All these functions of the C-BG-C circuit are impacted by drugs of abuse and help to shape responses to these drugs. The majority of abused substances have “rewarding” properties, and some of these drugs, including ethanol, can be perceived as rewarding or aversive depending on factors such as context and dose. Drugs of abuse also produce reinforcement learning, fostering instrumentally-conditioned habitual actions including those related to the drugs themselves. Cognitive processes are also impaired by drugs of abuse, with ethanol having well known actions on judgement and memory (Sullivan, Harris et al. 2010) . Drugs of abuse have demonstrable effects on action production, timing and duration that involve the C-BG-C circuits. In subsequent sections of this review we will discuss the neural substrates of these ethanol effects, both acute and chronic, and how they set the stage for aberrant C-BG-C circuit function that drives ethanol seeking/taking and alcohol use disorders.
