A Cross-Correlational review Between Neuroimaging and Hypnosis

FUNCTIONAL BRAIN IMAGING AND THE INDUCTION

OF TRAUMATIC RECALL:

A Cross-Correlational Review Between

Neuroimaging and Hypnosis

ERIC VERMETTEN1,2

University Medical Center and Central Military Hospital, Utrecht, The Netherlands

J. DOUGLAS BREMNER

Emory University and Emory Hospital, Atlanta, Georgia, USA

Abstract: The behavioral and psychophysiological alterations during

recall in patients with trauma disorders often resemble phenomena

that are seen in hypnosis. In studies of emotional recall as well as in

neuroimaging studies of hypnotic processes similar brain structures

are involved: thalamus, hippocampus, amygdala, medical prefrontal

cortex, anterior cingulate cortex. This paper focuses on cross-correla-

tions in traumatic recall and hypnotic responses and reviews correla-

tions between the involvement of brain structures in traumatic recall

and processes that are involved in hypnotic responsiveness. To further

improve uniformity of results of brain imaging specifically for trau-

matic recall studies, attention is needed for standardization of hyp-

notic variables, isolation of the emotional process of interest (state),

and assessment of trait-related differences.

In the last 10 years, there has been a rapid increase in our under-

standing of the brain processes that are involved in processing of

traumatic events (see Stern & Silbersweig, 2001). Much of this research

is related to the processing of stress, memory, and emotion (see reviews

of Armony & LeDoux, 1997; Baddeley et al., 2000; Bremner, Krystal,

Southwick, & Charney, 1995; Bremner & Narayan, 1998; Cahill, 2000;

LeDoux, 1993; McGaugh, Cahill, & Roozendaal, 1996; Nijenhuis,

The International Journal of Clinical

and Experimental Hypnosis

2004, Vol. 52, No. 3, pp. 280–312

Manuscript submitted November 02, 2002; final revision received October 24, 2003.

1

This study was supported NIMH 1R01MH56120-01A1, and a Veterans Administra-

tion Career Development Award to Dr. Bremner.

2

Address correspondence to Eric Vermetten, MD, PhD, Department Psychiatry,

University Medical Center Utrecht, Utrecht University, Heidelberglaan 100, 3584 XC

Utrecht, The Netherlands. E-mail: e.vermetten@azu.nl

0020-7144/04/5203-280$16.00 # The International Journal of Clinical and Experimental Hypnosis

280

Van der Hart, & Steele, 2002; Packard & Cahill, 2001; Phillips, Drevets,

Rauch, & Lane, 2003a, 2003b; and the special issues of the International

Journal Clinical and Experimental Hypnosis, April and July 2003). Among

the factors that contributed to this increase are the availability of high-

quality functional brain imaging techniques, cross-fertilization of

different disciplines (e.g., cognitive and developmental psychology,

nuclear medicine, pharmacology, molecular biology, psychiatry), and

the increasing specificity of induction procedures for traumatic recall in

study protocols. (For a description of the characteristics of two of the

main neuroimaging methods, functional magnetic resonance imaging

(fMRI) and positron emission tomography (PET), see the Appendix).

Innovative experimental designs in the field of neuroimaging have

increased our understanding of basic processes of memory storage and

emotion processing, lesion studies have pointed to brain regions that

are critically involved, and clinical studies in a variety of patient

populations have revealed a neural circuitry that is involved in differ-

ent disorders. These developments have also further contributed to our

current understanding of brain processes involved in pain, the phe-

nomenology of consciousness, and emotional processing in general and

have led to an understanding of regional patterns of activation and

deactivation.

Still, little is known about this neural circuitry that underlies (altera-

tion of) perceptual processing in patients with psychopathology in

which emotive processing is challenged in relation to exposure to

traumatic events. This alteration of perceptual processing can be

challenged by using visual, acoustic, or other sensory stimuli, or with

personalized narratives that induce recall of traumatic events. The

pattern of metabolic changes in the brain can be measured and corre-

lated with the subjective emotional response. This emotive process may

be paralleled by a set of involuntary/automatic processes that occur:

effects in heart rate, perceptual and emotional alteration, time distor-

tion, and analgesia (Hull, 2002), upon which patients may be selected

for assessment of their regional blood flow patterns (Lanius et al., 2002).

These studies have started to appear in scientific journals in the last 8

years but are still scarce.

Despite promising study results, the field of hypnosis has not fully

used the momentum that arose from these developments. Several

imaging studies in healthy populations have demonstrated differences

in the neural circuitry that is involved in response patterns across

hypnotic states, e.g., alterations of pain affect and pain modulation

(Faymondville et al., 2003; Rainville, Duncan, Price, Carrier, & Bushnell,

1997), alteration of visual processing (Kosslyn, Thompson, Costantini-

Ferrando, Alpert, & Spiegel, 2000), or hypnotic alteration of acoustic

perception (Szechtman, Woody, Bowers, & Nahmias, 1998). Most of

these studies have used high and low hypnotizable subjects to gain

NEUROIMAGING AND HYPNOSIS 281

insight in the neural mechanisms of perceptual alteration by measur-

ing alteration in regional brain blood flow. From these studies, it

appears that high hypnotizables are capable of modifying their brain

metabolism in response to a specific set of instructions to alter affect,

pain, or other experiences and have pointed out that subjects can

differentially alter (block or stimulate) certain perceptual functions,

e.g., ‘‘taking the color out of a picture’’ that is presented in front of

them. To a considerable extent, high hypnotizables are capable of

modifying the circuitry with which their brains process stimuli. To

date, few of these studies have used the cumulative power of combin-

ing these knowledge-based resources in neuroimaging studies in

patient populations.

It has been a decade since studies by Stutmann and Bliss (1985),

Spiegel, Hunt, and Dondershine (1988), and Frischholz, Lipman, Braun,

and Sachs (1992) empirically confirmed Janet’s early notions (1889) that

there is an overlap between the phenomena that are typically related to

hypnosis and the phenomena occurring in emotional recall in post-

traumatic stress disorder (PTSD). These patients have demonstrated

enhanced susceptibility to ‘‘hypnotic’’ situations, which traumatic re-

call can be considered to be. Hypnotic induction can mobilize a wide

spectrum of responses, varying from increased anxiety to flashbacks

that can occur with or without feelings of detachment to other dis-

sociative experiences, such as numbing or freezing, feelings of in-

voluntariness, and loss of self-agency.’’ Moreover, classic hypnotic

responses such as time distortion, analgesia, and derealization can

occur along with these memories. The content of the emotion is also

widespread and can change rapidly depending on the focus of atten-

tion: e.g., anger, shame, guilt, or disgust. These responses can have

bimodal effects, such as enhanced attention versus lowering of atten-

tion or out of body experiences versus detailed focus on details, and can

also be reflected on the level of psychophysiological alteration, e.g.,

increased versus decreased heart rate. Although these may be related to

hypnotic virtuosity, this has not been studied yet.

Within a general framework of identification, production, and reg-

ulation of emotional recall (see Phillips et al., 2003), hypnotic response

patterns are related to the involvement of different brain correlates

(Lanius et al., 2002). We pose that insight in these hypnotic response

patterns needs to be taken into account when analyzing brain correlates

of traumatic recall in trauma disorders, e.g., in PTSD but also in

dissociative identity disorder (DID) and borderline personality disor-

der (BPD). Moreover, hypnotic paradigms can provide additional

information regarding the involvement of involuntary mechanisms

in traumatic recall. In addition, we feel that by cross-correlating the

phenomenology and neurophysiology of traumatic recall and hypnosis

similarities in parameters, results can be found that improve our

282 ERIC VERMETTEN AND J. DOUGLAS BREMNER

understanding of hypnosis and basic elements of consciousness and

emotion. To explore this relation, we will review the imaging results in

these studies.

TRAUMA AS A HYPNOTIZING AGENT

It is a known fact that traumatic stress can mobilize responses that

have hypnotic features. These can be seen in a variety of situations,

e.g., in the battered and abused child who creates an invisible identity

so as not feel the pain and humiliation (identity alteration, amnesia,

R. Loewenstein, personal communication, November 2000), in jour-

nalists when watching an execution as an eyewitness (dissociation;

Freinkel, Koopman, & Spiegel, 1995), in survivors of the Estonia ferry

disaster who attempted to rescue other survivors (numbing; Ericksson

& Lundin, 1996), in people who witnessed victims jumping from the

World Trade Center on September 11, 2001 (verbal inhibition, Spiegel,

personal communication, 2001), or the responses in orphaned

Rawandan children (stupor). Traumatic experiences can mobilize hyp-

notic responses that resemble the hypnotic state during which intense

absorption in the hypnotic focal experience (Tellegen & Atkinson,

1974) can be achieved by means of a dissociation of experience

(Hilgard, 1977; Spiegel et al., 1988, p. 301). It was Janet who described

the splitting of consciousness that occurrs in response to traumatic

stress and the consequences of trauma on memory and identity. Janet

described a constellation of symptoms that we now categorize as PTSD

or dissociative disorders, including dissociative amnesia and fugue,

with a central assumption that different aspects of the traumatic

experience are not actively available to consciousness, although they

may have an influence on behavior (Loewenstein, 1993; Spiegel &

Carden˜ a, 1991).

The psychological processes that were captured as core components

of the hypnotic experience as described by Spiegel (1997) are: (a)

absorption; (b) dissociation, and (c) automaticity. These three factors have

been postulated because they explain the phenomena best in a hypnotic

situation (Spiegel & Carden˜ a, 1991). Hypnosis has been best defined as

an altered state of consciousness. Recently, a new definition of hypnosis

has been coined in which the use of the word hypnosis as part of the

hypnotic situation is not necessary for the induction nor description of

the state of hypnosis (A. Barabasz, personal communication, September

2003).

