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Copyright © 2006 British Society of Experimental & Clinical Hypnosis Contemp. Hypnosis 23: 15–32 (2006)Published by John Wiley & Sons, Ltd DOI: 10.1002/ch

Contemporary Hypnosis 15Contemp. Hypnosis 23(1): 15–32 (2006)Published online in Wiley InterScience(www.interscience.wiley.com) DOI : 10.1002/ch.35

FRONTAL FUNCTIONS, CONNECTIVITY AND NEURALEFFICIENCY UNDERPINNING HYPNOSIS AND

HYPNOTIC SUSCEPTIBILITY

John H. Gruzelier

Department of Psychology, Goldsmiths College, University of London, UK

Abstract

An update is provided o an earlier review (Gruzelier, 1998) o the range o evidence or neurophysiological changes in rontal and lateralized unctions with hypnosis, changeswhich have di erentiated high rom low hypnotically susceptible subjects, and whichled to a working model and neuropsychological translation o the hypnotic induction

process. New evidence is outlined rom an MRI/EEG study. This study also disclosed the importance o neural e ciency in le t lateral rontal and anterior cingulate structures,and their connectivity, or distinguishing high rom low hypnotic susceptibility both inhypnosis and in the everyday state. This ampli es earlier constructs such as cognitivefexibility. Though the ocus will be largely on the alteration o connections with theanterior brain and its corresponding alterations o unction, interhemispheric, posterior and subcortical connectivity is also considered. The practical implications or the interac-

tion between the hypnotherapist and subject are considered, including stage hypnosis.Copyright © 2006 British Society o Experimental & Clinical Hypnosis. Published byJohn Wiley & Sons, Ltd.

Key words: EEG, MRI, hypnosis, hypnotic susceptibility, neurophysiology, stagehypnosis

Neurocognitive changes with hypnosis

Selective inhibition, dissociation and disconnectionSince the time o Janet dissociation has been historically the dominating cognitive theoryo hypnosis (Hilgard, 1965; Bowers, 1992). Now a range o evidence is showing that

ollowing instructions o hypnosis a di erent and unusual pattern o abilities and dis-abilities is brought into play in hypnotizable subjects compared with the pre-hypnosisstate. These involve dissociations between cognitive processes, and disconnections

between brain regions together with selective inhibition and enhancement o abilities and processes (Gruzelier, 1998; 2004). The likening o hypnosis to an inhibitory process isenshrined in the term hypnosis, itsel derived rom Hypnos the god o sleep, and initiallymade popular by Pavlov’s inhibitory concepts. Early electrophysiological studies ound

no evidence o sleep per se (Craw ord and Gruzelier, 1992), nevertheless rontal inhibi-tion may represent one dynamic o rontal involvement in hypnosis (e.g. Gruzelier, 1990;1998; Woody and Bowers, 1994; Woody and Sadler, 1998), and one which may be analternative to disconnection, or be in parallel with it. The experimental evidence or changes in anterior brain activity will be considered in turn.



16 John Gruzelier


Error detection and evaluation Neurophysiological ractionation o processes, to include possible inhibition, has beendemonstrated between error detection processes and error evaluation processes and withthe apparent inhibition or uncoupling o the latter, both o which are processes emanating

rom the anterior cingulate. These processes were measured with event-related potentials

(ERPs) in a Stroop-like confict task (Kaiser, Barker, Haenschel, Baldeweg and Gruzelier,1997). The ERPs disclosed a dissociation not evident behaviourally. In the highly hypno-tizable participants error detection rates decreased and reaction times (RTs) were pro-longed ollowing instructions o hypnosis, as has been reported by others (NordbyHugdahl, Jasiukaitis and Spiegel, 1999; Jamieson and Sheehan, 2004). Coincidentallywith the behavioural impairment error detection waves were unaltered, implying thatmistakes in per ormance were being detected but went uncorrected. But an electrophysi-ological change did accompany the impaired per ormance, and this involved the ensuing

positive wave that ollows error-related negativity. This ‘error-related positivity’, which isassociated with error evaluation processes, was abolished. In contrast to the apparentneurocognitive dissociation in the hypnotizable participants, the low hypnotizable group,acting as a control or the e ect o hypnosis, showed no allo in per ormance behav-iourally ollowing instructions o hypnosis, and no change in their event-related potentials,which contained both error detection and error evaluation waves. Using ERP sourcelocalization procedures, the processes o error detection and evaluation, as refected in theerror-related negativity and positivity, have indeed localized to the anterior cingulate.

In sum a neurocognitive dissociation was demonstrated ollowing hypnosis. For whilehypnosis did not inter ere with the detection o errors in per ormance, hypnosis did inter ere with the deeper processing o the errors, theorized to give rise to a allo in

behavioural per ormance shown by the slow RTs. This dissociation may refect either inhibition/deactivation or disconnection. The psychological dissociation with hypnosishas eatures in common with the dissociation implicit in Hilgard’s demonstration o ahidden observer. Here pain analgesia is experienced, yet simultaneously the subject canrate the intensity o the administered pain.

As an incidental nding, in the same experiment during hypnosis an alteration speci cto the hypnotizable subjects was ound in EEG alpha coherence in the le t rontal lobe(Gruzelier, 1998). This will be seen to have parallels in the recent MRI/EEG study.

