My doctoral dissertation research integrates virology, genetics, and neurobiology with the aim of creating novel neural circuitry tracers. While general information flow in the retina from photon detection to action potentials through the optic nerve has been relatively well characterized, synaptic communication remains rather poorly understood. The dissection of this circuitry requires neuronal tracers that have the ability to label cells that are synaptically connected. Historically, neural tracers such as wheat germ agglutinin (WGA), nanobeads, and fluorescent dyes have aided this investigation. These reagents have the inherent limitations of dilution and questionable tracer specificity. These problems can be obviated either by creating a genetic model in which each cell in a circuit produces the tracer, or by using viruses, which are self- replicating entities. Using the murine retina, I aim to develop new tracing methods capable of labeling distinct circuit types in vivo. I will first develop a tool that permits viral Infection in small populations of a chosen cell type. Employing the specificity of the TVA/ASLV-A Interaction used by Wickersham and colleagues, a modified rabies virus containing the ASLV-A extracellular domain will be used to target specific TVA-expressing amacrine cells using this tool. The synaptic connectivity of these cells can be verified by physiological analyses. Lastly, using the rabies virus glycoprotein as a template, I will design a retrograde tracer that labels entire circuits permanently and specifically. Containing both Cre and GFP, it will have capabilities similar to viral transsynaptic tracers without the deleterious effects of metabolic alterations. This research will provide neuroscientists with a new tool for examining lineage tracing and two novel, distinct methods for tracing neuronal circuits in the CNS that will provide synaptic connectivity information in neural circuits, and will shed light on the relatively simple yet elegant circuitry of the retina. Fixing problems associated with aberrant neural circuitry, such as memory loss, blindness, and neurodeneratlon requires a fundamental understanding of the normal activites of these circuits. Therefore, by creating a tool to better dissect circuitry, my goal is to help elucidate the vastness of cognitive computation and the pathologies associated with abnormal circuitry function.

National Institute of Health (NIH)
National Institute of Neurological Disorders and Stroke (NINDS)
Predoctoral Individual National Research Service Award (F31)
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Special Emphasis Panel (ZRG1-F05-C (20))
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Gnadt, James W
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Harvard University
United States
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Jiang, Han; Wang, Lingyan; Beier, Kevin T et al. (2013) Lineage analysis of the late otocyst stage mouse inner ear by transuterine microinjection of a retroviral vector encoding alkaline phosphatase and an oligonucleotide library. PLoS One 8:e69314
Beier, Kevin T; Borghuis, Bart G; El-Danaf, Rana N et al. (2013) Transsynaptic tracing with vesicular stomatitis virus reveals novel retinal circuitry. J Neurosci 33:35-51
Hafler, Brian P; Surzenko, Natalia; Beier, Kevin T et al. (2012) Transcription factor Olig2 defines subpopulations of retinal progenitor cells biased toward specific cell fates. Proc Natl Acad Sci U S A 109:7882-7
Beier, Kevin T; Saunders, Arpiar; Oldenburg, Ian A et al. (2011) Anterograde or retrograde transsynaptic labeling of CNS neurons with vesicular stomatitis virus vectors. Proc Natl Acad Sci U S A 108:15414-9
Beier, Kevin T; Samson, Maria Elena S; Matsuda, Takahiko et al. (2011) Conditional expression of the TVA receptor allows clonal analysis of descendents from Cre-expressing progenitor cells. Dev Biol 353:309-20