Experiential, Neural, and Cognitive Influences on Decision Making in Rats

Thesis (Ph.D.)--University of Washington, 2012All animals have specific mechanisms in place to guide the numerous decisions they face daily. The act of deciding among possible behaviors is a process that involves learning about the relationships between actions and consequences, remembering past outcomes, and evaluating the current internal and external environment to inform an animal of its needs and available choices. The field of neuroeconomics has developed from a joint interest in how the brain guides this decision process that is shared by its parent fields of economics and neuroscience. Other fields provide critical insights into this topic: computer science contributes mathematical models of behavior, and psychology contributes analyses of the behavior itself, particularly in terms of an animal's underlying motivations and cognitive tools. The studies presented in this dissertation explore decision making in rats from both psychological and neuroscientific perspectives. The first study addresses whether and how an unrelated stressful experience affects reward-motivated behavior in a simple value-based foraging task. Rats who experienced an acute, uncontrollable stressful event were subsequently impaired in their ability to optimally update their behavior in response to changing rewards. The next study revealed that optimal performance on a similar value-based decision task does not require the independent contribution of several subregions of the prefrontal cortex. The final study dissociated particular measures of decision making from performance on other types of tasks, and found that an animal's individual preference for risky rewards was related to its behavioral sensitivity to rewards