 2005;Krystek and Kumar, 2016;Montgomery et al., 2018;Perri et al., 2020) leading to placebo responses (Benedetti, 2013) which can reduce pain and pain-related psychological symptoms in the general population (Liossi et al., 2006;Brugnoli, 2016;Wortzel and Spiegel, 2017;Rousseaux et al., 2020). Thus, suggestions may induce non opioid analgesia in highs, opioid placebo responses in lows and, probably, mixed reactions in mediums. ...
... In fact, it is strongly interconnected with the VTA (Strafella, Paus, Barrett, & Dagher, 2001;Diana, 2011) and it was shown that an increase of DLPFC activity leads to deactivation of ventral striatum, which in turn is related to reduced level of craving (Kober et al., 2010). Substance addictions can also be meant in terms of impulsive behaviors, and the DLPFC as a cognitive control area involving top-down attentional and inhibitory processes to counteract automatic intentions (Lapenta, Marques, Rego, Comfort, & Boggio, 2018;Metzuyanim-Gorlick & Mashal, 2016;Perri, 2020;Perri et al., 2020;Perri, Bianco, Facco, & Di Russo, 2021;Perrotta, Bianco, Berchicci, Quinzi, & Perri, 2021;Shackman, McMenamin, Maxwell, Greischar, & Davidson, 2009). By this point of view, the metacognitive control of the DLPFC is involved in the regulation of craving and drug seeking, explaining why this cortical region can modulate impulsive outcomes mediated by sub-cortical activations (Fraser & Rosen, 2012). ...
Transcranial direct current stimulation (tDCS) over the dorsolaterateral prefrontal cortex (DLPFC) has been indicated as a promising treatment for several addictions, while its contribution for smoking cessation was less investigated. In particular, the role of motivation to quit and the nicotine dependence level as possible mediators of tDCS effect needs to be deepened. In the present study, we recruited twenty smokers who did not look for a treatment to quit: most of them presented a mild level of nicotine addiction, and they were randomly assigned to active or sham group for receiving bilateral tDCS over the DLPFC. tDCS was provided for five consecutive days with anode over the right hemisphere: in the first and the last day the craving level was evaluated through a specific evoking procedure, and the daily cigarette consumption was recorded. Results showed that the active tDCS decreased by about 50% the cigarette craving, while the number of cigarettes smoked remained unchanged and no differences emerged in the sham group. The present study indicates the tDCS of the DLPFC as a possible treatment for smoking addiction because of its effectiveness in reducing craving. Further, as we recruited smokers with no motivation to quit, and the nicotine dependence level was a moderator of the tDCS effect, we suggest that its efficacy might be even greater in the severe smokers looking for a treatment.
... A common example of positive hallucinations is a color hallucination, for example, when hypnotized participants see a gray scale in different colors when suggested to do so McGeown et al., 2012). An example of negative hallucinations is the hypnosis-induced elimination or reduction of pain, inflicted by noxious stimuli (e.g., Perri et al., 2020; 2019; for review please see Thompson et al., 2019). Noteworthy, we categorized these responses as objective, as these suggestion-induced changes in perceptions can be objectively measured, for instance by implicit tasks or neuroimaging. ...
Hypnotic and posthypnotic suggestions are frequently and successfully implemented in behavioral, neurocognitive, and clinical investigations and interventions. Despite abundant reports about the effectiveness of suggestions in altering behavior, perception, cognition, and subjective sense of agency (SoA), there is no consensus about the neurocognitive mechanisms driving these changes. The present review starts with procedural descriptions of hypnosis, suggestions, and suggestibility, followed by a systematic and comparative review of prominent theories of hypnosis, highlighting their strengths and weaknesses, based on their power to explain existing observations in the domain of hypnosis. Thereafter, we propose a novel theory of hypnosis, accounting for empirical evidence and synthesizing concepts from hypnosis and neurocognitive theories. The proposed simulation-adaption theory of hypnosis (SATH) is founded on three elements: cognitive-simulation, top-down sensory-adaptation, and mental training. SATH mechanistically explains different hypnotic phenomena, such as alterations in the SoA, positive and negative hallucinations, motor suggestions, and effects of suggestions on executive functions and memory. Finally, based on SATH and its postulated neurocognitive mechanisms, a procedure-oriented definition of hypnosis is proposed.
... Compared to previous studies, further innovations consist in the administration of suggestions during alert hypnosis instead of posthypnotic suggestions and the recruitment of participants regardless of their responsiveness to hypnosis. In fact, investigations restricted to these individuals cannot be considered representative of the majority of subjects, making it better to include both high and medium hypnotizables (Jensen et al., 2017;Perri et al., 2020). In a previous study on the Stroop task in highs, the participants with a score of 10-12 on the French version of the Harvard Group Scale of Hypnotic Susceptibility Form A (HGSHS-A) and 9-11 on the French version of the Stanford Hypnotic Susceptibility Scale Form C were less than 6% of the population (Augustinova and Ferrand, 2012), indicating two main limitations of studies based on highs only: (a) the extremely strict selection of participants not reflecting the general population and (b) the possible variability of sample features since other studies report a rate of highs of 31% in the French version of the Harvard scale (Anlló et al., 2017) and 27.5 and 36.5% of subjects scoring 9-11 in the Italian and Mexican versions of Stanford Form C, respectively (no published French normative data are available to our knowledge) (De Pascalis et al., 2000;Sánchez-Armáss and Barabasz, 2005). ...
Compelling literature has suggested the possibility of adopting hypnotic suggestions to override the Stroop interference effect. However, most of these studies mainly reported behavioral data and were conducted on highly hypnotizable individuals. Thus, the question of the neural locus of the effects and their generalizability remains open. In the present study, we used the Stroop task in a within-subject design to test the neurocognitive effects of two hypnotic suggestions: the perceptual request to focus only on the central letter of the words and the semantic request to observe meaningless symbols. Behavioral results indicated that the two types of suggestions did not alter response time (RT), but both favored more accurate performance compared to the control condition. Both types of suggestions increased sensory awareness and reduced discriminative visual attention, but the perceptual request selectively engaged more executive control of the prefrontal cortex (PFC), and the semantic request selectively suppressed the temporal cortex activity devoted to graphemic analysis of the words. The present findings demonstrated that the perceptual and the semantic hypnotic suggestions reduced Stroop errors through common and specific top-down modulations of different neurocognitive processes but left the semantic activation unaltered. Finally, as we also recruited participants with a medium level of hypnotizability, the present data might be considered potentially representative of the majority of the population.
... In other terms, the pN activity might reflect the attentional control engaged by the task rules and driving the readiness activation according to the expected modality. Further, since the present study employed visual tasks, a posterior vN component, which might facilitate the bottomup processing of the next stimulus, was observed (see also Bianco, Berchicci, et al., 2019;Perri et al., 2020 for similar findings in different modalities). It is also interesting to note that the vN activity tended to be contralateral to the attended hemi-field. ...
