Project Summary/Abstract As the most common neurodegenerative disease of dementia, Alzheimer’s disease (AD) causes progressive memory loss and cognitive impairment. AD has neither a clear pathogenesis nor effective treatments. Its progression is marked by loss of neurons at the time of diagnosis. The proximal causes of this loss are not well understood. Nevertheless, neuronal loss follows loss of synapses, and earlier loss of synaptic function is a leading aspect of the disease. My goals are to gain expertise in modern principles and understanding of AD and animal models of AD from lectures, from access to our graduate training program in AD research and from my highly skilled mentoring team. I will use those skills to aid my research into the role of the synapse in AD. Based on preliminary data that loss of synaptic function in humanized APOE4 mouse models at excitatory synapses in the hippocampus, I propose that a critical factor in synaptic transmission is presynaptic Ca2+ signaling and homeostasis. Amongst, the first brain regions to be affected in AD patients is the hippocampus, a critical brain area for cognition and memory and we and others have observed APOE subtype dependent changes in evoked plasticity in hippocampal synaptic transmission. I propose to use high spatiotemporal resolution approaches to imaging synaptic transmission and presynaptic signal transduction. However, dynamic imaging of these events means that continuous irradiation causes photodamage and phototoxicity. For my research program and to overcome this problem, I have used my physics background to build a light sheet instrument, called lattice light-sheet (LLS) using the approach developed by Eric Betzig 1, that uses a linearly polarized sheet of light with a binary phase map of Bessel beams to form optical lattices which markedly increases the axial resolution to ~400 nm. It allows extremely fast image acquisition (up to 1 KHz frame rates) and minimal phototoxicity. Using the LLS microscope, I can resolve fast components of synaptic transmission, including neurotransmitter release. I have also developed a novel approach for LLS imaging of incoherent holography to scan the sample volume without moving the detection objective. This enables an increase in axial resolution and allows me to visualize intact neural tissue, with access to quantitative information of samples being imaged. Using the training possible through this K25 program I will now interrogate synaptic dysfunction in presynaptic terminals for its role in neurogenerative disorders, such as Alzheimer disease. I will combine my imaging expertise and resources that I have built in the Alford laboratory with the expertise and availability of mouse models of neurodegeneration available from my mentors, Drs Tai and Lazarov along with circuit expertise in the Tseng laboratory to understand loss of synaptic function associated with neurodegenerative disease. This provides the foundation for my training, adding ...