Wednesday, September 27, 2006

Brain correlates of hysteria.

The Tuesday Science section of the New York Times (Sept 26) has an interesting article on hysteria, a fashionable syndrome in the Victorian era which has "disappeared" during this century. Actually the term "conversion disorder" is now used to describe an ill-defined syndrome with no obvious physical cause, usually involving paralysis of a portion of the body or seizures. Sigmund Freud suggested from his case studies that hysteria is something in the psyche or the mind being expressed physically in the body.

The 19th-century French neurologist Jean-Martin Charcot, shown lecturing on hysteria

Peter W. Halligan at Cardiff, co-founder of the journal Cognitive Neuropsychiatry and his colleagues "analyzed the brain function of a woman who was paralyzed on the left side of her body (Cognition, 64, B1-B8, 1997). First they conducted numerous tests to ensure that she had no identifiable organic lesion...When the woman tried to move her “paralyzed leg,” her primary motor cortex was not activated as it should have been; instead her right orbitofrontal and right anterior cingulate cortex, parts of the brain that have been associated with action and emotion, were activated. They reasoned that these emotional areas of the brain were responsible for suppressing movement in her paralyzed leg."

Fig. 1. Relative rCBF (blood flow measured by magnetic resonance imaging) increases associated with movement of the right (good) leg. The figure reveals relative rCBF increases when the normal (right) leg is moved that do not occur when attempts to move the bad (left) leg are made. There is left hemisphere neuronal activation centered on the primary sensory and motor cortex. Additional activation is seen in the left inferior parietal cortex and the right inferior temporal cortex.
Fig. 2. Relative rCBF increases associated with attempted movement of the left (bad) leg. This reveals relative rCBF increases during attempts to move the bad (left) leg that did not occur when the good (right) leg was moved. There is activation in the right anterior cingulate and the right orbito-frontal cortex.

“The patient willed her leg to move,” Dr. Halligan said. “But that act of willing triggered this primitive orbitofrontal area and activated the anterior cingulate to countermand the instruction to move the leg. She was willing it, but the leg would not move.”

"Subsequent studies have bolstered the notion that parts of the brain involved in emotion may be activated inappropriately in patients with conversion disorder and may inhibit the normal functioning of brain circuitry responsible for movement, sensation and sight......Both its persistence and its pervasiveness suggest that hysteria may be derived from an instinctual response to threat. Total shutdown, in the form of paralysis, for example, is not an entirely untoward or unheard of response to an untenable situation. (Think of deer in the headlights.)"

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