Brain circuits implicated in psychogenic paralysis in conversion disorders and hypnosis

Area of Science:

• Neuroscience
• Psychiatry
• Neurology

Background:

• Conversion disorders present neurological symptoms without identifiable organic cause, often linked to emotional stress.
• The precise neural mechanisms underlying conversion disorders remain poorly understood.
• Recent advances in functional neuroimaging have provided new insights into these conditions.

Purpose of the Study:

• To review recent functional neuroimaging findings in conversion disorders.
• To explore neurobiological hypotheses for conversion symptoms, particularly motor deficits.
• To compare brain activation patterns in conversion disorders with those in hypnosis.

Main Methods:

• Review of functional neuroimaging studies in patients with conversion disorders.
• Comparison of brain activation patterns between conversion disorders and hypnosis.
• Analysis of studies focusing on motor and non-motor (somatosensory, visual) domains.

Main Results:

• Hyperactivation in ventromedial prefrontal cortex (VMPFC), precuneus, and limbic structures (amygdala) is observed in conversion disorders.
• Impaired recruitment of primary motor/sensory pathways at cortical or subcortical levels accompanies VMPFC/precuneus hyperactivation.
• Hypnosis shows predominant precuneus activation and attentional control system engagement, but lacks VMPFC activation.

Conclusions:

• Conversion deficits may stem from altered sensorimotor functions and self-awareness.
• Affective and sensory representations in VMPFC and precuneus may influence behavior in response to emotional states.
• These brain regions are crucial for self-representation, integrating memory, affect, and sensory information.