The anticipation of upcoming events is a key-feature of cognition. Previous investigations on anticipatory visuospatial attention mainly adopted transient and–more rarely–sustained tasks, whose main difference consists in the presence of transient or sustained cue stimuli and different involvement of top-down or bottom-up forms of attention. In particular, while top-down control has been suggested to drive sustained attention, it is not clear whether both endogenous and exogenous controls are recruited in transient attention task, or whether the cue-evoked attention may be interpreted as a mainly bottom-up guided process. To solve this issue, the present study focused on the preparatory brain activity of participants performing a sustained and a transient attention task. To this aim, the focus was on pre-stimulus event-related potential (ERP) components, i.e., the prefrontal negativity (pN) and the visual negativity (vN), associated with cognitive and sensorial preparation, emerging from prefrontal and visual areas, respectively. Results indicated that the pN was specific for the sustained task, while the vN emerged for both tasks, although smaller in the transient task, with a hemispheric lateralization contralateral to the attended hemifield. The present findings support the interpretation of the vN as a modality-specific index of attentional preparation, and suggest the presence of cognitive endogenous control in sustained tasks only, as revealed by the presence of a prefrontal activity that was interpreted as the locus of the top-down attentional modulation during the stimulus expectancy stage.
Background
Recent studies of neurostimulation reported alteration of hypnotizability and hypnotic phenomena after inhibition of the dorsolateral prefrontal cortex (DLPFC), but the different assessments of hypnosis and the stimulation parameters still left open many questions about the role of this brain region in hypnotizability. We aimed to administer inhibitory transcranial direct current stimulation (tDCS) over the left DLPFC to observe effects of stimulation on the hypnotic experience and the feeling of agency.
Methods
a procedure of hypnotic induction with suggestions was repeated twice: before and after the unilateral cathodal tDCS over the left DLPFC. The experience was assessed through a phenomenological assessment of hypnosis and sense of agency in thirty-three participants randomly assigned to the sham or the active group.
Results
active (inhibitory) tDCS enhanced the hypnotizability by 15.4% and altered a few dimensions of consciousness such as self-awareness and absorption. No changes emerged on the feeling of agency and pass rates for suggestions.
Conclusions
tDCS reflects a promising tool to alter the hypnotic phenomena and the responsiveness to hypnotic procedures. Neurocognitive implications are discussed for the construct of hypnotizability as well as for the role of the left DLPFC in the dimensions of consciousness such as self-awareness.
Human brain activity allows to anticipate future events and to prepare the next action accordingly; consistently, event-related potential (ERP) studies found action preparatory brain activities in the premotor and prefrontal cortex. In the present study, we investigated the preparatory activity in the sensory cortical regions. Slow cortical potentials were recorded during passive tasks, i.e., subjects expected for a sensory stimulus and no motor or cognitive response were required. In particular, we tested the hypothesis that perceptual anticipatory cortical mechanisms were modality specific. Three groups of 21 young adults underwent passive perceptual tasks in different sensory modalities (visual, auditory, or somatosensory). We confirmed the presence of a visual negativity (vN) component for the visual modality starting about 800 ms before stimulus with source in extrastriate areas and we found novel modality-specific sensory readiness components for the auditory and somatosensory modalities. The auditory positivity (aP) started about 800 ms before stimulus with source in bilateral auditory cortices and the somatosensory negativity (sN) started about 500 ms before stimulus with source in the somatosensory secondary cortex, contralateral to the stimulated hand. The scalp topography and intracranial sources of these three slow preparatory activities were mirrored with inverted polarity at early post-stimulus stage evoking the well-known visual P1, auditory N1, and somatosensory P100 components. Present findings contribute to widening the family of slow wave preparatory components, providing evidence about the relationship between top–down and bottom–up processing in sensory perception.
Hypnosis and meditation, as a whole, form a heterogeneous complex of psychosomatic techniques able to control mind and body regulation. Hypnosis has been pragmatically used for limited therapeutic targets, while Eastern meditation has much wider philosophical and existential implications, aiming for a radical liberation from all illusions, attachments, suffering and pain. The available data on the history, phenomenology, and neuropsychology of hypnosis and meditation show several common features, such as the following: (a) induction based on focused attention; (b) capability to reach an intentional control of both biologic-somatic activities and conscious-unconscious processes; (c) activation/deactivation of several brain areas and circuits (e.g., the default modality network and pain neuromatrix) with a relevant overlapping between the two. Copyright
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 hypnotic phenomena. As we learn more about the neurophysiological mechanisms underlying hypnosis and suggestion, we will strengthen our knowledge of both basic brain functions and a host of different psychological functions.
The omissions are infrequent errors consisting in missing responses to the target stimuli. This is the first study aimed at investigating the brain activities associated with omissions in a decision-making task. We recorded event-related potentials (ERPs) in 12 subjects which reported a suitable number of omissions in a visual go/no-go task. We investigated both the pre- and post-stimulus brain activities associated with correct and omitted trials. The electrical neuroimaging technique (BESA) was adopted to extract the anterior insula (aIns) activity associated with the prefrontal P2 component (pP2) peaking about 300 ms after the stimulus and reflecting the stimulus-response mapping process. We found that omissions were predicted by a delayed onset (about half a second) of two pre-stimulus components, i.e. the prefrontal negativity (pN) and the Bereitschaftspotential (BP) associated with the top-down control and the motor preparation, respectively. Further, at the post-stimulus stage the omission trials were characterized by the suppression of the pP2 (and the aIns activity as measured by BESA). No differences between omission and correct trials were detected at the level of the P1 and N1 visual components, as well as the P3. These findings would suggest that omissions are attentional lapsebased errors, as indicated by the delayed brain preparation before the stimulus onset. The reduced cortical activity during the preparation phase did not affect the visual processing; in contrast the stimulus categorization process at the level of the anterior insula did not start at all, resulting in the inability to reach a decision.
This study examined the relationship between the Hypnotic Induction Profile (HIP) and several psychological tests: Tellegen Absorption Scale (TAS), Spontaneity Assessment Inventory-Revised (SAI-R), Dissociative Experiences Scale (DES), Short-Form Boundary Questionnaire (SFBQ), Mini Locus of Control (MLOC), Testoni Death Representation Scale (TDRS), and the Interpersonal Reactivity Index (IRI). Two hundred and forty volunteers were administered the above tests; 78 of them were also administered the HIP, and its scores were compared to those on the other tests. A significant correlation was found among the TAS, DES, SFBQ, and IRI. The HIP was significantly correlated to the DES (r =.19 p1tail =.045), and the IRI-ec subscale (r =.19 p1tail =.044); 14 test items from DES, IRI, TAS, SAIR, and SFBQ were also significantly related to the HIP. The findings suggest that hypnotizability may relate to stronger perception of the inner world, decreased aptitude for managing memory processing, and increased sensitivity and empathy. Copyright
In cognitive tasks, error commission is usually followed by a performance characterized by post-error slowing (PES) and post-error improvement of accuracy (PIA). Three theoretical accounts were hypothesized to support these post-error adjustments: the cognitive, the inhibitory, and the orienting account. The aim of the present ERP study was to investigate the neural processes associated with the second error prevention. To this aim, we focused on the preparatory brain activities in a large sample of subjects performing a Go/No-go task. The main results were the enhancement of the prefrontal negativity (pN) component -especially on the right hemisphere- and the reduction of the Bereitschaftspotential (BP) -especially on the left hemisphere- in the post-error trials. The ERP data suggested an increased top-down and inhibitory control, such as the reduced excitability of the premotor areas in the preparation of the trials following error commission. The results were discussed in light of the three theoretical accounts of the post-error adjustments. Additional control analyses supported the view that the adjustments-oriented components (the post-error pN and BP) are separated by the error-related potentials (Ne and Pe), even if all these activities represent a cascade of processes triggered by error-commission.
