The neural basis of drug craving: An incentive-sensitization theory of addiction

The hypothesis that dopamine is important for reward has been proposed in a number of forms, each of which has been challenged. Normally, rewarding stimuli such as food, water, lateral hypothalamic brain stimulation and several drugs of abuse become ineffective as rewards in animals given performance-sparing doses of dopamine antagonists. Dopamine release in the nucleus accumbens has been linked to the efficacy of these unconditioned rewards, but dopamine release in a broader range of structures is implicated in the 'stamping-in' of memory that attaches motivational importance to otherwise neutral environmental stimuli.

Dopamine, learning and motivation

Enduring changes in brain and behavior produced by chronic amphetamine administration: A review and evaluation of animal models of amphetamine psychosis

Dopamine transmission in the initiation and expression of drug- and stress-induced sensitization of motor activity

Extraversion has two central characteristics: (1) interpersonal engagement, which consists of affiliation (enjoying and valuing close interpersonal bonds, being warm and affectionate) and agency (being socially dominant, enjoying leadership roles, being assertive, being exhibitionistic, and having a sense of potency in accomplishing goals) and (2) impulsivity, which emerges from the interaction of extraversion and a second, independent trait (constraint). Agency is a more general motivational disposition that includes dominance, ambition, mastery, efficacy, and achievement. Positive affect (a combination of positive feelings and motivation) is closely associated with extraversion. Extraversion is accordingly based on positive incentive motivation. Parallels between extraversion (particularly its agency component) and a mammalian behavioral approach system based on positive incentive motivation implicate a neuroanatomical network and modulatory neurotransmitters in the processing of incentive motivation. A corticolimbic-striatal-thalamic network (1) integrates the salient incentive context in the medial orbital cortex, amygdala, and hippocampus; (2) encodes the intensity of incentive stimuli in a motive circuit composed of the nucleus accumbens, ventral pallidum, and ventral tegmental area dopamine projection system; and (3) creates an incentive motivational state that can be transmitted to the motor system. Individual differences in the functioning of this network arise from functional variation in the ventral tegmental area dopamine projections, which are directly involved in coding the intensity of incentive motivation. The animal evidence suggests that there are three neurodevelopmental sources of individual differences in dopamine: genetic, "experience-expectant," and "experience-dependent." Individual differences in dopamine promote variation in the heterosynaptic plasticity that enhances the connection between incentive context and incentive motivation and behavior. Our psychobiological threshold model explains the effects of individual differences in dopamine transmission on behavior, and their relation to personality traits is discussed.

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Neurobiology of the structure of personality: Dopamine, facilitation of incentive motivation, and extraversion.

In view of similarities between the behavioral, biochemical, and electrophysiological effects of amphetamine and stress, we tested the hypothesis that presentation of a stressor, mild tail pressure, can sensitize an animal to the later effects of amphetamine, and vice versa. Our findings supported this hypothesis and suggest that amphetamine and at least some stressors may be interchangeable in their ability to induce a sensitization. The data raise the possibility that stress might be a common variable contributing to both amphetamine psychosis and some forms of schizophrenia.

https://science.sciencemag.org/content/sci/207/4428/329.full.pdf

Interchangeability of Stress and Amphetamine in Sensitization

The proposed hypothesis is directed toward explaining a number of disparate findings in terms of a stress-related interaction between the NE- and DA-containing systems in the brain. The deleterious behavioral effects of decreased DA activity, for example, may be counterbalanced by a similar decrease occurring in NE activity, such compensation being most likely to occur under conditions of stress. This hypothesis may have application to the understanding of neurological and mental disorders such as Parkinson's disease and schizophrenia.

https://science.sciencemag.org/content/sci/195/4279/646.full.pdf

Norepinephrine-dopamine interactions and behavior

Criteria for rationally evaluating animal models of posttraumatic stress disorder.

Tail pinch-induced eating, gnawing and licking behavior in rats: dependence on the nigrostriatal dopamine system.

Mild tail pinch administered to rats several times daily in the presence of sweetened mild induced immediate hyperphagia and led to considerable gain in body weight. Parallels are drawn with stress-induced hyperhagia and altered affective states in obese humans.

https://science.sciencemag.org/content/sci/191/4224/310.full.pdf

Seymour M. Antelman

Papers

Interchangeability of Stress and Amphetamine in Sensitization

Norepinephrine-dopamine interactions and behavior

Criteria for rationally evaluating animal models of posttraumatic stress disorder.

Tail pinch-induced eating, gnawing and licking behavior in rats: dependence on the nigrostriatal dopamine system.

Stress-induced hyperphagia and obesity in rats: a possible model for understanding human obesity