Dynamical Systems in Neuroscience:

Electrophysiology of Neurons 31V cVI=(V c -V)/RII(V c )analysisaxoninjectFigure 2.5: Two-wire voltage-clamp experiment on the axon: The top wire is used tomonitor the membrane potential V . The bottom wire is used to inject the current Iproportional to the difference V c − V to keep the membrane potential at V c .(a)presteppotentialstep potentials(b)V cV sV scurrent, I (pA)2000150010005000- 500instantaneous I-Vsteady-state I-VI 0 (V c ,V s )0 1 2 3 4 5time, msI (V s )current, I (pA)inward outward6004002000I (V s )-200I 0 (V c ,V s )-400-100 -50 0 50membrane potential, V (mV)Figure 2.6: Voltage-clamp experiment to measure instantaneous and steady-state I-Vrelation. Shown are simulations of the I Na +I K -model (see Fig. 4.1b); the continuouscurves are theoretically found I-V relations.