This article elucidates an integrative model of hypnosis that integrates social, cultural, cognitive, and neurophysiological variables at play both in and out of hypnosis and considers their dynamic interaction as determinants of the multifaceted experience of hypnosis. The roles of these variables are examined in the induction and suggestion stages of hypnosis, including how they are related to the experience of involuntariness, one of the hallmarks of hypnosis. It is suggested that studies of the modification of hypnotic suggestibility; cognitive flexibility; response sets and expectancies; the default-mode network; and the search for the neurophysiological correlates of hypnosis, more broadly, in conjunction with research on social psychological variables, hold much promise to further understanding of hypnosis.
The study investigates the neurocognitive stages involved in the speed-accuracy trade-off (SAT). Contrary to previous approach, we did not manipulate speed and accuracy instructions: participants were required to be fast and accurate in a go/no-go task, and we selected post-hoc the groups based on the subjects' spontaneous behavioral tendency. Based on the reaction times, we selected the fast and slow groups (Speed-groups), and based on the percentage of false alarms, we selected the accurate and inaccurate groups (Accuracy-groups). The two Speed-groups were accuracy-matched, and the two Accuracy-groups were speed-matched. High density electroencephalographic (EEG) and stimulus-locked analyses allowed us to observe group differences both before and after the stimulus onset. Long before the stimulus appearance, the two Speed-groups showed different amplitude of the Bereitschaftspotential (BP), reflecting the activity of the supplementary motor area (SMA); by contrast, the two Accuracy-groups showed different amplitude of the prefrontal negativity (pN), reflecting the activity of the right prefrontal cortex (rPFC). In addition, the post-stimulus event-related potential (ERP) components showed differences between groups: the P1 component was larger in accurate than inaccurate group; the N1 and N2 components were larger in the fast than slow group; the P3 component started earlier and was larger in the fast than slow group. The go minus no-go subtractive wave enhancing go-related processing revealed a differential prefrontal positivity (dpP) that peaked at about 330 ms; the latency and the amplitude of this peak were associated with the speed of the decision process and the efficiency of the stimulus-response mapping, respectively. Overall, data are consistent with the view that speed and accuracy are processed by two interacting but separate neurocognitive systems, with different features in both the anticipation and the response execution phases.
Anticipation increases the efficiency of cognitive processes by partial advance activation of the neural substrate involved in those processes. In the case of perceptual anticipation, a slow cortical potential named Stimulus-Preceding Negativity (SPN) has been identified. The SPN has been observed preceding four types of stimuli: (1) stimuli providing knowledge-of-results (KR) about past performance, (2) stimuli conveying an instruction about a future task, (3) probe stimuli against which the outcome of a previous task has to be matched, and (4) affective stimuli. The morphology and scalp distribution of the SPN is different in each of these cases, suggesting the presence of separable components. This article reviews more than 15 years of SPN research. Possible neurophysiological generators are considered, as well as models that may describe the generation of the SPN. Suggestions for future research into anticipatory processes and the associated psychophysiological measures are made. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
Emotional perception has been extensively studied, but only a few studies have investigated the brain activity preceding exposure to emotional stimuli, especially when they are triggered by the subject himself. Here, we sought to investigate the emotional expectancy by means of movement related cortical potentials (MRCPs) in a self-paced task, in which the subjects begin the affective experience by pressing a key. In this experiment, participants had to alternatively press two keys to concomitantly display positive, negative, neutral, and scrambled images extracted from the International Affective Pictures System (IAPS). Each key press corresponded to a specific emotional category, and the experimenter communicated the coupling before each trial so that the subjects always knew the valence of the forthcoming picture. The main results of the present study included a bilateral positive activity in prefrontal areas during expectancy of more arousing pictures (positive and negative) and an early and sustained positivity over occipital areas, especially during negative expectancy. In addition, we observed more pronounced and anteriorly distributed Late Positive Potential (LPPs) components in the emotional conditions. In conclusion, these results show that emotional expectancy can influence brain activity in both motor preparation and stimulus perception, suggesting enhanced pre-processing in the to-be-stimulated areas. We propose that before a predictable emotional stimulus, both appetitive and defensive motivational systems act to facilitate the forthcoming processing of survival-relevant contents by means of an enhancement of attention toward more arousing pictures.
Recent findings suggest the existence of a frontoparietal control system consisting of flexible hubs that regulate distributed systems (e.g., visual, limbic, motor) according to current task goals. A growing number of studies are reporting alterations of this control system across a striking range of mental diseases. We suggest this may reflect a critical role for the control system in promoting and maintaining mental health. Specifically, we propose that this system implements feedback control to regulate symptoms as they arise (e.g., excessive anxiety reduced via regulation of amygdala), such that an intact control system is protective against a variety of mental illnesses. Consistent with this possibility, recent results indicate that several major mental illnesses involve altered brain-wide connectivity of the control system, likely altering its ability to regulate symptoms. These results suggest that this "immune system of the mind" may be an especially important target for future basic and clinical research.
Nous proposons de discuter des études comportementales, électrophysiologiques et de neuroimagerie investiguant l’hypnose comme un processus de conscience ou comme un outil pour moduler les réponses cérébrales au repos ou lors de stimulations douloureuses. Différentes études ont mis en évidence une modification de l’activité cérébrale au niveau des réseaux interne (conscience de soi) et externe (conscience de l’environnement). Par ailleurs, les mécanismes cérébraux qui sous-tendent la modulation de la perception de la douleur sous-hypnose comprennent des régions telles les cortex cingulaire antérieur et frontal, les ganglions de la base et le thalamus. Combinée à une anesthésie locale et une sédation consciente chez les patients subissant une chirurgie, l’hypnose est également associée à une amélioration péri- et postopératoire du confort des patients et des chirurgiens. Enfin, l’hypnose peut être considérée comme un outil utile pour créer des symptômes de conversion et de dissociation chez des sujets sains, ce qui permet de mieux caractériser ces troubles en mimant des observations cliniques similaires.
