Figure 1.

Two-chamber Micro-Electro-Mechanical Systems (MEMS) device for reconstruction of hippocampal subregional circuits on a multi-electrode array. (A) Subregions in a slice of rat hippocampus (dissection follows red lines). (B) 60 electrode array with two chamber MEMS device. (C) Distribution of 22 electrodes in each chamber separated by 51 tunnels of 400 μm length aligned to the eight columns of electrodes. (D) Tunnel 3 × 10 μm cross-section aligned over an electrode pair (black oval). (E) Phase contrast imaging of live neurons over electrode array at 3 weeks. (F) Fluorescent labeling shows selective growth of axons from one compartment into another. (G) Sample recordings of high-pass filtered signals from one electrode in dentate gyrus (DG), tunnel and CA3 compartment. The dashed line marks the start of activity on the tunnel electrode, about 5 ms before activity on the CA3 electrode, both after substantial activity on the DG electrode. Note larger amplitudes for spikes in the tunnel.