T32 Research Alumni

PhD Thesis Advisor: Linda McLoon, PhD

Area of Research: Dr. Johnson’s thesis research focused understanding the potential molecular basis for infantile nystagmus syndrome, a condition characterized by continuous, uncontrolled eye oscillations that have a significant impact on visual acuity. Dr. Johnson tested several mouse strains and was the first to demonstrate that a muscle-specific mutation could result in nystagmus.

Scientific Interests: Dr. Johnson focused on potential, previously unidentified genes that control either the onset or maintenance of infantile nystagmus syndrome. Using RNA-seq technology, she focused on using a novel combinatorial approach to uncover possible genes involved in the etiology of infantile nystagmus syndrome.

Current Position: Research Fellow, Department of Ophthalmology, Boston’s Children/Harvard Medical School, Boston, MA.

Peer-reviewed Publications:

Johnson LL, Abrahante JE, McLoon LK. Comparative RNA-seq analysis of the extraocular muscles and innervating motor neurons in C57Bl/6 and albino mice. Mol Vis. 2026:32:in press.

Winker AJ, Johnson LL, McLoon LK. Effects of glial cell line-derived neurotrophic factor and ciliary neurotrophic factor on extraocular and limb muscle precursor cells. PMC13076467. J Histochem Cytochem. 2026 Jul-Aug;74(4):435-448.

Winker AJ, Johnson LL, Jadhav R, Nguyen C, Hitch E, McLoon LK. Effects of fibroblast growth factor 2 on muscle precursor cells from mouse limb and extraocular muscles. PMC12952651. PLoS One. 2026; 21(2): e0331355.

Winker AJ, Johnson LL, Jadhav R, Nguyen C, Hitch E, McLoon LK. Effects of fibroblast growth factor 2 on muscle precursor cells from mouse limb and extraocular muscles. bioRxiv preprint doi: https://doi.org/10.1101/2025.08.17.670754.

Narasimhan A, Min SH, Johnson LL, Roehrich H, Her T, Kelly RO, Angelini L, Yousefzadeh M, McLoon LK, Hauswirth WW, Niedernhofer LJ. The Ercc1^-/Δ mouse model of XFE progeroid syndrome undergo accelerated retinal degeneration. PMID: 39604117. Aging Cell, 2024; Nov 27:e14419.

Johnson LL, Abrahante JE, McLoon LK. Nystagmus in the B6(CG)Tyr(c-2J)/J albino mouse: A functional and RNA-seq analysis. PMC10787582. Invest Ophthalmol Vis Sci. 2024 Jan 2;65(1):26.

Johnson LL, Hebert S, Kueppers RB, McLoon LK. Nystagmus associated with the absence of MYOD expression across the lifespan in extraocular and limb muscles. PMC10503593. Invest Ophthalmol Vis Sci. 2023 Sep 1;64(12):24.

PhD Thesis Advisor: Harald Junge, PhD

Area of Research: Dr. Levey’s thesis research focused on understanding the molecular control of blood-brain and blood-retinal vasculature development.

Research Interests: Dr. Levey focused her thesis research on understanding the molecular control for maintaining the blood-retinal barrier, which is essential to maintain a healthy retina. She specifically examined the role of the Norrin/Frizzled4 signaling pathway, and the ability of specific members of this pathway to restore normal blood-retinal barrier function in an animal model.

Current Position: Postdoctoral fellow, Department of Cell Biology and Neuroscience, Rutgers-New Brunswick, New Brunswick, NJ.

Peer-Reviewed Publications:

Jo HN, Kiffmeyer E, Zhang C, Zhang L, Odame E, Dinh QC, Levey J, Howe M, Roux KJ, Fischer KD, Chen Z, Junge HJ. The calcium pump ATP2B1/PMCA1 regulates CNS vascular development by facilitating Norrin- and WNT7A/B-induced Frizzled4 signaling. PMC13469879. Cell Rep. 2026;45(7):117605.

Levey JE, Abedin Md, Zhang C, Odame E, Zhang L, Jo H-N^1,2, Douglas K, Chen Z, Junge HJ. The MDM2-p53 axis regulates norrin/frizzled4 signaling and blood-CNS barrier function. PMC1228884. Sci Signal. 2025 Jul 8;18(894):eadt0983.

Zhang L, Levey J, Abedin Md, Jo H-N, Odame E, Douglas K, Thoreen E, McPherson SW, Roehrich H, Seshagiri S, Angers S, Chen Z, Junge HJ. C1q limits cystoid edema by maintaining basal beta-catenin dependent signaling and blood-retina barrier function. PMC12643494. JCI Insight. 2025 Oct 14;10(22):e190227.

