Tourette Syndrome is a complex neurological disorder characterized by chronic involuntary motor tics and vocalizations. Unfortunately, the disruption in brain function that is responsible for Tourette Syndrome symptoms continues to elude researchers. However, there is evidence that the neurotransmitter dopamine (which functions to relay messages between cells in the brain) may be involved in the underlying abnormality in brain function associated with the disorder. This neurotransmitter is contained in groups of neurons that send information to discrete regions of the brain including the cortex as well as underlying subcortical areas. These cortical and subcortical areas interact with one another in a very complex, and as yet not entirely understood, manner. We propose that a decrease in the function of the dopamine containing neurons in the cortex leads to an increase in the activity of the subcortical dopamine neurons and this, in turn, gives rise to the symptoms associated with TS. Thus, drugs used in treating TS may reduce the symptoms of the condition by counteracting the heightened activity of the subcortical dopamine neurons. Our research is aimed at understanding the interaction between dopamine neurons in the cortex and those in subcortical areas. Specifically, we will examine how increases or decreases in the amount of dopamine in the cortex affect the amount of dopamine available in subcortical sites for relaying messages between neurons. This work will be accomplished using a relatively new technique called in vivo microdialysis which allows researchers to monitor the amount of dopamine in discrete regions of the brain in behaving animals. With the information gained from these experiments, we will begin to understand how a disruption in the interaction between the dopamine-rich brain regions may result in the involuntary motor tics and sounds associated with TS. This information will be critical in developing more effective treatments for this disorder. Janet Finlay, PhD. University of Pittsburgh, Pittsburgh, PA Award $25,000 Tourette Association of America Inc. – Research Grant Award 1992