We use the Drosophila taste system as a model to study how neural circuits integrate information from our internal and external worlds.
The taste system is a great model to study how the brain integrates different signals to generate flexible behavior. We use our sense of taste to determine what to eat, and our responses to food are profoundly gated by internal signals such as hunger, experience, and reward.
The fruit fly Drosophila offers a wiring diagram of the brain and genetic tools to study neural circuits at single-cell resolution. We combine a broad range of approaches, from molecular and cellular studies to optogenetics, functional imaging, connectomics, behavior, and computational analysis and modeling.
Below are some of our specific research areas.
How do flies integrate taste, hunger, and experience to guide their behavior?
Before dissecting how the nervous system processes a sensory cue, it is essential to understand the end goal of this processing: how does an animal use this cue to guide its behavior? Although the vast majority of taste research focuses on feeding behavior, taste can influence more complex behaviors such as exploration, foraging, and learning. We are characterizing these behavioral effects by combining naturalistic behavioral paradigms with quantitative analysis and modeling. We aim to build quantitative models to explain how flies select and transition between behaviors, and to ask how internal states such as hunger and experience reconfigure a fly’s actions and decisions.
Video of a hungry fly exploring and feeding in a small chamber. Its body parts are tracked using DeepLabCut, enabling quantitative analysis of behavior.
Left: Activity of sugar- or bitter-sensing taste neurons recorded by calcium imaging, showing different response dynamics (from Devineni et al., 2021). Right: Fly brain with axons of primary bitter-sensing neurons labeled in green and postsynaptic neurons labeled in red.
How does the taste circuit transform sensory responses into flexible motor signals?
While taste processing at the periphery has been well-studied, downstream taste circuits are largely unknown. We are taking a range of approaches to study how downstream circuits transform sensory responses, integrate internal cues, and generate flexible motor signals. We use computational analyses of the recently published synaptic connectome to investigate taste circuit architecture. We use optogenetic manipulations to test how different neurons contribute to behavior, and we use calcium imaging to investigate how they encode and transform sensory information. By imaging activity in different states, we also aim to determine how and where internal signals such as hunger modulate taste processing.
How are taste and reward signals integrated in health and disease?
Highly palatable foods like sugar activate reward pathways, and reward perception profoundly modulates food consumption. The dysregulation of reward pathways contributes to eating disorders such as binge eating. As in mammals, food reward in flies is encoded by dopamine neurons, and these reward neurons are also dysregulated in flies that overeat. We are using flies as a model to study how taste, hunger, and reward signals are integrated at the single-cell level, and how reward pathways differentially modulate feeding in health and disease.
Reward-encoding dopamine neurons in the fly brain that modulate feeding behavior.
Our research is funded by the NIH (NIDCD) and the Whitehall Foundation. We are grateful for their support!