Faculty Directory
John B. Troy

Professor Emeritus of Biomedical Engineering


2145 Sheridan Road
Tech E372
Evanston, IL 60208-3107

Email John Troy


Biomedical Engineering


Ph.D. Experimental Psychology, University of Sussex, East Sussex, England, UK

B.Sc. Biology with Physics, University of London King's College, London, England

Fellow, AIMBE

Research Interests

Professor Troy has been engaged in neuroscience research for more than 30 years, starting with his doctoral work studying visual signal processing by neurons of the cat lateral geniculate nucleus. He has continued throughout his career to investigate the functional properties of neurons of the retina and lateral geniculate nucleus of cat, monkey, mouse and rat. He has also investigated how different classes of retinal ganglion cell tile the retina. The underlying theme of this work has been to arrive at a full quantitative description of how retinal ganglion and lateral geniculate cells encode visual information in mammals, including the human being. Recently, Dr. Troy has expanded this effort to consider how the retina changes in disease states and what can be done to retard or reverse these changes. He has been collaborating with Dr. Xiaorong Liu in a study of ocular hypertension. Using a mouse model of glaucoma, they are investigating the progression of the disease and some drug treatments that might be effective in delaying or halting its progression.

More recently, Dr. Troy has expanded his interest to include technology development that can be used either to restore neural function or to assist neuroscience research, including the development of therapeutic agents. His laboratory has provided insight into how stimulus waveforms can be shaped to minimize tissue and electrode damage during electrical stimulation. It has developed and tested the effectiveness of nanoscale tipped electrodes for recording extracellular action potentials from mammalian axons in vivo. Since feasibility of nanoscale tips for neural recording has been established, one of the remaining challenges is to customize these tips to reduce impedance and improve recording signal over noise. His laboratory has also developed a new version of the patch clamp electrode which should permit longer term stable recordings of higher bandwidth than existing models. A variant of the system has been developed to avoid run-down of diffusible cytoplasmic compounds, ensuring a more physiological recording situation. The Troy laboratory has also been collaborating with Dr. Laxman Saggere and his students to develop a chemical neural prosthesis for diseases of photoreceptor degeneration. Under ideal conditions, this prosthesis would be implanted in the subretina following photoreceptor degeneration. If this can be accomplished, advantage can be made of the surviving retinal circuitry. One of the major challenges faced is to engineer a device that is flexible, photoactivated and which can incorporate a sufficiently large reservoir of neurotransmitter. This device is targeted for patients with the incurable diseases retinitis pigmentosa and age-related macular degeneration, with incidences of 1-2 and 20-25 million. Finally, Dr. Troy has recently begun a new project to develop a thalamic visual prosthesis. The goal is to implant electrodes into the lateral geniculate nucleus bilaterally to treat patients blinded through glaucoma, optic neuritis or bilateral eye loss. There are 60 million worldwide with glaucoma, 2-5 million with optic neuritis and 2 million with bilateral eye loss. There are many significant engineering challenges to this project, ranging from biocompatibility of the implant to safe charge injection regimens to mechanical mismatch between the electrode materials and brain tissue.



