Article Figures & Data
Figures
- Figure 1.
Schematic representation of excitotoxic lesions of the NAC core (A) and shell (B) for Experiment 1. Shaded areas represent the maximum (dark gray) and minimum (light gray) extent of the lesions for the animals included in the behavioral analyses. Coronal sections are taken from the following points in the anteroposterior plane beginning at top left: +1.7, +1.2, +1.0, and +0.7 mm anterior to bregma (Paxinos and Watson, 1998). C, Schematic representation of the placement of cannula tips for the NAC core (left) and shell (right) groups for Experiment 2.
- Figure 2.
A, Pavlovian conditioning. Mean number of magazine entries during the CS presentations and during the pre-CS intervals (±1 SEM) across days of Pavlovian training for the three lesioned groups. Rats in all groups learned to enter the magazine selectively during the stimulus periods. B, Instrumental conditioning. Mean lever-press responses for the three groups across days of training (±1 SEM). For the first day, each response was reinforced. Thereafter, responding was reinforced on an RR-5 schedule of reinforcement for days 2–4, and on an RR-10 schedule of reinforcement for days 5–7. Rats in all groups acquired the instrumental responses and increased response rates across days.
- Figure 3.
Effects of core and shell lesions on the outcome-specific and general forms of Pavlovian–instrumental transfer. A, Mean number of lever presses during the Pavlovian–instrumental transfer tests (+SEM). The number of responses during the baseline period in which no stimuli were present is displayed in each case. “Same” refers to the stimulus paired in training with the same outcome as was earned by the available lever. “Different” refers to the stimulus paired with the outcome earned by the other response. “General” refers to the third stimulus paired with the reward not earned by either response. Sham rats (left) demonstrated both outcome-specific and general transfer effects. The performance of shell rats (middle) was increased by stimulus presentation, but they showed no evidence of an outcome-specific PIT effect. In contrast, core rats (right) showed evidence of outcome-specific PIT but a reduced general PIT effect. *Responding during the stimulus was significantly different from responding during the baseline intervals (p < 0.01). ⋀Responding during the “same” stimulus was greater than during the “different” stimulus (p < 0.01). B, Effects of shell and core lesions on outcome-specific PIT. Mean lever presses during each of the same and different stimuli with baseline response rates for each group subtracted. *Responding was greater during the same compared to the different stimulus; **significant difference compared to the sham group. C, Effects of shell and core lesions on general PIT. Mean lever presses during the general stimulus for each group with their respective baseline response rates subtracted. **Significant difference compared to the sham group.
- Figure 4.
A, Pavlovian conditioning. Mean number of magazine entries during the CS presentations and during the pre-CS intervals (±1 SEM) across days of Pavlovian training for the core and shell groups. Both groups learned to enter the magazine selectively during the stimulus periods. B, Instrumental conditioning. Mean lever-press responses for the core and shell groups across days of training (±1 SEM). For the first day, each response was reinforced. Thereafter, responding was reinforced on an RR-5 schedule of reinforcement for days 2–4, and on an RR-10 schedule of reinforcement for days 5–7. Rats in both groups acquired the instrumental responses and increased response rates across days.
- Figure 5.
Effects of reversible inactivation of the core or shell on the outcome-specific and general forms of Pavlovian–instrumental transfer. A, Mean lever presses (+SEM) during each stimulus and the baseline intervals in the PIT tests following saline and muscimol infusions for rats in the shell group. Following saline, there was evidence of both specific and general PIT. Following inactivation, while there was still an excitatory influence of the stimuli, the outcome-specific PIT effect was lost. B, Mean lever presses (+SEM) in the PIT tests following saline and muscimol infusions for rats in the core group. Following saline, there was evidence of both specific and general PIT. Following inactivation, while the same stimulus still elevated performance relative to both baseline and the different stimulus, providing evidence of outcome-specific PIT, the general excitatory influence of the stimuli was reduced. **Significant increase from baseline (p < 0.0063); *p < 0.05; ⋀responding during the “same” stimulus was greater than during the “different” stimulus (p < 0.05). C, Effects of shell and core inactivation on outcome-specific PIT. Baseline responses were subtracted from lever presses during the same and different stimuli to further evaluate the effects of inactivation on any excitatory effects. *Greater responding during the same compared to the different stimulus; **reduction from saline treatment and a significant group difference. D, Effects of shell and core inactivation on general PIT. Mean lever presses during the general stimulus with the baseline response rate subtracted. **Reduction from saline treatment and a significant group difference.
Tables
Conditioning Instrumental training Transfer test S1–O1 S1 
S2–O2 R1→O1; R2→O2 S2 R1 vs R2 S3–O3 S3 -
During initial conditioning rats received pairing of three auditory cues, S1, S2, and S3 (noise, tone, and clicker, counterbalanced), with three separate outcomes, O1, O2, and O3 (pellet, sucrose, or polycose, counterbalanced). They then received instrumental training on two separate lever press actions, R1 and R2, each delivering one of the outcomes used in initial conditioning, O1 or O2. Finally a test was conducted on the levers in extinction in the presence of each of the three stimuli. The tests of S1 and S2 provide an assessment of the effects of the outcome-specific predictions of the cues. The test of S3, predicting an outcome not earned on the levers, provides a test of the general excitatory effects of reward prediction.
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