Figure 2.

Histological section of rat brain from region of electrode implant 8 weeks post implant. a,b: Low and high magnifications, respectively, of representative Nissl-stained coronal sections through the track of a stimulating carbon electrode. The arrow indicates the region near the tip. Although the track shows structural damage tissue surrounding the tip appears normal. A. X2.5; B. X10. c: Electrical recordings of chronically implanted metal wire electrodes in rat brain. This is the standard, non-magnetic compatible electrode used previously for rat studies d: similar recordings with the carbon fiber electrode. The top trace is a recording of spontaneous activity under isoflurane anesthesia. The bottom trace is the fourier transform, showing the frequency patterns in the rat cortex. The pattern of recording is similar with the two electrodes. The mv response is the same or higher for the carbon fibers, indicating that they have appropriate conductive properties for both stimulation and recording.