Absorption is defined as a narrowing and intensification of attention,

a disposition for having episodes of single total attention that fully

engage one’s representational resources (Tellegen & Atkinson, 1974).

Physiological arousal can produce this narrowing of attention, which is

directed more to central aspects of the traumatic experience than to

NEUROIMAGING AND HYPNOSIS 283

peripheral aspects (Christianson, 1992). Narrowing of attention can be

functional in that all attention can be devoted to essential threat stimuli

and defensive concerns. Dissociation can be described as a kind of

divided or parallel access to awareness where several systems may

have some independence. It refers to a compartmentalization of ex-

perience, which can be considered complementary to absorption. The

term refers both to its origins, i.e., the splitting of consciousness that

may occur during trauma, and to the subsequent process of associating

or assigning experiences, as they occur over and over in time, to specific

states of consciousness, ego centers, or affective states (Crabtree, 1992).

Dissociation can also be part of an autohypnotic process (e.g., ‘‘I am

invisible; I have no feelings’’), which is applied to reduce the perception

of pain and the personal implications of trauma (Van der Kolk &

Van der Hart, 1989). Automaticity may be defined as the tendency to au-

tomatically develop a belief in a suggested reality or the nonvolitional

transformation of a suggested idea to a suggested effect (Van Der Hart

& Van Der Kolk, 1991). Hypnotic automaticity reflects an altered sense

of self-agency consistent with a modification of the property of mineness

of self-generated intentions and voluntary actions. The involuntariness

is captured in this description as well, representing the recognition of

one’s own volition and capacity to act (P. Rainville, personal commu-

nication, September 25, 2002; cf. Krystal, 1988). A diagram illustrating

the shared neurophysiology of hypnosis with the neurophysiology of

traumatic recall situations in highly hypnotizable subjects is illustrated

in Figure 1.

HYPNOTIC SUSCEPTIBILITY IN TRAUMA-RELATED

PSYCHOPATHOLOGY

A central theme in trauma-related psychopathology is that physical,

emotional, or sexual trauma can play a major role in the shift of this

control function manifesting psychological dysfunctions and/or bodily

or somatic problems (Van Der Kolk et al., 1996). This can be viewed as a

Figure 1. Hypothesized similarities between hypnosis and traumatic recall. This diagram

may be especially true for high hypnotizable subjects, which is usually the case in

patients with PTSD. (Adapted from P. Rainville, personal communication, 2002).

284 ERIC VERMETTEN AND J. DOUGLAS BREMNER

disembodied process with an emphasis on the information processing

analysis of attention mechanisms but also as a state of engagement of

the body-self in the interaction with an object of consciousness, with

emphasis on the biological substrate for the representation of self

(Damasio, 1999) and the property of selfhood (Metzinger, 2000). This

disembodiment can also be seen as a disengagement strategy that

serves a natural defensive function (Gilbert, 2000).

Hypnotizability has been described as the fundamental capacity to

experience dissociation in a structured setting. It underlies the ability to

enter trance; it involves the ability to segregate and idiosyncratically

encode experience into separate psychological or psychobiological

processes (Janet, 1898). Like dissociation, hypnotizability can be related

to a lack of agency or control versus loss of control over psychological

and sometimes also physical functions. It is a dispositional term that

points to its manifestation under certain circumstances, e.g., hypnotic

induction. The critical alteration in these processes occurs in what

Damasio called ‘‘feeling of knowing,’’ which is a fundamental aspect of

self-reflective consciousness that can be separated in hypnosis (p. 280,

1999). Self-representation is a derivative of this fundamental function

of consciousness. It is thought that in hypnosis, and also in traumatic

situations, these representations can be disrupted or processed in

separate streams of information. Self-representation is a hierarchically

organized function with activity in some first-order maps in the brain

that are necessary (but not sufficient) for higher-order representation of

self (e.g., autobiographical self), regulation of cognition and behavior,

and other more extended forms of consciousness.

From these notions, hypnotic capacity can be considered to be both

a liability and an asset; from the perspective of a defense strategy, it

serves a protective purpose (e.g., not remembering or not feeling),

however it can also become maladaptive and lead to dysfunctions

(e.g., time gaps, estrangement from inner feelings, flashbacks) and

(psycho)pathology, like PTSD and dissociative or other trauma spec-

trum disorders. The disposition itself does not change but can be

considered ‘‘sensitized.’’ The symptoms of the dissociative and post-

traumatic states have been hypothesized to fit in a diathesis-stress

model that views pathological dissociation as originating from an

interaction between innate hypnotizability and traumatic experience

(Butler, Duran, Jasiukaitis, Koopman, & Spiegel, 1996). If traumatic

experiences involve a hypnotic process or induce a hypnotic state,

then we should expect traumatized patients to show higher hypnotiz-

ability, in particular while still suffering from their trauma-induced

disorder. One would expect that they have higher scores on classical

hypnotizability scales than other psychiatric patient groups and

healthy or trauma controls. Indeed, several studies supported the

hypothesis that trauma-spectrum-disorder patients demonstrate

NEUROIMAGING AND HYPNOSIS 285

higher scores on classic hypnotic susceptibility scales than other psy-

chiatric patient groups and normal control subjects (Frischholz et al.,

1992; Spiegel et al., 1988; Stutman & Bliss, 1985). Their attention and

arousal systems are altered, rendering them prone to entering hyp-

notic states, with a relative decoupling between irrelevant external

events and mental (emotional) states during hypnotic states. It is not

the experience of trauma; it is the psychopathology that accounts for

the difference in hypnotic susceptibility. What happens with their

hypnotic susceptibility after successful treatment is largely unknown.

Although Janet observed that recovered patients became less hypno-

tizable (Janet, 1898), this finding still awaits testing in systematic

research.

RECALL OF TRAUMATIC MEMORIES

The field of trauma spectrum disorders (consisting of PTSD, dis-

sociative disorders, (DD)), and perhaps also borderline personality

disorder (BPD, see Schmahl, McGlashan, & Bremner, 2002) has re-

ceived a great deal of interest in brain imaging studies. The phenom-

enology of theses disorders is at the heart of the interface between

memory and emotion.

Reexperiencing, Traumatic Recall, Flashbacks, and Flashbulb Memories

One of the most intriguing aspects of trauma disorders is the

reexperiencing phenomena. Numerous labels and descriptions have

been applied to this phenomenon (vanOyen Witvliet, 1997). In earlier

days traumatic recall was also described as ‘flashback’, the reliving of

the traumatic event with strong emotional involvement (Frankel, 1994).

Flashback can lead to sleeping problems, irritability, feeling worse with

traumatic reminders, and secondary avoidance. For a long time flash-

backs were assumed to lack a recognizable neurophysiological corre-

late – therefore they were thought to be at least as likely to be the

product of imagination as it is of memory (Frankel, 1994). However, in a

recent study in 62 PTSD patients comparing flashbacks with ordinary

autobiographical memory performance on cognitive tasks demon-

strated that flashback periods were associated with a specific decre-

ment in visuospatial processing, not specific with decrements on a

verbal processing task. Flashback periods were found to be associated

with increases in a wide range of autonomic and motor behaviors

(Hellawell & Brewin, 2002).

Flashbacks share a phenomenology with what has been described

by Brown and Kulik in 1977 as flashbulb memory, to refer to the vivid

recollections that humans may have of events considered to be of

particular significance to the individual. These memories were de-

scribed as having a photographic quality and as being accompanied

286 ERIC VERMETTEN AND J. DOUGLAS BREMNER

by a strong apparel of contextual information (weather, background

music, clothes worn, etc.) pertaining to the time and place where the

event was first known. From a memory point of view we now know

that these memories are not perfectly accurate and are subject to

decay, but what does not necessarily decay is their capacity to evoke

emotions similar to the ones felt upon when first exposed (Conway

et al., 1994). We feel that flashbulb memories are formed by the

activity of evolutionary old brain mechanism evolved to capture

emotional and cognitive information relevant to the survival of the

individual. In the modern neuroimaging era some of the original

assumptions made by Brown and Kulik have since been challenged,

but the phenomenon in question has remained an important area of

research (Davidson & Glisky, 2002; Sierra & Berrios, 1999). The ex-

periences share clinical features such as involuntary paroxysmal

repetition, sensory vividness, and a capacity to trigger emotions like

anxiety, shame, or anger.

We prefer to use the term ‘traumatic recall’. This can be defined as

imaginary (or virtual) re-exposure to a traumatic event in which the

person experienced, witnessed, or was confronted by death or serious

injury to self or others, and responded with intense fear, helplessness,

or horror, in which a re-experience of similar emotional responses

occur. They usually differ from usual/normal (autobiographical) mem-

ories in their emotional involvement (Van Der Kolk & Van Der Hart,

1991). Their nature is that a recall of the helplessness and uncontrol-

lability of the situation at that time, co-occurs with narrowing of the

attention so that ‘it feels like being back there’ (i.e., when and where the

traumatic event occurred). There can be a sense of loss of control or of

self-agency (‘‘That’s not who I am’’ or ‘‘It is not me to whom that

happened’’). There can be an autonomic response (such as tachycardia,

tachypnea, and diaphoresis) that can induce a feeling of panic (‘‘I’m not

going to make it’’). The recall may be activated by a variety of trauma-

related stimuli, thoughts about the trauma, the context, information

about the trauma, and trauma-related images, sounds, or smells, all

factors of which the person does not have to be aware. Veterans can

reveal this effect potently when they are exposed to darkness and

demonstrate augmented startle reflexes (Grillon, Morgan, Southwick,

Davis, & Charney, 1996).

