Figure 12. Extracellular electric field clamping system and induced slow periodic activity by electric fields.

A, experimental set‐up of the extracellular electric field clamp. An amplifier records the local electrical field, and a proportional controller generates an electrical field in a direction perpendicular to the dendrites capable of cancelling the electric field of the propagating event. B, electric recordings were obtained at three locations within the slice with one in the temporal region (REC1, bottom trace), one at the site of the clamp (REC2, middle trace), and one in the septal region (REC3, top trace). Activity was observed propagating from the temporal region to the septal region. With the field clamp stimulation applied, the local field potential (REC2, middle trace) was clamped to zero and slow periodic activity was blocked beyond the clamp site (REC3, top trace). C, amplitudes recorded at the three sites indicating that periodic activity was blocked at REC2 and REC3. D, propagating wave triggered by electrical stimulation. E, speed comparison between electrically triggered wave and spontaneous wave does not reveal any change. ^** P < 0.01; NS, not significant. [Color figure can be viewed at wileyonlinelibrary.com]