Figure 3.

Cable with a shunt shows a frequency preference in response to a ZAP extracellular stimulus. (A-1) AC extracellular stimulus current with an increasing frequency, i.e., ZAP current. (A-2) Frequency of the ZAP current as a function of the time t. The frequency of the ZAP current used here exponentially increases from 0 Hz to 200 Hz obeying $freq=200/(\exp \left(1\right)-1)\left[\exp \left(t/1000\right)-1\right]$. (B-1) The trace is the numerically obtained ZAP responses at the x = L end of the cable with a shunt (g = 880 pS). The arrowhead in panel B-1 indicates the maximum point of the amplitude responses at the shunt end of the cable with the shunt to the ZAP extracellular stimulus. (B-2) The trace is the numerically obtained ZAP responses at the x = L end of the cable without shunt (g = 0 pS). AC extracellular stimuli do not cause the frequency preference in the cable without the shunt. (C and D) The traces in panels C and D show numerically obtained responses at the shunt end (x = L) to ZAP injection currents into the shunt end (x = L) and the sealed end (x = 0), respectively. A subtraction of the numerical solution in panel D from that in panel C is equal to the response in panel B-1. The amplitudes responses to the ZAP injection current only into one end monotonically decrease with increasing frequency, in contrast with the frequency preference in response to the ZAP extracellular stimulus.