Functional neuroimaging studies show that hypnosis affects attention by modulating anterior cingulate cortex activation and uncoupling conflict monitoring and cognitive control function. Considering functional changes in the activation of the occipital and temporal cortices, precuneus, and other extrastriate visual areas, which account for hypnosis-induced altered reality perception, the role of mental imagery areas appears to be central under hypnosis. This is further stressed by the fact that motor commands are processed differently in the normal conscious state, deviating toward the precuneus and extrastriate visual areas. Functional neuroimaging also shows that posthypnotic suggestions alter cognitive processes. Further research should investigate the effects of hypnosis on other executive functions and personality measures.
Debate regarding the neural basis of the hypnotic state continues, but a recent hypothesis suggests that it may produce alterations in the default mode network (DMN). DMN describes a network of brain regions more active during low-demand compared to high-demand task conditions and has been linked to processes such as task-independent thinking, episodic memory, semantic processing, and self-awareness. However, the experiential and cognitive correlates of DMN remain difficult to investigate directly. Using hypnosis as a means of altering the resting ("default") state in conjunction with subjective measures and brain imaging, the authors found that the state of attentional absorption following a hypnotic induction was associated with reduced activity in DMN and increased activity in prefrontal attentional systems, under invariant conditions of passive visual stimulation. The findings that hypnosis and spontaneous conceptual thought at rest were subjectively and neurally distinctive are also relevant to understanding hypnosis itself.
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.
In cognitive neuroscience, an extensive debate concerns the mechanisms of inhibition and the relationship between inhibitory and behavioural control. Since the proactive mode of inhibition was first described, several studies have aimed to distinguish this form of inhibitory control from the reactive one. In fact, according to the dualistic models of cognitive control, the two forms of inhibition regulate the action control. However, most of the studies in this field neglected the role of attention in response inhibition, as well as the role of inhibition as an executive function. In the present article, emerging evidence in favour of a unitary mechanism of inhibition is reviewed: recent observations suggest that inhibition represents a default mode of the human brain, and that inhibitory control should not be dissociated from attentional control. Accordingly, the so-called proactive and reactive inhibition might reflect the contribution of the sustained and selective attention in the implementation of the default inhibitory control, which might be more properly termed as attentional inhibitory control (AIC).
Evidence of the integrated perspective of the AIC model is reviewed from the neural, cognitive and neuropsychological point of view. Theoretical and clinical implications are discussed.
A large literature indicated hypnosis as a useful tool to reduce pain perception, especially in high susceptible individuals. However, due to different methodological aspects, it was still not clear whether hypnosis modulates the early sensory processing of the stimuli or if it affects only the later stages of affective processing. In the present study, we measured the EEG activity of subjects with a medium level of hypnotizability while receiving electrical non-painful stimuli on the median nerve in the conditions of awake and hypnosis with suggestions of hypoesthesia. Subjective reports indicated that hypnosis reduced both the sensory and the affective perception of the stimuli. ERP data revealed that hypnosis reduced the activity of both the early (N20) and the late (P100, P150, P250) SEP components. Neuroelectric source imaging further confirmed the top-down hypnotic modulation of a network of brain areas including the SI (N20), SII (P100), right anterior insula (P150) and cingulate cortex (P150/P250). The present study provides neurophysiological evidence to the hypnotic regulation of somatosensory inputs outside of pain, that is since the earliest stage of thalamocortical processing. Also, because present subjects were selected regardless of the level of hypnotizability, inferences from the present study are more generalizable than investigations restricted to high-hypnotizable individuals.
This study aimed to determine the effects of neutral hypnosis and hypnotic temperature suggestions in thermal and pain thresholds compared to resting state. Sixteen healthy medium or high hypnotizable volunteers were enrolled. Hypnotizability was assessed with the Hypnotic Induction Profile (HIP); QST was checked in resting state, in neutral hypnosis, after suggestions of heat and cold, and after deinduction. A significant increase in heat threshold was recorded during hypnosis with both cold and heat suggestions compared to neutral hypnosis. HIP induction score showed a linear correlation with changes of temperature thresholds after heat and cold suggestions. Thermal suggestions may result in a significant increase of heat perception thresholds with respect to neutral hypnosis. HIP score is related to thermal threshold changes. QST is a valuable and manageable tool to measure temperature threshold change during hypnosis.
The topic of multiple personality, redefined as Dissociative Identity Disorders (DIDs) in the DSM-5, is an intriguing and still debated disorder with a long history and deep cultural and epistemological implications, extending up to the idea of possession. Hypnosis is an appealing and valuable model to manipulate subjective experience and get an insight on both the physiology and the pathophysiology of the mind-brain functioning; it and has been closely connected with DIDs and possession since its origin in 18th century and as recently proved the capacity to yield a loss of sense of agency, mimicking delusions of alien control and spirit possession. In this study we report on five very uncommon "hypnotic virtuosos" (HVs) free from any psychiatric disorder, spontaneously undergoing the emergence of multiple identities during neutral hypnosis; this allowed us to check the relationship between their experience and fMRI data. During hypnosis the subjects underwent spontaneous non-intrusive experiences of other selves which were not recalled after the end of the session, due to post-hypnotic amnesia. The fMRI showed a significant decrease of connectivity in the Default Mode Network (DMN) especially between the posterior cingulate cortex and the medial prefrontal cortex. Our results and their contrast with the available data on fMRI in DIDs allows to draw the hypothesis of a continuum between healthy mind - where multiple identities may coexist at unconscious level and may sometimes emerge to the consciousness - and DIDs, where multiple personalities emerge as dissociated, ostensibly autonomous components yielding impaired functioning, subject's loss of control and suffering. If this is the case, it seems more reasonable to refrain from seeking for a clear-cut limit between normality (anyway a conventional, statistical concept) and pathology, and accept a grey area in between, where ostensibly odd but non-pathological experiences may occur (including so-called non-ordinary mental expressions) without calling for treatment but, rather, for being properly understood.
In the present study, we report the results from a large sample of participants (N = 136), selected based on their EEG quality, to obtain event-related potential (ERP) normative data. All participants were tested in Simple Response Task (SRT) and Discriminative Response Task (DRT). A subset of 36 participants was tested also in Passive Vision task. Both pre- and post-stimulus ERPs were analyzed and compared among different tasks. Spatiotemporal patterns of all the observed components were analyzed using source analysis. Beside the well-known ERP components, we also described recently identified prefrontal components: the pre-stimulus prefrontal negativity (pN) associated to proactive cognitive (mainly inhibitory) control within the inferior frontal gyrus (iFg); the post-stimulus prefrontal N1, P1 and P2 (pN1, pP1 and pP2) involved in perceptual and visual-motor awareness (pN1 and pP1), and in stimulus-response mapping and decision-making (pP2) localized within the insular cortex. The large sample of high-quality EEG datasets allowed to identify four additional components: the pre-stimulus visual negativity (vN) originating in extrastriate visual areas and interpreted as a visual readiness activity; the post-stimulus prefrontal N2 and N3 (pN2 and pN3) components interpreted as feedback reactivation of the anterior insular cortex; and the post-stimulus prefrontal P3 (pP3), interpreted as persisting inhibitory activity of the iFg for inhibited trials.
