A Neuro-anatomical Model

Altered stress systems progressively impact on dopaminergic networks to cause the neuro-anatomical “brain signatures” of addiction (17).

Reward – stress activates the DS (87) and substance-related cues elicit dopamine release in DS (88) in line with addiction severity, suggesting the strengthening of substance-related habits as addiction progresses. This reflects a shift in reward processing from the VS to DS.

Stress and dopamine are both involved in habit learning (89, 90).  Lesions to the DS dopamine prevent habit formation (91).

Memory – elevated stress triggers excessive engagement of habitual processes, by changing the role of memory systems in behaviour. For example, acute stress before a learning task results in a predominantly habitual rather than a cognition-based role of memory in task completion (35).

Chronic stress causes opposing structural changes in neural networks subserving goal-directed and habitual action, with PFC atrophy and DS hypertrophy (35). Bias toward habitual responding…