Ph.D., University of California, San Diego
We study how the nervous system controls behavior by analyzing the simple neural networks that control spatial orientation behaviors and decision making in the nematode worm Caenorhabditis elegans. C. elegans has a small nervous system (302 neurons), whose neurons and connectivity pattern have been completely characterized. Together with an entirely sequenced genome and high accessibility to genetic analysis, this organism provides a unique opportunity to study the neural, molecular, and genetic basis of behavior. Our research integrates a wide range of analyses and experimental approaches, including quantitative analysis of behavior, neuronal ablation, computer modeling, electrophysiology, calcium imaging, optogenetics, and microfluidics.
Decision-making & Neuroeconomics
Studies of identical twins show that differences in decision making are partially explained by genetic factors. However, establishing the causality of individual decision-making genes has been challenging. We have recently shown that C. elegans makes value-based decisions (choices between options based on an internal assessment of their "subjective value"). We are now developing C. elegans as a new model system for the functional analysis of decision-making genes in a small circuit of neurons found to be necessary for value-based decision making.
Decision-making & Drugs of abuse
It has been known for centuries that smoking or ingesting preparations of the plant Cannabis sativa stimulates appetite. Users report persistent hunger while intoxicated, even if previously satiated. This feeling of hunger is often accompanied by a strong and speciﬁc desire for foods that are sweet or high in fat content, a phenomenon colloquially known as “the munchies.” These effects result from the action of plant-derived cannabinoids that mimic endogenous ligands called endocannabinoids. We have found that exposure of C. elegans to anandamide, an endocannabinoid common to nematodes and mammals, shifts both appetitive and consummatory responses toward preferred food food, an effect analogous to the munchies. We are now investigating the neuronal and genetic basis of cannabinoid effects on food-related decisions.
We are interested in studying scientific questions that can only be answered with new technologies. In the course of our research, we have developed new methods for investigating C. elegans decision-making behaviors, recording electrical signals from neurons and muscles, and combining neurophysiological and behavioral recordings in individual, freely crawling worms. These advances capitalize on our strengths in mathematics, computer science, engineering, and microfabrication.