Kristin Scott, PhD
Division of Neurobiology and Helen Wills Neuroscience Institute
University of California, Berkeley
(October 22, 2014)
Taste Processing in Drosophila
The experience of taste only begins on the tongue. Messages sent from the taste buds to the brain determine the behavior — whether a food is accepted or rejected. This process is further complicated by the fact that our behavior toward a certain taste can change based on how hungry we are and what experience we have had with the taste in the past (e.g. something that has made us sick in the past is less likely to be found palatable). Dr. Scott discussed her work on taste processing in Drosophila. Despite the simplified nervous system of fruit flies, they respond to many similar tastes as humans. Dr. Scott has determined that the Gustatory Receptor gene family plays an important role in detecting taste in the fruit fly. Dr. Scott is also examining how detection of taste can, through neuronal networks, drive motor behaviors.
The ability to identify food that is nutrient-rich and avoid toxic substances is essential for an animal’s survival. Although olfaction and vision contribute to food detection, the gustatory system acts as a final checkpoint control for food acceptance or rejection. The fruit fly, Drosophila melanogaster, tastes many of the same stimuli as mammals and provides an excellent model system for comparative studies of taste detection. The relative simplicity of the fly brain and behaviors, along with the molecular genetics and functional approaches available in Drosophila, allow the examination of gustatory neural circuits from sensory input to motor output. These studies provide insight into how taste compounds are detected and processed by the brain.
A major interest of the laboratory has been to identify and characterize the receptors that detect different taste compounds in Drosophila. Although insects show behavioral responses to taste compounds that are similar to mammals, the number and types of taste receptor molecules was unknown. Our work characterized the role of the Gustatory Receptor gene family in the detection of sweet and bitter compounds and the role of a class of ion channels in water and pheromone detection, and it identified a new taste modality, the taste of carbon dioxide. These studies uncovered molecular mechanisms of taste detection in insects and revealed that the principle of modality-selective cells is a conserved coding strategy.
Detection of taste compounds drives innate motor programs for feeding in Drosophila, making it an excellent model to study sensorimotor transformations. A major current research interest is to elucidate neural circuitry for taste behaviors to examine sensory propagation and behavioral decisions. In addition, responses to taste compounds are plastic and modified by intrinsic and extrinsic cues, such as hunger, satiety, and experience.
Our studies of plasticity have described neural mechanisms that modulate circuits and behavior, and resolved how single modulatory neurons can have widespread consequences for behavior.