Source Paper
The Role of the Nucleus Accumbens in Instrumental Conditioning: Evidence of a Functional Dissociation between Accumbens Core and Shell
Laura H. Corbit, Janice L. Muir, Bernard W. Balleine
Journal of Neuroscience • 2001
Contingency Degradation Test
Objective: Assessment of the ability to encode and respond to instrumental action-outcome contingencies, specifically testing whether lesions of nucleus accumbens core or shell impair contingency degradation learning
This is a Contingency Degradation Test protocol using rat as the model organism. The procedure involves 7 procedural steps, 2 materials. Extracted from a 2001 paper published in Journal of Neuroscience.
Model and subjects
rat • not specified • unknown • not specified • not specified
Study window
Estimated timing pending
Core workflow
Surgical lesion placement • Food deprivation • Instrumental training
Primary readouts
- Lever press response rates during instrumental training
- Rate of acquisition of lever-press response
- Selective reduction in performance on lever delivering devalued outcome
- Responding on both levers after devaluation
Key equipment and reagents
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Protocol Steps
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Surgical lesion placement
Bilateral excitotoxic lesions of nucleus accumbens core or shell subregions were created in experimental groups
Note: Three groups: core-lesioned, shell-lesioned, and sham-lesioned controls
View evidence from paper
“bilateral excitotoxic lesions of the nucleus accumbens core or shell subregions”
Food deprivation
Rats were food deprived prior to training
Note: Deprivation maintained throughout experiment to motivate lever pressing
View evidence from paper
“Rats were food deprived and trained to press two levers”
Instrumental training
Rats trained to press two levers, one delivering food pellets and the other delivering sucrose solution
Note: All animals acquired the lever-press response, though core-lesioned animals showed depressed acquisition rates and overall response rates
View evidence from paper
“All animals acquired the lever-press response although the rate of acquisition and overall response rates in core-lesioned animals were depressed”
Outcome devaluation via specific satiety
Post-training devaluation of one of the two outcomes using a specific satiety procedure to test contingency degradation
Note: Shell- and sham-lesioned rats showed selective reduction in performance on lever delivering prefed outcome; core-lesioned rats failed to show selective devaluation effect
View evidence from paper
“post-training devaluation of one of the two outcomes using a specific satiety procedure produced a selective reduction in performance on the lever that, in training, delivered the prefed outcome”
Contingency degradation test
Test to assess whether animals can encode instrumental action-outcome contingencies and respond appropriately when contingencies are degraded
Note: Core-lesioned rats failed to show selective devaluation effect and reduced responding on both levers, but subsequent tests revealed this was not due to impairment in recalling devalued outcome, discriminating outcomes, or encoding action-outcome contingencies
View evidence from paper
“Subsequent tests revealed that these effects of core lesions were not caused by an impairment in their ability to recall the devalued outcome, to discriminate the two outcomes, or to encode the instrumental action–outcome contingencies”
Pavlovian conditioning test
Assessment of Pavlovian conditioning ability in lesioned and control animals
Note: Core lesions did not have marked effect on Pavlovian conditioning; shell-lesioned rats showed no deficit in Pavlovian conditioning
View evidence from paper
“the core lesions did not have any marked effect on Pavlovian conditioning”
Pavlovian-instrumental transfer test
Test to assess transfer of incentive motivation from Pavlovian to instrumental conditioning
Note: Core lesions did not have marked effect; shell-lesioned rats failed to show positive transfer despite normal Pavlovian and instrumental conditioning
View evidence from paper
“they failed to show any positive transfer in the Pavlovian-instrumental transfer test”