| Abstract No.: | A-G1192 |
| Country: | Canada |
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| Title: | PARALLEL OCCURRENCE OF HABIT AND PREFERENCE LEARNING |
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| Authors/Affiliations: | 1 Elia Nahas*; 1 Norman White;
1 McGill University, Montreal, QC, Canada;
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| Content: | Previous research has shown that the dorsal striatum and amygdala are associated with reinforced stimulus-response (S-R) associations and acquisition of associations between neutral stimuli and affective responses (S-Affect), respectively. Performance on the Win-Stay (WS) task (used to measure S-R learning) is impaired by dorsolateral striatum but not amygdala lesions. Conversely, performance on the conditioned cue preference (CCP) is impaired by amygdala, but not dorsal striatum lesions.
Objectives
McDonald and Hong (2003) showed that normal rats trained on the WS task also exhibit a CCP, and that the WS and CCP behaviors are selectively impaired by dorsal striatum and amygdala lesions, respectively. This suggests that S-R and S-Affect learning occur simultaneously and independently during WS training. The present study aimed to investigate and extend this hypothesis.
Materials and Methods
Both the Win-Stay and CCP learning procedures were carried out in an automated 8-arm radial maze with opaque floors, walls and covers.
1. WS task: rats are placed in the maze with all 8 arms open. Three randomly selected arms are lit; when a rat enters and runs to the end of a lit arm it receives food; when it enters a dark arm no food is given. Upon exiting a reinforced arm the light on that arm extinguishes and a new randomly selected arm is lit. Normal rats reach 90% correct responses after approximately 200 trials distributed over 5 days due to reinforced S (light) – R (arm entry) learning.
2. CCP task: rats are confined in a lit maze arm with a supply of food and, on alternate trials, in a dark arm with no food. When subsequently given a choice with no food available normal rats spend more time in lit than in dark arms. Since the rats have never previously been reinforced for entering lit arms this preference cannot be due to S-R learning. Rather, the preference is due to a classically conditioned association between a neutral Stimulus (light) and the affective consequences of consuming the food (reward) (S-Affect learning).
Groups of rats were given either WS or CCP training followed by a preference test. Total time spent in the arms and number of arm entries were recorded; average dwell time per entry into the lit arms was calculated.
Results
Both training methods produced a preference for the lit arms. CCP-trained rats entered lit and dark arms equally often but had longer dwell times per entry. In contrast, WS-trained rats entered the lit arms more frequently than the dark arms but had approximately equal dwell times in both lit and dark arms.
Conclusion
These results suggest that the same behavioural outcome may arise from two different learning processes, WS training resulted in a preference due to repetition of the reinforced response; CCP training resulted in a preference due to increased dwell times (similar to being confined in lit arms during training). Future experiments will attempt to identify the neural substrates of these two types of preferences. |
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