Zhang L, Abedin M, Jo HN, Levey J, Dinh QC, Chen Z, Angers, S, Junge HJ. A Frizzled4-LRP5 agonist promotes blood-retina barrier function by inducing a Norrin-like transcriptional response. PMC10407957.  iScience. 2023;26(8):107415.

PhD Thesis Advisor: Gordon Smith, PhD.

Area of Research: Dr. Kettlewell’s thesis research focused on the spatial and temporal development of the visual cortex, with a particular focus on potential mechanisms that allow for developmental plasticity.

Research Interests: Dr. Kettlewell examined how brain circuits process sensory information during the course of development, specifically looking at the visual system. How do these develop and what goes wrong when there are neurodevelopmental disorders that results in visual system deficits? Dr. Kettlewell looked at large populations of neurons to try to understand the complex mechanisms that control normal function during the development of visual processing.

Current Position: Human Factors Engineer & UX, Consultant

Peer-Reviewed Publications:

Kettlewell L, Sederberg A, Smith G. Stereotyped spatiotemporal dynamics of spontaneous activity in visual cortex. Prior to eye opening. PMC12160389. J Neurosci. 2025;Apr 22:e1420242025.

PhD Thesis Advisor: Linda McLoon, PhD.

Area of Research: Dr. Winker’s thesis research focused on understanding the unique properties of the extraocular muscles that allow them to be preferentially spared in specific skeletal muscle degenerative disorders such as Duchenne muscular dystrophy.

Research Interests: the potential molecular control of the dynamic properties of the muscle precursor cells within the extraocular muscles

Current Position:  Freelance science writer, Boston

Peer-Reviewed Publications:

Winker AJ, Johnson LL, McLoon LK. Effects of glial cell line-derived neurotrophic factor and ciliary neurotrophic factor on extraocular and limb muscle precursor cells. PMC13076467. J Histochem Cytochem. 2026 Jul-Aug;74(4):435-448.

Winker AJ, Johnson LL, Jadhav R, Nguyen C, Hitch E, McLoon LK. Effects of fibroblast growth factor 2 on muscle precursor cells from mouse limb and extraocular muscles. PMC12952651. PLoS One. 2026; 21(2): e0331355.

PhD Thesis Advisors: Michael-Paul Schallmo, PhD and Stephen Engel, PhD

Area of Research: Dr. Montoya’s thesis research focused on characterizing differences in visual perception in a condition called visual snow syndrome. Visual snow syndrome is a chronic brain disorder that affects how visual information is processed, and the disorder is characterized by continual flickering of dots across the entire visual field.

Research Interests: The impact on visual snow syndrome on visual perception is not well understood. Dr. Montoya focused on how individuals afflicted with visual snow syndrome perceive the world. Her studies developed a novel method to study this condition, as well as increased our understanding of factors that might reduce its visual effects. Additional studies examined visual perception in individuals with psychosis.

Current Position: Postdoctoral Fellow, University of Pennsylvania

Peer-Reviewed Publications:

Nie S, Montoya SA, Schallmo MP, Engel SA. Perception of visual noise patterns depends on correlations produced in V1: A simulation study. J Vis. 2026;26:10. doi: 10.1167jov26.10.10.

Montoya SA, Moser HR, Kamath RS, Chong LS, Grant AN, Marjańska M, Sponheim SR, Engel SA, Olman CA, Schallmo MP. Center-surround processing in psychosis. Biol Psychiatry Cogn Neurosci Neuroimaging. 2026; Mar 30:S2451-9022(26)00089-3.

Sheldon AA, Moser HR, Abdullahi KS, Allison KD, Mulder CB, Montoya SA, Sponheim SR, Marjańska M, Schallmo MP. Aperiodic slope reflects glutamatergic tone in the human brain. Brain Res. 2026;1874:150161.

Montoya SA, Hillstrom AJ, Allison KD, Mulder CB, Moser HR, Lee MS, Schallmo MP, Engel SA. Visual snow is susceptible to the motion aftereffect. Invest Ophthalmol Vis Sci. 2025;66:23.

Montoya SA, Mulder CB, Allison KD, Lee MS, Engel SA, Schallmo MP. What does visual snow look like? Quantification by matching a simulation. J Vis. 2024 Jun 3;24(6):3.

Kamath RS, Weldon KB, Moser HR, Montoya S, Abdullahi KS, Burton PC, Sponheim SR, Olman CA, Schallmo MP. Impaired contour object perception in psychosis. Biol Psychiatry Cogn Neurosci Neuroimaging. 2024 Dec 16:S2451-9022(24)00378-1.