Pain and hypnotic analgesia

The anterior cingulate has also been implicated in the underpinning o hypnosis-induced analgesia (Faymonville, Laureys, Degueldre, DelFiore, Luxen, Franck, Lamy and Maquet,2000; Rainville, Duncan, Price, Carrie and Bushnell,, 1997; Rainville, Ho bauer and Paus, 1999; Derbyshire, Whalley, Stenger and Oakley, 2004), as we have demonstrated electrophysiologically (Cro t, Williams, Haenschel and Gruzelier, 2002). Here ‘inhibi-tion’ as an explanatory concept can be ruled out. In response to pain ul stimuli weexamined ast requency 40 Hz gamma oscillations in view o their putative role inunderpinning conscious perception (e.g. Tallon-Baudrey and Bertrand, 1999). In keepingwith this evidence the magnitude o rontal gamma oscillations in the pre-hypnosis statewas ound positively correlated with the intensity o the a ective response to pain.

However, ollowing instructions o hypnosis, while the relation was retained in thosewith low hypnotizability, the relation no longer held in those with high hypnotizability.In other words outside o hypnosis the greater the distress experienced by the painstimuli, the higher the amplitude o the gamma oscillations, whereas during hypnosisdistress was unrelated to the magnitude o the gamma oscillations.



Frontal connectivity and hypnosis 17


Application o low resolution source localization methodology (LORETA) con rmed that the generation o the gamma oscillations arose rom the midline anterior cingulate,in keeping with the extensive literature on the subjective distress o pain and this rontalstructure. O theoretical importance was the nding that the magnitude o the gammaoscillations was unchanged, indicating no change in arousability/activation per se. The

results support a selective dissociation with hypnosis o rontal and anterior cingulate processes rom somatosensory cortices, without alteration in anterior activation levels;in other words with no evidence o inhibition.

Voluntary auditory attentionIn an auditory attention task, with recording o rontal and parietal ERPs, an accumula-tion o anterior inhibitory processes was disclosed with the course o hypnosis in hyp-notizable subjects (Gruzelier, Gray and Horn, 2002). Speci cally, rom the prehypnosis

baseline to early and later stages, over 40 minutes o hypnotic induction, the hypnotizable participants showed a progressive reduction o attention related negativity (N100) in

rontal electrodes. These dynamics were not paralleled by changes in subsequent cogni-tive memory-related components (P300), nor were they ound in parietal recordings. This

provided urther evidence o regional changes and/or dissociated changes in hypnotiz-able subjects. We note that bilateral attenuation o the N100 di erence wave is charac-teristic o rontally lesioned patients, whether or not the lesion is lateralized.

Interestingly in subjects with low hypnotic susceptibility the N120 was negligible intheir pre-hypnosis baseline, and became progressively larger with hypnosis. This wasthe opposite result to the one seen in hypnotizable subjects. The act that both low and high hypnotizable groups undergo changes with hypnosis, but o ten in opposite direc-tions, was disclosed in a previous study, now considered.

Automatic auditory attentionThe concept o inhibition was introduced in our rst study o hypnosis published twodecades ago (Gruzelier and Brow, 1985). This involved electrophysiological recordingo orienting and habituation processes to novel tones interspersed with the induction o hypnosis. Orienting responses were recorded with electrodermal activity, a pure measureo sympathetic autonomic responsiveness. Highly susceptible subjects showed a reduc-tion in responses with hypnosis when compared with several control conditions, whereassubjects with low susceptibility showed increased responding, the opposite e ect. At the

same time both groups shared evidence rom other autonomic parameters o attentionalengagement. In the subjects with low hypnotizability reverse e ects were ound withmore orienting responses and slower habituation, a pattern which is in keeping withenhanced sustained attention as may occur with apprehension. The acilitation o habitu-ation with hypnosis in hypnotizable subjects was then replicated in an experimentdesigned to compare hypnosis with simulating hypnosis in subjects with medium/highhypnotizability (Gruzelier, Allison and Conway, 1988).

Critical central infuences on autonomic orienting responses include rontal modula-tory connections o the orbito rontal and dorsolateral cortices with the limbic system,

particularly the amygdala and hippocampus. The amygdala has been shown to exert

mainly excitatory infuences on orienting activity whereas the inhibitory action o thehippocampus acilitates the habituation (inhibition) o the orienting response with stimu-lus repetition (e.g. Gruzelier and Venables, 1972; Pribram and McGuinness, 1975; Gray,1982). Accordingly the highly hypnotizable group showed evidence in line with reduced orbito rontal-amygdaloid excitatory infuences on responding and increased dorsolateral-



18 John Gruzelier


hippocampal inhibitory infuences. The infuence o hypnosis on electrodermal orientingand habituation was compatible with the neuroanatomical evidence o De Benedittis and Sironi (1988) arising rom recordings o intracranial electrical activity obtained duringhypnosis. They ound that hypnosis involved unctional inhibition o the amygdala and activation o the hippocampus.

We also ound evidence o shi ts in hemispheric infuences as a result o hypnosis inthe hypnotizable subjects now considered.

Hemispheric asymmetry as a dynamic in dissociation and disconnectionElectrodermal orienting response asymmetriesIn the orienting response study above, electrodermal activity was recorded bilaterally toinvestigate hemispheric infuences (Gruzelier, Brow, Perry, Rhonder and Thomas, 1984).Despite the attenuation in responding occurring with hypnosis, a reversal in asymmetryin orienting response amplitudes could be detected when compared with the neutralcondition. With hypnosis right hemispheric rontolimbic infuences predominated inhighly susceptible subjects.

