Dopamine activated reward circuits

These paired processes, known as initiation and adaptation, do not represent a new concept. We ve long known that taking a drug one time can have very different effects from taking it repeatedly. Perhaps the most familiar examples are the drugs of abuse. For example, the acute effect of cocaine is to produce an intense but brief euphoria. Cocaine produces this effect by enhancing neurotransmission in dopamine-activated reward circuits in the brain. These initiating effects happen very quickly in response to the action of cocaine in the synapse. 

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