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Development of a Novel Delay Discounting Task: Evaluation of Nicotinic Receptor Blockade
Roseman, Paige Lee
Roseman, Paige Lee
Abstract
Delay discounting is a commonly used measure to assess impulsive decision-making. Many of the tasks used involve providing access to a small, immediate reward and a larger, delayed reward, with a choice of the immediate reward thought to reflect greater impulsivity. However, these tasks do not allow assessment of the effects of immediate versus delayed access to multiple reward levels. Moreover, a direct comparison of the effects of delay before or after reward access is confounded by reward amount. In order to address these issues, additional choices must be made available. In the present experiment, rats were trained in an 8-arm automated radial maze. Three of the arms offered immediate access to low (0.01 ml tap water), medium (0.06 ml), or high (0.10 ml) rewards with a delay imposed after reward access. Three different arms offered delayed access to low, medium or high rewards. In the standard task, the delays were matched before or after reward access for each reward amount (10 seconds for low reward, 30 seconds for medium reward, and 60 seconds for high reward). With sufficient training, animals exhibited a significant preference for immediately accessible arms. Additional task manipulations increased the probability of entering an immediately accessible arm and efforts to attenuate this preference, by increasing the delay on immediately accessible arms, had only a minor effect on performance. Finally, administration of the nicotinic receptor antagonist, mecamylamine, did not significantly affect performance. The present experiment represents an initial effort to characterize performance in a novel maze task that allows a direct comparison between immediate and delayed access for matched rewards.
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Thesis is part of Honors ETD pilot project, 2008-2013. Migrated from Dspace in 2016.
Date
2010-05-10
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Keywords
Delay aversion, Impulsivity
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Department
Neuroscience