Neural basis of reward and craving--a homeostatic point of view

Here, it is argued that the interoceptive system, which provides information about the subject's internal state and is integrated in the insular cortex, and not the subcortical ventral striatum, is the critical neural substrate for reward-related processes. Understanding the internal state of the individual, which is processed via this system, makes it possible to develop new interventions that are aimed at treating reward-dysfunction disorders, ie, substance and alcohol dependence. Although the ventral striatum is important for signaling the degree to which rewarding stimuli are predicted to occur, this system alone cannot account for the complex affective, cognitive, and behavioral phenomena that occur when individuals come into contact with potentially rewarding stimuli. On the other hand, the interoceptive system is able to make connections between all cortical, subcortical, and limbic systems to orchestrate a complex set of responses. Craving and urges are among the most notable responses, and may have important functions to preserve homeostasis.