Storage and Retrieval of Traumatic Memories

With long-term storage, memories are shifted from hippocampus

to neocortical areas, where the sensory impressions take place (Kim &

Fanselow, 1992; Phillips & LeDoux, 1992). This shift in the process of

memory storage to the cortex may represent a shift from conscious

representational memory (explicit memory) to unconscious memory

processes (episodic and implicit memory) that indirectly affect

NEUROIMAGING AND HYPNOSIS 287

behavior (Wallenstein, Eichenbaum, & Hasselmo, 1998). The cogni-

tive neuroscience perspective (see Brewin, 2001) favors a dual re-

presentational model of traumatic memories that proposes separate

memory systems underlying vivid reexperiencing versus ordinary

autobiographical memories of trauma. These two can be separated in

hippocampally-dependent and non-hippocampally-dependent forms

of memory, and are differentially affected by extreme stress. Within

this system, the strength of traumatic memories relates, in part, to

the degree to which certain neuromodulatory systems, particularly

catecholamines and glucocorticoids, are activated by the traumatic

experience (Cahill, 1997; Hasselmo, 1995). Both the quantity of re-

lease of these stress hormones, and the functional availability of the

target brain areas (e.g. hippocampus) modulate the encoding of

memories of the stressful event; ineffectiveness of the system may be

responsible for breakdown in the stream of events and changes in

the central and peripheral processing of the events. This can lead to

the wide spectrum of memory symptoms, ranging from hypermne-

sia, amnesia, deficits in declarative memory, delayed recall of abuse,

and other memory alterations or distortions in trauma disorder

patients.

It should be kept in mind that traumatic memories are not fixed or

indelible, but can change over time. Enhanced memory for the gist of

emotional events seems to be a dominant theme. What is encoded

depends on what was perceived, and what is encoded determines

what will be retrieved (Tulving & Thomson, 1973). Neuroimaging

may shed a light on the retrieval aspect of memory and its emotional

involvement by investigating brain processes that are occurring dur-

ing traumatic recall (Baddeley et al., 2000; Bremner, Krystal, Charney,

& Southwick, 1996; Sara, 2000; Zola, 1998). In PTSD patients ‘traumatic

cues’, such as a particular sight or sound reminiscent of the original

traumatic event, typically can induce a cascade of anxiety and fear-

related symptoms, sometimes without conscious recall of the original

traumatic event. This traumatic stimulus may not always be easy to

identify; it may be that through exposure to a movie, a smell, or more

subtle, a gesture or voice, a memory is metaphorically ‘reawakened’ –

traumatic memories can remain indelible for years or decades and

can be recalled by a variety of stimuli and stressors. A model of

extinction to explain this does not seem to qualify in these cases; a

better model seems to be the failure of successful inhibition of

traumatic memories.

Traumatic recall may not always be processed in an integrated mode

of consciousness. This may be a discontinuous experience with amnesic

gaps. Zimbardo, LaBerge, and Butler (1993) compared the emotional,

cognitive, and physiological responses of subjects experiencing induced

physiological arousal with and without awareness of the source of their

288 ERIC VERMETTEN AND J. DOUGLAS BREMNER

arousal. When subjects received posthypnotic suggestions for arousal

(increases in heart and respiration rate) with and without amnesia for

its source only hypnotizable subjects were expected to differ between

conditions. Indeed, for the hypnotizable subjects, unexplained arousal

produced significant and dramatic effects when compared with

explained arousal, including misattributions (Zimbardo et al., 1993).

These experiments demonstrated that ‘discontinuous experiences’ can

contribute to the development of psychopathological symptoms in

normal persons. But recall can also be hypnotically blocked, e.g. by

posthypnotic suggestion. Here a disruption of retrieval like in post-

hypnotic amnesia or posthypnotic suggestion refers to a subjects diffi-

culty in remembering, after hypnosis. This is not a state-dependent

memory, but it does involve a disruption of retrieval processes similar

to the functional amnesias observed in clinical dissociative disorders. In

a situation like this implicit memory, however, is largely spared, and

may underlie subjects’ ability to recognize events that they cannot

recall (Kihlstrom, 1997).

INDUCTION PROCEDURES OF TRAUMATIC RECALL

Recall of traumatic events in imaging studies is usually embedded

in a so-called ‘‘activation paradigm’’ of re-experiencing traumatic

events. In this paradigm, the patient is asked to briefly (for 1 to 2

minutes) recall a memory that is induced by a personal narrative,

smell, picture, or sound with different traumatic load (traumatic vs.

neutral). For the purpose of this paper, we focus on the recall induced

through emotional or cognitive induction. For the purpose of this

paper, we focus on the recall induced through emotional or cognitive

induction.

Traumatic Recall Through Emotional and Cognitive Induction

Typically in a traumatic-script procedure, the patient writes a

narrative of his or her two most traumatic personal events some days

before the scanning. Usually two neutral texts are made at that time for

the no-activation scan. This text is edited for length (30–40 seconds) and

content. The script is audio taped or can be read during the scan

procedure. The script can then be presented in first or second person,

usually present tense. Immediately before each scan the participant is

instructed to ‘‘close your eyes, listen carefully to the audiotape or voice

and imagine the described events as vividly as possible, as if you were

actually participating in the event again’’ (cf. Lanius et al., 2001; Osuch

et al., 2001; Shin et al., 2000). The participant is then usually scanned 6

to 12 times with a 10-minute interval between scans. When the patient

is lying in the scanner, and the radioactive ligand is administered

intravenously, a trauma script (prepared by a participating patient)

NEUROIMAGING AND HYPNOSIS 289

similar to the one below (B. Elzinga, personal communication, July

2000) can be read:

Listen carefully to the script, and try to imagine as vividly as possible

the experience:

My mom is taking a shower. Dave comes up to me in the living room, where I

am standing. He is whispering in my ear, ‘‘I would prefer to kiss your private

part.’’ I think he is saying that as he presses my breast. Soon his hands sweep

down to my private area and he begins to massage it. His touch is not

welcoming; his pressing my breast hurt me and so does his touching my private

area. I am confused and afraid. Mom can come out of the bathroom any minute.

I want to tell him ‘‘stop,’’ but I don’t. It seems as if I can’t find my voice.

Eventually, I make gestures that imply I don’t want any more touching. He

eventually stops, after calling my name a couple of times. I am relieved, and I

seek some quiet corner of the apartment, just as my mom comes out of the

shower.

Now, continue to imagine the experience from the beginning to the end,

until I ask you to stop.

When applying the model of induction of emotional memories in a

trauma population, some points need to be considered:

(1) A prerequisite for successful implementation of a recall paradigm and

completion of the task in neuroimaging research is the ability of

the participating subjects to have reasonable control over their emo-

tional response in recalling traumatic events. In a PET paradigm, they

need to be able to return to a normal state within approximately 10

minutes. Subjects may – even though they are informed and have given

informed consent – become tearful, panicked, and emotionally over-

whelmed during the recall and feel an urge to suppress these responses.

Sometimes this fails and leads to termination of the scan (Osuch et al.,

2001).

(2) Extreme stress, high or low arousal, and fatigue are distinct psycholog-

ical factors that can separately and interactively affect how information

is processed – rendering it especially influential because it is not sub-

mitted to critical reality testing in a calm, relaxed, and rested state. This is

what Bowers described as a situation in which type II unconscious

influences occur. These describe how information is processed outside

normal awareness, initiative, and volition, speaking of dissociated experi-

ence and dissociated control as two complementary aspects of hypnotic

responsiveness (Bowers, 1973). Low-level monitoring of the process

when exposed to traumatic slides and sounds and calling this to a halt

will typically occur in the trauma-control subject; the situation is dif-

ferent in patients with PTSD. Their dissociated experience refers to the

fact that the (induced) state of affairs seems to occur nonvolitionally, –

which means here that the effort involved is not well presented in

conscious experience. These observations contribute to a framework

in which brain correlates of traumatic recall can be understood as

dissociated control. Upon asking subjects to voluntarily start recalling

290 ERIC VERMETTEN AND J. DOUGLAS BREMNER

a situation (‘‘Now continue to imagine the experience from the begin-

ning’’), some will anticipate becoming stressed and voluntarily control

the situation, and some will become upset and may not be able to stop

recalling (involuntary response).

(3) An important aspect in recall inductions is the content of intrusions.

Research studies suggest that they are not random fragments of the

experience. Typically, they represent stimuli that were present shortly

before the moments with the largest emotional impact (Ehlers et al.,

2002). They need not be sensory per se. Reynolds and Brewin de-

scribed elaborations of the original experience as the most intrusive,

linked to preoccupations with appraisals of the trauma and its se-

quelae, rather than presenting trauma memories (Reynolds & Brewin,

1998). This needs to be taken into account when preparing a narrative

script.

(4) Of importance in the induction of traumatic recall for brain imaging

studies is the theme of general versus specific induction of trauma-

related memories. Typically, in a general paradigm a standardized set

of images or words is presented, and the response pattern in the target

population can be calculated by averaging the responses. In a trauma-

specific paradigm, an individual induction is prepared before the brain

imaging procedure. In this paradigm, the surprise effect of the induc-

tions is somewhat diminished since the subject will recognize his or

her specific elements. Ehlers provides examples of the specific (sen-

sory) nature of the traumatic events from which it appears that

traumatic triggers are specific for both nature and content of the

trauma-related stimulus. In designing an experiment using olfaction

as a trauma-related cue in combat-related PTSD, we were to choose a

traumatic smell that could either be specific for each person or a smell

that all veterans reported as a trigger for traumatic memories. All

veterans had been exposed to diesel during their combat experience,

and diesel was present throughout the war. This smell therefore

seemed to qualify as both a generic and specific trauma-related smell

in the population (Vermetten, Schmahl, Southwick, & Bremner, 2003).

The same can be applied to trauma-related words and other types of

sensory stimulation.