Outside o hypnosis hypnotizable subjects were also asymmetric, in act in the courseo stimulus repetition they showed a shi t rom an initial right-sided pre erence, in linewith the right hemisphere’s role in global orienting, to a le t hemispheric pre erence, inline with le t-sided involvement in the local orienting process. This dynamic was com-

patible with the putative fexibility o hypnotizable subjects in their neurocognitive pro-cessing abilities, as outlined below. In those with low susceptibility there was no reliableasymmetry in either condition. In other words hypnosis produced a shi t in the activa-tional balance o ronto-limbic infuences to avour the right hemisphere.

Ideational fuencyThe rst clear neuropsychological nding o le t rontal involvement in hypnosis involved delineation o dissociations between three neuropsychological tests o ideational fuency.These were selected to di erentiate between anterior le t and right hemispheric unctionsand also within the le t hemisphere to delineate between anterior dorsolateral and tem-

poral unctions (Gruzelier and Warren, 1993). The results disclosed an imbalance indorsolateral pre rontal unctions, an imbalance that disadvantaged pre rontal le t hemi-sphere processes (indexed by word fuency to letter designated categories), and avoured anterior right hemisphere processes (indexed by fuency or designs). At the same time

le t temporal unctions (indexed by fuency or words belonging to semantic categories)remained activated. The latter result would ollow the necessary le t temporal word comprehension abilities required in listening to the verbal induction; though with prac-tice these might be given over to rudimentary right hemispheric comprehension abilities(Gruzelier, 1998).

This di erential pattern between the two types o verbal fuency generation wasreplicated by Kallio et al. (2001). They also ound that the reduction in fuency correlated

positively with hypnotic susceptibility, and also with inter erence on the Stroop conficttask, a task also shown to involve anterior unctions to include the anterior cingulate(Botvinik, Nystrom, Fissell, Carter and Cohen, 1999).

These unique patterns o neuropsychological abilities and disabilities between cogni-tive abilities could not be anticipated by social actors including expectation or task demands, explanations avoured by some theorists, nor were they part and parcelo normal unctioning, all o which rules out an explanation based on expectancy.Expectancy theory could not have predicted the dissociation between the three tests





(Gruzelier, 2000a) and the ocal inhibition/deactivation o the le t pre rontal ideational process.

Haptic discriminationsLateral unctional shi ts with hypnosis have been demonstrated in somatosensory pro-

cessing in a total o three investigations. Here reductions in le t hemispheric haptic pro-cessing times coincided with enhancements in right hemispheric processing (Gruzelier et al., 1984; Cikurel and Gruzelier, 1990), and in the rst experiment the degree o reduc-tion in the le t hemispheric processing time correlated with the depth o hypnosis. It wasalso the case that the hypnotizable subjects had superior le t than right hemispheric dis-criminations in the prehypnosis state.

One o the ollow-up experiments (Cikurel and Gruzelier, 1990) contained the active-alert hypnosis procedure o Banyai and Hilgard (1976) with participants pedalling a sta-tionary bicycle with instructions o mental invigoration. The demonstration o thehemispheric shi t in activation while pedalling precluded an explanation o the lateralshi t based on a nonspeci c actor such as relaxation. Deep relaxation measured bysensory reduction in a foatation tank while producing right hemispheric haptic enhance-ment, was without the simultaneous reductions (inhibition) in le t hemispheric hapticabilities (Raab and Gruzelier, 1994), ound with hypnosis. Thus relaxation is an impor-tant component but cannot account or the le t anterior inhibitory e ects o hypnosis.

Brightness discriminationHemispheric asymmetry o unction in visual processing in hypnosis was examined using a standard divided visual- eld apparatus in which fashes o light o varying bright-ness were presented in the peripheral visual elds (McCormack and Gruzelier, 1993).Following instructions o hypnosis an enhancement o right hemispheric perceptualsensitivity or brightness discriminations (the d prime psychophysical metric derived

rom signal detection theory) was ound in highly susceptible subjects. On the other hand le t hemisphere sensitivity remained unchanged, and there ore was seen to be indepen-dent/dissociated rom the right hemisphere. Cognitive con ounds were excluded becausethere was no corresponding hemispheric dissociation in the psychophysical index o cognitive infuences on perception (beta).

Interestingly comparisons o the highly hypnotizable subjects with those with mediumlevels o susceptibility indicated in the latter an increase in perceptual sensitivity which

was bilateral. Bilateral enhancement would be consistent with a less ocal enhancemento posterior processes with hypnosis. This result was also ound in the previous hapticsorting study in participants with moderate levels o hypnotic susceptibility (Cikurel and Gruzelier, 1990).

Tone probe ERPsCortical evoked potentials (ERPs) were recorded to tone probes rom electrodes placed over the anterior temporal lobes bilaterally at T3 (le t) and T4 (right). This probe strategyenables cortical activation patterns to be assessed during concurrent tasks. The tone

probes were presented simultaneously either with a hypnotic induction or a story read

by the hypnotist, or were presented in a neutral baseline condition. The temporal elec-trode placements were compared with central electrode derivations (C3,4), and the twotasks were re erred to the baseline where there was no cognitive task (Jutai, Gruzelier,Golds and Thomas, 1993). In participants with medium/high susceptibility the N100attentional wave to the tones disclosed greater right temporal responsivity (T4) ollowing



20 John Gruzelier


the induction o hypnosis, whereas the expected le t temporal advantage (T3) was shownwhen listening to the control story. In contrast participants with low hypnotizabilityshowed the le t-sided pre erence to both the story and hypnosis.

