Robert G. Smith, Ph.D

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

Contact information
Department of Neuroscience
Rm 123, Anatomy-Chemistry Bldg /6058
University of PA School of Medicine
422 Curie Blvd.
Philadelphia, PA 19104-6058
Office: 215-573-3211
Education:
- (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

Puthussery T, Venkataramani S, Gayet-Primo J, Smith RG, Taylor WR: NaV1.1 Channels in Axon Initial Segments of Bipolar Cells Augment Input to Magnocellular Visual Pathways in the Primate Retina. J Neurosci. 33(41): 16045-16059, October 2013.

Nikonov S, Lyubarsky A, Fina M, Nikonova E, Sengupta A, Chinniah C, Ding X-Q, Smith R, Pugh E, Vardi N, Dhingra A. : Cones respond to light in the absence of transducin Beta3 subunit. J. Neurosci 33: 5182-5194, March 2013 Notes: doi: 10.1523/jneurosci.5204-12.2013.

Abbas SY, Hamade KC, Yang EJ, Nawy S, Smith RG, Pettit DL: Directional Summation in non-Direction Selective Retinal Ganglion Cells. PLoS Comput Biol 9(3): e1002969, March 2013 Notes: doi:10.1371/journal.pcbi.1002969.

Taylor WR, Smith RG: The role of starburst amacrine cells in visual signal processing. Vis Neurosci 29: 73-81, January 2012 Notes: doi: 10.1017/S0952523811000393.

Trenholm S, Johnson K, Li X, Smith RG, Awatramani GB : Parallel mechanisms encode direction in the retina. Neuron 71: 683-694, August 2011 Notes: doi: 10.1016/j.neuron.2011.06.020

Schachter MJ, Oesch N, Smith RG, Taylor WR.: Dendritic Spikes Amplify the Synaptic Signal to Enhance Detection of Motion in a Simulation of the Direction-Selective Ganglion Cell. PLoS Comput Biol 6(8): e1000899, Aug 2010 Notes: doi:pii: e1000899. 10.1371/journal.pcbi.1000899.

Lipin MY, Smith RG, Taylor WR.: Maximizing contrast resolution in the outer retina of mammals. Biol Cybernetics 103: 57-77, July 2010 Notes: doi: 10.1007/s00422-010-0385-7.

Yin L, Smith, R.G., Sterling, P. and Brainard D.H: Physiology and morphology of color-opponent ganglion cells in a retina expressing a dual gradient of S and M opsins. J. Neurosci. 29: 2706-2724, 2009.

Borghuis, B.G., Sterling, P. and Smith, R.G. : Loss of sensitivity in an analog neural circuit. J. Neurosci. 29: 3045-3058, 2009.

Xu, Y, Sulaiman, P, Fedderson, R., Liu, J., Smith, R.G. and Vardi, N: Retinal On- bipolar cells express a new PCP-2 splice variant that accelerates the light response. J. Neurosci. 28: 8873-8884, 2008.

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Last updated: 10/23/2014
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