(5) Laboratory studies have demonstrated that central cues of a traumatic

event are usually well remembered, whereas memory for peripheral

details is poor (Christianson, 1992). The narrowing of attention is often

used as an explanation for this finding. High anxiety and arousal are

thought to focus the attention on central aspects, such as the weapon

used, and hinder a full processing of the situation. It is thought that

changes in the perfusion of limbic brain structures that coincide with the

high arousal and/or anxiety, such as the amygdala and the hippocam-

pus, can lead to fragmented memories and personality fragmentation

(Spiegel, 1989; Van Der Kolk, Burbridge, & Suzuki, 1997). Narratives

should be written according to these notions.

(6) In all imaging studies in traumatic recall, the patient anticipates the

presentation of trauma (-related) material, and some researchers have

performed a dry run with the patient. Then the subject is not ‘‘cold’’ to

NEUROIMAGING AND HYPNOSIS 291

the trauma cue. It needs to be taken into account that this may dampen

the activation of the brain when exposed to the challenge.

(7) Last, in addition to the first observation of this section, many clinicians

have described a ‘‘dissociative’’ or ‘‘hypnotic’’ blocking of perceptual

aspects as an adaptive response to trauma. Pain in recall can be blocked,

time processing can be distorted, or processing of the perception of

emotions like threat cannot be adequately processed. Patients may

dissociate during the experience and unless this is assessed at each

between-scan interval (to assess whether this is a positive or negative

phenomenon, see Lanius et al., 2002; Nijenhuis et al., 2002) it may

explain a difference in participant responding. In case patients do

dissociate, a systematic procedure needs to be administered to help

reorient them to the common environment and enable them to continue

with the scanning procedure reliably. In PET protocols, this is especially

important since the production of radioactive material is delivered in a

time-wise manner, and typically each interscan interval is set to 10

minutes.

FUNCTIONAL BRAIN IMAGING RESULTS IN TRAUMATIC

RECALL IN TRAUMA DISORDERS

To date, 12 imaging studies that used a symptom provocation

paradigm in PTSD have been published. Seven studies used PET

(Bremner, Narayan, et al., 1999; Bremner, Staib, et al., 1999; Osuch

et al., 2001; Pissiota et al., 2002; Rauch et al., 1996; Shin et al., 1997, 1999),

three used fMRI (Lanius et al., 2001, 2002; Rauch et al., 2000), and two

used SPECT as imaging technique (Liberzon et al., 1999; Zubieta et al.,

1999). The design, patient population, induction method, measure of

recall, psychophysiological coregistration, and changes in brain me-

tabolism are tabulated in Table 1. These studies have used various chal-

lenge models, exposing the subject – at varying levels of complexity –

to perceptual stimulations that range from exposing patients to slides

and sounds, smells of trauma-related experiences, to reading narrative

scripts, to the administration of pharmacologic agents like yohimbine

(see reviews by Bremner, 2002; Hull, 2002). Reexperiencing of traumatic

events typically coincides with heightened attention, lack of awareness

for the surroundings, and loss of perception of time. At the same time,

emotions of fear, shame, disgust, anger, and sadness, may occur and

sometimes coincide with dissociation, freezing, and other psychophy-

siological arousal phenomena (Nijenhuis et al., 1998).

The first PET studies in traumatic recall used combat slides and

sounds and script-driven imagery in PTSD patients. The results sug-

gested that symptoms associated with traumatic recall were mediated

by the limbic and paralimbic systems within the right hemisphere.

Activation of visual cortex corresponded to the visual component of

PTSD reexperiencing phenomena (Rauch et al., 1996). When generating

Note. TC ¼ trauma controls, HC ¼ healthy controls, HR ¼ heart rate, GSR ¼ Galvanic Skin Response, SUDS ¼ Subjective Units of Distress,

PAG ¼ periaquaductal gray, ri ¼ right, le ¼ left, act ¼ n accumbens, VAS ¼ visual analog scale, CADSS ¼ Clinician Administrated Dissociative Symptom

Scale, STAIS ¼ State-Trait Anxiety Inventory Trait Test, MVA ¼ Motor Vehicle Accident, VVIQ ¼ vividness visual imagery questionnaire.

mental images of combat-related pictures, increased regional cerebral

blood flow (rCBF) in the ventral anterior cingulate cortex (ACC) and

right amygdala was seen; when viewing combat pictures, subjects with

PTSD showed decreased rCBF in Broca’s area (Shin et al., 1997). These

first PET studies of traumatic recall in PTSD have since led to a rapid

increase in similar studies modifying the experimental condition and/

or study population.

There is overlap but also considerable diversity in various traumatic

recall studies. The ACC, middle and superior temporal, middle frontal,

right orbitofrontal, occipital, hippocampal, parahippocampal, anterior

temporal, and inferior frontal cortices have all been implicated in

different studies, demonstrating either increases or decreases in perfu-

sion depending on the study conditions and sample population

(Phillips et al., 2003a, 2003b). In general, in comparison to trauma-

control subjects, these studies reveal an exaggerated response activa-

tion in the right (Rauch et al., 1996; Shin et al., 1997) or left (Liberzon

et al., 1999) amygdala, and in the sensorimotor cortex (Bremner,

Narayan, et al., 1999; Shin et al., 1997) and attenuated responses within

the medial prefrontal cortex (mPFC) (Bremner, Narayan, et al., 1999;

Shin et al., 1999) in patients with PTSD. In line with this, imaging

studies of normal autobiographical memory (i.e., no emotional activa-

tion) in healthy subjects compared to memory-control tasks have

pointed to mPFC and (left) hippocampus that are just particularly

responsive to such memories (Conway et al., 1999); other studies point

to right frontal cortices, medial parietal cortex, and cerebellum (Nyberg,

Forkstam, Petersson, Cabeza, & Ingvar, 2002).

Current studies support a model of PTSD in which (a) the amygdala

is hyperresponsive to threat-related stimuli, and (b) interconnected

areas may provide insufficient ‘‘top-down’’ inhibition by mPFC and

ACC of amygdala response. This relative dysfunction of mPFC and

ACC is thought to lower the threshold of amygdala response to fearful

stimuli and is central to symptom mediation (Pitman, Shin, & Rauch,

2001; Villarreal & King, 2001). Thus, dysfunction of the mPFC areas

may provide a neural correlate of a failure of extinction of fearful

stimuli in PTSD.

Recall induction of emotion specifically activated the ACC. This

brain structure is critically involved in cognitive induction of emo-

tional responses and processes attention, executive functions, and

semantic and episodic memory. ACC activation represents a normal

brain response to traumatic stimuli that serves to inhibit feelings of

fearfulness when there is no true threat. Failure of activation in this

area and/or decreased blood flow in the adjacent subcallosal gyrus

(area 25) may lead to increased fearfulness that is not appropriate for

the context, facilitating exaggerated emotional and behavioral re-

sponses (hyperarousal) to conditioned stimuli (Hamner, Lorberbaum,

296 ERIC VERMETTEN AND J. DOUGLAS BREMNER

& George, 1999). Posterior cingulate cortex (PCC) and motor cortex

and anterolateral prefrontal cortex are also known to modulate

emotion and fear responsiveness (Bremner, 2002). PCC plays an

important role in visuospatial processing and is therefore an impor-

tant component in the preparation for coping with a physical threat.

PCC also has functional connections with the hippocampus and

adjacent cortex.

In a meta-analysis of PET and fMRI studies of general emotional

activation reviewing 43 PET and 12 fMRI activation studies spanning

almost a decade of research, Phan, Wager, Taylor, and Liberzon (2002)

describe brain areas that are involved in emotion induction with

cognitive demand, typical paradigms of the recall of autobiographical

elements or visual imagery:

Approaching Pain's Layers Through Hypnosis

Under the suggestive power of hypnosis, subjects can be convinced that they're feeling pain when no stimulus is given. Other subjects can be taught to control the amount of pain they feel, as with a dial. Appearing to work well in as many as 15% of people tested, hypnosis can tap into the brain's ability to produce and modulate pain as well as the maddening subjectivity of the experience. Using sophisticated brain imaging techniques in concert with the power of suggestion, scientists are getting closer to parsing the emotional and sensory aspects of pain. "Studies with hypnosis are very elegant," says Northwestern University's Apkar Apkarian, noting that such studies were some of the first to separate different aspects of pain. Stuart Derbyshire, at the University of Pittsburgh, notes hypnosis' parlor-trick reputation: "People think they'll be clucking like a chicken." But serious study can be done under highly controlled circumstances. Hypnosis is about becoming highly focused on one thing and allowing that focus to be controlled externally, he says. In Derbyshire's recent experiment,1 subjects were told that when tapped on the foot once, they would experience 30 seconds of heat pain; two taps to the foot indicated a 30-second period of rest. But some hypnotized subjects reported experiencing pain in absence of the noxious stimulus. Derbyshire considered such pain to be hypnotically induced. This hypnotically induced pain triggered brain activation very similar to that for actual heat pain. In the control case, subjects were asked to imagine pain without any noxious stimulus. Under this imaginary condition, pain was not experienced by most subjects and only fleetingly in two subjects; brain activation was absent in the areas usually associated with such pain. Derbyshire, however, did not have a nonhypnotized control, suggesting that the increase in pain experience might have been due to the expectation of pain. But he still achieved his objectives, he contends--generating a pain experience without a stimulus. "We expected to use hypnosis to bring about that effect, but it really doesn't matter to us that much if it was not actually due to the hypnosis," he says. Where Derbyshire created a pain experience without a stimulus, imaging and pain researcher Pierre Rainville typically employs a methodology that changes the experience of an actual stimulus. As part of an influential 1997 study,2Rainville, an assistant professor of stomatology at the University of Montreal, had hypnotized subjects and told them to imagine a dial that they could turn up or down to affect the sensation of their hand, which was immersed in hot water. Positron emission tomography imaging studies showed that the modulation of the sensory area of the somatosensory cortex was proportional to the subjective modulation that the subjects were reporting. In related experiments, Rainville and colleagues targeted the emotional aspect. They told subjects that they'd feel a burning, pricking sensation in their hand, but through suggestion convinced subjects that they were experiencing various levels of pain intensity. In fact, the sensation was the same in each case; only the external suggestion differed. At the end of each scan, subjects reported what trials were more or less unpleasant. Researchers found the corresponding modulation in the anterior cingulate cortex, the cortical part of the limbic system. It's still unclear, however, whether hypnosis facilitates a widely applicable model for pain exploration. When Derbyshire talks about hypnosis at conferences, he still gets people saying "That's very interesting, but what's it got to do with the real world?" Roughly 15% of the population can be easily hypnotized such that their pain experience is altered. "The onus is on us to prove why that is," says Derbyshire. Rainville downplays the downsides, saying that only another 15% are not responsive, meaning 85% are somewhat to very responsive. Picturing a therapeutically relevant use for such methods, Rainville notes, "It's important to realize that even if someone might not be highly responsive, it doesn't mean they wouldn't get some benefit." References 1. S.W.G. Derbyshire et al., "Cerebral activation during hypnotically induced and imagined pain," Neuroimage, 23:392-401, September 2004. 2. P. Rainville et al., "Pain affect encoded in human anterior cingulate but not somatosensory cortex," Science, 277:968-71, 1997. -

