Exploring Alzheimer’s Disease Through Microcircuits: A Summer of Discovery at Johns Hopkins

Written by: Sebastian Zamarripa

I am so excited to share the work I’ve gotten the opportunity to collaborate on here at The Johns Hopkins University this summer. As a continuing member of the Kuchibhotla lab in the department of Psychological and Brain Sciences, I have progressed through several key cellular and molecular components of an upcoming project centered on inhibitory/disinhibitory microcircuits, and their disruption or modulation in Alzheimer’s Disease (AD).

a micrograph of a mouse hippocampus treated via Immunohistochemistry to stain for Parvalbumin-expressing (PV+) inhibitory interneurons.
A micrograph of a mouse hippocampus treated via Immunohistochemistry to stain for Parvalbumin-expressing (PV+) inhibitory interneurons. 

So far, I’ve learned to conduct important molecular and cellular assays on mouse models of AD such as tissue immunohistochemistry (IHC) and imaging, as well as a novel RNA Multiplexed Fluorescence In-Situ Hybridization. This is important as understanding transcriptomic changes in microcircuits of AD model mice can give insight as to the molecular factors that influence dementia or cognitive decline. Setting up strong objectives and key results (OKR’s) to monitor in advance has helped me make the most of my time here during the summer. I have been able to open myself up to asking more questions to other lab-mates and learning as much as I possibly can. For example, an illuminating conversation with a lab-mate specializing in in-vivo two photon imaging has opened the door for me to begin training for such protocols in the fall. This is crucial because the next step in our project will be to outline the behavioral impacts of the molecular changes we observe in AD mice, and potentially discern a mechanism for the selective retrieval of auditory-based memories often seen in patients of AD whom experience breaks of lucidity with auditory cues, like music.

Sebastian Zamarripa in his AD lab
Sebastian using the same fluorescent microscope (Zeiss Axio-observer) to collect images of the mouse Auditory Cortex. This was to confirm successful viral-induced expression of calcium-sensitive fluorescent protein gCAMP6 and to colocalize that signal with fluorescently immunolabeled VIP+ (Vasoactive Peptide-expressing) interneurons. This essentially ensured our Adeno-associated virus (AAV) injection worked properly and selectively drove gCAMP6 expression in VIP+ interneurons alone. 

Overall, I am grateful for the work and learning I’ve done this summer, but even more excited about what the future holds as I dive further into this project!

By Life Design Lab
Life Design Lab