The results demonstrated a lateral advantage in avour o right anterior temporal lobeactivity speci c to the more hypnotizable participants with hypnosis, suggestive o a

right hemispheric processing o the hypnotist’s message, relying on the more rudimen-tary right hemispheric comprehension abilities. The group with low hypnotizabilityexhibited le t anterior temporal activation, which did not distinguish between the hyp-nosis and story conditions, and was congruent with le t hemispheric pre erence or verbalcomprehension.

Neural e ciency and individual di erences in hypnotic susceptibility

The thesis is developed elsewhere (Gruzelier, 2002a) that hypnotizability has manyadvantages, aside rom susceptibility to hypnosis, and these stem rom the putativeunderpinnings o neurophysiological and cognitive fexibility/e ciency. Evans (1991)has reviewed two decades o his research on the theme o fexibility. He has related hypnotizability, inter alia, with the acility or random number generation, and the fexi-

ble control o sleep (Evans and Graham, 1980). He reported that the ability to respond to suggestion in sleep in the REM phase correlated positively both with hypnotizabilityand with the acility or alling asleep in the laboratory; a phenomenon which signi esthe ability or dissociative control outside o awareness and volition.

Craw ord (1989) and Craw ord and Gruzelier (1992) used cognitive fexibility as anexplanatory construct when reviewing cognitive and neurophysiological ndings thathave di erentiated high rom low hypnotic susceptibility. These included task-related hemispheric speci city ound only in highly susceptible subjects independent o hypno-sis, along with unctional neuropsychophysiological changes as a result o hypnoticinstructions. Similarly the ability to prime wider networks o association between corti-cal representational networks has been theorized to be associated with both hypnotiz-ability and hypnosis (Shames and Bowers, 1992). The cognitive, a ective and neurophysiological fexibility o the hypnotizable participant includes superior abilitiesin absorption, creativity, dissociation, attention and vividness o imagery; these are allwell known correlates o hypnotizability (Gruzelier, 2002a, 2006). Recent evidenceincludes adaptive advantages or protection against cardiac hazard (Santarcangelo and

Sebastiani, 2004).The experiments that have been outlined in the previous sections disclosed severalexamples o di erences between hypnotizability groups in control conditions withouthypnosis. Highly hypnotizable participants had superior le t hemispheric haptic sortingability (Gruzelier et al., 1984) and word fuency (Gruzelier and Warren, 1993), and exhibited hemispheric cognitive congruency in an apparent shi t rom global (righthemisphere) to local (le t hemisphere) orienting processes (Gruzelier et al., 1984).

Perhaps most striking o all was the di erence in the ERP N100 attentional componentacross the rontal chain in the auditory detection task (Gruzelier et al., 2002). This com-

ponent was augmented in highly hypnotizable subjects, refecting the engagement o

ocussed attention processes, whereas it was virtually absent in those with low hypnotiz-ability, as would occur with the ailure to engage rontal attentional circuits which may

ollow distraction. In line with the rontal model o hypnosis the N100 attention wave was progressively attenuated in hypnotizable subjects with the course o hypnosis, and aswould occur with disengagement o rontal processes. In those with low hypnotizability





the N100 attention wave progressively increased, as would occur with progressive engage-ment o attention. A similar increase in responsiveness was also shown in the electroder-mal orienting responses o those with low hypnotizability (Gruzelier and Brow, 1985),whereas responses were attenuated with hypnosis in hypnotizable subjects. These groupcharacteristics led to predictions about BOLD measurements in MRI now described.

Confict monitoring with MRI and EEG

But rst to consider the dynamics o blood fow oxygenation and cognitive processing and their implications or individual di erences. As will be seen this largely overlooked issuehas somewhat discom orting implications or the eld o brain localization with MRI and PET. For essentially the more e cient the cognitive processing is, the less the oxygenationrequirement. With learning activation decreases, so that the greater the learning and thehigher the intelligence the greater the decrease in activation, especially in rontal brainregions associated with reasoning (Haier, Siegel, Maclachlan, Soderling, Lottenberg and Buchsbaum, 1992a; Haier, Siegel, Tang, Abel and Buchsbaum 1992b; Duncan, Seitz,Kolodny, Bor, Herzog, Ahmed, Newell and Emslie, 2000; Gray and Thompson, 2004;

Neubauer, Grabner, Freudenthaler, Beckman, Guthke, 2004). In other words the moreintelligent brain requires less metabolism and consequently is less likely to show MRIactivation. One implication or MRI studies in general is that one cannot be certain thatless intelligent/e cient brains will process in the same way as less intelligent/e cient

brains so that regions utilized or processing in the ormer may go undetected. Notwithstanding, the clear implication here is that when considering the fexibility

hypothesis, less activation will be predicted at baseline in participants with high hypno-tizability than in those with low hypnotizability.

