synapse formation, we used previously described chambers with microgrooves 900 μm in length separating the compartments (Taylor et al., 2005). For the μLP chambers, we used the same mask design for the microgrooves, but the second layer mask was redesigned to include the additional perfusion channel and inlet wells and to have a reduced total microgroove length. We have included drawings of both of these masks with exact dimensions (Figure S3). The inlet wells for the perfusion channels were punched using 6 mm diameter sharpened stainless steel tubing. The outlet port was punched using a 15 gauge luer stub adapter (Intramedic).
