A dopamine imbalance triggers Parkinson's disease and drug addition -- two opposite diseases. How it worked to do this in the brain had been a mystery. New research shows dopamine strengthens and weakens the two primary circuits in the brain that control our behavior. This provides new insight into why a flood of dopamine can lead to compulsive, addictive behavior and too little dopmaine can leave Parkinson's patients frozen and unable to move.
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