Theses Doctoral

Understanding the molecular, cellular, and circuit defects characterizing the early stages of Alzheimer’s disease

Virga, Daniel Michael

One of the most foundational and personal philosophical questions one can ask is what makes you, you? In large part, you are made up of your relationships, experiences, and memories. The hippocampus, a brain region which is critical for the formation of memories, has been the focus of neuroscience research for decades due partially to this function, which is foundational to our individuality. In Alzheimer’s disease (AD), one of the most common and well-researched neurodegenerative diseases in the world, the hippocampus is one of the earliest targets. Despite extensive work on AD, we still lack a coherent understanding of what is causing the disease, the mechanisms by which it is causing neuronal dysfunction and death within the hippocampus and other brain regions, and how it ultimately causes deficits in cognition and behavior, leading to an erosion of our selves.

In this thesis, I explore three independent but related questions: 1) what molecular mechanisms are causing early synaptic loss in AD, specifically within the hippocampus, 2) what molecular effectors are responsible for establishing and maintaining intracellular architecture in hippocampal neurons, which are exploited in early AD, and 3) how and when does the hippocampal circuit dysfunction in AD progression?

Using a variety of experimental techniques, ranging from in utero and ex utero electroporation, primary murine and human neuronal cell culture, longitudinal confocal microscopy, immunohistochemistry, biochemistry, cell and molecular biology, in vivo two-photon calcium imaging, and behavioral assays, I have found that, within CA1 of the hippocampus, synapse loss requires degradation of the dendritic mitochondrial network, activity and input specificity are driving mitochondrial compartmentalization within CA1 neurons through the same pathway that is aberrantly overactivated in AD, and the hippocampal circuit is overly rigid in encoding the environment as the disease progresses.


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More About This Work

Academic Units
Biological Sciences
Thesis Advisors
Polleux, Franck
Ph.D., Columbia University
Published Here
July 5, 2023