Fig. 11.

Compound action potentials simulated with the head model. A: The spatial distribution of the current sources along the active cylinder is biphasic in the beginning and three-phasic thereafter. The three-phasic transmembrane currents can be simulated by 2 dipoles defined by the half-wave gravity points 1–2 and 2–3. Lower diagram corresponds to Fig. 4B. B: Recorded signal at position X (full line) and 3 mm further in x-direction (dashed line). In both cases CAP peak I coincides exactly with the time (t = 750 μs) when transmembrane currents reach their maximum amplitude. C: Near field response, as in B, but electrode is only 0.1 mm from the surface of the active nerve segment.