This item is under embargo and not available online per the author's request. For access information, please visit http://libanswers.wustl.edu/faq/5640.
Date of Award
Doctor of Philosophy (PhD)
Economic decision-making requires the computation and comparison of subjective values. Several lines of evidence suggest that these processes are mediated by circuits in orbitofrontal cortex (OFC). Neurons in OFC encode the subjective values of choice options and outcomes, and damage to this area leads to selective deficits in value-guided behavior. To understand the nature of choice more thoroughly, it is useful to consider the features of OFC circuits that can limit or enhance information processing. In this document, I present work examining two factors that influence encoding in OFC: noise correlation and value adaptation. In the first study, I show that noise correlations in OFC are small but non-negligible, and that the structure of these correlations constrains the resolution of value representation in OFC. I go on to show that correlation structure predicts a weak relationship between single-neuron variability and decision outcomes in the context of a uniform linear model of decision making. These findings are consistent with empirical data and support the hypothesis that OFC mediates value-based decision-making. In the second study, I investigate how neurons in OFC adapt to changes in the value distribution. I show that neurons adapt to both maximum and minimum available values, but that the dynamic range does not completely remap across conditions. While intermediate adaptation is sub-optimal, it indicates that OFC neurons can partially compensate for changes in the scale of decisions, allowing increased resolution of value encoding in high-magnitude conditions. In summary, decision-making may be limited by correlated noise, but the effect of this constraint is relatively small. Moreover, variability introduced by noise correlation may be partially ameliorated by adaptation to the value range.
Chair and Committee
Timothy Holy, Martha Bagnall, Lawrence Snyder, Todd Braver,
Conen, Katherine E., "Correlated Variability and Adaptation in Orbitofrontal Cortex during Economic Choice" (2018). Arts & Sciences Electronic Theses and Dissertations. 1521.
Available for download on Wednesday, April 03, 2019