Selected Publications


  1. Feng, L., Puyang, Z., Chen, H., Liang, P.-J., Troy, J.B. and Liu, X. (2017) Overexpression of brain-derived neurotrophic factor protects large retinal ganglion cells following optic nerve crush in mice. eNeuro4 e0331-16.2016 1–8.
  2. Puyang, Z., Gong, H.-Q., He, S.-G. Troy, J., Liu, X. and Liang, P.-J. (2017) Different functional susceptibilities of mouse retinal ganglion cell subtypes to optic nerve crush injury. Experimental Eye Research 162 97-103.
  3. Rountree, C.M., Inayat, S., Troy, J.B. and Saggere, L. (2016) Differential stimulation of the retina with subretinally injected exogenous neurotransmitter: A biomimetic alternative to electrical stimulation. Scientific Reports6 38505.
  4. Feng, L., Chen, H., Yi, J., Troy, J.B., Zhang, H.F. and Liu, X. (2016) Long-term protection of retinal ganglion cells and visual function in mice with ocular hypertensionInvestigative Ophthalmology and Visual Science 57 3793-3802.
  5. Nguyen, H.T., Tangutooru, S.M., Rountree, C.M., Kantzos, A.J., Tarlochan, F., Yoon, W.J. and Troy, J.B. (2016) Thalamic visual prosthesis. IEEE Transactions on Biomedical Engineering 63 1573-1580.
  6. Puyang, Z., Feng, L., Liang, P.-J., Troy, J.B. and Liu, X. (2016) Retinal ganglion cell loss is delayed following optic nerve crush in NLRP3 knockout mice. Scientific Reports 6 20998.
  7. Troy, J.B. (2015) Visual Prostheses: Technological and Socioeconomic Challenges. Engineering 1 288-291. 
  8. Inayat, S., Rountree, C.M., Troy, J.B. and Saggere, L. (2015) Chemical stimulation of rat retinal neurons: Feasibility of an epiretinal neurotransmitter-based prosthesis. Journal of Neural Engineering 12 016010.
  9. Chen, H., Zhao, Y., Liu, M., Feng, L., Puyang, Z., Liang, P., Zhang, H.F., Cang, J., Troy, J.B. and Liu, X. (2015) Progressive degeneration of retinal and superior collicular function in ice with sustained ocular hypertension. Investigative Ophthalmology and Visual Science 56 1971-1984.
  10. Feng, L., Zhao, Y., Yoshida, M., Yang, J., Kim, T.D., Cang, J., Troy, J.B. and Liu, X. (2013) Sustained Ocular Hypertension Induces Dendritic Degeneration of Mouse Retinal Ganglion Cells that Depends on Cell-type and Location. Investigative Ophthalmology and Visual Science 54 1106-1117.
  11. Inayat, S., Pinto, L.H. and Troy, J.B. (2013) Minimizing Cytosol Dilution in Whole-Cell Configuration for the Patch-Clamp Technique. IEEE Transactions on Biomedical Engineering60 2042-2051.
  12. Hore, V.R.A., Troy, J.B. and Eglen, S.J. (2012) Parasol cell mosaics are unlikely to drive the formation of orientation pinwheels in primary visual cortex. Visual Neuroscience 29 283-299.
  13. Inayat, S., Zhao, Y., Cantrell, D.R., Dikin, D.A., Pinto, L.H. and Troy, J.B. (2010) A novel way to go whole-cell in patch-clamp experiments. IEEE Transactions on Biomedical Engineering 57 2764-2770.
  14. Zhao, Y., Inayat, S., Dikin, D.A., Ruoff, R.S. and Troy, J.B. (2010) Impedance characterization and modeling of an improved patch clamp device. Proceedings of the Institution of Mechanical Engineers, Part N: Journal of Nanoengineering and Nanosystems 223 121-131.
  15. Cantrell, D.R., Cang, J., Troy, J.B. and Liu, X. (2010) Non-centered spike-triggered covariance analysis reveal neurotrophin-3 as a developmental regulator of receptive field properties of ON-OFF retinal ganglion cells. PLoS Computational Biology 6 e1000967.
  16. Passaglia, C.L., Freeman, D.K. and Troy, J.B. (2009) Effects of remote stimulation on the modulated activity of cat retinal ganglion cells. Journal of Neuroscience 29 2467-2476.
  17. Cantrell, D.R., Inayat, S., Taflove, A., Ruoff, R.S. and Troy, J.B. (2008) Incorporation of the electrode-electrolyte interface into finite element models of metal microelectrodes.  Journal of Neural Engineering5 54-67 (cover picture).
  18. Maddox, D.M., Vessey, K.A., Yarbrough, G.L., Invergo, B.M., Cantrell, R.D., Inayat, S., Troy, J.B., Balannik, V., Hicks, W.L., Hawes, N.L., Byers, S., Smith, R.S., Hurd, R., Howell, D., Gregg, R.G., Chang, B., Naggert, J.K., Pinto, L.H., Nishina, P.M. and McCall, M.A. (2008) Allelic variance between metabotropic glutamate receptor 6 mutants, Grmnob3 and Grmnob4 results in differences in retinal ganglion cell visual responses. Journal of Physiology586.18 4409-4424.
  19. Crook, J.D., Peterson, B.B., Packer, O,S., Robinson, F.R., Troy, J.B. and Dacey, D.M. (2008) Y-cell receptive field and collicular projection of parasol ganglion cells in macaque monkey retina. Journal of Neuroscience28 11277-11291.
  20. Crook, J.D., Peterson, B.B., Packer, O.S., Robinson, F.R., Gamlin, P.D., Troy, J.B. and Dacey, D.M. (2008) The smooth monostratified ganglion cell: evidence for spatial diversity in the Y-cell pathway to the LGN and superior colliculus in the macaque monkey. Journal of Neuroscience 28 12654-12671.
  21. Zhao, Y., Inayat, S., Dikin, D.A., Singer, J.H., Ruoff, R.S. and Troy, J.B. (2008) Patch Clamp Technique: Review of the Current State of the Art and Potential Contributions from Nanoengineering. Proceedings of the Institution of Mechanical Engineers, Part N: Journal of Nanoengineering and Nanosystems222 1-11.