In vivo microelectrode arrays for neuroscience

Microelectrode arrays (MEAs) are devices capable of recording extracellular action potentials (spikes) from many neurons simultaneously and with high spatial and temporal resolution. MEAs have emerged as an invaluable tool for understanding how networks of neurons govern complex sensory, motor and decision-making processes. In this Primer, we introduce various in vivo MEA designs and describe their construction, characterization and applications. We describe approaches for effective device implantation and the use of MEA recordings in behavioural experiments. We then discuss strategies for obtaining high-quality and stable electrophysiological recordings, including through mitigating the foreign body reaction. We introduce the reader to spike sorting approaches with a focus on semi-automated sorting of high-channel-count data, as well as to the analysis of sorted spikes and their uses. Finally, we cover future trends and emerging MEA technology designed to expand current capabilities and overcome limitations, with a focus on biomimetic and multifunctional devices. This Primer should provide the reader with a foundation in the fundamental principles of MEA technology for in vivo use.