While much is known about the core components and the operation of the circadian molecular clock and its neuroanatomical location in the model organism Drosophila, very little is known about how this circadian molecular clock interacts with electrical signaling in the pacemaker neurons. It is an open questions as to how circadian molecular clock controls pacemaker neuronal electrical activity and synaptic output that ultimately controls animal behavior. The physiological interactions between pacemaker neuron electrical signaling and the circadian molecular clock and animal behavior will be studied by direct physiological analysis using patch clamp and imaging of adult whole brain neurons as well as transgenic expression of modified ion channels in the circadian pacemaker neurons of Drosophila. Transgenic strategies have been devised to (1) electrically silence pacemaker neurons and (2) electrically hyper-excite pacemaker neurons. Each of these manipulations of pacemaker neuronal electrical activity causes striking changes in circadian behavior.
The Specific Aims are to: (1) Map the functional subsets of the pacemaker neural circuit by electrical silencing, neurotransmitter markers, and immunocytochemistry; (2) Determine the mechanism of electrically hyper-excitation induced rhythm splitting and NaChBac expression's functional rescue of the electrically silenced pacemaker neural circuit; (3) Map the electrophysiological properties of wild-type and modified channel-expressing Drosophila pacemakers. These studies will elucidate the physiological mechanisms that determine circadian behavior in a well studied model organism. Ultimately, this work may provide powerful new tools for the general study of neural circuits and novel molecular-genetic strategies for studying and treating human diseases of aberrant cellular electrical excitability.
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