The therapeutic treatment for ICD also stems from the fact that there is some evidence indicating the association of low cerebral serotonin function and excessive impulsiveness.

Preliminary research in the field, he says, suggests that a low serotonin function in the brain is linked to impulsive behavior.

Increasing the levels of serotonin in these pathways, by reducing serotonin reuptake and hence increasing serotonin function, is one of the therapeutic approaches to treating depression.

Fluoxetine has also been shown to affect swimming activity in shellfish; whether this is linked to a disturbance of serotonin function in the brain is still unknown.

It is entirely possible that a genetic variation in one or more genes that regulate serotonin function makes these people feel briefly more suicidal, rather than less, when exposed to the drugs.

It is well known that patients with the disorder have altered serotonin function compared with normal controls.

Most experts now believe that some disturbance in serotonin function in the brain is a central component, if not the primary culprit, in producing the pain and other symptoms of migraine.

The best current theory, said Dr. Joel R. Saper, director of the Michigan Headache and Neurological Institute in Ann Arbor, holds that "people are born with or acquire a disturbance in serotonin function."

He suggested that the implantation accidentally disrupted serotonin function in that region.

The serotonin transporter is also present in platelets; there, serotonin functions as a vasoconstrictive substance.