David Marshak, PhD

Email:  [email protected]
Phone:  713-500-5617
Access to CV

Biography

A Primate Retinal Connectome

The long-term goal of our research is a description of neural circuits in the primate retina at the level of synapses between identified populations of neurons, a retinal connectome.  We are now collaborating with the Neitz Laboratory at the University of Washington on a study of the neural circuits that process information from blue cones in macaque retina.  They have imaged serial sections of central macaque retina using serial block-face scanning electron microscopy, and we are working with them to reconstruct the individual neurons and describe their synapses.  We are beginning in the outer plexiform layer, where the rods and cones interact with horizontal cells, inhibitory local circuit neurons.  The rods and cones also provide input to bipolar cells, which convey signals to the inner retina, where their targets include retinal ganglion cells, the projection neurons of the retina.

The focus of this study is on the central retina, where midget bipolar cells and their targets, midget ganglion cells, receive input from a single cone.   The midget ganglion cells are generally thought to mediate the perception of red and green because they receive excitatory input from a single red or green cone and inhibitory input from the surrounding cones.  However, this idea was called into question by a recent psychophysical study.  Using adaptive optics, it was possible to stimulate a single red or green cone at a time in human subjects.  This generally did not give rise to the perception of color; most cones yielded a sensation of white.  Only a few cones seemed to generate color sensations.  Our working hypothesis is that one type of horizontal cell, called H2, conveys information from the blue cones to a subset of midget bipolar cells that, in turn, provide excitatory input to the to a subset of midget ganglion cells that give rise to the sensation of color.  We have seen synapses in the neuropil of the outer plexiform layer, and we are now reconstructing the pre- and post-synaptic neurons to test this hypothesis.  We will also analyze the synaptic output of two types of bipolar cells that selectively contact blue cones.  We are particularly interested in their connections with amacrine cells, inhibitory neurons of the inner retina.  Our working hypothesis is that these amacrine cells also contribute to the perception of color.

Educational Philosophy

I have been very fortunate to spend my entire career teaching graduate and professional students, all very bright and highly motivated to learn.  Most of my efforts have gone toward teaching first year medical students about human anatomy, a topic that they find difficult, but rewarding, to learn.  In the new curriculum, my lectures are now short videos online, and I do my teaching in person in the anatomy laboratory.  I have also promoted active learning by posting quizzes, consisting of 40-50 fill-in-the-blank questions per lecture, on Canvas. I give a traditional lecture on the development of the gastrointestinal system, but it is augmented with videos.

In my research laboratory, we have a very diverse group with training in a wide variety of disciplines, and we collaborate frequently with other investigators using approaches entirely different than ours.  I have been able to achieve my teaching goals in Vision I, where I do not lecture at all. Instead, teams of graduate students make presentations on the topic based on recent scientific papers. I also participate in the Vision Journal Club.

I have trained two Ph.D. students in my laboratory, and they have both been very successful.   The first, Roy Jacoby, is now an assistant professor at Baylor College of Medicine, and the second, Matt Gastinger, is a support manager at Bitplane Scientific Software.  An M.S. student, Alejandro Vila, went on to get a Ph.D. and now represents Olympus in Southern California.  I have also mentored some outstanding postdoctoral fellows at UT Houston.  Elizabeth Yamada, Yongchun Yu and Nobuo Kouyama are now associate professors.  Sally Firth, Hideo Hoshi, Renata Frazao and Hiromasa Satoh are assistant professors.  Ye Long is a researcher at Baylor College of Medicine, Garrett Kenyon is a staff scientist at Los Alamos National Laboratory, Nicolai Larsen is a physician-scientist, and Donna Stafford is an academic administrator.

