Neuroscience of Motivated Behavior
Animals have multiple competing drives attempting to differentially influence their behavior. How does a coherent behavior emerge when conflicting needs demand the organism respond? Since I began my research career as an undergraduate at Providence College, I have been driven by these and similar questions and sought to understand the neural circuits that govern motivated behavior.
Current research (Betley Lab, University of Pennsylvania)
Hunger and competing survival needs
Hunger has the remarkable ability to override other motivational drives—including competing needs like itch, maternal care, social interaction, and even pain—to facilitate food consumption. Agouti-related peptide (AgRP)-expressing neurons in the arcuate nucleus of the hypothalamus are essential in this process as their activity is recruited by hunger, and through multiple discrete projections they have the capacity to facilitate food consumption and suppress neural circuits that promote behaviors that compete with food consumption. Using a combination of behavior, optogenetic manipulation, and photometry, I study the mechanisms through which AgRP neurons interact with neural circuits for fear to understand how behavioral choices are made at a network level, and how organisms prioritize concurrent motivations.
Hypothalamic response and adaptation to exercise
The hypothalamus must sense and respond to metabolic challenges to appropriately coordinate behavior and peripheral metabolic responses. Exercise is one such metabolic challenge that confers long-term adaptations such as changes in glucose homeostasis, body composition, and exercise performance. Surprisingly, a population of ventromedial hypothalamic neurons that express the transcription factor steroidogenic factor-1 play an essential role in mediating these changes. I am investigating the neurophysiological response of these neurons during exercise and determining if their activation independent of exercise is sufficient to drive exercise-like changes in metabolism and behavior.
Graduate research (Warden Lab, Cornell University)
Initiation of goal-directed movements
To make a decision, no matter how large or small, an organism’s brain must synthesize a wide array of information—the current sensory environment, past experience and knowledge, and internal state—all within an instant to produce a behavior that is consistent with the animal’s goals and is appropriate given the current context. When a behavioral decision is ultimately made, how is this behavior initiated? In my graduate work, I characterized a population of medial prefrontal cortical neurons that project to the ventral tegmental area and are active upon the initiation of goal-directed movements in a reward-seeking paradigm, and upon the switch from passive to active behavior in escape contexts. Our findings revealed a neural circuit sufficient to switch between goals and initiated goal-directed movements, and offer insight into executive control over subcortical goal representation.
Adaptive termination of goal-directed behavior
How are goal-directed behaviors terminated when the effort required to perform them is no longer worthwhile? To address this question, we monitored lateral habenula activity during a reward-seeking task and found that tonic activity is elevated when mice are disengaged from the task. This elevation occurs both when disengagement is due to reward omission (negative valence) and because sufficient reward has been consumed (positive valence). Further, optogenetically inhibiting the lateral habenula prolongs task engagement. Collectively, this work offers a perspective on how motivated behaviors are initiated and then adaptively terminated by the brain.
Throughout my training as a graduate student and postdoctoral fellow, I have made it a point to integrate undergraduates into my research. I have directly mentored eleven undergraduate students, four of whom have written independent senior theses and seven of whom are co-authors on my manuscripts. Within my broader research goals, I identify smaller projects that my students can take ownership of and expand upon given their interests. I also make strides to reach out to students who come from backgrounds traditionally underrepresented in the sciences, working with organizations like Penn First Exposure to Research in the Biological Sciences (FERBS) to recruit such students into my research program.