Electrodes implanted in the EP remain in position over the two-week stimulation interval.

<p>Representative photomicrographs illustrate unilateral electrode placement in the EP following Kluver-Barrera staining. (<b>A</b>) Low magnification image shows the approximate placement of the stimulating electrode prior to its removal post mortem and the tissue damage related to the removal process. The active electrode tip diameter is 150 μm whereas the shaft of the electrode is 400 μm in diameter. (<b>B</b>) High magnification of the electrode tip’s position in the EP. <b>(C)</b> EP neurons are visible in a nearby coronal section (≈160 μm caudal), indicating that a significant portion of the EP remained intact. Rats in which electrodes were found to be positioned more than 250 μm away from the EP were excluded from analysis based on previous estimates of current spread [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0133957#pone.0133957.ref020" target="_blank">20</a>]. Scale bar in A = 1000 μm, C = 500 μm.