Subtractive and Divisive Inhibition: Effect of Voltage-Dependent Inhibitory Conductances and Noise

  • Authors:
  • Brent Doiron;André Longtin;Neil Berman;Leonard Maler

  • Affiliations:
  • Physics Department, University of Ottawa, Ottawa, Canada K1N 6N5;Physics Department, University of Ottawa, Ottawa, Canada K1N 6N5;Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa,Canada K1H 8M5;Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa,Canada K1H 8M5

  • Venue:
  • Neural Computation
  • Year:
  • 2001

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Abstract

The influence of voltage-dependent inhibitory conductances on firing rate versus input current (f-I) curves is studied using simulations from a new compartmental model of a pyramidal cell of the weakly electric fish Apteronotus leptorhynchus. The voltage dependence of shunting-type inhibition enhances the subtractive effect of inhibition on f-I curves previously demonstrated in Holt and Koch (1997) for the voltage-independent case. This increased effectiveness is explained using the behavior of the average subthreshold voltage with input current and, in particular, the nonlinearity of Ohm's law in the subthreshold regime. Our simulations also reveal, for both voltage-dependent and -independent inhibitory conductances, a divisive inhibition regime at low frequencies (f 40 Hz). A simple leaky integrate-and-fire type model that incorporates the voltage dependence supports the results from our full ionic simulations.