Figure 10.
Electrical configuration of the cell and electrodes. Left: Physical model. The cell is schematized in gray, and the isopotential surfaces are labeled as S1, S2, S3. Right: equivalent electric circuits for the impedances calculated between the intracellular and extracellular electrodes, as well as between extracellular and ground electrodes. This corresponds to the isopotential surfaces S1−S2 (Region 1–2) and S2−S3 (Region 2–3), respectively. S2b is the part of surface S2 where the current directly goes to the extracellular medium, whereas S2a is the part of S2 where the current that passes through the intracellular medium before going extracellular (soma + dendrite). In other words, in Region 2–3, we have taken Eq. 3b where Zg is a resistance. Rg is the resistance between the ground and the first isopotential surface which includes the neuron. Note that the drawing with equipotential surfaces (left) is a schematic drawing where the only goal is to illustrate the link between equivalent electric circuits (right), the physical models and the experimental measurements (Online Appendix A). To see this figure in color, go online.