Figure 18.

Simplified depiction of recording radius and 1/r extracellular potential decay from point sources overlaid with sketch of microelectrode array with inter-site spacing of 150 microns. (a) Two point sources depicted, one nearly equidistant from two recording sites, the other very close to one recording site. (b) Eight point sources overlaid. Each point sources is assumed to be detectable at a distance of 140 microns from the source, and the strength of the extracellular potential is assumed to decrease as 1/r. Each source is detectable on at most 2 electrode recording sites, and will be observed with large amplitude on at most 1 electrode recording site.