In the Stroop task color words are shown in various print colors. When print colors are named or classified with button presses, interference occurs if word meaning is color-incongruent and facilitation if it is congruent. Although the Stroop effects in vocal and manual task versions are similar, it is unclear whether the underlying mechanisms are equivalent. We addressed this question by (a) recording event-related brain potentials (ERPs), (b) manipulating the lexicality of neutral stimuli, and (c) giving posthypnotic suggestions (PHS) that written words would lose their meaning. The Stroop effect in the vocal version was twice its manual counterpart. PHS strongly reduced both effects by a similar amount, supporting a common semantic locus during reading. Task- and hypnosis-invariant lexicality effects for neutral words ruled out presemantic reading loci. Articulation-artifact corrected ERPs showed taskinvariant Stroop effects in N400 amplitudes, supporting similar semantic loci. However, in the vocal task response-locked ERPs indicated a task-specific Stroop effect over left-inferior frontal and parietal scalp sites, suggesting interference during word production. Interestingly, PHS increased the N1 and decreased the N2 components in ERPs, regardless of congruency, indicating enhanced proactive executive control and diminished demands on conflict-monitoring, respectively. Stroop effects in the N400 were reduced by PHS, confirming their semantic locus. In conclusion, vocal and manual Stroop versions seem to share semantic loci of conflict. The bigger vocal Stroop effect may be attributable to additional loci during word production lexicon. Apparently, PHS diminish Stroop effects by enhancing proactive executive control over lexico-semantic conflicts.
The Bereitschaftspotential (BP) and the P3 are well-known event-related potentials (ERP) usually observed during self-paced and externally-triggered tasks. Recently, the BP was detected also in externally-triggered tasks before stimulus onset. However, doubts have been raised about the authenticity of the BP in these tasks due to possible overlaps with the previous trial P3 (hereinafter s-1 P3). Here, we aim to test the authenticity of the BP in externally-triggered tasks by comparing ERPs obtained during two visuo-motor response tasks with different ISIs allowing (Short-ISI; 1000-2000 ms) or not (Long-ISI; 2000-4000 ms) P3-BP overlaps. In line with previous research, we hypothesize that BP and the s-1 P3 contribute independently to the scalp-detected activities during these tasks. ERPs were recorded from fourteen healthy participants during the Short-ISI and Long-ISI visuo-motor response tasks. Amplitudes and latencies of pre (BP and pN) and post stimulus ERP components (P1, pN1, pP1, N1, pP2, dpP2, N2 and P3) were compared between conditions. No effect of ISI was found on the amplitude of any pre and post stimulus components. In contrast, longer ISI is associated with earlier onsets of the BP and pN components. In visuo-motor response tasks, the BP is independent from the P3 elicited by the previous trial (s-1 P3), even using relatively short ISI. Since the different ISIs did not affect the amplitude of the BP and the P3 components, we conclude that also a short ISI can be adopted safely and conveniently to keep a reasonable duration of the overall experiment.
Both playing a musical instrument and playing sport produce brain adaptations that might affect sensory-motor functions. While the benefits of sport practice have traditionally been attributed to aerobic fitness, it is still unknown whether playing an instrument might induce similar brain adaptations, or if a specific musical instrument like drums might be associated to specific benefits because of its high energy expenditure. Since the aerobic costs of playing drums was estimated to be comparable to those of average sport activities, we hypothesized that these two groups might show both behavioral and neurocognitive similarities. To test this hypothesis, we recruited 48 young adults and divided them into four aged-matched groups: 12 drummers, 12 athletes, 12 no-drummer musicians and 12 non-athletes. Participants performed a visuo-motor discriminative response task, namely the Go/No-go, and their cortical activity was recorded by means of a 64-channel electroencephalography (EEG). Behavioral performance showed that athletes and drummers were faster than the other groups. Electrophysiological results showed that the pre-stimulus motor preparation (i.e. the Bereitschaftspotential or BP) and attentional control (i.e., the prefrontal negativity or pN), and specific post-stimulus components like the P3 and the pP2 (reflecting the stimulus categorization process) were enhanced in the athletes and drummers’ groups. Overall, these results suggest that playing sport and drums led to similar benefits at behavioral and cognitive level as detectable in a cognitive task. Explanations of these findings, such as on the difference between drummers and other musicians, are provided in terms of long-term neural adaptation mechanisms and increased visuo-spatial abilities.
Proactive brain control optimizes upcoming actions and inhibits unwanted responses. In the present event-related potential (ERP) study, participants freely decided in advance whether to respond or not to an upcoming stimulus, then prepared or not the action according to their decision; finally, a stimulus was delivered, and subjects had to respond (or not). During the decision-making stage, a prefrontal negativity raised bilaterally in case no-response was decided, reflecting the first brain signal of proactive inhibition. Simultaneously, slow activity raised over premotor cortices independently from the decision taken, and then raised during the preparation phase only in the case of response decision (as a sort of accelerator). When the decision was not to respond, the prefrontal activity remained sustained (as a sort of brake) and showed a right-lateralized distribution during the preparation phase. Overall, we described the time-course of a proactive accelerating-braking system regulating self-control of actions.
Research on preparatory brain processes taking place before acting shows unexpected connections with cognitive processing. From 50 years, we know that motor-related brain activity can be measured by electrocortical recordings 1–3 s before voluntary actions. This readiness potential has been associated with increasing excitably of premotor and motor areas and directly linked to the kinematic of the upcoming action. Now we know that the mere motor preparation is only one function of a more complex preparatory activity. Recent research shows that before any action many cognitive processes may occur depending on various aspects of the action, such as complexity, meaning, emotional valence, fatigue and consequences of the action itself. In addition to studies on self-paced action, the review considers also studies on externally-triggered paradigms showing differences in preparation processes related to age, physical exercise, and task instructions. Evidences from electrophysiological and neuroimaging recording indicate that in addition to the motor areas, the prefrontal, parietal and sensory cortices may be active during action preparation to anticipate future events and calibrate responses.
Imaging of the living human brain elucidates the neural dynamics of hypnosis; however, few reliable brain patterns emerge across studies. Here, we methodically assess neuroimaging assays of hypnosis to uncover common neural configurations using a twofold approach. First, we systematically review research on the neural correlates of hypnotic phenomena; then, we meta-analyze these collective data seeking specific activation and deactivation patterns that typify hypnosis. Anchored around the role of top-down control processes, our comprehensive examination focuses on the involvement of intrinsic brain networks known to operationalize cognitive control and self-referential cognition, including the executive, salience, and default networks. We discuss how these neural dynamics may relate to contemporary theories of hypnosis and show that hypnosis correlates with activation of the lingual gyrus—a brain region involved in higher-order visual processing and mental imagery. Our findings help to better understand the neurobiological substrates comprising the appellation hypnosis.
