Chronic in vivo multi-circuit neurophysiological recordings in mice.

While genetically modified mice have become a widely accepted tool for modeling the influence of gene function on the manifestation of neurological and psychiatric endophenotypes, only modest headway has been made in characterizing the functional circuit changes that underlie the disruption of complex behavioral processes in various models. This challenge partially arises from the fact that even simple behaviors require the coordination of many neural circuits vastly distributed across multiple brain areas. As such, many independent neurophysiological alterations are likely to yield overlapping circuit disruptions and ultimately lead to the manifestation of similar behavioral deficits. Here we describe the expansion of our neurophysiological recording approach in an effort to quantify neurophysiological activity across many large scale brain circuits simultaneously in freely behaving genetically modified mice. Using this expanded approach we were able to isolate up to 70 single neurons and record local field potential (LFP) activity simultaneously across 11 brain areas. Moreover, we found that these neurophysiological signals remained viable up to 16 months after implantation. Thus, our approach provides a powerful tool that will aid in dissecting the central brain network changes that underlie the complex behavioral deficits displayed by various genetically modified mice.