Chronic recording of extracellular neuronal activity in behaving animals

Two methods for recording extracellular neuronal activity in unanesthetized, unrestrained rats are described in this unit. Both use chronically-implanted bundles of fine microwires to record electrophysiological activity. One method provides recordings of single and/or multiple unit activity from individual wires in a bundle (monotrode). Discrimination of individual neuronal potentials is based on action potential amplitude, or on a combination of action potential amplitude and shape. The second method uses a 2- to 4-microwire array (stereotrode-tetrode) to yield multiple unit recordings. Discrimination of individual neuronal potentials is based on action potential shapes and the relative amplitude of action potentials recorded simultaneously on the different wires in the array. These methods can provide stable, long-term recording of neuronal activity during a variety of behavioral paradigms.