The limbic system supports a variety of functions particularly emotion, fear or elation, needs and urgency, long term memory, and olfaction. Addiction induced negative affect, mood and fear are associated with amygdale and hippocampus human temporal lobe structures (Fig. 1). Limbic urgency helps drive impulsive behaviors (Crews and Boettiger 2009). Across drugs of addition, the progression from abuse to addiction involves increasing drug wanting, negative emotional urgency and decreasing behavioral control (Jentsch and Taylor 1999; Robinson and Berridge 2003). Thus, the neurobiology of addiction involves dysfunctional frontal cortex behavioral control as well as exaggerated limbic urgency (Fig. 1). This review will present the hypothesis that innate immune gene induction in frontal cortex blunts behavioral control, whereas it amplifies limbic negative affect and bad feelings.
