10] - Simultaneous in Vivo Voltammetric and Electrophysiological Recording with Carbon Fiber Microelectrodes

Abstract

This chapter describes simultaneous in vivo voltammetric and electrophysiological recording with carbon fiber microelectrodes. In a study conducted in 1981, it was found that the carbon fiber electrodes that had been designed for single-unit recording were also usable for electrochemical—voltammetric—detection of iontophoretically ejected noradrenaline, dopamine, or serotonin. In the initial experiments in vivo of the study, the electrodes were switched manually between the two types of amplifier. Later it was found that a form of linear sweep voltammetry, usually known as cyclic voltammetry, could work out at much faster sweep rates than had previously been used without damage to either the tissue or the working electrode. Using a triphasic ramp voltage lasting 15 or 20 ms in total, iontophoretically ejected amines could be detected at submicromolar levels. This new technique was called fast cyclic voltammetry (FCV). As the discovery that FCV could be used to detect dopamine released from nerve terminals following electrical stimulation of dopaminergic axons, interest in FCV increased rapidly, and it can now be numbered as one of the major techniques in neuroelectrochemistry. The chapter presents a review of the way in which these two applications of carbon fiber electrodes—namely, unit recording and FCV, can be combined together in a single electrode.