Area of Expertise

Neuroanatomy
Electron Microscopy
Immunohistochemistry

Research Information

https://med.uth.edu/nba/faculty/david-w-marshak-phd/

Publications

Read my PubMed publications

Publication Information

  • Yu, Y.C., Satoh, H., Wu, S.M. and Marshak, D.W.  Histamine enhances voltage-gated potassium currents of ON bipolar cells in macaque retina.  Investigative Ophthalmology and Visual Science 50, 959-965, 2009.
  • Klump, K. E., Zhang, A.-J. , Wu, S. M., and Marshak, D.W. Parvalbumin-immunoreactive amacrine cells of macaque retina.  Visual Neuroscience 26, 287-296, 2009.
  • Field, G.D., Greschner, M., Gauthier, J.L., Rangel, C., Shlens, J., Sher, A., Marshak, D.W., Litke, A.M. and Chichilnisky, E.J. High sensitivity rod photoreceptor input to the blue-yellow color opponent pathway in macaque retina. Nature Neuroscience 12: 1159-64, 2009.
  • Akimov, N., Marshak, D.W., Frishman, L.J., Glickman R.D. and Yusupov R.G.  Histamine reduces flash sensitivity of ON retinal ganglion cells in primate retina.  Investigative Ophthalmology and Visual Science, 51: 3825-3834, 2010.
  • Yu, Y, Satoh, H. , Vila, A., Wu, S.M., and Marshak, D.W. Effects of histamine on light responses of amacrine cells in tiger salamander retina. Neurochemical Research, 36, 645-654, 2011.
  • Frazão, R., McMahon, D.G., Schunack, W., Datta, P., Heidelberger, R. and  Marshak, D.W.  Histamine elevates free intracellular calcium in mouse retinal dopaminergic cells via H1-receptors.  Investigative Ophthalmology and Visual Science, 52, 3083-3088, 2011.
  • Logan J.M., Thompson, A.J. and Marshak, D.W. Testing to enhance retention in human anatomy. Anatomical Sciences Education, 5,243-248, 2011.
  • Vila, A., Satoh, H.,  Rangel, C.,  Mills, S.L.,  Hoshi, H.,  O’Brien, J., Marshak, D.R., MacLeish, P.R. and Marshak, D.W.  Histamine receptors of cones and horizontal cells in Old World monkey retinas. Journal of Comparative Neurology, 520, 528-543, 2012.
  • Bordt AS, Perez D, Tseng L, Liu WS,  Neitz J, Patterson SS, Famiglietti EV and Marshak DW. Synaptic inputs from identified bipolar and amacrine cells to a sparsely branched ganglion cell in rabbit retina. Visual Neuroscience, 36:E004, 2019. PMID: 31199211.
  • Patterson SS, Kuchenbecker JA, Anderson JR, Bordt AS, Marshak DW, Neitz M and Neitz J.  An S-cone circuit for edge detection in the primate retina.  Scientific Reports 9:11913, 2019.  PMID: 31417169
  • Patterson SS, Bordt AS, Girresch RJ, Linehan CM, Bauss J, Yeo E, Perez D, Tseng L, Navuluri S, Harris NB, Matthews C, Anderson JR, Kuchenbecker JA, Manookin MB, Ogilvie JM, Neitz J, and Marshak DW.  Wide-field amacrine cell inputs to ON parasol ganglion cells in macaque retina. Journal of Comparative Neurology  2019 Dec 17. [Epub ahead of print]  PMID: 31845339.

I have been teaching human anatomy to the first-year medical students since I arrived here in 1984. My other educational efforts include: founding and directing the Electron Microscopy course for graduate students, being Principal Investigator of a training grant to provide research experience in neuroscience to medical students, conducting educational research and serving as codirector of the Musculoskeletal and Dermatology Module  for the second-year medical students. In addition to imparting knowledge to medical and graduate students, I am continually trying to improve my own skills as a teacher and mentor.

Educational Honors and Awards

  • 2009-16, 2018 Dean’s Teaching Excellence Award
  • 2010 Best Lecturer in Gross Anatomy, University of Texas Medical School
  • 2013 Academy of Master Educators, University of Texas Medical School at Houston
  • 2016 University of Texas Regents’ Outstanding Teaching Award

Educational Service on the University of Texas Health Science Center Committees

  • Summer Research Program for Undergraduates, Neuroscience Program Representative 1988-present
  • Graduate School of Biomedical Sciences, Academic Standards Committee 1990-1993
  • Review committee for the 2018 UTHealth GSBS Dissertation Award 2018

Teaching Responsibilities

  • Human Gross Anatomy 1984-2015
  • Neuroscience 1986-1988
  • Developmental Anatomy 1987, 1994
  • Fundamentals of Clinical Medicine, facilitator 1994-1995
  • Anatomy and Oncology for Medical Physics 1997-1998
  • Anatomy Dissection (MS4 elective)2009-present
  • Systems Neurobiology 1991, 1998-2000
  • Cellular Neurobiology 1990-1997
  • Vision I 1987-present
  • Vision II 1994
  • Neurochemistry 1986-1988
  • Principles and Techniques of Electron Microscopy 1985-1992
  • Current Topics in Neuroscience 1997-2011
  • Seminars in Neuroscience 2006-2011
  • Systems Neuroscience 2010
  • Module Director, Musculoskeletal and Dermatology 2014-present
  • Developmental Anatomy 2015-2017
  • Foundations of Medical Science 2016-present

Educational Grant Support

  • Teagle Foundation Subcontract (Principal Investigator, Jessica Logan)
    1. Implementing and evaluating distributed practice and self-testing in the classroom
    2. Grant number: R03032
    3. Period of support: July 1, 2008 to June 30, 2011
    4. Total direct costs: $45,468
  • National Institute of Neurological Diseases and Stroke Training Grant (Principal Investigator)
    1. Title: Short term training in neuroscience
    2. Grant number: NS064931
    3. Period of support: July 1, 2009 to June 30, 2014
    4. Total direct costs: $157,350

Refereed Original Articles in Education Journals

  • Logan J.M., Thompson, A.J. and Marshak, D.W. Testing to enhance retention in human anatomy. Anatomical Sciences Education, 5, 243-248, 2011.
  • Marshak, D.W., Oakes, J., Hsieh, P-H., Chuang, A.Z. and Cleary, L.J.  Outcomes of a  Rotational Dissection System in Gross Anatomy. Anatomical Sciences Education, 8, 438-44, 2015.