Fig. 4

a–c The Green’s functions $G_{m^{-}}(x,y,t)$, $G_{m^{+}}(x,y,t)$, and $G_{n^{\pm }}(x,y,t)$ for a model in Fig. 2 when $x=10\text{ μm}$ and $y=100\text{ μm}$. Parameters: $a=2\text{ μm}$, $D=50000{\text{ μm}}^2\text{/ms}$, $\tau =2\text{ ms}$, $C=1{\text{ μF/cm}}^2$, $R_a=100\mathrm{\Omega }\text{\hspace{0.17em}cm}$, $r=100\mathrm{\Omega }{\text{\hspace{0.17em}cm}}^2$, $L=5{\text{ H\hspace{0.17em}cm}}^2$, $R_{\mathrm{GJ}}=100\text{ M}\mathrm{\Omega }$. d–f Voltage profiles on each segment in response to a rectangular pulse of strength ${\eta }_0=2\text{ nA}$ and duration ${\tau }_R=5\text{ ms}$ applied to segment $m^{-}$. Note that different y-axis limits are used in c and f