It is a central goal of neuroscience to elucidate how the nervous system generates learning. In the past, ethologists and geneticists established many behavioral paradigms of learning and characterized genes that regulate learning. However, in most cases we still cannot explain how learning occurs, partly due to our incomplete understanding of how the molecular machinery acts in a network of neurons to process information in an experience-dependent manner. Therefore, we would like to address how neural circuits causally link the “micro-level” understanding of molecules with the “macro-level” characterization of behavior.

To this end, we chose to study a form of aversive olfactory learning that resembles the Garcia effect, a fundamental form of learning whereby animals learn to avoid the smell or taste of a food that makes them ill. We use C. elegans, because we can use genetic, molecular and imaging tools to characterize how the function of its small (302 neurons) and completely-mapped nervous system regulates behavior. In the past, we have identified a neuronal network for the aversive olfactory learning, elucidated the properties of the key neurons, characterized conserved signaling pathways underlying learning, and defined how the function of the network generates naive and learned behavior.

Our goal is to achieve a holistic understanding of learning by addressing all levels of the underlying neural network from sensory perception to motor execution. Eventually, we will be able to test our understanding by manipulating neuronal functions with genetic or optical tools, “erasing” or “writing in” experience-dependent changes to predictably modulate behavior.