Ubadah Sabbagh's Dissertation Defense (5/11/2021) The development, cytoarchitecture, and circuitry of the ventral lateral geniculate nucleus
Dissertation Defense: The development, cytoarchitecture, and circuitry of the ventral lateral geniculate nucleus
Ubadah Sabbagh
Graduate Student, Virginia Tech Translational Biology, Medicine, and Health
Graduate Research Assistant, Fox Lab, Fralin Biomedical Research Institute at VTC
May 11, 2021 at 1:00 p.m.
About this Dissertation
In the visual system, retinal axons convey visual information from the outside world to dozens of distinct retinorecipient brain regions. In rodents, two major areas that are densely innervated by this retinal input are the dorsal lateral geniculate nucleus (dLGN) and ventral lateral geniculate nucleus (vLGN), both of which reside in the thalamus. The dLGN is well-studied and known to be important for classical image‐forming vision. The vLGN, on the other hand, is associated with non‐image‐forming vision and its neurochemistry, cytoarchitecture, and retinothalamic connectivity all remain unresolved, raising fundamental questions of its role within the visual system. Sabbagh, mentored by Dr. Michael Fox, sought to shed light on these important questions by studying the cellular and extracellular landscape of the vLGN and map its connectivity with the retina. Using in situ hybridization, immunohistochemistry, electrophysiology, and genetic reporter lines, Sabbagh found that the two major laminae of vLGN, the retinorecipient externa`l vLGN (vLGNe) and the non‐retinorecipient internal vLGN (vLGNi) are composed of distinct types of neurons and have distinct extracellular landscapes. In vLGNe, the researchers discovered at least six transcriptionally distinct subtypes of inhibitory neurons that are distributed into distinct adjacent sublaminae. Using trans‐synaptic viral tracing and in vitro electrophysiology, we found that cells in each these sublaminae receive direct inputs from retina. Lastly, by genetically removing this visual input to the vLGN, Sabbagh found that the organization of these sublaminae is dramatically disrupted, suggesting a crucial role for sensory input in the cytoarchitectural maintenance of the vLGN. Taken together, these results not only identify novel subtypes of vLGN cells, but they also point to new means of organizing visual information into parallel pathways – by anatomically creating distinct sensory channels. This subtype-specific organization may be key to understanding how the vLGN receives, processes, and transmits light‐derived signals in the subcortical visual system.
More About the Candidate and Project
Education
Virginia Tech Translational Biology, Medicine, and Health, Ph.D. Candidate
Univerity of Missouri - Kansas City, B.S., Biology
Training
Graduate Research Assistant, Fox Lab, Fralin Biomedical Research Institute at VTC
Mentor
Michael A. Fox, Ph.D., Professor, Fralin Biomedical Research Institute at VTC, and Director, School of Neuroscience, College of Science
Committee Members
- Sarah M. Clinton, Ph.D., Associate Professor, School of Neuroscience, College of Science
- Christopher K. Thompson, Ph.D., Assistant Professor, School of Neurscience, College of Science
- Yuchin Albert Pan, Ph.D., Associate Professor and Commonwealth Research Commercialization Fund Eminent Research Scholar in Developmental Neurosciencem, Fralin Biomedical Research Institute at VTC
Honors
- 30 Under 30, Forbes Magazine
- Young Investigator Award, American Society for Neurochemistry
- Ben Barres Fellow, Cold Spring Harbor Laboratory
- D-SPAN F99/K00 Fellow, NIH
- Early Career Policy Fellow, Society for Neuroscience
- Neuroscience Scholars Fellow, Society for Neuroscience
- Finalist, PD Soros Fellowship for New Americans
Presentations
Poster: Sabbagh U, Govindaiah G, Somaiya RD, Wei JC, Ha RV, Guido W & Fox MA. Diverse GABAergic neurons form subtype-specific sublaminae in the ventral LGN. Gordon Conference on Thalamocortical Interactions. Ventura, CA, US.
Oral: Sabbagh U & Fox MA. Dissecting the Structure and Circuitry of the Ventral LGN. Gordon Conference on Thalamocortical Interactions. Ventura, CA, US.
Poster: Sabbagh U, Wei J, Ha R, & Fox MA. Diverse inhibitory neurons form specialized laminae in the ventral LGN. Society for Neuroscience. Chicago, IL, US.
Poster: Sabbagh U, Monavarfeshani A, & Fox MA. Distribution and development of molecularly distinct perineuronal nets in visual thalamus. Society for Neuroscience. San Diego, CA, US.
Publications
Sabbagh U, Somaiya RD, Fox MA. Development and maintenance of subtype-specific vLGN sublaminae. In prep.
Su J, Liang Y, Sabbagh U, Olejníková L, Russell AL, Pan YA, Triplett JW, Fox MA. A cell-ECM mechanism for connecting the ipsilateral eye to the brain. Under review.
Somaiya RD, Huebschman NA, Chaunsali L, Sabbagh U, Tewari BP, Fox MA. Development of astrocyte morphology and function in the mouse visual thalamus. Under review.
Sabbagh U, Govindaiah G, Somaiya RD, Wei JC, Ha RV, Guido W, Fox MA. (2020). Diverse GABAergic neurons form subtype-specific sublaminae in the ventral LGN. Journal of Neurochemistry. (PMID: 32497303).
Rasmussen R & Sabbagh U#. (2020). Neural Polyamory: One cell forms meaningful connections with hundreds of partners. Cell Systems, 10(5), 381-383. [#corresponding author] (PMID: 32437682).
Su J, Charalambakis NE, Sabbagh U, Somaiya RD, Monavarfeshani A, Guido W, Fox MA. (2020). Retinal inputs signal astrocytes to recruit interneurons into visual thalamus. Proceedings of the National Academy of Sciences. (PMID: 31964831).
Sabbagh U, Monavarfeshani A, Su K, Zabet-Moghadam M, Cole J, Su J, Mirzaei M, Gupta V, Salekdeh GH, Fox MA. (2018). Distribution and development of molecularly distinct perineuronal nets in visual thalamus. Journal of Neurochemistry. (PMID: 30326149).
Monavarfeshani A, Knill CN, Sabbagh U, Su J, Fox MA. (2017). Region-and Cell-Specific Expression of Transmembrane Collagens in Mouse Brain. Frontiers in Integrative Neuroscience. (PMID: 28912695).
Monavarfeshani A, Sabbagh U, Fox MA. (2017). Not a one-trick pony: Diverse connectivity and functions of the rodent lateral geniculate complex. Visual Neuroscience. (PMID: 28965517).
Sabbagh U, Mullegama S, Wyckoff GJ. (2016). Identification and evolutionary analysis of potential candidate genes in a human eating disorder. BioMed Research International, 2016. (PMID: 27088090).
- Trainee Advisory Committee, Society for Neuroscience
- Co-Founder and Board member, Black In Neuro
- Director of Judging, Virginia State Science and Engineering Fair
- Founder, VTC Student Outreach Program; Chair
- Chair, SfN symposium on “Cell type-specific subcortical sensory circuits”