Dissociation in hysteria and hypnosis: evidence from cognitive neuroscience

Abstract

Jean-Martin Charcot proposed the radical hypothesis that similar brain processes were responsible for the unexplained neurological symptoms of 'hysteria', now typically diagnosed as 'conversion disorder' or 'dissociative (conversion) disorder', and the temporary effects of hypnosis. While this idea has been largely ignored, recent cognitive neuroscience studies indicate that (i) hypnotisability traits are associated with a tendency to develop dissociative symptoms in the sensorimotor domain; (ii) dissociative symptoms can be modelled with suggestions in highly hypnotisable subjects; and (iii) hypnotic phenomena engage brain processes similar to those seen in patients with symptoms of hysteria. One clear theme to emerge from the findings is that 'symptom' presentation, whether clinically diagnosed or simulated using hypnosis, is associated with increases in prefrontal cortex activity suggesting that intervention by the executive system in both automatic and voluntary cognitive processing is common to both hysteria and hypnosis. Nevertheless, while the recent literature provides some compelling leads into the understanding of these phenomena, the field still lacks well controlled systematically designed studies to give a clear insight into the neurocognitive processes underlying dissociation in both hysteria and hypnosis. The aim of this review is to provide an agenda for future research.

Brain circuits implicated in psychogenic paralysis in conversion disorders and hypnosis

“…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

“…Evidence from neuroimaging studies indicates that primary sensory as well as motor cortices processing remain functionally intact in patients with hysterical sensorymotor disorders, suggesting that dissociation may result from disturbance of executive regions modulating attention, response selection and inhibition such as for example the prefrontal cortex [5]. Hypnotic procedures can induce symptoms similar to those seen in hysteria and may permit better understanding of neural processes of conversion disorders (see Table 4).…”

“…Hypnotizability is measured as the number of conversion and dissociation symptoms that the person is able to display'' [34]. Subjects under hypnosis are thus suggested to consciously demonstrate motor or sensory phenomena, while patients with hysteria have unconscious fixed ideas based on unconscious suggestions or autosuggestions that remain isolated from the rest of their mind and are expressed through motor or sensory disturbances [5]. According to Janet, dissociation can be seen as a ''narrowing of the field of consciousness'' resulting in the compartmentalization of normally integrated mental functions, while Freud proposed that dissociative processes result from a psychological defense mechanism that converts emotional distress into physical symptoms [5].…”

Treatment of Functional (Psychogenic) Movement Disorders

“…Similar alterations of brain function have been suggested to occur in FMD and hypnotic states [38][39][40]. Moene et al [41] conducted a RCT in a group of 45 patients with conversion disorder (motor type) or somatization disorder (with motor conversion symptoms) evaluating the efficacy of adding hypnosis to a standard inpatient treatment.…”