Cognitive Dynamics During Perceptual Decision Making in the Rat

Abstract

Decision making refers to the cognitive and neural mechanisms that generate choices.

Decision making is a ubiquitous feature of daily life. In this thesis I present two studies

that develop models of decision making based on rat auditory behavioral tasks. Both

studies build descriptions of latent cognitive variables that are guiding rat behavior.

In the first study, we examined behavioral data from a pharmacological inactivation of

a prefrontal cortical region known as the Frontal Orienting Fields (FOF). Inactivation

of the FOF during decision making produced strong biases in the rats behavior.

I developed a neural model to ask what functional role of the FOF could explain

these results: evidence integration, decision formation, or post-decision memory. The

modeling study concluded that only a post-decision memory role can explain the data.

In the second study, I developed a decision making task in a dynamic environment.

The ideal observer in a dynamic environment must integrate evidence over time, but

also discount old evidence that may no longer be informative of the current state of

the environment. Using a task with discrete pulses of evidence, exactly computed the

dynamics of the ideal observer over time. The optimal timescale for discounting is

dependent on the experimenter-controlled statistics, but also the subject’s accuracy

in detecting the noisy evidence. When incorporating both of these factors, I find

that rats adopt the optimal timescale for evidence accumulation and discounting.

I developed a behavioral model to track the moment-by-moment dynamics of the

accumulated evidence within each trial. Both of these studies developed quantitative

descriptions of cognitive decision variables evolving with the rat’s brains during each

trial of a decision making task. Detailed descriptions of cognitive variable dynamics

can then be used in the analysis of neural data to investigate the neural mechanisms

underlying decision making.