Healthy sleep/wake cycles depend on the proper integration of neural circuits that control arousal and sleep. Insight on the interactions between these circuits will promote our ability to treat sleep disorders. Recent published work shows that a subset of weakly circadian neurons in the Drosophila pacemaker circuit is physiologically responsive to sensory input and contributes to behavioral arousal (Sheeba et al., 2008;Parisky et al., 2008;Shang et al., 2008). An integrative combination of molecular, physiological, and behavioral approaches to illuminate an interface between circadian and arousal neural circuits is proposed. Towards this goal, novel methods to electrophysiologically record Drosophila pacemaker neurons in whole brain preparations and in dissociated neuronal cultures are described. Another key recent technical advance is to image per promoter cycling for the entire PER-expressing central brain circadian circuit at single cell resolution for multiple days. This was achieved by combining a highly sensitive low-light imaging system with a robust long-term Drosophila whole brain culture system that we recently co-developed (Ayaz et al., 2008). To the best of our knowledge, this is the first example of a preparation that permits long-term multi-day imaging of a sensory-enabled entire neural circuit.
The Specific Aims are:
Specific Aim 1. Determine the specificity, coupling, and underlying signal transduction of CRYPTOCHROME-dependent light-induced rapid changes in pacemaker neuron firing rate.
Specific Aim 2. Determine whether large lateral ventral neurons contribute to behavioral arousal.
Specific Aim 3. Determine the pattern of PER cycling for entire circadian circuit in response to light activation and exogenously induced firing of the large LNv arousal neurons at high spatial and temporal resolution by whole brain per-luc imaging. These studies will reveal critical operations that occur between arousal and circadian circuits. The proposed work will likely provide new insights for mammalian circadian biology in a rapid and cost effective manner and the molecular genetic and physiological tools described herein will be used in the future by other laboratories for studying neural circuits and disorders of electrical excitability.

Public Health Relevance

Sleep disruption can occur due to aberrant activity of arousal neurons which delay sleep onset and lower sleep maintenance, thus understanding the interactions between arousal, circadian and sleep circuits is of critical importance. Our recent work identifies a group of light-driven neurons that interface circadian and arousal circuits in Drosophila and share many physiological characteristics with mammalian sleep regulating arousal neurons. We propose to determine the functional properties of these arousal neurons and their modulation of the circadian circuit.

National Institute of Health (NIH)
National Institute of Neurological Disorders and Stroke (NINDS)
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Biological Rhythms and Sleep Study Section (BRS)
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Whittemore, Vicky R
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University of California Irvine
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Fogle, Keri J; Baik, Lisa S; Houl, Jerry H et al. (2015) CRYPTOCHROME-mediated phototransduction by modulation of the potassium ion channel ?-subunit redox sensor. Proc Natl Acad Sci U S A 112:2245-50
Das, Antara; Holmes, Todd C; Sheeba, Vasu (2015) dTRPA1 Modulates Afternoon Peak of Activity of Fruit Flies Drosophila melanogaster. PLoS One 10:e0134213
Roberts, Logan; Leise, Tanya L; Noguchi, Takako et al. (2015) Light evokes rapid circadian network oscillator desynchrony followed by gradual phase retuning of synchrony. Curr Biol 25:858-67
Helfrich-Förster, Charlotte; Nitabach, Michael N; Holmes, Todd C (2011) Insect circadian clock outputs. Essays Biochem 49:87-101
Fogle, Keri J; Parson, Kelly G; Dahm, Nicole A et al. (2011) CRYPTOCHROME is a blue-light sensor that regulates neuronal firing rate. Science 331:1409-13
Sheeba, Vasu; Fogle, Keri J; Holmes, Todd C (2010) Persistence of morning anticipation behavior and high amplitude morning startle response following functional loss of small ventral lateral neurons in Drosophila. PLoS One 5:e11628
Ayaz, Derya; Leyssen, Maarten; Koch, Marta et al. (2008) Axonal injury and regeneration in the adult brain of Drosophila. J Neurosci 28:6010-21
Sheeba, Vasu; Fogle, Keri J; Kaneko, Maki et al. (2008) Large ventral lateral neurons modulate arousal and sleep in Drosophila. Curr Biol 18:1537-45
Sheeba, Vasu; Sharma, Vijay K; Gu, Huaiyu et al. (2008) Pigment dispersing factor-dependent and -independent circadian locomotor behavioral rhythms. J Neurosci 28:217-27
Sheeba, Vasu; Gu, Huaiyu; Sharma, Vijay K et al. (2008) Circadian- and light-dependent regulation of resting membrane potential and spontaneous action potential firing of Drosophila circadian pacemaker neurons. J Neurophysiol 99:976-88

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