Differential effects on effort discounting induced by inactivations of the nucleus accumbens core or shell

Behav Neurosci. 2010 Apr;124(2):179-91. doi: 10.1037/a0018932.


The authors investigated the contribution of the nucleus accumbens (NAc) core and shell to effort-based decision making using a discounting procedure. Selection of 1 lever delivered a smaller, 2-pellet reward immediately, whereas the other lever delivered a 4-pellet reward after a fixed ratio of presses (2, 5, 10, or 20) that increased over 4 blocks of 10 discrete choice trials. Subsequent testing employed an equivalent delays procedure, whereby the relative delay to reward delivery after selection of either option was equalized. In well-trained rats, inactivation of the core, but not the shell, via infusion of GABA A/B agonists muscimol/baclofen reduced preference for the high-effort option under standard conditions and also when rats were tested using an equivalent delays procedure. However, inactivation of the core did not alter preference for 4-pellet versus 2-pellet rewards when the relative costs of each option were the same (1 press). Thus, the NAc core, but not the shell, appears to be part of a neural circuit that biases choice toward larger rewards associated with a greater effort cost. Furthermore, the contributions by the NAc core to this form of decision making can be dissociated from its role in delay discounting.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Baclofen / administration & dosage
  • Baclofen / pharmacology*
  • Conditioning, Operant / drug effects
  • Decision Making* / drug effects
  • Drug Combinations
  • GABA Agonists / administration & dosage
  • GABA Agonists / pharmacology*
  • Male
  • Microinjections
  • Muscimol / administration & dosage
  • Muscimol / pharmacology*
  • Nucleus Accumbens / anatomy & histology
  • Nucleus Accumbens / drug effects
  • Nucleus Accumbens / physiology*
  • Physical Exertion* / drug effects
  • Rats
  • Rats, Long-Evans
  • Reinforcement Schedule
  • Reward


  • Drug Combinations
  • GABA Agonists
  • Muscimol
  • Baclofen