Hypnosis: From Stage Hypnosis to the lab

From the stage to the lab Neuroimaging studies are helping hypnosis shed its 'occult' connotations by finding that its effects on the brain are real. By Lea Winerman Monitor Staff Print version: page Mention hypnosis, and for many people the image that comes to mind is a charlatan with a watch swinging back and forth, seducing otherwise sensible audiences into barking like dogs or clucking like chickens. Today, though, psychologists and others are using hypnosis to help patients stop smoking, lose weight or control pain. But despite this newfound respect for the method, scientists still aren't sure precisely how hypnosis–whether on stage or in a clinician's office–works. For years, they've been trying to determine whether hypnotized people actually feel and see things differently than the nonhypnotized or whether the hypnotized give in to some combination of concentration and social pressure to follow hypnotists' demands. Now, in the past decade or so and with the advent of neuroimaging technology like functional magnetic resonance imaging (fMRI), researchers have begun to get some answers. Recent studies have found that when hypnotized people act on hypnotists' suggestions, their brains really do process information differently. When they're told to see colors, for example, the color-processing parts of their brains light up–despite the absence of any real color in front of them. "This is an exciting time for us," says Columbia University psychologist and hypnosis researcher Amir Raz, PhD. "Neuroimaging technology allows us to really look at what's going on in the brain during hypnotic suggestion." Now, Raz and others are beginning to branch out, to try to figure out why hypnosis works and why some people are more hypnotizable than others. They hope that their research will lead to not only a better understanding of a previously mysterious phenomenon, but also to more effective hypnosis treatments. New findings In one recent study, Raz found that he could use hypnosis to negate the Stroop effect, a task that demonstrates how attention processes can interfere with each other. In the task, participants view the names of colors printed in different colors of ink–for example, the word "red" printed in blue ink–and try to say the name of the ink color while ignoring the words. But people who are literate read the words automatically and so find the task difficult. They often respond slowly and mistakenly read the words rather than identify the ink color. In a recent study, published in the Proceedings of the National Academy of Sciences (Vol. 102, No. 28, pages 9,978–9,983), Raz and his colleagues tested eight highly hypnotizable people and eight who weren't hypnotizable at all. The researchers performed a hypnotic induction, using methods such as guided imagery and visualization. Then, they told the participants that they would later see "meaningless symbols" printed in different colors of ink, and that when they did, they should press a computer key corresponding to the correct ink color. Next, the researchers brought the participants out of hypnosis, put them in an fMRI machine and showed them the Stroop stimuli. But the hypnotizable patients who had been told that they'd see gibberish seemed, in fact, to see gibberish: They performed the task almost 10 percent faster than the nonhypnotized participants, and made fewer mistakes. "It appears that these people were not playing games, and they were not acting," says Raz. "They were genuinely not reading the words." The fMRI results were also striking. The hypnotizable participants showed less activity in an area called the anterior cingulate cortex, which is active when people are trying to resolve conflicting information from different sources–information like conflicting word names and colors. Studies that have examined other types of hypnotic suggestions have found similar evidence. For example, Harvard psychologist Stephen Kosslyn, PhD, found that when he told hypnotized subjects that they would see gray-scale printed, Mondrian-like patterns in color, the participants showed activation in the same area of the brain–the right fusiform gyrus–as when they viewed actual color prints, according to a study published in theAmerican Journal of Psychiatry (Vol. 157, No. 8, pages 1,279–1,284). That area didn't light up, however, when the subjects weren't hypnotized and Kosslyn simply suggested that they visualize the drawings in color. Another experiment found that hypnotically induced pain activated the same brain areas as "real" pain. In this 2004 study, published in Neuroimage (Vol. 23, No. 1, pages 392–401), University College London psychologist David Oakley, PhD, and his colleagues told eight highly hypnotizable participants that they would feel heat-related pain. They found that the same pain-processing areas of the brain–in the thalamus, anterior cingulate cortex and other areas–were active in those subjects as in subjects who actually touched a 120-degree metal probe. Subjects who simply imagined the pain, meanwhile, didn't show the same active brain areas. The interpretation The accumulating evidence suggests that people respond to hypnotic suggestion by actually "feeling" or "seeing" the suggested stimulus, be it pain or color. The question that researchers have yet to answer, Oakley says, is how those changes come about. Scientists are still split on the issue: Some believe that hypnosis puts people into a trance state in which the brain behaves measurably differently than it does in other states. Others, meanwhile, believe that hypnosis is simply an intense form of concentration or focused attention. So far, neuroimaging studies haven't been able to distinguish between the two. To do so, a researcher would need to find a difference in brain activity between a hypnotized and a nonhypnotized person–specifically, a difference unrelated to the effects of any particular suggestion such as seeing color, says University of Plymouth psychology professor Irving Kirsch, PhD. "Nobody has yet disentangled the effect of suggestion from the effect of hypnotic induction," Kirsch says. "That's probably the next step." In fact, he and Raz have begun to address the question with behavioral measures. In one study, published in February in Psychological Science (Vol. 17, No. 2), they repeated the Stroop experiment but this time included a condition in which they simply told the highly hypnotizable participants, who were not hypnotized at that time, that they would see gibberish rather than words. The researchers found that, for these highly suggestible people, the suggestion alone was enough to improve performance on the task. "We now have evidence showing that highly hypnotizable people do not need to be hypnotized in order to benefit from suggestion," Raz says. That indicates that hypnosis may be a normal state of consciousness rather than an altered state–and that some people who are particularly good at experiencing imaginative suggestions are the ones who can be hypnotized, Kirsch explains. Meanwhile, researchers who believe that hypnosis alters the brain's functioning in some fundamental way say that the new findings don't negate that possibility. John Gruzelier, PhD, a psychologist at Imperial College in London, acknowledges that easily hypnotizable people are more suggestible even when not hypnotized. However, he says, the hypnosis itself still makes a difference. "It's my feeling that we wouldn't bother going through the whole rigmarole of hypnosis if it was unnecessary," he says. Raz and Kirsch hope that this and other work will also begin to help explain why some people are more highly hypnotizable than others, and will give researchers insight into who is most likely to benefit from hypnosis.

The Mind Prepared: Hypnosis in Surgery

1280   Editorials | JNCI Vol. 99, Issue 17  | September 5, 2007 In 1846, a Scottish surgeon named James Esdaile reported 80%

surgical anesthesia using hypnosis as the sole anesthetic for amputa-

tions in India. His work caused sufficient stir that when ether anes-

thesia was demonstrated in what is now called the Ether Dome at

the Massachusetts General Hospital on October 16 of that same

year, a surgeon strode to the front of the amphitheater and said,

“Gentlemen, this is no humbug,” to distinguish his surgical team’s

demonstration from Esdaile’s report. It has taken us a century and

a half to rediscover the fact that the mind has something to do with

pain and can be a powerful tool in controlling it: the strain in pain

lies mainly in the brain.

In this issue of the Journal, Montgomery et al. (

1 ) report

the results of a randomized trial conducted among 200 patients

who underwent excisional breast biopsy or lumpectomy for breast

cancer. Patients were assigned to either routine anesthesia plus

nondirective empathic listening (the control condition) or a very

brief 15-minute presurgery hypnosis session. The hypnosis, which the

authors describe in very cursory fashion, consisted of “a relaxation-

based induction (including imagery for muscle relaxation), sug-

gestions for pleasant visual imagery, suggestions to experience

relaxation and peace, specifi c symptom-focused suggestions

(i.e., to experience reduced pain, nausea, and fatigue), a deepening

procedure, and instructions for how patients could use hypnosis

on their own following the intervention session.” This brief hyp-

notic preparation was suffi cient to produce a statistically signifi cant

reduction in the use of propofol and lidocaine; yet despite this,

patients in the intervention group reported less pain, nausea, fatigue,

discomfort, and emotional upset than did patients in the control

group. Doing good also meant doing well, in that the use of hypnosis

also resulted in a cost savings of $772.71 per patient, due largely to

shorter time in the operating room

— an average of 10.6 minutes.

This impressive study builds on the work of Lang and col-

leagues, who in a series of studies have shown that use of hypnosis

during interventional radiologic procedures results in reduced use

of anesthetic medication, less pain and anxiety, shorter procedure

time (an average of 18 minutes) (

2 , 3 ), and cost savings of $338 per

procedure (

4 ). These results were, surprisingly, independent of age

and hypnotizability (

5 ). The ability to be hypnotized is a stable

trait that can be reliably measured in 5 minutes or less (

6 ). Children

are, in general, more hypnotizable than adults, and there are simi-

lar fi ndings of relief of distress among children who are taught

self-hypnosis before undergoing voiding cystourethrograms (

7 ).

