Dynamical Systems in Neuroscience:

Two-Dimensional Systems 119membrane voltage, V (mV)injected current, I200-20-40-60-80105resttransition(bifurcation)I=4.51spiking00 50 100 150 200 250 300time (ms)Figure 4.29: Transition from rest state to repetitive spiking in the I Na,p +I K -model withinjected ramp current I; see also Fig. 4.26, Fig. 4.28, and Fig. 4.30. Notice that thefrequency of spiking is initially small, and then it increases as the amplitude of theinjected current increases.0.60.5n-nullcline0.4K + activation variable, n0.30.2V-nullcline0.10limit cycle attractor-80 -70 -60 -50 -40 -30 -20 -10 0 10 20membrane voltage, V (mV)Figure 4.30: Limit cycle attractor (bold) in the I Na,p +I K -model when I = 10 (comparewith Fig. 4.26 and Fig. 4.28).