In Vivo Monitoring of Oxygen Fluctuation Simultaneously at Multiple Sites of Rat Cortex during Spreading Depression

Spreading depression (SD) is a common pathological process in the brain shown as propagating neuronal depolarization followed by activity depression over the brain, and it is closely related to migraines and epilepsy. Although O2 is known to fluctuate during SD, the difference of O2 responses at different sites in the same brain region remains unknown. In this study, we develop an in vivo electrochemical method with microelectrode arrays (MEAs) to monitor, in real time, O2 fluctuation at multiple sites of rat cortex during SD with high spatial/temporal resolution. Platinum nanoparticles are electrochemically deposited on the multiplexed electrodes of the MEAs to monitor O2 fluctuation simultaneously and selectively via a four-electron reduction process. Configuration of electrode arrays is designed rationally to exclude the probable crosstalk between neighbor recording electrodes during simultaneous measurements. With the MEAs, we find both the basal O2 levels and O2 fluctuations at different sites of the...