We investigated confict monitoring with a Stroop-like inter erence task while subjects were scanned with MRI and while their EEG was recorded in a separate session(Egner, Jamieson and Gruzelier, 2005). In both sessions we success ully demonstrated the Stroop confict e ect on behavioural per ormance and ound that in line with other evidence (Carter, MacDonald, Botvinick, Ross, Stenger, Noll and Cohen, 2000; Mac-Donald, Cohen, Stenger and Carter, 2000; Botvinik, Cohen and Carter, 2004) the conficttask involved the anterior cingulate (ACC), which increased in activation with increasinglevels o confict monitoring. At the same time (with high levels o confict), a cognitivecontrol centre in the le t lateral rontal cortex (LPC) was engaged (MacDonald et al.,

2000). There were two main MRI hypnosis ndings disclosed by a signi cant Groupx Session interaction in the blood oxygenation ACC response. In hypnotizable subjectsthere was an increase in ACC activation rom baseline to hypnosis, and this was to ahigher level than ound in subjects with low hypnotizability in whom there was a non-signi cant decrease in activation. There was also a weak tendency or those with lowhypnotizability to have higher activation at baseline (p < 0.13). In other words the highlysusceptible subjects were compromised by hypnosis, whereas those with low hypnotiz-ability tended to improve, perhaps due to practice. These di erential changes have acounterpart with our auditory discrimination ERP study (Gruzelier et al., 2002).

It was also the case that the ACC compromise with hypnosis was not paralleled by

compromise in the LFC (le t in erior rontal gyrus) region that is associated with cogni-tive control and is activated signi cantly more in the higher di culty level conditions.In other words there was no commensurate increase in blood oxygenation in the hypno-tizable subjects in the LFC as had occurred in the ACC, a result representing an uncou-

pling or dissociation between the ACC and LFC with hypnosis. This interpretation was



22 John Gruzelier


borne out by EEG recordings during the same task in a separate session. EEG coherencemeasures indicated that ollowing instructions o hypnosis, what characterized the highlysusceptible subjects was a reduction in connectivity between the anterior cingulate and the le t dorsolateral pre rontal cortex (F3), as refected in the gamma rhythm coherence,with the converse e ect in those with low susceptibility. There was no such interaction

between group and session in the corresponding right homolateral site (F4). This evi-dence assists in clari ying the nature o the alteration in rontal unctions with hypnosis.The le t in erior rontal locus that was activated in this investigation has been implicated in contention scheduling, and contextual control processes including associating externalcues with appropriate actions (Passingham, Toni and Rushworth, 2000; Shallice, 2002;Koechlin, Ody and Kouneiher, 2003). This underscores the disruption o executive unc-tions with hypnosis through disconnectivity.

In a separate analysis, as presented at the British Association meeting, baseline di -erences between the groups emerged clearly, as shown in Figure 1. Blood oxygenation

level-dependent (BOLD) responses to di erent levels o response confict were assessed by random e ect analyses comparing event-related activation in moderate versus lowconfict trials (moderate confict contrast), and in high versus low confict trials (highconfict contrast), excluding error trials. Based on previous studies, the analyses werecarried out or a priori regions o interest covering the ACC (Brodmann areas 24 and 32) and the le t dorsolateral pre rontal cortex (Brodmann area 9). Following the reporto Macdonald et al. (2000) moderate response confict conditions activated cingulate and medial rontal gyri while the high response confict contrast resulted in cingulate activa-tion, and additionally activation in le t superior, middle and in erior rontal gyri. Thesecontrasts were analysed in the hypnotic groups separately. Clear di erences in confict-related attentional processing emerged. At baseline, in the low susceptibility group bothmoderate and high confict elicited substantial activation in both regions, whereas inhighly susceptible participants the moderate confict contrast did not result in any sig-ni cant activation, and the high confict contrast only produced limited cingulate activa-tion. As above with hypnosis these patterns o confict-related processing were reversed.Thus, without group di erences in behavioural per ormance levels, highly susceptible

participants were characterized by a higher e ciency o executive attention than participants with low susceptibility at baseline, and by relatively impaired executive unctionin the hypnotic state.

Neuropsychological translation o the classical induction o hypnosisThe earlier ndings with hypnotic relaxation led to a neuropsychological translation o the nature o hypnosis as induced by the conventional procedure aimed at producing astate o relaxation (Gruzelier, 1988, 1990, 1998). It is important to note that or the main

part in our studies we have deliberately avoided active challenges, which must providean added level o complexity in elucidating undamental processes in hypnosis, let alonethe stunts involved in hypnosis or entertainment. Accordingly our hypnotic relaxationmay be thought o as akin to what has been termed ‘neutral hypnosis’. As will be seen,anterior brain unctions represent a cardinal region in the induction o the hypnotic

process, and in accounting or the character o the hypnotic susceptibility trait.A three-stage working model o the induction process was evolved:The rst stage involves the traditional instructions to xate on a small object and to

listen to the hypnotist’s voice. Here was posited an attentional network including thala-mocortical systems and parieto rontal connections to engage a le t anterior ocussed





attention control system. This underpins the ocussed, selective attention that is inherentin visual xation and listening to the hypnotist’s voice. Together these processes requirele t hemispheric rontotemporal processing.

The second stage replaces eye xation with eye closure, suggestions o atigue atcontinued xation, and tiredness together with deep relaxation. It is posited that this setsin motion rontolimbic inhibitory processes with dissociative or uncoupling conse-quences, le t-sided in particular, encompassing orbito rontal and dorsolateral rontalregions and limbic structures such as the amygdala, hippocampus and cingulate. Theseunderpin the suspension o reality testing and critical evaluation, and the handing over o executive and planning unctions to the hypnotist; in other words the ‘letting go’

component o the hypnotic induction. This letting go is accompanied by a lateral shi ttowards a right hemispheric pre erence.

