Josh Larkin will present his data during the undergraduate oral seminars in the Behavioral and Neural Adaptation section of the Mary Gates Symposium. Josh's abstract is reprinted below.
Neural and Behavioral Context-Based Differences in Rats
· Joshua (Josh) Larkin, Senior, Psychology Mary Gates Scholar
· Sheri Mizumori, Psychology
· Marsha Penner, Psychology
Decision-making is a complex behavior where one must weigh cost and benefit to maximize the likelihood of the best possible outcome. A common example of this is a decision between a small yet certain reward (e.g. $1 or 1 piece of candy), and a larger uncertain reward (e.g. $10 or 10 pieces of candy 50% of the time). It has been suggested that context and dopamine levels play a critical role in the willingness of decision makers to take risks. We tested this hypothesis by assessing behavioral and neural differences between groups of rats trained on an equivalent risk-based paradigm conducted in different contexts. Rats started training in an operant chamber or a decision maze, and then switched contexts (i.e. tasks). These tasks involved the rat making a decision between two levers or doors, one of which was associated with a certain small reward (1 sugar pellet), and the other which is associated with a large (4 sugar pellets) reward that appeared with decreasing probability (100%, 50%, 25%, 12.5%). To test the influence that dopamine has on risk taking behavior, we used a dopamine antagonist (flupenthixol) to inhibit dopamine in both the maze and operant chamber contexts. Our results suggest that when analyzed as a group, rats are less willing to take risks in the maze context. We hypothesize this is because risk taking on the maze is a more complex behavior, perhaps because of a longer delay between a choice and reward delivery. Our pharmacological findings of high numbers of trials in which levers were not pressed in the chamber, or trials not run on the maze, suggest that blocking dopamine interferes with the ability of rats to make risky decisions. Together, these results support the idea that risk-based decision-making is influenced by many factors, including context and dopamine.