Robert G. Smith, Ph.D

faculty photo
Adjunct Associate Professor of Neuroscience
Department: Neuroscience
Graduate Group Affiliations

Contact information
Department of Neuroscience
Rm 130, John Morgan Bldg
University of PA School of Medicine
422 Curie Blvd.
Philadelphia, PA 19104
Office: 215-573-3211
- (Biology)
Haverford College, 1971.
University of Pennsylvania, College of General Studies, 1982.
Ph.D. (Neuroscience)
University of Pennsylvania, 1989.
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Description of Research Expertise

RESEARCH INTERESTS: Understanding how the structure, biophysical properties, and synaptic connections of a neuron influence its signal processing function within the surrounding neural circuit.

RESEARCH TECHNIQUES: Analysis of the role of synaptic and biophyical properties, morphology, and noise in a neural circuit's performance. Electrophysiological recordings. Computer simulation of neural circuitry. Ideal observer analysis of neural circuit performance.

RESEARCH SUMMARY: My laboratory studies how retinal circuitry processes visual signals. We analyze what is known about a circuit, construct a biophysically realistic model of it, and through simulation attempt to reconcile the circuit's known physiological properties with the function of its neural components. This allows us to suggest a functional interpretation for biophysical features such as dendritic branching, density of voltage-gated membrane channels, and specific location, strength, and properties of synaptic inputs. Including the noise properties of membrane channels and synaptic vesicle release, we generate realistic noise properties that we compare directly with recordings from live neurons. We currently study 4 circuits: 1) the cone photoreceptor to horizontal cell network, 2) the pathway from rod photoreceptors to ganglion cells used during dark adaptation, 3) the brisk-transient (alpha) ganglion cell, its spike generator, and its presynaptic circuitry, and 4) the direction-selective ganglion cell and the starburst amacrine network that shapes its responses.

Description of Other Expertise

Programming skill in the C and C++ programming languages, numerical integration. Analog and digital electronics design.

Selected Publications

Wu W, Kim YJ, Dacey DM, Troy JB, Smith RG: Two mechanisms for direction selectivity in a model of the primate starburst amacrine cell. Vis Neurosci 40: E003, May 2023 Notes:

Huang X, Kim AJ, Ledesma HA, Ding J, Smith RG, Wei W. (2022) : Visual stimulation induces distinct forms of sensitization of On-Off direction-selective ganglion cell responses in the dorsal and ventral retina. J Neurosci 42(22): 4449-4469, Jun 2022 Notes:

Kim YJ, Peterson BB, Crook JD, Joo HR, Wu J, Puller C, Robinson FR, Gamlin PD, Yau K-W, Viana F, Troy JB, Smith RG, Packer OS, Detwiler PB, Dacey DM: Origins of direction selectivity in the primate retina. Nature Communications 13: 2862, May 2022 Notes:

Jain V, Hanson L, Sethuramanujam S, Michaels T, Gawley J, Gregg RG, Pyle I, Zhang C, Smith RG, Berson D, McCall MA, Awatramani GB: Gain control by sparse, ultra-slow glycinergic synapses. Cell Reports 38: 110410, Feb 2022.

Behrens C, Yadav SC, Korympidou MM, Zhang Y, Haverkamp S, Irsen S, Schaedler A, Lu X, Liu Z, Lause J, St-Pierre F, Franke K, Vlasits A, Dedek K, Smith RG, Euler T, Berens P, Schubert T: Retinal horizontal cells use different synaptic sites for global feedforward and local feedback signaling. Current Biology 32: 1-14, Feb 2022 Notes:

Hellmer CB, Hall LM, Bohl JM, Sharpe ZJ, Smith RG, Ichinose T: Cholinergic feedback to bipolar cells contributes to motion detection in the mouse retina. Cell Reports 37(11): 110106, 12 2021 Notes:

Chen Q, Smith RG, Huang X, Wei W.: Preserving inhibition with a disinhibitory microcircuit in the retina. eLife 2020 Dec 3;9:e62618, Dec 2020 Notes: DOI: 10.7554/eLife.62618.

Oesterle J, Behrens C, Schröder C, Hermann T, Euler T, Franke K, Smith RG, Zeck G, Berens P.: Bayesian inference for biophysical neuron models enables stimulus optimization for retinal neuroprosthetics. eLife 2020;9:e54997., Oct 2020 Notes: doi: 10.7554/eLife.54997.

Bligard GW, DeBrecht J, Smith RG, Lukasiewicz PD : Light-Evoked Glutamate Transporter EAAT5 Activation Coordinates with Conventional Feedback Inhibition to Control Rod Bipolar Cell Output. J. Neurophysiol. 123(5): 1828-1837, May 2020 Notes: DOI: 10.1152/jn.00527.2019

Percival KA, Venkataramani S, Smith RG, Taylor WR: Directional Excitatory Input to Direction-Selective Ganglion Cells in the Rabbit Retina. J. Comp. Neurol 527: 270-281, Jan 2019 Notes: doi: 10.1002/cne.24207.

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Last updated: 05/23/2024
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