The third stage involves instructions o relaxed, passive imagery leading to a redis-tribution o unctional activity and an augmentation o posterior cortical activity, par-ticularly o the right hemisphere in the highly susceptible subjects. Simpli ying the verbal

Figure 1. High confict BOLD responses in low and high hypnotically susceptible subjects, at baseline and in hypnosis. (A) Brain activation (Talairach x = 6, z = 35) in ROIs in high conficttrials at baseline or low (le t panel) and high (right panel) hypnotizability participants. (B) Brainactivation (Talairach x = 6, z = 35) in ROIs in high confict trials in hypnosis or low (le t panel)and high (right panel) hypnotizability participants. Activity is displayed at FDR = 0.05 with anextent threshold o at least eight contiguous voxels, superimposed on a single subject MNI T*1scan supplied with SPM99.



24 John Gruzelier


content o the induction message may also acilitate right hemispheric processing as doesemphasizing past experience and emotion.

The participants with low susceptibility in contrast ail to show engagement o le trontal attentional control mechanisms, or i there is ocal attentional engagement, the

subject with low susceptibility ails to undergo the ‘inhibitory’, letting go process.

Accordingly this provides two reasons or ostensibly willing subjects not to undergohypnosis. The retarded habituation o orienting responses to stimuli irrelevant to hyp-nosis is consistent with vigilant, broad attention or distractibility, and slow habituationoccurs with anxiety (Gruzelier and Phelan, 1991). Letting go requires reassurance aboutthe lack o unwanted consequences o hypnosis, such as a loss o control or ailure tocome out o hypnosis, which may preoccupy naïve subjects. We have theorized that thealleviation o these worries may account with practice or evidence o ocusing o atten-tion, and through practice with sel -hypnosis allow bene ts such as natural killer cellenhancement (Gruzelier, 2002b).

In sum the ‘letting go’ stage, which is cardinal to hypnosis, is underpinned by theselective inhibition or disconnection o rontal unctions rom posterior and subcortical

unctions, leading to the giving over and the placing o the executive and planning unc-tions under the hypnotist’s infuence, to suspension o critical evaluation and realitytesting, as well as to alterations in the control o the supervisory attentional system(Gruzelier, 1990, 1998; Craw ord and Gruzelier, 1992; Woody and Bowers, 1994; Woodyand Sadler, 1998). Oakley et al. (personal communication) investigating this three-stagetemporal process or depth o hypnosis in an MRI scanner con rm the impact o the‘letting go’ stage or increasing the depth o hypnosis.

A neurophysiological theory o altered top-down infuences in stagehypnosis

The author has proposed that rontal unctions are undamental to the stage hypnotist’s persuasion (Gruzelier, 2000b, 2004). The thesis began with a landmark neuropsy-chological case o an alteration in personality through a brain lesion. In 1848 PhineasGage, a railway artisan working on the trans-Canadian railway, su ered a devastatinginsult to the head ollowing a dynamite explosion which drove an iron bar through hischeek on a trajectory through the rontal cortex. A ter the accident the socially abidingand popular worker displayed extraverted, ne arious, impulsive and pro ane behaviour,

making decisions against social convention and contrary to his best interest. Havingundergone a change o personality and character he ended his li e as a airground sideshow (shades o the appeal o stage-hypnosis). Reconstruction with MRI rom

photographic images o the skull has con rmed that it was the ventromedial or orbitalaspects o the rontal cortex that were damaged (Damasio, 1994). It should be empha-sized that the damage was de nitely not on a par with anything as pronounced as rontallobotomy

The Damasios undertook a programme o research on patients with damage to theventromedial pre rontal cortex. They contrived a task that simulated real-li e decisionmaking while leaving intellectual unctions una ected. Patients were guided only by

immediate prospects, and were oblivious to the consequences and positive or negativea ective value o their uture actions (Damasio, 1994; Bechara, Damasio, Damasio and Anderson, 1994; Bechara, Tranel, Damasio and Damasio 1996; Bechara, Damasio,Tranel and Damasio, 1997; Bechara, Damasio, Damasio and Lee, 1999; Bechara, Damasioand Damasio, 2000). Furthermore the patients continued to behave disadvantageously





a ter being made aware o the consequences o their actions (Bechara et al. 1997; Becharaet al. 1999). From simultaneous recordings o autonomic electrodermal activity anabsence o anticipatory responses was disclosed, and was interpreted as an unavailabilityo emotionally related knowledge with which to in orm decision making in social situa-tions. This led to a ‘somatic marker’ hypothesis, which, inter alia, proposed that a de -

ciency in a ect and eeling in anticipation o action played a critical role in impaired decision making about the uture actions o rontal patients (Damasio, 1994). It is theventromedial pre rontal cortex which processes the association between behaviouraloutcome and the corresponding emotional outcome, an association contained in a dis-

positional rather than an explicit orm. The emotional somatosensory image, via reactiva-tion o a somatic memory, marks the potential outcome o actions as either positive or negative. In other words, it is not that the patient with medial rontal damage cannotexperience and express emotion, as hypothesized to be the case in psychopathy or in thesyndrome belle indi erence: the patient does eel emotion, but there is a ailure to adjust

behaviour according to past experience, because the eelings based on past experienceare no longer engaged. Accordingly there is a reliance on the immediate advantage asopposed to the uture advantage, which can no longer be predicted accurately (Schoen-

baum et al. 1998), and this appraisal is particularly aulty in unpredictable circumstances.Social behaviour is disrupted, and ‘previously well adapted individuals become unableto observe social conventions, and unable to decide advantageously on matters pertainingto their own lives’ (Bechara et al., 2000:295).

