One of the characteristics of Tourette’s syndrome is that tics and other symptoms frequently appear in stressful situations when people are under emotional pressure. Thus, there appears to be some extent of dysfunction in the interaction between neural systems involved in emotional and motor responses. A potential site for such interactions is the nucleus accumbens, that is the limbic aspect of the striatal complex. The accumbens is connected with both motor-related and emotion-related neural circuits. We have recently reported that neurons in this nucleus can be activated by their cortical inputs only when they are gated by concurrent activation of inputs originated from the hippo-campus, which may be providing context-sensitive activation of the cortical-accumbens-cortical circuitry. The aims of this project are to test the degree of convergence of cortical and limbic inputs to the nucleus accumbens, and to assess the role of the neurotransmitter dopamine on these interactions. Dopamine blockers have been successful in treating Tourette’s symptoms, and a potential site for this effect may be their ability to modulate the integration of cortical and limbic inputs to the nucleus accumbens. We will study the effects of dopamine-related drugs and of activation of dopamine-containing brain systems on these interactions on nucleus accumbens neurons recorded intracellularly in vivo. These experiments may provide a model of the interactions between motor and limbic systems that take place in the ventral striatum, and information about that model’s possible relevance to the dependence of Tourette’s motor symptoms on environmental factors. Patricio O’Donnell, M.D., Ph.D. University of Pittsburgh, Pittsburgh, PA Award $24,425 Tourette Association of America Inc. – Research Grant Award 1995