Christopher G. Vecsey, Ph.D. - US grants

DESCRIPTION (provided by applicant): Interactions between sleep and learning in Drosophila melanogaster: what is the role of PDF target neurons? Understanding the nature and purpose of sleep is currently one of the major goals in neuroscience research. It is clear that sleep is regulated by a combination of circadian and homeostatic systems, and that sleep and memory formation are tightly linked. However, it remains unclear what mechanisms at the circuit and molecular levels mediate these interactions. In the studies proposed here, the powerful Drosophila model system will be used to tackle these issues. It has recently been shown that a cluster of cells once thought to be purely part of the circadian system also play a role in homeostatic sleep regulation. These are the ventral lateral neurons (LNvs), which produce the peptide neurotransmitter PDF. However, it is unknown what the crucial targets of these cells are, or if they are involved in signaling that an organism needs additional sleep following sleep deprivation or learning. By combining genetic manipulations to both increase and decrease the excitability of LNv target cells with cutting edge electrophysiological recordings, this research will expand our understanding of the circuit- and molecular-level strategies that animals use to modulate sleep and memory formation. PUBLIC HEALTH RELEVANCE: Sleep disturbances are highly prevalent in today's society, resulting from shift work, sleep disorders, aging, psychiatric disorders, or simply from an extremely busy lifestyle. Understanding what strategies the brain uses to regulate the amount and quality of sleep that an animal obtains is therefore of urgent importance from a public health standpoint. The proposed research will address this issue by examining the mechanisms used to regulate sleep in response to sleep deprivation and learning experiences.

Project Summary Sleep disturbances are increasingly common and are associated with a variety of comorbidities and other public health consequences. It is therefore critical to improve our understanding of the neural mechanisms that control the timing and quality of sleep. Key signaling molecules that regulate sleep in animals ranging from flies to humans come from the family of neuropeptide transmitters. These molecules have sparse expression levels and selective effects on behavior, including sleep, making them prime candidates for the development of focused drug treatments with minimal side effects. However, the mechanisms by which these molecules act individually and in concert to regulate target cells in the brain and thus behavior are poorly understood. This proposal will take advantage of the powerful genetics and relatively simple sleep network organization of the fruit fly, Drosophila melanogaster, to address how neuropeptides function at the molecular, cellular, and behavioral levels to regulate sleep. In Aim 1, we will perform live fluorescent imaging to identify cellular targets and intracellular signaling mechanisms downstream of the receptor for the newly described sleep regulator, neuropeptide F (NPF), and determine how this molecule interacts with two additional established sleep regulators, short neuropeptide F (sNPF) and pigment dispersing factor (PDF). In Aim 2, we will carry out optogenetic activation of neuronal populations producing these same neuropeptides either individually or in combination, and record the effects on sleep behavior. In combination, the proposed work will allow us to establish the causal roles of key neuropeptide signaling molecules in the control of sleep, expanding our understanding of the mechanisms that control sleep and wakefulness at the molecular and circuit levels. In turn, this knowledge will provide a basis for the design of more effective treatments of human sleep abnormalities. This R15 AREA proposal will directly involve undergraduate students in all aspects of the research, including designing experiments, carrying out studies involving techniques of genetic manipulation, molecular and cellular neurobiology, and behavioral analysis. Their experiences will provide formative training for future careers in biomedical fields.