Dynamical Systems in Neuroscience:

94 Two-Dimensional SystemsI Na,pneuronI KI0high-thresholdI KI(V)=I L +I Na,p +I KILa bcurrent (pA)100-1000low-thresholdI(V)=I L +I Na,p +I KI K-100 E -50 0 50KE Namembrane potential, V (mV)-100E -50 0 50KE Namembrane potential, V (mV)Figure 4.1: The I Na,p +I K -model (4.1, 4.2). Parameters in (a): C = 1, I = 0, E L = −80mV, g L = 8, g Na = 20, g K = 10, m ∞ (V ) has V 1/2 = −20 and k = 15, n ∞ (V ) hasV 1/2 = −25 and k = 5, and τ(V ) = 1, E Na = 60 mV and E K = −90 mV. Parametersin (b) as in (a) except E L = −78 mV and n ∞ (V ) has V 1/2 = −45; see Sect. 2.3.5.Figure 4.2: Harold Lecar (back), RichardFitzHugh (front), and Cathy Morris atNIH Biophysics Lab, summer of 1983.