Project Abstract
To ensure survival
, animals must satisfy a variety of needs that lead to what are often mutually
exclusive motivated behaviors. An example of such a behavior is sleep, a process that has
been described in a variety of species ranging from jellyfish to humans. Although the precise
function of sleep remains unknown, there is ample evidence supporting the notion that sleep is
required for maintaining optimal physiological and behavioral performance. Importantly, sleep is
regulated by two processes, the circadian clock which gates the occurrence of sleep, and the
sleep homeostat which controls the intensity and duration of sleep. Beyond the clock and the
homeostat, a variety of sensory inputs and internal states can modulate sleep in significant
ways. For example, animals can dramatically modify, reduce, or completely forego sleep if their
internal needs and/or external circumstances demand it. Importantly, sleep competes with other
essential motivated behaviors, such as feeding. This implies that the decision to engage in,
remain in, or exit sleep behavior must be weighed against the drive to perform other key
motivated behaviors. Thus, to maximize survival, organisms must constantly assess their
environment and their internal needs and alter their physiology and behaviors accordingly. The
mutually exclusive nature of sleep and feeding behaviors implies that each of these individual
motivational drives must not only be able to modulate the neuronal circuits underlying their
associated behavior but also those of the competing one. Although much is known about neural
circuits regulating individual behaviors, interactions between them are less well characterized.
Understanding how behavioral decisions are made, and how the neuronal circuits underlying
different behaviors interact, is a key aspect of modern neurobiology that will help us understand
how the nervous system can help organisms adapt to an ever-changing environment and
prioritize behaviors in a way that maximizes survival. We have identified two novel sleep-
promoting neurons in the Drosophila central nervous system. Interestingly, these neurons also
modulate feeding. In addition, we discovered that the activity of these two neurons is regulated
by diet composition. In this proposal, we will use the power of the Drosophila model to
investigate how these two neurons modulate sleep and feeding. We will identify the circuits,
genes and neuromodulators involved in these relationships. Since the molecular mechanisms
that regulate feeding and sleep are evolutionary conserved between Drosophila and mammals,
we anticipate that this proposal will uncover regulatory principles that are relevant to human
physiology.
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