In a study of a similar population to that of Montgomery et al. (

1 ),

of women undergoing large core needle biopsy for breast cancer

diagnosis, Lang et al. (

8

) showed that hypnosis statistically sig-

nifi cantly reduced anxiety but had a lesser effect on the modest

pain associated with the procedure. Thus, the study in this issue

contributes to an impressive body of research using randomized

prospective methodology in sizeable patient populations to dem-

onstrate that adjunctive hypnosis substantially reduces pain and

anxiety during surgical procedures while decreasing medication

use, procedure time, and cost. If a drug were to do that, everyone

would by now be using it.

So why don’t they? For one thing, there is no mediating indus-

try to sell the product

— dangling watches are out of fashion for

hypnotic inductions. Plus, there is still lingering suspicion that

hypnosis reeks of stage show trickery. After all, the magic wand

originated with Mesmer’s use of a magnetic stick to presumably

alter magnetic fi elds in patients’ bodies. Yet hypnosis is the oldest

Western form of psychotherapy. Hypnosis is a state of highly

focused attention, with a constriction in peripheral awareness and

a heightened responsiveness to social cues (

5 ). It is most similar to

the everyday state of becoming so absorbed in a good movie or a

novel that one enters the imagined world and suspends awareness

of the usual one, a condition playwrights refer to as the “suspen-

sion of disbelief.” This state can exert powerful infl uence on mind

and body. Altering perception using hypnosis results in brain

Correspondence to:  David Spiegel, MD, Department of Psychiatry and

Behavioral Sciences, Stanford University School of Medicine, 401 Quarry Rd,

Ste 2325, Stanford, CA 94305-5718 (e-mail:

dspiegel@stanford.edu ).

DOI:  10.1093/jnci/djm131

© The Author 2007. Published by Oxford University Press. All rights reserved.

For Permissions, please e-mail: journals.permissions@oxfordjournals.org.

changes that literally reduce pain perception [rather than merely

altering the response to pain (

9  –  12 )]. Indeed, simply changing the

wording of the hypnotic instruction from “you will feel cool, tin-

gling numbness more than pain” to “the pain will not bother you”

alters the brain location of the analgesia from the somatosensory

cortex to the anterior cingulate gyrus (

9 , 13 ). Hypnotic alteration

of color perception results in bidirectional changes in blood fl ow

in the portions of the visual cortex that process color vision — blood

fl ow in this region increases when color is imagined rather than

seen and decreases when color is hypnotically drained from a col-

orful stimulus ( 14 ). Thus, there is good neurophysiologic reason

to believe that hypnosis is potentially a powerful tool to alter per-

ception of pain and associated anxiety.

You have to pay attention to pain for it to hurt, and it is

entirely possible to substantially alter pain perception during sur-

gical procedures by inducing hypnotic relaxation, transforming

perception in parts of the body, or directing attention elsewhere.

The key concept is that this psychological procedure actually

changes pain experience as much as many analgesic medications

and far more than placebos (

15  –  17 ). There is recent evidence

from studies of the placebo effect that activity in the anterior cin-

gulate gyrus is linked to that in the periaqueductal gray, a brain-

stem region that is crucial to pain perception (

18 ). Hypnotic

analgesia is real, no less palpable an analgesic than medication,

although the pathways are different and do not seem to involve

endogenous opiates (

19 ). Rather, hypnosis seems to involve brain

activation via dopamine pathways (

20  –  22 ). Thus, it is not surpris-

ing that hypnosis, which mobilizes attention pathways in the

brain, can be used effectively to reduce pain perception and atten-

dant anxiety.

Cancer is a disease that hijacks patients’ attention. Those com-

ing for diagnostic surgery are understandably anxious about the

outcome. They are thus hyperattentive to every pain and its possi-

ble implications. The operating room is a novel environment, and

humans have evolved to pay special attention to new and poten-

tially threatening situations. Thus, a means of redirecting atten-

tion while using the brain to induce physical relaxation rather than

promote muscle tension can be especially helpful to cancer patients

during their initial surgery. It is now abundantly clear that we can

retrain the brain to reduce pain: “fl oat rather than fi ght.” Esdaile

would have been proud to read this issue of the Journal. He might

even have said, “Ladies and Gentlemen, this is no humbug.”

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This Is Your Brain Under Hypnosis

By 

SANDRA BLAKESLEE

Published: November 22, 2005

Hypnosis, with its long and checkered history in medicine and entertainment, is receiving some new respect from neuroscientists. Recent brain studies of people who are susceptible to suggestion indicate that when they act on the suggestions their brains show profound changes in how they process information. The suggestions, researchers report, literally change what people see, hear, feel and believe to be true.

Don Hogan Charles/The New York Times

SEEING RED Dr. Amir Raz, rear, and Miguel Moeno demonstrate the hypnosis test.

The new experiments, which used brain imaging, found that people who were hypnotized "saw" colors where there were none. Others lost the ability to make simple decisions. Some people looked at common English words and thought that they were gibberish.

"The idea that perceptions can be manipulated by expectations" is fundamental to the study of cognition, said Michael I. Posner, an emeritus professor of neuroscience at the University of Oregon and expert on attention. "But now we're really getting at the mechanisms."

Even with little understanding of how it works, hypnosis has been used in medicine since the 1950's to treat pain and, more recently, as a treatment for anxiety, depression, trauma, irritable bowel syndrome and eating disorders.

There is, however, still disagreement about what exactly the hypnotic state is or, indeed, whether it is anything more than an effort to please the hypnotist or a natural form of extreme concentration where people become oblivious to their surroundings while lost in thought.

Hypnosis had a false start in the 18th century when a German physician, Dr. Franz Mesmer, devised a miraculous cure for people suffering all manner of unexplained medical problems. Amid dim lights and ethereal music played on a glass harmonica, he infused them with an invisible "magnetic fluid" that only he was able to muster. Thus mesmerized, clients were cured.

Although Dr. Mesmer was eventually discredited, he was the first person to show that the mind could be manipulated by suggestion to affect the body, historians say. This central finding was resurrected by Dr. James Braid, an English ophthalmologist who in 1842 coined the word hypnosis after the Greek word for sleep.

Braid reportedly put people into trances by staring at them intently, but he did not have a clue as to how it worked. In this vacuum, hypnosis was adopted by spiritualists and stage magicians who used dangling gold watches to induce hypnotic states in volunteers from the audience, and make them dance, sing or pretend to be someone else, only to awaken at a hand clap and laughter from the crowd.

In medical hands, hypnosis was no laughing matter. In the 19th century, physicians in India successfully used hypnosis as anesthesia, even for limb amputations. The practice fell from favor only when ether was discovered.

Now, Dr. Posner and others said, new research on hypnosis and suggestion is providing a new view into the cogs and wheels of normal brain function.

One area that it may have illuminated is the processing of sensory data. Information from the eyes, ears and body is carried to primary sensory regions in the brain. From there, it is carried to so-called higher regions where interpretation occurs.

For example, photons bouncing off a flower first reach the eye, where they are turned into a pattern that is sent to the primary visual cortex. There, the rough shape of the flower is recognized. The pattern is next sent to a higher - in terms of function - region, where color is recognized, and then to a higher region, where the flower's identity is encoded along with other knowledge about the particular bloom.

The same processing stream, from lower to higher regions, exists for sounds, touch and other sensory information. Researchers call this direction of flow feedforward. As raw sensory data is carried to a part of the brain that creates a comprehensible, conscious impression, the data is moving from bottom to top.

Bundles of nerve cells dedicated to each sense carry sensory information. The surprise is the amount of traffic the other way, from top to bottom, called feedback. There are 10 times as many nerve fibers carrying information down as there are carrying it up.

These extensive feedback circuits mean that consciousness, what people see, hear, feel and believe, is based on what neuroscientists call "top down processing." What you see is not always what you get, because what you see depends on a framework built by experience that stands ready to interpret the raw information - as a flower or a hammer or a face.

The top-down structure explains a lot. If the construction of reality has so much top-down processing, that would make sense of the powers of placebos (a sugar pill will make you feel better), nocebos (a witch doctor will make you ill), talk therapy and meditation. If the top is convinced, the bottom level of data will be overruled.

Ralph Crane/Time Life Pictures/Getty Images

Bernard C. Gindes and his hypnosis machine in 1967.

This brain structure would also explain hypnosis, which is all about creating such formidable top-down processing that suggestions overcome reality.

According to decades of research, 10 to 15 percent of adults are highly hypnotizable, said Dr. David Spiegel, a psychiatrist at Stanford who studies the clinical uses of hypnosis. Up to age 12, however, before top-down circuits mature, 80 to 85 percent of children are highly hypnotizable.

One adult in five is flat out resistant to hypnosis, Dr. Spiegel said. The rest are in between, he said.

In some of the most recent work, Dr. Amir Raz, an assistant professor of clinical neuroscience at Columbia, chose to study highly hypnotizable people with the help of a standard psychological test that probes conflict in the brain. As a professional magician who became a scientist to understand better the slippery nature of attention, Dr. Raz said that he "wanted to do something really impressive" that other neuroscientists could not ignore.

The probe, called the Stroop test, presents words in block letters in the colors red, blue, green and yellow. The subject has to press a button identifying the color of the letters. The difficulty is that sometimes the word RED is colored green. Or the word YELLOW is colored blue.

For people who are literate, reading is so deeply ingrained that it invariably takes them a little bit longer to override the automatic reading of a word like RED and press a button that says green. This is called the Stroop effect.

