For technical reasons such as stimulation artifacts and the unavailability of adequate commercial systems, MEAs are very seldom used for both stimulation and recording in one preparation. We have overcome some of the technical difficulties, and have developed closed-loop electrophysiology systems, including hardware and software, as part of an ongoing effort to study learning and information processing in vitro (Wagenaar et al., 2004, 2005a,b; Wagenaar and Potter, 2004).