Faculty and Research
Faculty by Name
Kristin Scott
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Kristin Scott
Associate Professor of Neurobiology*
*and Member of the Helen Wills Neuroscience Institute
Research Interests
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We study taste perception in the fruit fly, Drosophila Melanogaster, to examine how sensory information is processed by the brain. We use a combination of molecular, genetic, electrophysiological and behavioral approaches to study taste circuits. Our aims are to understand how different tastes are distinguished by the brain and how taste perception is modified by experience.
Current Projects
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The gustatory system in Drosophila is crucial for detecting food, selecting sites to lay eggs and recognizing mates. Taste neurons are distributed on many parts of the fly's body surface and they recognize taste stimuli such as sugars, salts, acids, alcohols and noxious chemicals. We have recently characterized a large family of ~60 candidate gustatory receptor genes (GRs). These receptors provide essential molecular markers that we are using to examine taste recognition both in the periphery and in the CNS.
Ligand specificity and behavioral specificity of different gustatory receptorss. To understand the function of different gustatory neurons, we are determining the ligands that different taste neurons recognize and the behaviors that they mediate. We are identifying ligands by a combination of genetic cell ablations and receptor misexpression studies, coupled with behavioral paradigms and calcium imaging experiments to assay taste responses. For example, gustatory neurons containing the same receptor gene can be ablated by genetically expressing a toxin and taste defects can be tested by simple behavioral assays, like food choice discrimination measured by food-coloring uptake. We are also expressing calcium-sensitive flourescent proteins in taste neurons-this allows us to monitor taste responses in the entire population of gustatory neurons in vivo with single cell resolution. We recently identified taste cells that recognize bitter substances and other cells that recognize sugars using these approaches. It would be interesting to determine whether there are specialized cells for salts and acids as well. These studies provide a starting point for determining how different tastes are represented in the brain.
Sensory maps in the brain. In other sensory systems, information from the periphery is mapped in the brain to provide a representation of the external world in the internal wiring. For example, there are tonotopic maps of auditory projections and somatosensory maps of touch projections. The gustatory system of the fly is interesting both because neurons express unique complements of receptors and because neurons are distributed in an orderly array along the body surface. We are using molecular genetic approaches to examine whether gustatory projections are segregated according to the receptor that is expressed in the periphery and whether there is a topographic map of gustatory information. Chemosensory bristles contain one mechanosensory neuron as well as taste neurons, and we are examining how these two different sensory modalities are represented in the brain. Our motivation is to understand the internal representation of gustatory information in the first relay.
Information processing in the brain. The subesophageal ganglion of the fly brain contains both axons of gustatory neurons and dendrites of motor neurons involved in taste behaviors. This suggests that the fly may have simple and localized taste circuits, with few connections between sensory stimulus and motor response. In addition, projection neurons may relay gustatory information to higher brain centers, perhaps for more complex associations. We are interested in mapping the functional and anatomical components of taste circuits using a variety of approaches. Genetic approaches to label subsets of neurons in the brain, behavioral screens for taste mutants, and calcium imaging of taste responses in the brain will help elucidate these circuits. These studies will provide insight into the integration of gustatory cues and the difference between sweet versus bitter, and will set the stage to examine how taste circuits are modified by learning and other sensory stimuli. We plan to study increasingly complex problems of neural integration by examining how different stimuli impinge upon taste circuits.
Selected Publications
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Taste Representations in the Drosophila Brain.[Z. Wang, A. Singhvi, P. Kong and K. Scott (2004) Cell 117, 981-991]
A Chemosensory Gene Family Encoding Candidate Gustatory and Olfactory Receptors in Drosophila. [K. Scott, R. Brady, A. Cravchik, P. Morozov, A. Rzhetsky, C. Zuker and R. Axel (2001) Cell 104, 661-673]
The sweet and the bitter of mammalian taste. [K. Scott (2004) Current Opinion in Neurobiology 14, 423-427]
Last Updated 2004-09-02