Figure 7.

Simulation of mIPSC decay kinetics. (A) The graph illustrates the changes in 10–90% rise time and decay τ in relation to the distance of the synapse from the soma in a model cell. A recorded fast mIPSC was used as a synaptic conductance. (B) Top, superimposed synaptic currents measured at the soma for synapses located at 0 μm (black) and 1000 μm (red) away from the soma. Traces were aligned at the peak. Bottom, superimposed traces from a synaptic current originating 1000 μm away from the soma of the model cell (red) and a slow decaying recorded mIPSC (green). (C) Schematic representation of the six-state Markov model of GABA receptor activation used (left). U, unbound; B, bound; O, open,; and D, desensitized states. A list of rate constants used to simulate fast and slow decay GABA currents is shown on the right. on1 and on2 binding rate constants are in M⁻¹s⁻¹ and the rest rate constant in s⁻¹. (D) Top, computationally generated macroscopic current simulations for fast and slow decay parameters. Bottom, examples of simulated GABA_A mIPSCs resulting from the summation of stochastic opening of 20 single channels. (E) Population histogram showing the distribution of decay τ for fast (black) and slow (red) simulated mIPSCs.