This may be extrapolated to hypnosis, with its inherent selective suppression or dis-connection o selected rontal unctions, including orbito- rontal-amygdaloid connec-tions, as shown in our electrodermal orienting response studies (Gruzelier and Brow,1985; Gruzelier et al., 1988), and extending to the orbital rontal cortex (OFC) and itsconnections with the confict monitoring capabilities o the anterior cingulate. Relevanceto an understanding o stage hypnosis becomes apparent. On stage the hypnotically sus-ceptible subject responds without embarrassment to the immediate contingencies, i.e. theinstructions o the hypnotist to enact behaviour typically making the subject appear a

ool, in order to provide entertainment or the audience. Furthermore the participant persists in doing so even though cognitively aware, just as is ound in the OFC lesioned patient. Accordingly, what is missing in the stage hypnosis participant is the association, based on past experience, o the emotional consequences o the actions instructed by thehypnotist, such as emotional appraisal o likely humiliation. Behaviour is governed by

the immediate context, i.e. the instructions o the hypnotist. Negative consequences canno longer be predicted.Thus neuropsychology o altered rontal unctions, including selective disconnection,

may o er an explanation or the attraction o hypnosis or entertainment. An explanationor why subjects allow themselves to be made a ool o , to su er humiliation without

embarrassment, o ten appearing to have undergone a personality change, and so to provide the necessary theatrical display to maintain the popularity o stage hypnosis withthe general public, now chiming with the cultural appetite or ‘reality’ entertainment.

Orbito rontal cortex, right hemisphere and the therapeutic relationship

Lateralized unctional alterations leading to right hemispheric pre erential activationwere ound to be an important dynamic o hypnosis, as outlined here, while or a reviewo earlier evidence see Craw ord and Gruzelier (1992). The orbital and medial rontalcortex, theorised to play a role in stage hypnosis, has a special relationship with the right



26 John Gruzelier


hemisphere. As Cavada and Schultz (2000:205) concluded in the oreword to an issuedevoted to the orbital rontal cortex in the journal Cerebral Cortex , ‘The orbito rontalcortex is involved in the critical human unctions, such as social adjustment and thecontrol o mood, drive and responsibility, traits that are crucial in de ning the ‘personal-ity’ o an individual.’ This region exerts the highest level o control over emotional behav-

iour, by virtue o having the only direct cortical connections with the amygdala,hypothalamus, and brain stem reticular activating system. This region, which is anatomi-cally larger in the right hemisphere, takes executive control over the right hemisphere per se, and bilateral executive control o the limbic system and autonomic nervous system.

The right hemisphere matures earlier than the le t, and is dominant or the attachment process between mother and in ant (Schore, 1994). Attachment involves the regulationo biological synchrony between people and transactions, which mediate the socialconstruction o the brain or which the right hemisphere is dominant. The right hemi-sphere also has unctional advantages or the control o attention and emotion, prosodyand acial recognition, unconscious processes such as implicit memory and preattentive

acial emotions, as well as the representation o somatic and visceral states and sel -related material through its control over the limbic and autonomic nervous systems (e.g.Hugdahl, 1995; Pizzagali, Regard and Lehmann, 1999; Keenan, Wheeler, Gallup and Pasual-Leone, 2000).

In therapy, just as in studies o the empathetic processes between the intuitivelyattuned mother and her in ant, the a ective synchrony is o ten nonverbal. Resonance iswith a ective bodily states, rather than being cognitive in nature (Schore, 1997). Thisspontaneous communication is mediated by the right-sided limbic system (Buck, 1994),which as shown in our limbic-mediated electrodermal recording becomes dominant inhypnosis (Gruzelier et al., 1984). The empirical results showing the shi t o unctionalactivity to advantage the right hemisphere with conventional hypnotic relaxation, supportthe well known clinical experiences and metaphors o access to right hemispheric pro-cesses with hypnosis (Pedersen, 1984)).

Thalamo-cortical unctions

More than 70% o thalamocortical connections are with anterior cortex. This acilitatesthe rontal lobe’s executive unctions in playing a moderating role throughout the corticalmantle as well as subcortically through the limbic structures and the brainstem. This

gives rise to wider implications or rontal infuences on behaviour in hypnosis. Therelease o unctions rom rontal inhibitory control may not only enhance posterior brainactivity but also release subcortical activity. Thalamo-cortical connections, and espe-cially pre rontal connections, are central to consciousness circuits (Zeman, 2002). Theseare directly involved in the alterations o consciousness experienced in hypnosis(Rainville et al. 2000) including alterations in arousal at either extreme, such as seizureand stupor (Kleinhauz and Behan, 1981).

Thalamocortical loops that involve orbito rontal-limbic circuits such as orbito rontal-hypothalamus-amygdala-brainstem reticular ormation not only regulate internal arousal

processes, but also appraise changes in the external environment by processing sensory

in ormation including the ace and voice. This allows an integration o adaptive bodilyresponses with ongoing emotional and attentional states, and the regulation o interper-sonal and social behaviour (Dolan, 1999; Critchley, Elliott, Mathias and Dolan, 2000).These circuits provide a mnemonic repository o visceral and somatic states and materialrelated to sel (Damasio, 1994). By a selective shutting down o customary everyday





rontal executive and inhibitory unctions, hypnosis provides access to past memories o cognitive, a ective and somatic events (Damasio’s ‘somatic marker’). This may explainhow somatic memory, including surgical operations in childhood that involve the altera-tion and reduction o consciousness with anaesthetic (Hilgard, Hilgard and Newman,1961), and the reinstatement o epilepsy (Page and Handley, 1993), may arise with

