title: Effort-related functions of nucleus accumbens dopamine and associated forebrain circuits.
abstract: BACKGROUND
  Over the last several years, it has become apparent that there are critical problems with the hypothesis that brain dopamine (DA) systems, particularly in the nucleus accumbens, directly mediate the rewarding or primary motivational characteristics of natural stimuli such as food. Hypotheses related to DA function are undergoing a substantial restructuring, such that the classic emphasis on hedonia and primary reward is giving way to diverse lines of research that focus on aspects of instrumental learning, reward prediction, incentive motivation, and behavioral activation.
  
  
  OBJECTIVE
  The present review discusses dopaminergic involvement in behavioral activation and, in particular, emphasizes the effort-related functions of nucleus accumbens DA and associated forebrain circuitry.
  
  
  RESULTS
  The effects of accumbens DA depletions on food-seeking behavior are critically dependent upon the work requirements of the task. Lever pressing schedules that have minimal work requirements are largely unaffected by accumbens DA depletions, whereas reinforcement schedules that have high work (e.g., ratio) requirements are substantially impaired by accumbens DA depletions. Moreover, interference with accumbens DA transmission exerts a powerful influence over effort-related decision making. Rats with accumbens DA depletions reallocate their instrumental behavior away from food-reinforced tasks that have high response requirements, and instead, these rats select a less-effortful type of food-seeking behavior.
  
  
  CONCLUSIONS
  Along with prefrontal cortex and the amygdala, nucleus accumbens is a component of the brain circuitry regulating effort-related functions. Studies of the brain systems regulating effort-based processes may have implications for understanding drug abuse, as well as energy-related disorders such as psychomotor slowing, fatigue, or anergia in depression.
authors.affiliation: Division of Behavioral Neuroscience, Department of Psychology, University of Connecticut, Storrs, CT, 06269-1020, USA. john.salamone@uconn.edu
authors.forename: J D
authors.initials: JD
authors.lastname: Salamone
authors.forename: M
authors.initials: M
authors.lastname: Correa
authors.forename: A
authors.initials: A
authors.lastname: Farrar
authors.forename: S M
authors.initials: SM
authors.lastname: Mingote
mesh_terms: D000818:Animals; D002755:Choice Behavior; D003216:Conditioning, Operant; D003863:Depression / Q000378:metabolism / Q000523:psychology; D004298:Dopamine / Q000378:metabolism*; D005221:Fatigue / Q000378:metabolism / Q000523:psychology; D005247:Feeding Behavior; D006801:Humans; D009042:Motivation; D009043:Motor Activity; D009434:Neural Pathways / Q000378:metabolism; D018377:Neurotransmitter Agents / Q000378:metabolism*; D009714:Nucleus Accumbens / Q000378:metabolism*; D005082:Physical Exertion; D016548:Prosencephalon / Q000378:metabolism*; D011597:Psychomotor Performance; D051381:Rats; D012054:Reinforcement, Psychology; D012201:Reward; D019966:Substance-Related Disorders / Q000378:metabolism / Q000523:psychology
chemical_list: D018377:Neurotransmitter Agents; D004298:Dopamine