The classic Stroop task demonstrates the persistent and automatic effects of the meaning of color words that are very hard to inhibit when the task is to name the word color. Post-hypnotic instructions may enable highly-hypnotizable participants to inhibit the automatic access to word meaning. Here we compared the consequences of hypnosis alone and hypnosis with post-hypnotic instructions on the Stroop effect and its facilitation and inhibition components. Importantly, we studied the mechanisms of the hypnosis effects at the neural level by analyzing EEG frequencies. Highly hypnotizable participants performed the Stroop task in a counterbalanced design following (1) post-hypnotic suggestions that words had lost their meaning, (2) after hypnosis alone, and (3) in a control condition without hypnosis. The overall Stroop effect and both its facilitation and interference components, were not significant after the post-hypnotic suggestion but in both other conditions. Hypnosis alone neither affected the Stroop effect nor – in contrast to some previous reports and claims – overall performance. EEG recorded during the Stroop task showed a significant increase in both frontal theta and frontal beta power when participants were under the impact of post-hypnotic suggestions, in comparison to the two other sessions. Together, these findings indicate that post-hypnotic suggestions – but not hypnosis alone - are powerful tools for eliciting top down processes. Our EEG findings could be interpreted as clue that this is due to the investment of additional cognitive control.
Practicing sport at top level requires excellent physical and cognitive skills. The goal of the present study was to investigate whether specific sport practice may affect the preparation-perception-action stages of processing during a visuo-motor task requiring perceptual discrimination and fast response. We recruited 39 participants (two groups of professional fencers and boxers, and a control group; N=13 for each group) and measured behavioral performance and event-related potentials (ERPs) while performing a go/no-go task. Results revealed that athletes were faster than controls, while fencers were more accurate than boxers. ERP analysis revealed that motor preparation, indexed by the Bereitschaftspotential (BP), was increased in athletes than controls, whereas the top-down attentional control, reflected by the prefrontal negativity (pN) component, was enhanced only in fencers when compared to controls. Most of the post-stimulus ERPs i.e. the N1, the N2, the P3, and the pP2, were enhanced in fencers. Combat sports require fast action execution, but the preparatory brain activity might differ according to the specific practice required by each discipline. Boxers might afford to commit more errors (as reflected by high commission error rate and by a small pN amplitude), while fencers have to be as much fast and accurate as possible (thanks to an enhanced pN amplitude). Although the possible influence of repetitive head blows on cerebral activity cannot be excluded in boxers, our results suggest that cognitive benefits of high level sport practice might also be transferred to the daily (i.e., no sport-related) activities.
Studies on perceptual decision-making showed that manipulating the proportion of target and non-target stimuli affects the behavioral performance. Tasks with high frequency of targets are associated to faster response times (RTs) conjunctively to higher number of errors (reflecting a response bias characterized by speed/accuracy trade-off) when compared to conditions with low frequency of targets. Electroencephalographic studies well described modulations of post-stimulus event-related potentials as effect of the stimulus probability; in contrast, in the present study we focused on the pre-stimulus preparatory activities subtending the response bias. Two versions of a Go/No-go task characterized by different proportion of Go stimuli (88% vs. 12%) were adopted. In the task with frequent go trials, we observed a strong enhancement in the motor preparation as indexed by the Bereitschaftspotential (BP, previously associated with activity within the supplementary motor area), faster RTs, and larger commission errors rate than in the task with rare go trials. Contemporarily with the BP, a right lateralized prefrontal negativity (lateral pN, previously associated with activity within the dorsolateral prefrontal cortex) was larger in the task with rare go trial. In the post-stimulus processing stage, we confirmed that the N2 and the P3 components were larger for rare trials, irrespective of the Go/No-go stimulus category. The increase of activities recorded in the preparatory phase related to frequency of targets is consistent with the view proposed in accumulation models of perceptual decision for which target frequency affects the subjective baseline, reducing the distance between the starting-point and the response boundary, which determines the response speed.
This study explores whether self-reported depth of hypnosis and hypnotic suggestibility are associated with individual differences in neuroanatomy and/or levels of functional connectivity. Twenty-nine people varying in suggestibility were recruited and underwent structural, and after a hypnotic induction, functional magnetic resonance imaging at rest. We used voxel-based morphometry to assess the correlation of grey matter (GM) and white matter (WM) against the independent variables: depth of hypnosis, level of relaxation and hypnotic suggestibility. Functional networks identified with independent components analysis were regressed with the independent variables. Hypnotic depth ratings were positively correlated with GM volume in the frontal cortex and the anterior cingulate cortex (ACC). Hypnotic suggestibility was positively correlated with GM volume in the left temporal-occipital cortex. Relaxation ratings did not correlate significantly with GM volume and none of the independent variables correlated with regional WM volume measures. Self-reported deeper levels of hypnosis were associated with less connectivity within the anterior default mode network. Taken together, the results suggest that the greater GM volume in the medial frontal cortex and ACC, and lower connectivity in the DMN during hypnosis facilitate experiences of greater hypnotic depth. The patterns of results suggest that hypnotic depth and hypnotic suggestibility should not be considered synonyms.
Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.
Objective:
The aim of the present study was to investigate the cortical correlates of the intraindividual coefficient of variation (ICV) in a go/no-go task, focusing on the prefrontal cortex (PFC) contribution and evaluating both pre- and poststimulus brain activity.
Method:
We recorded event-related potentials (ERPs) in 40 subjects, arranged a posteriori in 2 groups on the basis of their ICV values. By this method, we formed the consistent (low ICV; n = 20) and inconsistent (high ICV; n = 20) group: the age, speed, and accuracy performance of the 2 groups were matched.
Results:
The prestimulus anticipatory PFC activity, as reflected by the prefrontal negativity (pN) wave, and the poststimulus P3 component were larger in the consistent than in the inconsistent group. In contrast, no differences were observed between groups in the brain activities associated to motor preparation and early sensory processing.
Conclusions:
Data are interpreted as an enhanced top-down control in consistent performers, likely characterized by a greater sustained attention on the task. (PsycINFO Database Record
A female patient with multiple chemical sensitivity and previous anaphylactoid reactions to local anaesthetics was admitted for removal of a thigh skin tumour under hypnosis as sole anaesthesia. The hypnotic protocol included hypnotic focused analgesia and a pre-operative pain threshold test. After inducing hypnosis, a wide excision was performed, preserving the deep fascia, and the tumour was removed; the patient's heart rate and blood pressure did not increase during the procedure. When the patient was de-hypnotised, she reported no pain and was discharged immediately. Our case confirms the efficacy of hypnosis and demonstrates that it may be valuable as a sole anaesthetic method in selected cases. Hypnosis can prevent pain perception and surgical stress as a whole, comparing well with anaesthetic drugs.
