Fast Scan Cyclic Voltammetry in Behaving Animals

Gaining insight into the mechanisms by which neural transmission governs behavior remains a central goal of behavioral neuroscience. Multiple applications exist for monitoring neurotransmission during behavior, including fast-scan cyclic voltammetry (FSCV). This technique is an electrochemical detection method that can be used to monitor subsecond changes in concentrations of electroactive molecules such as neurotransmitters. In this technique, a triangular waveform voltage is applied to a carbon fiber electrode implanted into a selected brain region. During each waveform application, specific molecules in the vicinity of the electrode will undergo electrolysis and produce a current, which can be detected by the electrode. In order to monitor subsecond changes in neurotransmitter release, waveform application is repeated every 100 ms, yielding a 10 Hz sampling rate. This chapter describes the fundamental principles behind FSCV and the basic instrumentation required, using as an example system the detection of in vivo phasic dopamine changes in freely-moving animals over the course of long-term experiments. We explain step-by-step, how to construct and surgically implant a carbon fiber electrode that can readily detect phasic neurotransmitter fluctuations and that remains sensitive over multiple recordings across months. Also included are the basic steps for recording FSCV during behavioral experiments and how to process voltammetric data in which signaling is time-locked to behavioral events of interest. Together, information in this chapter provides a foundation of FSCV theory and practice that can be applied to the assembly of an FSCV system and execution of in vivo experiments.