Figure 5.

Dependence of $V_{\text{m}}^{\text{S}2}$ on S2 pulse amplitude

A, a cell (length: 101 μm) stimulated with four successive S1-S2 stimuli with identical S1 and S2 amplitudes (+4.5 and +31.4 V cm⁻¹, respectively). A, upper set of traces, the superimposed signals from all sites for one such pulse pair. A, lower set of traces, the superimposed $V_{\text{m}}^{\text{S}2}$ responses from site 3 for all 4 stimuli. $V_{\text{m}}^{\text{S}2}$ remained unaltered with successive stimuli. B, another cell (length: 210 μm) that was also stimulated with 4 successive stimuli but of increasing S2 amplitude. B, bottom portion, the resultant $V_{\text{m}}^{\text{S}2}$ responses from site 7 shown individually and also superimposed. The temporal behaviour (I–IV) of $V_{\text{m}}^{\text{S}2}$ response varied with S2 amplitude (see text for details).