FIG. 5.

Parameter regions of interest varying $f_{K1}$ in both cells. Our analysis focuses on the blue region where fractions of $I_{K1}$ current are heterogeneous; by convention, cell-1 has $f_{K1}$ ( $f_{K1}^{(1)}$) values above the Hopf bifurcation (HB) point that trigger action potentials (APs), while cell-2 has $f_{K1}$ ( $f_{K1}^{(2)}$) below the HB point.