hypnosis.Such a shutting down mechanism there ore acilitates age regression. The association between hypnosis with an unpleasant childhood event has been a potent source o nega-tive reactions involving revivi cation o emotionally laden and somatic events (or takingthe orm o retrograde amnesia), and alterations o arousal with autonomic signs. Sequelaehave included chronic depression and PTSD symptoms (Gruzelier, 2000b, 2004); disso-ciative episodes ollowing age regression to the time o WWII trauma (Kleinhauz,Drey uss, Behan, Goldberg and Azikri, 1979); surgical operations in childhood involvingthe alteration and reduction o consciousness with anaesthetic (Hilgard et al., 1961); the

production o stupor (Kleinhauz and Behan, 1981); and the reinstatement o epilepsy(Page and Handley, 1993). Where there were multiple memory cues in this associativenetwork o negative episodes, adverse e ects may be compounded (Page and Handley,1993). A cumulative memory e ect was observed when an unpleasant experience inchildhood with chemical anaesthesia, and the countdown while that anaesthetic took e ect, were associated respectively with a change in arousal with hypnosis and thedehypnosis countdown (Hilgard et al., 1961). The reduction in rontal infuences willalso lead to cognitive con usion and distortions o body schema.

Conclusion

Our programme o research has repeatedly provided support or alterations o anterior brain unctions as a signi cant actor in the infuence o hypnosis in hypnotizable subjects, and one that is not seen in subjects o low hypnotizability who are in receipt o thesame instructions. In order to avoid misunderstanding, it has been emphasized through-out that the results in no way imply a global inhibition, disconnection or deactivation o the rontal lobes. The ERP study which sampled both earlier and later stages o hypnosisindicated that alterations may change with the temporal course o hypnosis. Le t rontal

unctions appear to be selectively more prone to alteration than right-sided unctions, but given the cognitive fexibility/neural e ciency o the hypnotizable subject some

rontal unctions bilaterally may conceivably be enhanced depending on the instructionso hypnosis given.Consideration o the literature on hypnotizability (Heap et al., 2004) discloses that

this is the rst time that neural e ciency as de ned by the MRI BOLD index has beenintroduced as a construct to distinguish high rom low hypnotizability. Neural e ciencycan be seen to ampli y the construct o cognitive fexibility. As has been developed elsewhere (Gruzelier, 2002a) a highly fexible nervous system may under some circum-stances be a vulnerable one and refect vulnerabilities or pathology through both imbal-ances in the internal milieu and susceptibilities to psychological stressors. The evidenceo associations with the schizotypal personality provides one such example (Jamieson

and Gruzelier, 2001; Gruzelier, De Pascalis, Jamieson, Laidlaw, Naito, Bennett and Dwivedi, 2004). Recent evidence shows strong relations in medical students betweenhypnotizability and a range o personality variables, including low sel -directedness,schizotypy, a ective distress, anxiety and depression, as well as with altered states o consciousness, imaginative involvement, and sel -transcendence (Laidlaw, Dwivedi,



28 John Gruzelier


Naito and Gruzelier, 2004). This is not the rst time that an apparent predisposition to psychopathology has been theorized to construe evolutionary bene ts such as provoca-tive theories o the evolution o man and culture through schizotypal characteristics(Jaynes, 1976; Horrobin, 2001).

Finally another dynamic reviewed here concerns the enhancement o some right

hemispheric processes in hypnosis. Right hemispheric involvement in hypnosis has been a popular though controversial view amongst hypnotherapists and scientists(Craw ord and Gruzelier, 1992), and has provided a highly appropriate metaphor in theclinic (Pedersen, 1984). Right hemisphericity as a trait o hypnosis was also popular,

but or this we ound no support (Gruzelier, 1998). In some groves o academe lateraliza-tion is anathema ollowing journalistic popularization o theories o hemisphericspecialization. Our results (Gruzelier et al., 1984; Jutai et al., 1993; McCormack and Gruzelier, 1993; Egner et al., 2005) should not be trivialized as evidence or simplistic

binary le t-right dynamics. The brain consists o unctional networks extending bilaterally, and with excitatory as well as inhibitory dynamics, both o which requireneuronal activation and metabolism. And while on this theme, be mind ul too, thataltered states o consciousness have only very recently been considered by some arespectable subject o scienti c investigation in cognitive neuroscience (see Dietrich,2003; Vaitl, Birbaumer, Gruzelier, Jamieson, Kotchoubey, Kübler, Lehmann, Miltner,Ott, Pütz, Sammer, Strauch, Strehl, Wackermann and Weiss, 2005, or some restorationto avour). Currently then our evidence o disconnectivities o the le t lateral pre rontalcortex in our MRI/EEG study contribute to growing evidence o a neurophysiological

basis to hypnosis and other altered states o consciousness (see also Rainville et al., 1999;Halligan, Athwal and Oakley, 2000; Kosslyn, Thompson and Constantini-Ferrando,2000; Spiegel, 2003). Much urther research is required to elucidate the exact nature o the processes involved.

Acknowledgement

Written while in receipt o EU New In ormation Technologies grant: Presenccia; Appli-cation, Creative Presence States.

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Address for correspondence: John GruzelierDepartment o PsychologyGoldsmiths College

New CrossLondonSE14 6NWUK Email: [email protected]

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