Neuropsychophysiological evidence is reviewed testing a three-stage, top-down working model of the traditional hypnotic relaxation induction involving: (1) a thalamocortical attentional network engaging a left frontolimbic focused attention control system underpinning sensory fixation and concentration on the induction; (2) instatement of frontolimbic inhibitory systems through suggestions of tiredness at fixation and relaxation whereby anterior executive functions are suspended and directed by the induction; (3) engagement of right-sided temporoposterior functions through passive imagery and dreaming. A selectivity of action in high susceptibles was a hallmark of the studies. Increased Stroop interference coincided with maintenance of error detection and abolition of error evaluation potentials, interpreted as dissociation of cognitive and affective executive systems of the anterior cingulate. Verbal, category and design fluency tasks were dissociated with hypnosis centring on left anterior processes as seen in left lateral and medial reduced EEG connectivity. Limbic modulated electrodermal orienting responses and frontal modulated mismatch negativity waves were inhibited. Asymmetries in electrodermal and electrocortical responses to tones shifted to favour the right hemisphere, an asymmetry also seen in visual sensitivity. Haptic processing and visual sensitivity disclosed more distributed changes in medium susceptibles, while low susceptibles were characterized by poorer attentional functions at baseline and improvements through the induction. Copyright © 1998 British Society of Experimental and Clinical Hypnosis
Background:
Schizophrenia and bipolar disorder share overlapping symptoms and risk genes. Shared aberrant functional connectivity is hypothesized in both disorders and in relatives.
Methods:
We investigated resting state functional magnetic resonance imaging in 70 schizophrenia and 64 psychotic bipolar probands, their respective first-degree relatives (n = 70 and 52), and 118 healthy subjects. We used independent component analysis to identify components representing various resting state networks and assessed spatial aspects of functional connectivity within all networks. We first investigated group differences using five-level, one-way analysis of covariance (ANCOVA), followed by post hoc t tests within regions displaying ANCOVA group differences and correlation of such functional connectivity measures with symptom ratings to examine clinical relationships.
Results:
Seven networks revealed abnormalities (five-level one-way ANCOVA, family-wise error correction p < .05): A) fronto-occipital, B) midbrain/cerebellum, C) frontal/thalamic/basal ganglia, D) meso/paralimbic, E) posterior default mode network, F) fronto-temporal/paralimbic and G) sensorimotor networks. Abnormalities in networks B and F were unique to schizophrenia probands. Furthermore, abnormalities in networks D and E were common to both patient groups. Finally, networks A, C, and G showed abnormalities shared by probands and their relative groups. Negative correlation with Positive and Negative Syndrome Scale negative and positive scores were found in regions within network C and F respectively, and positive correlation with Positive and Negative Syndrome Scale negative scores was found in regions in network D among schizophrenia probands only.
Conclusions:
Schizophrenia, psychotic bipolar probands, and their relatives share both unique and overlapping within-network brain connectivity abnormalities, revealing potential psychosis endophenotypes.
Identifying personality traits and neural signatures that predict placebo responsiveness is important, both on theoretical and practical grounds. In the present functional magnetic resonance imaging (fMRI) study, we performed multiple-regression interaction analysis to investigate whether hypnotic susceptibility (HS), a cognitive trait referring to the responsiveness to suggestions, explains interindividual differences in the neural mechanisms related to conditioned placebo analgesia in healthy volunteers. HS was not related to the overall strength of placebo analgesia. However, we found several HS-related differences in the patterns of fMRI activity and seed-based functional connectivity that accompanied placebo analgesia. Specifically, in subjects with higher HS, the placebo response was related to increased anticipatory activity in a right dorsolateral prefrontal cortex focus, and to reduced functional connectivity of that focus with brain regions related to emotional and evaluative pain processing (anterior mid-cingulate cortex/medial prefrontal cortex); an opposite pattern of fMRI activity and functional connectivity was found in subjects with lower HS. During pain perception, activity in the regions reflecting attention/arousal (bilateral anterior thalamus/left caudate) and self-related processing (left precuneus and bilateral posterior temporal foci) was negatively related to the strength of the analgesic placebo response in subjects with higher HS, but not in subjects with lower HS. These findings highlight HS influences on brain circuits related to the placebo analgesic effects. More generally, they demonstrate that different neural mechanisms can be involved in placebo responsiveness, depending on individual cognitive traits.
Objective:
We evaluated the working hypothesis that the EEG activity associated to non-painful and painful stimuli in condition of waking state (no hypnotic procedure) was related to the hypnotizability level.
Methods:
Hypnotizability level was measured in 16 healthy subjects through the Italian version of the Stanford Hypnotic Susceptibility Scale (SHSS, score: 0-12). EEG data (56 electrodes) were recorded during non-painful and painful electrical stimuli applied to the left index finger. Cortical activity (vertex N1-P2 complex) was compared in subjects with low hypnotizability level (N=8, SHSS:0-6) vs. subjects with high hypnotizability level (N=8, SHSS:7-12).
Results:
The amplitude of the N1-P2 complex was lower in the High-hypnotizability compared to the Low-hypnotizability group over primary sensorimotor cortex (C3 and C4 electrodes) and centro-parietal midline areas (Cz and Pz electrodes) for non-painful and painful stimuli. The SHSS showed a statistically significant negative correlation with the vertex N1-P2 complex at C3 and Cz (r=-0.5, p<0.05) electrodes for non-painful stimuli.
Conclusion:
Compared to the Low-hypnotizability subjects, High-hypnotizability subjects showed a reduced cortical activity related to non-painful and painful stimuli.
Significance:
The results suggest a relationship between hypnotizability and cortical activity related to non-painful and painful stimuli in the condition of waking state (no hypnotic effect).
Cognitive hypotheses of hypnotic phenomena have proposed that executive attentional systems may be either inhibited or overactivated to produce a selective alteration or disconnection of some mental operations. Recent brain imaging studies have reported changes in activity in both medial (anterior cingulate) and lateral (inferior) prefrontal areas during hypnotically induced paralysis, overlapping with areas associated with attentional control as well as inhibitory processes. To compare motor inhibition mechanisms responsible for paralysis during hypnosis and those recruited by voluntary inhibition, we used electroencephalography (EEG) to record brain activity during a modified bimanual Go-Nogo task, which was performed either in a normal baseline condition or during unilateral paralysis caused by hypnotic suggestion or by simulation (in two groups of participants, each tested once with both hands valid and once with unilateral paralysis). This paradigm allowed us to identify patterns of neural activity specifically associated with hypnotically induced paralysis, relative to voluntary inhibition during simulation or Nogo trials. We used a topographical EEG analysis technique to investigate both the spatial organization and the temporal sequence of neural processes activated in these different conditions, and to localize the underlying anatomical generators through minimum-norm methods. We found that preparatory activations were similar in all conditions, despite left hypnotic paralysis, indicating preserved motor intentions. A large P3-like activity was generated by voluntary inhibition during voluntary inhibition (Nogo), with neural sources in medial prefrontal areas, while hypnotic paralysis was associated with a distinctive topography activity during the same time-range and specific sources in right inferior frontal cortex. These results add support to the view that hypnosis might act by enhancing executive control systems mediated by right prefrontal areas, but does not produce paralysis via direct motor inhibition processes normally used for the voluntary suppression of actions.
Introduction:
According to the cold control theory of hypnosis (Dienes and Perner, 2007), hypnotic response occurs because of inaccurate higher order thoughts of intending. The dorsolateral prefrontal cortex (DLPFC) is a region likely involved in constructing accurate higher order thoughts. Thus, disrupting DLPFC with low frequency repetitive transcranial magnetic stimulation (rTMS) should make it harder to be aware of intending to perform an action. That is, it should be easier to respond to a hypnotic suggestion.
