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

New information regarding neuronal circuits that control food intake and their hormonal regulation has extended our understanding of energy homeostasis, the process whereby energy intake is matched to energy expenditure over time. The profound obesity that results in rodents (and in the rare human case as well) from mutation of key signalling molecules involved in this regulatory system highlights its importance to human health. Although each new signalling pathway discovered in the hypothalamus is a potential target for drug development in the treatment of obesity, the growing number of such signalling molecules indicates that food intake is controlled by a highly complex process. To better understand how energy homeostasis can be achieved, we describe a model that delineates the roles of individual hormonal and neuropeptide signalling pathways in the control of food intake and the means by which obesity can arise from inherited or acquired defects in their function.

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Central nervous system control of food intake

Cannon, Barbara, and Jan Nedergaard. Brown Adipose Tissue: Function and Physiological Significance. Physiol Rev 84: 277–359, 2004; 10.1152/physrev.00015.2003.—The function of brown adipose tissue i...

Brown Adipose Tissue: Function and Physiological Significance

https://lsa.umich.edu/psych/research&labs/berridge/publications/Berridge&RobinsonBrResRev1998.pdf

What is the role of dopamine in reward: hedonic impact, reward learning, or incentive salience?

We hypothesize that there is a general bias, based on both innate predispositions and experience, in animals and humans, to give greater weight to negative entities (e.g., events, objects, personal traits). This is manifested in 4 ways: (a) negative potency (negative entities are stronger than the equivalent positive entities), (b) steeper nega tive gradients (the negativity of negative events grows more rapidly with approach to them in space or time than does the positivity of positive events, (c) negativity domi nance (combinations of negative and positive entities yield evaluations that are more negative than the algebraic sum of individual subjective valences would predict), and (d) negative differentiation (negative entities are more varied, yield more complex conceptual representations, and engage a wider response repertoire). We review evi dence for this taxonomy, with emphasis on negativity dominance, including literary, historical, religious, and cultural sources, as well as the psychological literatures on learning, attention, impression formation, contagion, moral judgment, development, and memory. We then consider a variety of theoretical accounts for negativity bias. We suggest that 1 feature of negative events that make them dominant is that negative entities are more contagious than positive entities.

/pdf/negativity-bias-negativity-dominance-and-contagion-2njh4nr8pi.pdf

Negativity Bias, Negativity Dominance, and Contagion

Glucagon-Like Peptide-1 Receptor Signaling in the Lateral Parabrachial Nucleus Contributes to the Control of Food Intake and Motivation to Feed

Bilateral electrophysiologically guided lesions were placed in the nucleus of the solitary tract (NST), the parabrachial nucleus (PBN), and the ventral posteromedial thalamic nucleus (VPMpc) of rats, and 15-min intake and taste reactivity (TR) responses elicited by 3 concentrations each of sucrose, NaCl, HCl, and quinine (Q) HCl were subsequently measured. Compared with controls, NST lesions had no significant effects on intake, and rats with PBN lesions consumed significantly more QHCl, sucrose, NaCl, and HCl. Thalamic lesions decreased sucrose intake. Analysis of TR responses showed that the QHCl threshold for aversive responses increased after VPMpc, PBN, and NST lesions. Rats with NST or PBN lesions were unresponsive to increasing sucrose concentration. TR responses elicited by NaCl and HCl were similar across the groups.

Central gustatory lesions: I. Preference and taste reactivity tests.

The effects of glossopharyngeal and chorda tympani nerve cuts on the ingestion and rejection of sapid stimuli: an electromyographic analysis in the rat.

Seven sugars, two sugar alcohols, and a nonnutritive sweetener were orally administered to naive rats with and without gastric drainage fistulas. Although all taste solutions were ingested, only glucose evoked a statistically significant elevation of insulin levels. This rise was independent of a rise in glycemia. The preeminence of oral glucose as an elicitor of preabsorptive insulin secretion is especially striking, considering that glucose is neither the most intense (as measured electrophysiologically) nor the most palatable (as measured by behavioral preference tests) taste stimulus tested. These results suggest the existence of a gustatory and/or gastrointestinal chemoreceptor that is most responsive to glucose.

Harvey J. Grill

Papers

Glucagon-Like Peptide-1 Receptor Signaling in the Lateral Parabrachial Nucleus Contributes to the Control of Food Intake and Motivation to Feed

Central gustatory lesions: I. Preference and taste reactivity tests.

The effects of glossopharyngeal and chorda tympani nerve cuts on the ingestion and rejection of sapid stimuli: an electromyographic analysis in the rat.

Oral glucose is the prime elicitor of preabsorptive insulin secretion.

Isohedonic tastes support a two-dimensional hypothesis of palatability