Excitable cells, such as neurons, produce action potentials (APs) that in extracellular recordings are often referred to as spikes. The contributions of each cell must be isolated from the background noise and from those of the other cells. This chapter focuses on state-of-the-art techniques addressing the problem of spike sorting, including the resolution of overlapped action potentials (APs). It proposes the mathematical modeling of multiunit recordings and the complexity in the resolution of overlapped APs. Then, the summarizes state-of-the-art spike sorting algorithms and discusses the advantages and limitations of each and the applicability of these methods for different types of experimental demands.
