It has been suggested that @entity935 in nucleus accumbens is involved in the process of enabling organisms to overcome work-related response costs. One way of controlling work costs with operant schedules is to use fixed ratio schedules with different ratio requirements. In the present study, the effects of nucleus accumbens @entity935 depletions were investigated using six schedules: fixed ratio 5, 20, 50, 100, 200, and 300. In the first three schedules the food reinforcement consisted of one 45 mg food pellet per ratio completed. In the remaining schedules the food reinforcement per ratio completed was increased to two pellets for fixed ratio 100, four pellets for fixed ratio 200, and six pellets for fixed ratio 300. All @entity35 were trained extensively prior to surgery, and @entity35 were able to maintain high levels of responding on all schedules up to the fixed ratio 300. After training, @entity35 were injected with either @entity9050 vehicle or @entity2955 into the nucleus accumbens. @entity35 were tested post-surgically on each of the schedules, with 3 days of testing per schedule. @entity35 with nucleus accumbens @entity935 depletions exhibited @entity146 that were highly dependent upon the ratio value. There were small and transient effects of @entity935 depletion on fixed ratio 5 lever pressing, but as the ratio value got larger the impairment became greater. On the fixed ratio 20 and 50 schedules, response rates were partially reduced in @entity935 -depleted @entity35 . Responding on the fixed ratio 200 and 300 schedules was severely impaired, and on the last day of fixed ratio 300 testing no @entity935 -depleted @entity35 obtained a single reinforcer. These data are consistent with previous reports that accumbens @entity935 depletions enhance 'ratio strain', making @entity35 more sensitive to high ratio values. The induction of ratio strain by @entity935 depletions does not appear to be related to a @entity1277 , and seems to be relatively independent of the baseline rate of responding and the overall density of food reinforcement across the session. We conclude that @entity935 in nucleus accumbens may be important for enabling @entity35 to overcome behavioral constraints such as work-related response costs, and may be critical for the behavioral organization and conditioning processes that enable animals to emit large numbers of responses in the absence of primary reinforcement.

Nucleus accumbens XXXX depletions make animals highly sensitive to high fixed ratio requirements but do not impair primary food reinforcement.

@entity146 :: ('MESH:D001523', 'Disease') :: ['behavioral deficits'] @entity935 :: ('MESH:D004298', 'Chemical') :: ['dopamine'] @entity1277 :: ('MESH:D001068', 'Disease') :: ['loss of appetite'] @entity35 :: ('10116', 'Species') :: ['Rats', 'rats'] @entity2955 :: ('MESH:D016627', 'Chemical') :: ['6-hydroxydopamine'] @entity9050 :: ('CHEBI:38290', 'Chemical') :: ['ascorbate']
@entity935 :: (MESH:D004298,Chemical) :: ['dopamine']
