Source Paper
Dissociation in Effects of Lesions of the Nucleus Accumbens Core and Shell on Appetitive Pavlovian Approach Behavior and the Potentiation of Conditioned Reinforcement and Locomotor Activity byd-Amphetamine
John A. Parkinson, Mary C. Olmstead, Lindsay H. Burns, Trevor W. Robbins, Barry J. Everitt
Journal of Neuroscience • 1999
Intra-NAcc Amphetamine Infusion and Drug Response Testing
Objective: To investigate the functional dissociation of nucleus accumbens (NAcc) core and shell subregions in mediating amphetamine-potentiated conditioned reinforcement and locomotor activity in rats
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Equipment3
Materials2
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Protocol Steps
Pavlovian conditioning training
Rats were initially trained to associate a neutral stimulus (Pavlovian CS) with food reinforcement (US)
Note: This is the initial training phase before lesion surgery
View evidence from paper
“Rats were initially trained to associate a neutral stimulus (Pavlovian CS) with food reinforcement (US)”
Excitotoxic lesion surgery
Selective excitotoxic lesions were made to destroy either the NAcc core or shell, with sham-lesioned controls
Note: Lesions were selective to either core or shell subregion
View evidence from paper
“After excitotoxic lesions that selectively destroyed either the NAcc core or shell, animals underwent additional CS–US training sessions”
Post-lesion Pavlovian retraining
After lesion surgery, animals underwent additional CS–US training sessions to reestablish the Pavlovian association
Note: Core-lesioned animals showed impairment during these sessions; shell-lesioned animals showed no deficit
View evidence from paper
“After excitotoxic lesions that selectively destroyed either the NAcc core or shell, animals underwent additional CS–US training sessions”
Instrumental conditioning with conditioned reinforcer
Animals were tested for acquisition of a new instrumental response that produced the CS acting as a conditioned reinforcer (CR)
Note: This measures the ability to learn a new response reinforced by the previously conditioned stimulus
View evidence from paper
“then were tested for the acquisition of a new instrumental response that produced the CS acting as a conditioned reinforcer (CR)”
Intra-NAcc amphetamine infusion and testing
Animals were infused intra-NAcc with d-amphetamine at doses of 0, 1, 3, 10, or 20 μg before each session during instrumental conditioning testing
Note: Infusions were given before each session to assess dose-dependent effects on CR responding and locomotor activity
View evidence from paper
“Animals were infused intra-NAcc with d-amphetamine (0, 1, 3, 10, or 20 μg) before each session”
Measurement of CR lever and control lever responding
During amphetamine infusion sessions, responding on both the CR lever (reinforced) and control lever (nonreinforced) was measured
Note: Core-lesioned animals showed reduced selectivity with amphetamine increasing responding on both levers
View evidence from paper
“intra-NAcc amphetamine infusions dose-dependently increased responding on both the CR lever and a nonreinforced (control) lever”
Measurement of locomotor activity
Locomotor activity was measured during amphetamine infusion sessions to assess stimulant effects
Note: Shell lesions produced hypoactivity and attenuated amphetamine-induced activity; core lesions produced hyperactivity and enhanced amphetamine effects
View evidence from paper
“Shell lesions produced hypoactivity and attenuated amphetamine-induced activity. In contrast, core lesions resulted in hyperactivity and enhanced the locomotor-stimulating effect of amphetamine”