Simultaneously recording and perturbing neural circuits with millisecond-scale temporal precision is a cornerstone of optogenetics research, but the methods for doing so are not always easily accessible. A variety of labs have come up with ad hoc ways to incorpoate fiber optic cables into existing multielectrode implant designs. Very few of these solutions have been documented or published, even though this is becoming an increasingly popular technique. Fortunately, the Moore Lab at Brown University recently published a manuscript on their “flexDrive,” a lightweight implant that can hold multiple fiber optic cables and 16 electrodes (Voigts et al., 2013).
The basic concept is similar to the designs from Matt Wilson’s lab involving a ring of electrodes, each driven by its own screw (Kloosterman et al., 2009). But it introduces a novel spring-based drive mechanism that significantly reduces both the weight of the implant and the time it takes to build. In contrast to previously published designs (Anikeeva et al., 2011), each of the electrodes on the flexDrive can be moved independently—a feature that is essential for maximizing the number of well-isolated single units that can be recorded.
The authors have put a lot of effort into making their designs as accessible as possible. They’ve created a complete online assembly manual, which includes all the design files and a list of parts. Still, labs that don’t have much previous experience building electrode implants might find it difficult to obtain all the components necessary to build the flexDrive. Because so many aspects of the design have been optimized, it requires a number of non-standard parts. It would be nice if the community could figure out a way to eliminate the high barrier to building designs such as this one, perhaps by creating a centralized mechanism for ordering supplies.
Anikeeva P, Andalman AS, Witten I, Warden M, Goshen I, et al. 2011. Optetrode: A multichannel readout for optogenetic control in freely moving mice. Nat Neurosci 15: 163-70
Kloosterman F, Davidson TJ, Gomperts SN, Layton SP, Hale G, et al. 2009. Micro-drive array for chronic in vivo recording: drive fabrication. J Vis Exp
Voigts J, Siegle JH, Pritchett DL, Moore CI. 2013. The flexDrive: An ultra-light implant for optical control and highly parallel chronic recording of neuronal ensembles in freely moving mice. Front Sys Neurosci 7