A model of behavioral treatments for self-mutilation behavior in Lesch-Nyhan syndrome.

Lesch-Nyhan syndrome is a rare genetic disorder, caused by a mutation in the gene coding for the enzyme hypoxanthine-guanine phosphoribosyltransferase, which is characterized by hyperuricemia and its associated symptoms along with motor disorders and compulsive self-mutilation. We show that the temporal difference learning algorithm that has been often used to interpret dopaminergic activity in the basal ganglia offers an explanation for the self-mutilation behaviors. We propose that a dysfunctional dopamine signal inadvertently reinforces early, accidental injurious behavior that is initially caused by clumsiness owing to the motor disorders. Simulations of this model reproduce findings on the results of behavioral treatments for dealing with self-mutilation behaviors.