Modelling intrinsic electrophysiological properties of ON and OFF retinal ganglion cells |
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Authors: | Tatiana Kameneva Hamish Meffin Anthony N Burkitt |
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Institution: | (1) Department of Electrical Engineering, The University of Melbourne, Bld. 193 room 4.2, VIC, 3010, Australia;(2) NICTA Victoria Research Lab, The University of Melbourne, Lvl 2/ Bldg. 193, VIC, 3010, Australia;(3) The Bionic Ear Institute, 384-388 St, East Melbourne, VIC, 3002, Australia |
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Abstract: | ON and OFF retinal ganglion cells (RGCs) display differences in their intrinsic electrophysiology: OFF cells maintain spontaneous
activity in the absence of any input, exhibit subthreshold membrane potential oscillations, rebound excitation and burst firing;
ON cells require excitatory input to drive their activity and display none of the aforementioned phenomena. The goal of this
study was to identify and characterize ionic currents that explain these intrinsic electrophysiological differences between
ON and OFF RGCs. A mathematical model of the electrophysiological properties of ON and OFF RGCs was constructed and validated
using published patch-clamp data from isolated intact mouse retina. The model incorporates three ionic currents hypothesized
to play a role in generating behaviors that are different between ON and OFF RGCs. These currents are persistent Na + , I
NaP, hyperpolarization-activated, I
h, and low voltage activated Ca2 + , I
T, currents. Using computer simulations of Hodgkin-Huxley type neuron with a single compartment model we found two distinct
sets of I
NaP, I
h, I
T conductances that correspond to ON and OFF RGCs populations. Simulations indicated that special properties of I
T explain the differences in intrinsic electrophysiology between ON and OFF RGCs examined here. The modelling shows that the
maximum conductance of I
T is higher in OFF than in ON cells, in agreement with recent experimental data. |
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Keywords: | |
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