Microglial response to implanted electrodes. (a–c) Typical responses, with electrode track denoted, to platinum, P3MT, and PEDOP, respectively. Magnification factor: (d) Summary of responses for all animals tested. Number of animals tested were: Platinum, n=10, P3MT, n=8, PEDOP, n=9. Standard errors are indicated for each type of electrode. Scale marker in (a)–(c) corresponds to 250 microns.