UC Berkeley

How does the brain make decisions in an evolving and changing world? To make effective decisions, one needs to both understand the situation, or context, in which a decision will be made, but also how the world, and one’s decision, may change as that situation unfolds. The inability to flexibly change or adapt one’s actions to a changing environment leads to persistent dysfunction and distress and is characteristic across the spectrum of psychiatric disorders. The uniting theme across this thesis is the identification of the neural circuitry that underlies flexible decision-making in our dynamic world.In Chapter 1, I explore how local neural activity encodes value across distinct social settings. Specifically, I test the hypothesis that orbitofrontal cortex (OFC) does not just encode the value of different options, as has been shown previously, but also encodes the social state of the task and modulates the value encoding of the different options in a state-by-state manner. I find that high-frequency activity (HFA) encodes the value of options for oneself, along with that of a social partner, but that the form of value encoding changes between two discrete social contexts.In Chapter 2, I expand my focus to include an extended prefrontal-limbic circuit that controls decision making across a dynamically changing environment. Specifically, I test the hypothesis that a distributed prefrontal-limbic circuit, connected via theta-band synchrony, supports decision-making when rewards and threats dynamically increase and decrease together, a context that is known to be anxiolytic in humans and other animals.In Chapter 3, I put forward a statistical tool that can be employed by cognitive neuroscientists to test for relationships between external or internal dynamic predictors and discrete events of interest. These models, called Joint Models of Longitudinal and Survival Data were developed in the field of public health to understand how changing biomarkers and treatments predict mortality. Here, I apply the models to both behavioral and neural data collected over time to predict trial-level decisions.In sum, this work addresses the complexity and dynamic nature of human decisions and provides neural and behavioral data on how context shapes the neural dynamics guiding our everyday behavior.