State-of-the-Art Microwire Array Design for Chronic Neural Recordings in Behaving Animals

Over the last two decades, many laboratories around the world have started to rely on microelectrode arrays formed by fine microwires, organized in different geometrical configurations, to chronically record the extracellular activity of populations of individual neurons in both anesthetized and behaving animals (Nicolelis et al. 1997, 2003; Lebedev et al. 2006; Verloop and Holsheimer 1984; Williams et al. 1999). As the field of chronic multielectrode recordings evolved, so did the designs of such microwire-based arrays. Indeed, during the last 13 years, our laboratory at the Duke University Center for Neuroengineering (DUCN) has specialized in producing a large variety of microwire array configurations that can now be utilized in a large variety of species (e.g., mice, rats, monkeys, and intraoperative human recordings). In particular, our efforts have been directed at producing arrays that can be utilized in experimental protocols demanding simultaneous recordings from large samples of single neurons (e.g., 50 to 500), distributed across multiple cortical and subcortical brain sites in fully awake and behaving animals over long periods of time (months to years). The goal of this chapter, therefore, is to review the DUCN accumulated experience and describe its current state-of-the-art design and fabrication approach for producing high-quality microwire-based arrays for chronic, multisite, neural ensemble recordings.