May 2007
Volume 48, Issue 13
Free
ARVO Annual Meeting Abstract  |   May 2007
A Mathematical Model of Signal Propagation in the Starburst Amacrine Cell Network
Author Affiliations & Notes
  • G. A. Enciso
    Ohio State University, Columbus, Ohio
    Mathematics,
  • A. V. Dmitriev
    Ohio State University, Columbus, Ohio
    Neuroscience,
  • D. Terman
    Ohio State University, Columbus, Ohio
    Mathematics,
  • S. C. Mangel
    Ohio State University, Columbus, Ohio
    Neuroscience,
Investigative Ophthalmology & Visual Science May 2007, Vol.48, 5969. doi:
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    • Get Citation

      G. A. Enciso, A. V. Dmitriev, D. Terman, S. C. Mangel; A Mathematical Model of Signal Propagation in the Starburst Amacrine Cell Network. Invest. Ophthalmol. Vis. Sci. 2007;48(13):5969.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose:: Displaced starburst amacrine cells (SACs) are retinal interneurons that exhibit directionally selective (DS) light responses in the rabbit retina. They depolarize to stimuli that move centrifugally through the receptive field surround and hyperpolarize to stimuli that move centripetally through the surround (Gavrikov et al., 2003, 2006). SACs also depolarize to stationary light stimuli flashed in the receptive field center and hyperpolarize to stationary light stimuli flashed in the receptive field surround 1 mm distance from the soma. We have begun to model the SACs and their associated retinal network to examine the circuitry and mechanisms that underlie their responses to moving and stationary light stimuli.

Methods:: We are implementing a mathematical model of SACs and their associated retinal network using a tightly interconnected network of in silico neurons. The DS responses of SACs are highly sensitive to the activity of NKCC2 and KCC2, two subtypes of chloride cotransporter that increase and decrease intracellular chloride concentrations, respectively. Because it has been shown that the differential distribution of NKCC2 on the proximal dendrites and KCC2 on the distal dendrites of SACs results in a GABA-evoked depolarization and hyperpolarization at the NKCC2 and KCC2 compartments, respectively, and underlies the DS light responses of SACs (Gavrikov et al., 2006), we have modeled SACs with a higher chloride concentration in their proximal, compared to their distal dendrites so that GABA depolarizes the SACs proximally, but hyperpolarizes the cells distally. In the model, GABA is released from the distal portions of SACs onto the proximal and distal dendrites of other SACs, and glutamate, which is always excitatory, is released from bipolar cells onto the proximal and distal dendrites of SACs.Results and

Conclusions:: Our modeling efforts have focused on determining the combination of parameters of the SAC network that facilitates lateral propagation of a local signal evoked either electrically or by light. These results will enable us to understand the conditions under which SACs can generate DS responses to moving light stimuli.

Keywords: computational modeling • amacrine cells • retinal connections, networks, circuitry 
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