Conversion disorder revisited.

Conversion disorder is defined as a psychiatric illness whose symptoms or deficits, affecting voluntary motor or sensory function, cannot be explained by a neurological or general medical condition. Proposing a strategy in the search for the neural mechanisms underlying conversion disorder is a difficult task, partly because key features of the illness inherently lie on a continuum with other psychiatric disorders, such as depression and posttraumatic stress disorder. Recent brain imaging studies have revealed neural circuits involved in complex mental processes potentially related to conversion disorder. These studies are reviewed, together with neuroimaging work in conversion disorder and brain imaging studies that have enriched the conceptualization of memory and emotion in posttraumatic stress disorder and major depression. Analysis of this information from a symptom-based rather than a disease-category perspective leads to a brain-based cognitive model of conversion disorder. This model suggests that disconnected crosstalk between the individual subdivisions of the anterior cingulate and the prefrontal cortex might provide a neuroscientific basis for the psychodynamic dissociation hypothesis, traditionally the bedrock explanation of the relationship between internal conflict and physical deficit. The model also suggests novel research approaches, as well as opportunities for potential therapeutic interventions.