I. Introduction
Neuroscience research has benefited greatly from methods of large-scale, multichannel extracellular neural recordings of the brain. By applying high-density microelectrodes into various brain regions, scientists can understand the brain functions and develop brain–machine interfaces to power sophisticated prosthetic and therapeutic devices [1]–[3]. The most important components in extracellular neural recordings are action potentials (APs), also known as spikes, which have a bandwidth up to 10 kHz and amplitudes of 50–500 V [4]. The ability of APs to encode information in different brain structures has been extensively studied. For instance, spiking activity in the motor cortex has been used to develop assistive devices to restore lost functions in patients with paralysis [5].