Understanding how the structure and biophysical properties of
a neuron influence the signal processing function of the surrounding
neural circuit.
Intracellular and extracellular recording from retinal neurons,
computer simulation of signal and noise properties, analysis of
the role of biophysical and system properties in real cell and
model through ideal observer analysis.
Currently we are studying how neural circuits in the retina process
visual signals transmitted to the brain. We record signal and
noise properties of retinal neurons, in a contrast discrimination
task. We construct a biophysically-based model of the same neuron,
and run the same experiment on it. We analyze the neuron's performance
(i.e. signal and noise properties) with an ideal observer, testing
how well the model performs compared with the real neuron. We
then change the model to identify which properties are necessary
for good performance in the discrimination task. This allows us
to suggest a functional interpretation for biophysical features
such as dendritic branching, density of voltage-gated channels,
and specific location and strength of synaptic inputs. We are
currently focussing on 2 circuits: 1) how the ganglion cell spike
generator processes its synaptic inputs, 2) the pathway from rod
photoreceptors to ganglion cells used during dark adaptation.
KEY WORDS: Computer simulation; neural circuitry; retina;
noise; synapse.
Dhingra, N.K., and Smith, R. (2004) Spike generator limits efficiency
of information transfer in a retinal ganglion cell. J. Neurosci.
24: 2914-2922. Source
Freed, M.A., Smith, R.G., and Sterling, P. (2003) Timing of quantal
release from the retinal bipolar terminal is regulated by a feedback
circuit. Neuron, 38: 89-101. Source
Dhingra, N.K., Kao, Y.-H., Sterling, P., and Smith, R.G. (2003)
Contrast threshold of a brisk-transient ganglion cell. J Neurophysiol.
89:2360-2369. Source
van Rossum, M.C.W., O'Brien, B., and Smith, R.G. (2003) Effects
of noise on the spike timing precision of retinal ganglion cells.
J. Neurophysiol. 89:2406-2419. Source
DeVries, S. Qi, X-F, Smith, R, Makous, W., and Sterling, P. (2002)
Electrical coupling between mammalian cones. Current Biology 12:
1900-1907. Source
Hsu, A., Smith, R.G., Buchsbaum, G., and Sterling, P. (2000) Cost
of coupling to trichomacy in foveal cones. J. Opt. Soc. Am. A
17: 635-640. Source
