The goal of our research is to elucidate the molecular machinery underlying sleep and to define the role of sleep in the consolidation of long-term memory. Sleep is involved in many physiological processes, and disturbances in sleep are a hallmark of many diseases, including neurodegenerative disorders such as Alzheimer's disease, in which memory deficits are prominent. An understanding of the relation between sleep dysfunction and memory loss may help us to better define the pathophysiology of these diseases. We are interested in bridging past behavioral studies, which have shown that sleep is needed for the consolidation of memory, with current knowledge about the molecular mechanisms underlying memory storage. Mice are an ideal system with which to explore the relationship between sleep and memory consolidation. Our recent work has used genetic and pharmacological approaches in mice to demonstrate that protein kinase A (PKA) activity is critically important for long-term memory storage. There are striking parallels between the effects of sleep deprivation and the effects of pharmacological manipulation of the PKA signaling pathway on the consolidation of memory. Both sleep deprivation and inhibition of PKA disrupt the consolidation of memory only at discrete times following training and these times vary depending on the strength of the training protocol. Based on this, we propose to examine the role of the cAMP/PKA/CREB signaling pathway in the behavioral effects of sleep deprivation on hippocampus-dependent tasks in mice.
In Specific Aim 1, we will determine the effects of total sleep deprivation as well as rapid eye movement (REM) and non-REM (NREM) sleep deprivation on contextual fear conditioning, a single-trial hippocampus-dependent learning task in mice.
Specific Aim 2 will focus on biochemical and molecular assays to directly measure changes in PKA activity and phospho-CREB levels in the hippocampus after sleep deprivation and contextual fear conditioning.
Specific Aim 3 will investigate the hypothesis that sleep may modulate memory storage through the prominent cholinergic flux to the hippocampus that occurs during REM sleep.
In Specific Aim 4, we will examine sleep architecture in mice with genetic alterations in the cAMP/PKA/CREB signaling pathway to test the hypothesis that memory consolidation deficits in these mice are due to altered patterns of sleep. The broad-based experimental design of this proposal, using genetic, pharmacological, electrophysiological and behavioral approaches, will bring us closer to an understanding of the molecular and biochemical processes underlying sleep and enable us to define the role that sleep plays in memory consolidation.
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