Hypnosis and Conversion Hysteria: A Unifying Model

Abstract

There are many similarities between the symptoms of conversion hysteria and phenomena produced in hypnotic contexts. This paper reviews some of those similarities and considers more general features associated with both hypnotic phenomena and conversion hysteria symptoms such as lack of concern, perceived involuntariness, the display of ''implicit knowledge'' and their apparently compliant nature. Neurophysiological and brain-imaging studies of hypnotically produced effects and conversion symptoms are described, which implicate frontal cortical structures in moderating the respective changes elsewhere in the brain, particularly in cingulate cortex. A recurrent theme is the apparent paradox which exists between, on the one hand, the subjective reality and involuntariness of both hypnotic phenomena and the symptoms of conversion hysteria and, on the other, the fact that objectively they appear to be role-congruent enactments responsive to the manipulation of motivational factors, expectancy, and social influence. A model of consciousness and self-awareness is presented which attempts to resolve that paradox whilst describing similar mechanisms underlying hypnotic phenomena and conversion hysteria symptoms. The model develops the idea of a central executive structure, similar to the notion of a supervisory attentional system, acting outside self-awareness but at a late stage of information processing which can be directly influenced from both internal and external sources to produce the relevant phenomena. The paper ends by proposing that as conversion disorder, pain disorder, and the dissociation disorders appear to be linked by a common mechanism they should be classified together under the heading of auto-suggestive disorder.

Brain circuits implicated in psychogenic paralysis in conversion disorders and hypnosis

“…Similar increases in right IFG activity were found during left hypnotic paralysis using EEG recording [16] in another group of volunteers performing the same Go/NoGo paradigm in normal and hypnotic states. These findings accord with the view that hypnotic suggestions act through modulation of attentional systems that may allow selective filtering of sensory, motor, or even conceptual representations from conscious awareness [18,38,64,73].…”

“…In further support of a functional link between deficits produced by conversion and those induced by hypnosis, a few neuroimaging studies have reported that motor paralysis under hypnosis is associated with modulation of brain activity in ACC and ventral prefrontal regions [37,108]. Thus, some recent accounts have proposed that conversion symptoms might be produced by similar cognitive mechanisms as hypnotic suggestion, implicating an active inhibition of the access of sensory or motor representation to conscious awareness [10,64]. To clarify the putative links between these conditions, we also investigated the effect of a hypnotically suggested paralysis on brain activity during the same Go/NoGo motor task as described above (Fig.…”

“…For example, Pavlov (best known for his work on associative conditioning) proposed that emotional arousal arising in subcortical centers requires inhibitory control from cortical centers (especially in the frontal lobe), such that in some situations of strong arousal, [67]. An active inhibition of motor, sensory, or even cognitive processes preventing their integration into conscious awareness was also proposed by more recent authors [10,64,78]. Other accounts have built on the notion that conversion symptoms may more often affect the left than right hemibody, on the one hand, and evidence that the right hemisphere might be dominant for emotion processing, on the other hand, to suggest a role for impaired communication or integration between the two hemispheres [29,34,90].…”

Neurophysiology of hypnosis

“…Later study on a larger cohort of subjects confirmed the involvement of orbitofrontal cortex [67], as well as of ACC [11] in hypnotically suggested motor paralysis. Both of these brain areas were proposed to be involved in active inhibition of movement by disconnecting premotor/prefrontal areas from primary motor cortex [45]. A recent EEG study in healthy volunteers reported a distinctive EEG topographic activity pattern during hypnotic paralysis with a specific source in right inferior frontal cortex, as compared to the control condition, indicating the key role of this brain region in executive control mechanisms [8].…”

The creativity of dissociation

“…Similar behavior has been reported in recent studies of hypnotic blindness and visual conversion disorder (a.k.a. hysterical blindness), in which subjects seem to be influenced by objects or information of which they are apparently unaware (Bryant & McConkey, 1989a-c;Oakley, 1999).…”