Rhd2132 16 channel amplifier board

We used a custom-made eight-channel multielectrode. It consisted of a pair of tetrodes (four twisted 12 μm tungsten wires each) and a reference (single 50 μm tungsten wire). First, both tetrodes and the reference were slid into a metal capillary which was fixed on a small plexiglass plate controlled by a micromanipulator. Then, the tetrode tips were cut at a 45-degree angle with carbide scissors to improve tissue penetration and the two bundles were glued together using methacrylate, with their tips separated by 50–100 μm. The reference was also glued to the tetrodes approximately 500 μm from their tips, helping to straighten the ensemble (Figure 1C). Each electrode impedance at 1 kHz was adjusted to approximately 150 KΩ using gold electroplating. The plexiglass plate contained the plugs for connecting every independent wire, which in turn were connected to the amplifier (Intan RHD2132 16-channel amplifier board). An interface board (RHD2000 USB interface board) allowed to simultaneously acquire neuronal data and the timing of visual stimuli (TTL pulses indicated the start and end of each visual stimulus). Data were acquired at 30 kHz and recorded on a PC using Intan software (RHD2000 Evaluation System Software).

Custom made monopolar electrodes were constructed from 200 μm polyimide-coated stainless steel wire (Plastics One) soldered to gold connector pins (A–M Systems). They were implanted in the PFC (RC: +2.5 mm, ML: ±1.0 mm, DV: −1.5 to −2.0 mm brain surface, relative to bregma) and dorsal CA1 of the HPC (RC: −2.1 mm, ML: ±2.0 mm, DV: −1.4 mm brain surface, relative to bregma) using a stereotaxic frame (Kopf stereotaxic instruments). A ground/reference electrode was implanted in the cerebellum (RC: −6.0 mm, ML 0.0 mm, DV: −2.0 mm brain surface, relative to bregma). Up to five anchoring screws (J. I. Morris) were distributed around the skull, and the entire assembly was secured in place with dental cement (Stoelting Co.). After surgery, mice were individually housed for 1 week prior to recording.
Local field potentials (LFPs) were sampled at a rate of 1 kHz in the OpenEphys GUI (Siegle et al., 2017 (link)) with an RHD2000 USB interface board and RHD2132 16-channel amplifier board with a wire adaptor for custom electrode wiring (Intan). Video tracking was collected with an overhead mounted Flea3 camera (FLIR) at 30 frames per second. Timestamps were synchronized with LFPs in the OpenEphys GUI via TTL outputs.