From Occasional Choices to Inevitable Musts: A Computational Model of Nicotine Addiction

Figure 3

The pathways taking role in goal-directed behaviors. Actor and critic elements of reinforcement learning are shown with dotted lines. GPi/SNr: globus pallidus internus/substantia nigra pars compacta; I: external inputs; NAc: nucleus accumbens; n-s-c: opponent-processes stimulated by nicotine presence; PFC: prefrontal cortex; STN: subthalamic nucleus; Str: dorsal striatum (caudate and putamen); Thl: thalamus; VTA: ventral tegmental area.