Optogenetic Stimulation Shifts the Excitability of Cerebral Cortex from Type I to Type II: Oscillation Onset and Wave Propagation
A: The curve of Hopf bifurcation points (solid line) indicates the critical values of Je and Ji where oscillations emerge. The dotted line represents our proposed relationship between Je and Ji during optogenetic stimulation. It is a sigmoidal function of Je that saturates at Ji = 4. B: The supercritical Hopf bifurcation under the proposed relationship between Je and Ji. Notice the slow rise in oscillation amplitude. C: Simulated ramp protocol under the same conditions. The excitatory current was ramped from Je = 0 (Ji = 0) to Je = 3 (Ji = 4) over a period of t = 4 seconds to mimic the ramp protocol by .