The Concurrent Foraging Task: An Operant Behavioral Task to Improve Pre-Clinical TBI Modeling of Suboptimal Decision-Making
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Date
2023-05
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The Ohio State University
Abstract
Traumatic brain injuries (TBIs) affect over 2.8 million Americans annually, typically resulting in a chronic deficit in decision-making. This deficit is replicated in rats after TBI. The mechanism is unknown, and current temporal and probabilistic behavioral tasks to measure this deficit in rodents fall short in capturing decision-making processes after brain injury because rats are less sensitive to time delays and probabilistic choices. Thus, the objective of this project was to build an effort-based task to isolate decision-making processes by measuring sensitivity to reinforcement contingencies in rats. The Concurrent Foraging Task (CFT) is an operant two-lever behavioral task where one lever is set to a fixed ratio (FR) and one to a progressive ratio (PR) schedule of reinforcement. The FR lever has a constant lever press requirement to earn a reinforcer, and the PR lever's press requirement increases with each consecutive PR choice, but reset once the FR lever is chosen (switch point). Behavior on this task was evaluated using PR requirements at switch points and reinforcement density (RD) (# of presses / # of reinforcers). The efficacy of the CFT was evaluated with male (n=6) and female (n=6) rats across 3 conditions: Linear PR/FR8, Exponential PR/FR8, and Exponential PR/FR16. The second experiment included an amphetamine challenge to disrupt decision-making behavior. In both experiments, rats demonstrated sensitivity to reinforcement contingencies by achieving similar RDs but did not consistently switching at optimal PR requirements across conditions. Amphetamine increased omissions and variability of PR switch points and decreased RD for each condition. Additionally, there were no sex differences found in the current data, but this is an ongoing study that will have inferential statistics run at the conclusion of the project. The CFT is an effective alternative to current temporal and probabilistic tasks for assessing decision-making, but the ideal option depends on the target behavior being measured.
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Keywords
TBI, decision-making, novel task