From actions to habits: neuroadaptations leading to dependence

Abstract

Recent work on the role of overlapping cerebral networks in action selection and habit formation has important implications for alcohol addiction research. As reviewed below, (1) these networks, which all involve a group of deep-brain structures called the basal ganglia, are associated with distinct behavioral control processes, such as reward-guided Pavlovian conditional responses, goal-directed instrumental actions, and stimulus-driven habits; (2) different stages of action learning are associated with different networks, which have the ability to change (i.e., plasticity); and (3) exposure to alcohol and other addictive drugs can have profound effects on these networks by influencing the mechanisms underlying neural plasticity.

Figure 1

Schematic illustration showing cortico-basal ganglia networks in relation to serial adaptation. A shift from the associative to the sensorimotor cortico-basal ganglia network is observed during habit formation. SOURCE: Yin and Knowlton 2006.

Figure 2

The cortico-basal ganglia networks. An illustration of the major corticostriatal projections and dopaminergic projections in terms of the four major cortico-basal ganglia networks and their corresponding behavioral functions. Emphasis is placed on the spiraling midbrain–striatum–midbrain projections, which allows information to be propagated forward in a hierarchical manner. Note that this is only one possible neural implementation; interactions via different thalamo–cortico–thalamic projections also are possible (Haber 2003). SOURCE: Yin and Balleine 2008.