Montoya SA, Mulder CB, Lee MS, Schallmo MP, Engel SA. Adapting to visual noise alleviates visual snow. Invest Ophthalmol Vis Sci. 2023 Dec 1;64(15):23.

PhD Thesis Advisor: Deborah Ferrington, PhD

Area of Research: Dr. Fisher’s PhD thesis research focused on understanding the role of mitochondria in the etiology and progression of age-related macular degeneration.

Research Interests: Dr. Fisher’s thesis research focused on how failures in mitochondrial homeostasis may lead to an accumulation of damaged and dysfunctional mitochondria, a hallmark of pathology in age related macular degeneration (AMD). He examined mitochondrial form and function in primary cultures of pigment epithelial cells (RPE) from human donors. He also studied autophagy in mouse RPE, with an emphasis on Akt and mTOR signaling, as the autophagy pathways have direct links to AMD in human RPE, where dysfunctional autophagy has been reported. Determining which step of mitochondrial homeostasis is defective will allow for future development and investigation of therapeutics that have the potential to prevent or delay vision loss early in disease

Current Position: Senior Clinical Evidence Specialist, Medtronic

Peer-Reviewed Publications:

Fisher CR, Shaaeli AA, Ebeling MC, Montezuma SR, Ferrington DA. Investigating mitochondrial fission, fusion, and autophagy in retinal pigment epithelium from donors with age-related macular degeneration. Sci Rep. 2022;12(1):21725.

Ebeling MC, Fisher CR, Kapphahn RJ, Stahl MR, Shen S, Qu J, Montezuma SR, Ferrington DA. Inflammasome activation in retinal pigment epithelium from human donors with age-related macular degeneration. Cells. 2022;11(13):2075.

Fisher CR, Ebeling MC, Geng Z, Kapphahn RJ, Roehrich H, Montezuma SR, Dutton JR, Ferrington DA. Human iPSC- and primary-retinal pigment epithelial cells for modeling age-related macular degeneration. Antioxidants (Basel). 2022;11(4):605.

Fisher CR, beling MC, Ferrington DA. Quantification of mitophagy using mKeima-mito in cultured human primary retinal pigment epithelial cells. Exp Eye Res. 2022;217:108981.

Ferrington DA, Fisher CR, Kowluru RA. Mitochondrial defects drive degenerative retinal diseases. Trends Mol Med. 2020;26(1):105-118. PMC6938541.

Karim MR*, Fisher CR^*, Kapphahn RJ, Polanco JR, Ferrington DA. Investigating AKT activation and autophagy in immunoproteosome-deficient retinal cells. PLoS ONE. 2020;15(4):e0231212. ^*Co-first author. PMC7147741.

Terluk M, Ebeling M, Fisher CR, Kapphahn R, Yuan C, Kartha RV, Montezuma SR, Ferrington DA. N-acetyl-L-cysteine protects human retinal pigment epithelial cells from oxidative damage: Implications for age-related macular degeneration. Oxid Med Cell Longev. 2019;Aug 14:5174957. PMC6710748.

PhD Thesis Advisor: Yasushi Nakagawa PhD

Area of Research: Dr. Monko’s research focused on understanding the intrinsic molecular mechanisms that control thalamic development and the roles of thalamic input in neocortical development.

Research Interests: The thesis research of Dr. Monko focused on how sensory-specific input regulates development in primary sensory areas of the mouse neocortex area-specific axonal projections from the mammalian thalamus crucially shape unique cellular organization in target neocortical areas in the adult brain. Whether and how these axons organize the mature neocortical cytoarchitecture by controlling neurogenesis and early cell fate specification is poorly understood. He showed that mutant mice lacking the majority of thalamocortical axons have a reduced number of superficial-layer neurons in primary sensory areas of the postnatal brain. Furthermore, thalamic afferents enhance embryonic neurogenesis and promote layer four fate by the neonatal stage. Finally, he identified VGF, a neuropeptide specifically expressed by sensory thalamic nuclei, as a molecule that regulates neonatal establishment of laminar fate. In summary, these studies revealed that extrinsic cues from sensory thalamic projections have an early role in the formation of areal cytoarchitecture by enhancing the production and specification of layer 4 neurons. For the remainder of his thesis research, he studied the unique interplay between thalamocortical axons, microglia, and neurogenesis in developing sensory cortical areas.

Current Position: napari – manager, software development; Augsburg University, Instructor (parttime)

Peer-Reviewed Publications:

Monko T, Rebertus J, Stolley J, Salton SR, Nakagawa Y. Thalamocortical axons regulate neurogenesis and laminar fates in the early sensory cortex. Proc Natl Acad Sci USA 2022 May 31;119(22):e2201355119. PMC9295754.