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. 2009 May 20;96(10):3959–3976. doi: 10.1016/j.bpj.2009.02.046

Figure 8.

Figure 8

Effect of VSFP2.3 sensing capacitance on the amplitude of sub- and suprathreshold synaptic potentials and action potential initiation in simulations of a layer 5 pyramidal neuron. (A) Schematic representation of the simulated layer 5 pyramidal neuron. An excitatory synaptic conductance (time constant rise: 0.3 ms; decay: 3 ms; zero reversal potential) was activated in a compartment of the distal dendrite. (B1) Synaptic potentials at the cell body for a synaptic peak conductance of 10% below spike threshold and increasing densities (0, 200, 500, 1000 VSDs/μm2) of VSFP2.3 (Model 1). (B2) Same as B1, but for a synaptic conductance 20% above spike threshold. (C1) State of activation (nS+; 0 ≤ nS+ ≤ 1) of the VSFP2.3 voltage sensing domain in the somatic membrane as function of membrane voltage (black) for the same stimulus as in B1 compared to steady-state (gray) with 200 VSFP2.3 units/μm2. (C2) Same as C1, but applying a stimulus 20% above threshold. Numbers 1–4 indicate the different phases of sensor activation during action-potential firing as referred to in the text.