Method:
Twenty-four medium hypnotisable subjects received low frequency rTMS to the left DLPFC and to a control site, the vertex, in counterbalanced order. The hypnotist was blind to which site had been stimulated. Subjects rated how strongly they expected to respond to each suggestion, and gave ratings on a 0-5 scale of the extent to which they experienced the response, for four suggestions (magnetic hands, arm levitation, rigid arm and taste hallucination). The experimenter also rated behavioural response.
Results:
Low frequency rTMS to the DLPFC rather than vertex increased the degree of combined behavioural and subjective response. Further, subjects did not differ in their expectancy that they would respond in the two conditions, so the rTMS had an effect on hypnotic response above and beyond expectancies.
Conclusions:
The results support theories, including cold control theory, postulating a component of hypofrontality in hypnotic response.
contains critical analysis of the following questions: are there neuropsychophysiological differences between low and high hypnotizable individuals in nonhypnotic (waking) or hypnosis conditions / are there any systematic changes in such neuropsychophysiological processes during hypnotic rest or during specific hypnotic phenomena that differ from those obtained in nonhypnotic conditions / are these moderated by a hypnotic susceptibility level (PsycINFO Database Record (c) 2012 APA, all rights reserved)
Context Focused hypnotic concentration is a model for brain control over sensation and behavior. Pain and anxiety can be effectively alleviated by hypnotic suggestion, which modulates activity in brain regions associated with focused attention, but the specific neural network underlying this phenomenon is not known.
Objective To investigate the brain basis of hypnotizability.
Design Cross-sectional, in vivo neuroimaging study performed from November 2005 through July 2006.
Setting Academic medical center at Stanford University School of Medicine.
Patients Twelve adults with high and 12 adults with low hypnotizability.
Main Outcome Measures Functional magnetic resonance imaging to measure functional connectivity networks at rest, including default-mode, salience, and executive-control networks; structural T1 magnetic resonance imaging to measure regional gray and white matter volumes; and diffusion tensor imaging to measure white matter microstructural integrity.
Results High compared with low hypnotizable individuals had greater functional connectivity between the left dorsolateral prefrontal cortex, an executive-control region of the brain, and the salience network composed of the dorsal anterior cingulate cortex, anterior insula, amygdala, and ventral striatum, involved in detecting, integrating, and filtering relevant somatic, autonomic, and emotional information using independent component analysis. Seed-based analysis confirmed elevated functional coupling between the dorsal anterior cingulate cortex and the dorsolateral prefrontal cortex in high compared with low hypnotizable individuals. These functional differences were not due to any variation in brain structure in these regions, including regional gray and white matter volumes and white matter microstructure.
Conclusions Our results provide novel evidence that altered functional connectivity in the dorsolateral prefrontal cortex and dorsal anterior cingulate cortex may underlie hypnotizability. Future studies focusing on how these functional networks change and interact during hypnosis are warranted.
The neurophysiological substrates of hypnosis have been subject to speculation since the phenomenon got its name. Until recently, much of this research has been geared toward understanding hypnosis itself, including the biological bases of individual differences in hypnotizability, state-dependent changes in cortical activity occurring with the induction of hypnosis, and the neural correlates of response to particular hypnotic suggestions (especially the clinically useful hypnotic analgesia). More recently, hypnosis has begun to be employed as a method for manipulating subjects' mental states, both cognitive and affective, to provide information about the neural substrates of experience, thought, and action. This instrumental use of hypnosis is particularly well-suited for identifying the neural correlates of conscious and unconscious perception and memory, and of voluntary and involuntary action.
In this paper the similarities in the structural and functional organization of motor preparation and attension are discussed. A crucial structure in this organization is the thalamus, a complex of sensory and motor nuclei that transmits information from subcortical origins to the cortex. For the most part, the thalamus is overlapped by the nucleus reticularis, which has a local inhibitory influence on the underlying nuclei. This serves as a gating mechanism for the transmission of sensory information to the cortex. Skinner and Yingling (1977) have provided arguments in favor of a frontal control in the gating of sensory information. The present paper extends their suggestions to the motor system: a similar gating mechanism for the transmission of subcortical motor information to the cortex is hypothesized, also under frontal control. Slow potentials recorded during motor preparation and attention for an upcoming stimulus show a different distribution over the scalp. These distributions are interpreted as an indication of which thalamic gates are open to transmit information to the cortex. Probe responses (spinal reflexes, evoked potentials, and the startle reflex) can also be used to investigate which thalamocortical gates are open under certain experimental conditions. It is concluded that the sensory and motor input to the cortex are subjected to a similar control mechanism.
Novel stimuli or electric stimulation of the mesencephalic reticular formation (MRF) produced large positive slow potentials (SPs) in rostral nucleus reticularis thalami (RVA) that accompanied the negative SPs known to occur in frontal cortex. SP durations (20-30 sec) were similar to the periods of unit inhibition the occur in RVA following MRF stimulation. Trains of 8 c/sec medial thalamic stimuli produced phasic negative SPs in RVA similar in duration to the intervals of unit excitation that follow each stimulus pulse. These results suggest that the polarity and duration of the SPs in RVA reflect changes in excitation of the underlying neurons. Direct activation of a specific region of RVA produced complete inhibition of visual cortex responses evoked by optic tract stimuli, a finding which suggests that RVA has an inhibitory action on the thalamus. A tone reinforced by electric shock also elicited SPs in frontal cortex (negative) and RVA (positive). In contrast to the long duration of the MRF- or novelty-elicited SPs, the durations of the conditioned SPs were phasic and were regulated by the tone-shock interval. Bilateral cryogenic blockade of the interconnections between the frontal cortex and medial thalamus abolished SPs of all origins in the frontal cortex. The blockade also abolished conditioned SPs in RVA, but did not affect the MRF-elicited ones. Thus, the subcortical SPs that accompany orienting to novel stimuli are distinct from those which occur during the higher cognitive process of conditioned expectancy and require the integrity of the mediothalamic-frontocortical system.
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.
Very highly hypnotizable subjects are rare, easily induced, and able to manifest the whole spectrum of hypnotic phenomena, including post-hypnotic amnesia. The aim of this study was to detect and localize by means of quantitative functional MRI and EEG changes in cortical activity during hypnosis induction and deep "pure hypnosis" in a hypnotic "virtuoso" subject. We focused on areas forming the default mode network (DMN), since previous studies found that very highly suggestible subjects in hypnosis showed decreased activity in anterior DMN. During undisturbed hypnosis, our "virtuoso" subject showed not only detectable changes in DMN, but also peculiar activations of non-DMN areas and hemispheric asymmetries of frontal lobe connectivity. Our findings confirm that hypnosis is associated with significant modulation of connectivity and activity which involve the DMN but are not limited to it, depending on the depth of the hypnotic state, the type of mental content and emotional involvement.