Sixteen people, half highly hypnotizable and half resistant, went into Dr. Raz's lab after having been covertly tested for hypnotizability. The purpose of the study, they were told, was to investigate the effects of suggestion on cognitive performance. After each person underwent a hypnotic induction, Dr. Raz said:

"Very soon you will be playing a computer game inside a brain scanner. Every time you hear my voice over the intercom, you will immediately realize that meaningless symbols are going to appear in the middle of the screen. They will feel like characters in a foreign language that you do not know, and you will not attempt to attribute any meaning to them.

"This gibberish will be printed in one of four ink colors: red, blue, green or yellow. Although you will only attend to color, you will see all the scrambled signs crisply. Your job is to quickly and accurately depress the key that corresponds to the color shown. You can play this game effortlessly. As soon as the scanning noise stops, you will relax back to your regular reading self."

Dr. Raz then ended the hypnosis session, leaving each person with what is called a posthypnotic suggestion, an instruction to carry out an action while not hypnotized.

Days later, the subjects entered the brain scanner.

In highly hypnotizables, when Dr. Raz's instructions came over the intercom, the Stroop effect was obliterated, he said. The subjects saw English words as gibberish and named colors instantly. But for those who were resistant to hypnosis, the Stroop effect prevailed, rendering them significantly slower in naming the colors.

When the brain scans of the two groups were compared, a distinct pattern appeared. Among the hypnotizables, Dr. Raz said, the visual area of the brain that usually decodes written words did not become active. And a region in the front of the brain that usually detects conflict was similarly dampened.

Top-down processes overrode brain circuits devoted to reading and detecting conflict, Dr. Raz said, although he did not know exactly how that happened. Those results appeared in July in The Proceedings of the National Academy of Sciences.

A number of other recent studies of brain imaging point to similar top-down brain mechanisms under the influence of suggestion. Highly hypnotizable people were able to "drain" color from a colorful abstract drawing or "add" color to the same drawing rendered in gray tones. In each case, the parts of their brains involved in color perception were differently activated.

Brain scans show that the control mechanisms for deciding what to do in the face of conflict become uncoupled when people are hypnotized. Top-down processes override sensory, or bottom-up information, said Dr. Stephen M. Kosslyn, a neuroscientist at Harvard. People think that sights, sounds and touch from the outside world constitute reality. But the brain constructs what it perceives based on past experience, Dr. Kosslyn said.

Most of the time bottom-up information matches top-down expectation, Dr. Spiegel said. But hypnosis is interesting because it creates a mismatch. "We imagine something different, so it is different," he said.

Source: The New York Times

Hypnosis and Susceptibility

Braid made a rough distinction between different stages of hypnosis which he termed the first and second conscious stage of hypnotism; he later replaced this with a distinction between "sub-hypnotic", "full hypnotic", and "hypnotic coma" stages. Jean-Martin Charcot made a similar distinction between stages named somnambulism, lethargy, and catalepsy. However, Ambroise-Auguste Liébeault and Bernheim introduced more complex hypnotic "depth" scales, based on a combination of behavioural, physiological and subjective responses, some of which were due to direct suggestion and some of which were not. In the first few decades of the 20th century, these early clinical "depth" scales were superseded by more sophisticated "hypnotic susceptibility" scales based on experimental research. The most influential were the Davis-Husband and Friedlander-Sarbin scales developed in the 1930s. Andre Weitzenhoffer and Ernest R. Hilgard developed the Stanford Scale of Hypnotic Susceptibility in 1959, consisting of 12 suggestion test items following a standardised hypnotic eye-fixation induction script, and this has become one of the most widely-referenced research tools in the field of hypnosis. Soon after, in 1962, Ronald Shor and Emily Carota Orne developed a similar group scale called the Harvard Group Scale of Hypnotic Susceptibility (HGSHS). Whereas the older "depth scales" tried to infer the level of "hypnotic trance" based upon supposed observable signs, such as spontaneous amnesia, most subsequent scales measure the degree of observed or self-evaluated responsiveness to specific suggestion tests, such as direct suggestions of arm rigidity (catalepsy).

Source Wikipedia

Ideo-dynamic reflex and hypnosis

The first neuro-psychological theory of hypnotic suggestion was introduced early on by James Braid who adopted his friend and colleague William Carpenter's theory of the ideo-motor reflex response to account for the phenomenon of hypnotism. Carpenter had observed from close examination of everyday experience that under certain circumstances the mere idea of a muscular movement could be sufficient to produce a reflexive, or automatic, contraction or movement of the muscles involved, albeit in a very small degree. Braid extended Carpenter's theory to encompass the observation that a wide variety of bodily responses, other than muscular movement, can be thus affected, e.g., the idea of sucking a lemon can automatically stimulate salivation, a secretory response. Braid therefore adopted the term "ideo-dynamic", meaning "by the power of an idea" to explain a broad range of "psycho-physiological" (mind-body) phenomena. Braid coined the term "mono-ideodynamic" to refer to the theory that hypnotism operates by concentrating attention on a single idea in order to amplify the ideo-dynamic reflex response. Variations of the basic ideo-motor or ideo-dynamic theory of suggestion have continued to hold considerable influence over subsequent theories of hypnosis, including those of Clark L. Hull, Hans Eysenck, and Ernest Rossi. It should be noted that in Victorian psychology, the word "idea" encompasses any mental representation, e.g., including mental imagery, or memories, etc. Source Wikipedia

Hypnosis, Consciousness vs. unconconscious mind

Some hypnotists conceive of suggestions as being a form of communication directed primarily to the subject's conscious mind, whereas others view suggestion as a means of communicating with the "unconscious" or "subconscious" mind. These concepts were introduced into hypnotism at the end of 19th century by Sigmund Freud and Pierre Janet. The original Victorian pioneers of hypnotism, including Braid and Bernheim, did not employ these concepts but considered hypnotic suggestions to be addressed to the subject's conscious mind. Indeed, Braid actually defines hypnotism as focused (conscious) attention upon a dominant idea (or suggestion). Different views regarding the nature of the mind have led to different conceptions of suggestion. Hypnotists who believed that responses are mediated primarily by an "unconscious mind", like Milton Erickson, made more use of indirect suggestions, such as metaphors or stories, whose intended meaning may be concealed from the subject's conscious mind. The concept of subliminal suggestion also depends upon this view of the mind. By contrast, hypnotists who believed that responses to suggestion are primarily mediated by the conscious mind, such as Theodore Barber and Nicholas Spanos tended to make more use of direct verbal suggestions and instructions. Source Wikipedia

Hypnosis and the systems theory

Systems theory, in this context, may be regarded as an extension of Braid's original conceptualization of hypnosis[89][page needed] as involving a process of enhancing or depressing nervous system activity. Systems theory considers the nervous system's organization into interacting subsystems. Hypnotic phenomena thus involve not only increased or decreased activity of particular subsystems, but also their interaction. A central phenomenon in this regard is that of feedback loops, which suggest a mechanism for creating hypnotic phenomena.[90][91] Source Wikipedia

Hypnosis and the information theory

An approach loosely based on Information theory uses a brain-as-computer model. In adaptive systems, feedback increases the signal-to-noise ratio, which may converge towards a steady state. Increasing the signal-to-noise ratio enables messages to be more clearly received. The hypnotist's object is to use techniques to reduce interference and increase the receptability of specific messages (suggestions).[88] Source Wikipedia

Hypnosis and Cognitive -behavioral theory

Barber, Spanos, & Chaves (1974) proposed a nonstate "cognitive-behavioural" theory of hypnosis, similar in some respects to Sarbin's social role-taking theory and building upon the earlier research of Barber. On this model, hypnosis is explained as an extension of ordinary psychological processes like imagination, relaxation, expectation, social compliance, etc. In particular, Barber argued that responses to hypnotic suggestions were mediated by a "positive cognitive set" consisting of positive expectations, attitudes, and motivation. Daniel Araoz subsequently coined the acronym "TEAM" to symbolise the subject's orientation to hypnosis in terms of "trust", "expectation", "attitude", and "motivation". Barber et al., noted that similar factors appeared to mediate the response both to hypnotism and to cognitive-behavioural therapy (CBT), in particular systematic desensitization. Hence, research and clinical practice inspired by their interpretation has led to growing interest in the relationship between hypnotherapy and CBT.

Source Wikipedia

Hypnosis, Social role -taking theory

The main theorist who pioneered the influential role-taking theory of hypnotism was Theodore Sarbin. Sarbin argued that hypnotic responses were motivated attempts to fulfill the socially-constructed role of hypnotic subject. This has led to the misconception that hypnotic subjects are simply "faking". However, Sarbin emphasised the difference between faking, in which there is little subjective identification with the role in question, and role-taking, in which the subject not only acts externally in accord with the role but also subjectively identifies with it to some degree, acting, thinking, and feeling "as if" they are hypnotised. Sarbin drew analogies between role-taking in hypnosis and role-taking in other areas such as method acting, mental illness, and shamanic possession, etc. This interpretation of hypnosis is particularly relevant to understanding stage hypnosis in which there is clearly strong peer pressure to comply with a socially-constructed role by performing accordingly on a theatrical stage. Hence, the social constructionism and role-taking theory of hypnosis suggests that individuals are enacting (as opposed to merely playing) a role and that really there is no such thing as a hypnotic trance. A socially-constructed relationship is built depending on how much rapport has been established between the "hypnotist" and the subject (see Hawthorne effect, Pygmalion effect, andplacebo effect).

