Graduate Student - Ph.D.

Helen Wills Neuroscience Institute

University of California, Berkeley (Berkeley, CA)

Jonathan D Wallis

Differentiating the neural selectivity for the valuation of stimuli and actions in the mammalian prefrontal cortex

Machines are poor at learning to make decisions in volatile environments. They are not designed to learn relationships between stimuli in the environment, responses that are potentially appropriate, and the outcomes of those responses. Humans, on the contrary, excel at learning these stimulus-response-outcome (SRO) relationships. This project will probe the neural mechanisms underlying SRO learning in an animal model. Past studies have implicated regions of the prefrontal cortex (PFC) to be involved in components of SRO tasks. Robust neural activity arises in lateral PFC (LPFC) during SR tasks, while the medial PFC (MPFC) activity correlates with RO relations. Lesions of the orbital frontal cortex (OFC) result in insensitivity to changes of learned SO associations. Our project will compare the neuronal firing patterns across these regions (LPFC, MPFC, and OFC) as our subjects perform three separate tasks: a response-outcome (RO) task, a stimulus-outcome (SO) task, and a novel SRO task. Our specific aims are as follows:

1. To test whether neurons in medial PFC encode RO contingencies in working memory relative to neurons in lateral PFC.

2. To test whether neurons in medial PFC encode RO contingencies, while neurons in orbital PFC encode stimulus-outcome contingencies.

3. To examine whether overlearning decreases the encoding of RO contingencies relative to SR contingencies.

SIGNIFICANCE: Understanding the neural mechanisms underlying action control at the single neuron level has the potential to highlight novel treatments for illnesses involving dysfunctional behavioral control. This includes addictive behavior, as well as other forms of compulsive behavior, such as obsessive-compulsive disorder. Another application of this research is the adaptation of these principles in cognitive control towards machines and neural prosthetics.

2007-present  T. O. Liu Memorial Fellowship in Neuroscience

2007 National Science Foundation-Neuroscience-Honorable Mention

2006 National Science Foundation-Neuroscience-Honorable Mention

2005 National Science Foundation-Biomedical engineering-honorable mention

2004 Chinese-American Institute of Engineers and Scientists Scholarship