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Rewards

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short term rewards & long term rewards.

Reward cycle2.gif

Dopamine

Dopamine is involved in reward. Dopamine appear to play a central role in cost-benefit analysis[1]. It seems to be part of the reward sytem There appear to be multiple dopamine-sensitive decision regions.

Dopamine depletion in ventral striatum reduces propensity for physical effort [2] D1 (dopamine 1) receptor blockade in ACC reduces preference for expending effort for rats[3].It is non-discriminative between reward types, dopaminergic firing in VTA does appear to reflect subjective (action) value with integrated responses to both delay and reward amount[4]. Dopaminergic neurons send diffuse projections to striatum (nigrostriatal pathway) and prefrontal cortex (mesocortical pathway) and thereby transmit a pleasure values or teaching signal to a variety of brain regions, for learning, stimulus evaluation, and directed action. [5].

Nucleus Accumbens

Nucleus accumbens play part in reward sytem[6]. Natural reward behaviors and drug reward converge on a common neural pathway, the mesolimbic dopamine (DA) system, in which the nucleus accumbens (NAc) plays a central role[7]

Hormones effects

Food

There are substantial hormonal influences on behavior. For example, circulating hormones such as leptin and ghrelin act as satiety and hunger signals, reporting the status of body energy reserves (e.g. adipose tissue), energy requirements, and acute nutrient intake to hypothalamic and midbrain targets in the central nervous system that regulate feeding behavior[8]. They also act on brain regions (in particular dopaminoceptive areas) implicated in human decision-making[9][10].

Metabolic state itself may thus directly affect the neural expression of preference, exemplified by findings that physiological state influence preferences for economic risk in humans[11]

Genetic polymorphisms affecting DRD2 receptor expression alter neuronal responses to food reward[12]

DRD4 polymorphisms modulate the incentive value of alcohol in alcoholics[13]

Impulsivity

Serotonin deplition[14] and NMDA antagonism [15]promotes impulsivity

References

  1. ↑ Phillips PEM, Walton ME, Jhou TC. Calculating utility: Preclinical evidence for cost– benefit analysis by mesolimbic dopamine. Psychopharmacology. 2007;191: 483– 495.
  2. ↑ Salamone JD, Correa M, Farrar A, Mingote SM. Effort-related functions of nucleus accumbens dopamine and associated forebrain circuits. Psychopharmacology. 2007;191: 461– 482.
  3. ↑ Schweimer J, Hauber W. Dopamine D1 receptors in the anterior cingulate cortex regulate effort-based decision-making. Learning & Memory. 2006;13: 777–782
  4. ↑ Roesch MR, Calu DJ, Schoenbaum G. Dopamine neurons encode the better option in rats deciding between differently delayed or sized rewards. Nature Neuroscience. 2007;10: 1615– 1624.
  5. ↑ Volkow ND, Wang GJ, Telang F, et al. Dopamine increases in striatum do not elicit craving in cocaine abusers unless they are coupled with cocaine cues. NeuroImage. 2008;39: 1266– 1273)
  6. ↑ Kyle K. Pitchers1,Vincent Vialou,Eric J. Nestler,Steven R. Laviolette, Michael N. Lehman and Lique M. Coolen, 2013, Natural and Drug Rewards Act on Common Neural Plasticity Mechanisms with ΔFosB as a Key Mediator
  7. ↑ Kelley AE (2004) Memory and addiction: shared neural circuitry and molecular mechanisms. Neuron 44:161–179.
  8. ↑ Korotkova, Sergeeva, Eriksson et al., 2003
  9. ↑ Hommel, Trinko, Sears et al., 2006
  10. ↑ Krügel, Schraft, Kittner et al., 2003
  11. ↑ Symmonds M, Emmanuel J, Drew M, Batterham R, Dolan R. Metabolic state alters economic decision-making under risk in humans. PLoS ONE. 2010b; 5: e11090.
  12. ↑ Felsted JA, Ren X, Chouinard-Decorte F, Small DM. Genetically determined differences in brain response to a primary food reward. Journal of Neuroscience. 2010;30: 2428– 2432.
  13. ↑ MacKillop J, Menges DP, McGeary JE, Lisman SA. Effects of craving and DRD4 VNTR genotype on the relative value of alcohol: An initial human laboratory study. Behavioral and Brain Functions. 2007;3: 11
  14. ↑ Denk F, Walton M, Jennings K, Sharp T, Rushworth M, Bannerman D. Differential involvement of serotonin and dopamine systems in cost-benefit decisions about delay or effort. Psychopharmacology. 2005;179: 587– 596.
  15. ↑ Floresco SB, Tse MTL, Ghods-Sharifi S. Dopaminergic and glutamatergic regulation of effort-and delay-based decision-making.
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