Psychologists such as Robert Baker and Graham Wagstaff claim that what we call hypnosis is actually a form of learned social behaviour, a complex hybrid of social compliance, relaxation, and suggestibility that can account for many esoteric behavioural manifestations.^{[87][page needed]}

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Hypnosis and Mind-dissociation

This surprisingly simple theory was proposed by Y.D. Tsai in 1995^[86] as part of his psychosomatic theory of dreams. Inside each brain, there is a program " I " (the conscious self) which is distributed over the conscious brain and coordinates mental functions (cortices), such as thinking, imagining, sensing, moving, reasoning … etc. "I" also supervises memory. Many bizarre states of consciousness are actually the results of dissociation of certain mental functions from "I". When a person is hypnotized, it might be that his/her imagination is dissociated and sends the imagined content back to the sensory cortex, resulting in dreams or hallucinations; or that some senses are dissociated, resulting in hypnotic anesthesia; or that motor function is dissociated, resulting in immobility; or that reason is dissociated and he/she obeys the hypnotist's orders; or that thought is dissociated and not controlled by reason, hence strives to straighten out his/her body between two chairs. A command can also be acted out long after the hypnosis session, as follows: The subject obeys the voice of reason in normal state, but when hypnotized, reason is replaced by the hypnotist's command to make decisions or believes, and will be very uneasy if he/she does not do things as decided or his/her belief is contradicted. Hypnotherapy is also based on this principle.

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Neodissociation and Hypnosis

Ernest Hilgard, who developed the "neodissociation" theory of hypnotism, hypothesised that hypnosis causes the subjects to divide their consciousness voluntarily. One part responds to the hypnotist while the other retains awareness of reality. Hilgard made subjects take an ice water bath. They said nothing about the water being cold or feeling pain. Hilgard then asked the subjects to lift their index finger if they felt pain and 70% of the subjects lifted their index finger. This showed that even though the subjects were listening to the suggestive hypnotist they still sensed the water's temperature.^[85] Source Wikipedia

Dissociation and Hypnosis

Pierre Janet originally developed the idea of dissociation of consciousness from his work with hysterical patients. He believed that hypnosis was an example of dissociation, whereby areas of an individual's behavioural control separate from ordinary awareness. Hypnosis would remove some control from the conscious mind, and the individual would respond with autonomic, reflexive behaviour. Weitzenhoffer describes hypnosis via this theory as "dissociation of awareness from the majority of sensory and even strictly neural events taking place."^{[84][page needed]} Source Wikipedia

Hypnosis and Neuropsychology

Neurological imaging techniques provide no evidence of a neurological pattern that can be equated with a "hypnotic trance". Changes in brain activity have been found in some studies of highly responsive hypnotic subjects. These changes vary depending upon the type of suggestions being given.^[77][78] However, what these results indicate is unclear. They may indicate that suggestions genuinely produce changes in perception or experience that are not simply a result of imagination. However, in normal circumstances without hypnosis, the brain regions associated with motion detection are activated both when motion is seen and when motion is imagined, without any changes in the subjects' perception or experience.^[79] This may therefore indicate that highly suggestible hypnotic subjects are simply activating to a greater extent the areas of the brain used in imagination, without real perceptual changes. Another study has demonstrated that a color hallucination suggestion given to subjects in hypnosis activated color-processing regions of the occipital cortex.^[80] A 2004 review of research examining the EEG laboratory work in this area concludes:

Hypnosis is not a unitary state and therefore should show different patterns of EEG activity depending upon the task being experienced. In our evaluation of the literature, enhanced theta is observed during hypnosis when there is task performance or concentrative hypnosis, but not when the highly hypnotizable individuals are passively relaxed, somewhat sleepy and/or more diffuse in their attention.^[81]

The induction phase of hypnosis may also affect the activity in brain regions which control intention and process conflict. Anna Gosline claims:

"Gruzelier and his colleagues studied brain activity using an fMRI while subjects completed a standard cognitive exercise, called the Stroop task.

The team screened subjects before the study and chose 12 that were highly susceptible to hypnosis and 12 with low susceptibility. They all completed the task in the fMRI under normal conditions and then again under hypnosis.

Throughout the study, both groups were consistent in their task results, achieving similar scores regardless of their mental state. During their first task session, before hypnosis, there were no significant differences in brain activity between the groups.

But under hypnosis, Gruzelier found that the highly susceptible subjects showed significantly more brain activity in the anterior cingulate gyrus than the weakly susceptible subjects. This area of the brain has been shown to respond to errors and evaluate emotional outcomes.

The highly susceptible group also showed much greater brain activity on the left side of the prefrontal cortex than the weakly susceptible group. This is an area involved with higher level cognitive processing and behaviour."^[82][83]

Source Wikipedia

Hypnosis and Hyper-suggestibility

Braid can be taken to imply, in later writings, that hypnosis is largely a state of heightened suggestibility induced by expectation and focused attention. In particular, Hippolyte Bernheim became known as the leading proponent of the "suggestion theory" of hypnosis, at one point going so far as to declare that there is no hypnotic state, only heightened suggestibility. There is a general consensus that heightened suggestibility is an essential characteristic of hypnosis.

If a subject after submitting to the hypnotic procedure shows no genuine increase in susceptibility to any suggestions whatever, there seems no point in calling him hypnotised, regardless of how fully and readily he may respond to suggestions of lid-closure and other superficial sleeping behaviour.^[73]

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The state versus nonstate debate

The central theoretical disagreement is known as the "state versus nonstate" debate. When Braid introduced the concept of hypnotism he equivocated over the nature of the "state", sometimes describing it as a specific sleep-like neurological state comparable to animal hibernation or yogic meditation, while at other times he emphasised that hypnotism encompassed a number of different stages or states which were an extension of ordinary psychological and physiological processes. Overall, Braid appears to have moved from a more "special state" understanding of hypnotism toward a more complex "nonstate" orientation. State theorists interpret the effects of hypnotism as primarily due to a specific, abnormal and uniform psychological or physiological state of some description, often referred to as "hypnotic trance" or an "altered state of consciousness." Nonstate theorists rejected the idea of hypnotic trance and interpret the effects of hypnotism as due to a combination of multiple task-specific factors derived from normal cognitive, behavioural and social psychology, such as social role-perception and favorable motivation (Sarbin), active imagination and positive cognitive set (Barber), response expectancy (Kirsch), and the active use of task-specific subjective strategies (Spanos). The personality psychologist Robert White is often cited as providing one of the first nonstate definitions of hypnosis in a 1941 article:

Hypnotic behaviour is meaningful, goal-directed striving, its most general goal being to behave like a hypnotised person as this is continuously defined by the operator and understood by the client.^[72]

Put simply, it is often claimed that whereas the older "special state" interpretation emphasises the difference between hypnosis and ordinary psychological processes, the "nonstate" interpretation emphasises their similarity.

Comparisons between hypnotised and non-hypnotised subjects suggest that if a "hypnotic trance" does exist it only accounts for a small proportion of the effects attributed to hypnotic suggestion, most of which can be replicated without hypnotic induction.

Source Wikipsdia

Psychotherapy/Hypnotherapy

Hypnotherapy is the use of hypnosis in psychotherapy.^[59] It is used by licensed physicians, psychologists, and others. Physicians and psychiatrists may use hypnosis to treat depression, anxiety, eating disorders, sleep disorders, compulsive gaming, and posttraumatic stress.^[60][61] Certified hypnotherapists who are not physicians or psychologists often treat smoking and weight management. (Success rates vary: a meta-study researching hypnosis as a quit-smoking tool found it had a 20 to 30 percent success rate, similar to other quit-smoking methods^[62], while a 2007 study of patients hospitalised for cardiac and pulmonary ailments found that smokers who used hypnosis to quit smoking doubled their chances of success.^[63])

In a July 2001 article for Scientific American titled "The Truth and the Hype of Hypnosis", Michael Nash wrote:

...using hypnosis, scientists have temporarily created hallucinations, compulsions, certain types of memory loss, false memories, and delusions in the laboratory so that these phenomena can be studied in a controlled environment.^[45]

Controversy surrounds the use of hypnotherapy to retrieve memories, especially those from early childhood or (alleged) past-lives. The American Medical Association and the American Psychological Association caution against repressed memory therapy in cases of alleged childhood trauma, stating that "it is impossible, without corroborative evidence, to distinguish a true memory from a false one."^[64] Past life regression, meanwhile, is often viewed with skepticism.^[65]

Source Wikipedia

Military Applications

A recently declassified document obtained by The Black Vault Freedom of Information Act archive, shows that hypnosis was investigated for military applications.[55] However, the overall conclusion of the study was that there was no evidence that hypnosis could be used for military applications, and also that there was no clear evidence for whether 'hypnosis' actually exists as a definable phenomena outside of ordinary suggestion, high motivation and subject expectancy. According to the document,

The use of hypnosis in intelligence would present certain technical problems not encountered in the clinic or laboratory. To obtain compliance from a resistant source, for example, it would be necessary to hypnotise the source under essentially hostile circumstances. There is no good evidence, clinical or experimental, that this can be done.

Furthermore, the document states that:

It would be difficult to find an area of scientific interest more beset by divided professional opinion and contradictory experimental evidence…No one can say whether hypnosis is a qualitatively unique state with some physiological and conditioned response components or only a form of suggestion induced by high motivation and a positive relationship between hypnotist and subject…T.X. Barber has produced “hypnotic deafness” and “hypnotic blindness,” analgesia and other responses seen in hypnosis—all without hypnotizing anyone…Orne has shown that unhypnotized persons can be motivated to equal and surpass the supposed superhuman physical feats seen in hypnosis.

The study concludes:

It is probably significant that in the long history of hypnosis, where the potential application to intelligence has always been known, there are no reliable accounts of its effective use by an intelligence service.

Research into hypnosis in military applications is further verified by the MKULTRA experiments, also conducted by the CIA.[56] According to Congressional testimony[57], the CIA experimented with utilizing LSD and hypnosis for mind control. Many of these programs were done domestically and on participants who were not informed of the study's purposes or that they would be given drugs.[57]

The full paper explores the potentials of operational uses[58].

Source Wikipedia