Hst 32v g20

Multichannel recordings were performed with connecting the head-connector of the animal to a preamplifier (20-fold gain, band-pass filtered, HST/32V-G20; Plexon Inc.) and a data acquisition system (Neural Data Acquisition System Recorder Recorder/64; Plexon Inc.). The cable harness was wrapped by a metal mesh for bite protection. Tension of the cable was relieved by a spring and a turnable, motorized commutator (Plexon Inc.) that permits free movement and rotation of the animal in the box. Broadband signals were recorded continuously using a preamplifier (Plexon REC/64 Amplifier; 1Hz-6 kHz) during the training with a sampling frequency of 12 kHz. LFPs were sampled with 2 kHz, visualized online (NeuroExplorer, Plexon Inc. Recording Controller) and stored offline for further analysis. To avoid ground loops between recording system, shuttle-box and the animal we ensured proper grounding of the animal via its common ground and left the grid floor on floating voltage.

For electrophysiological recording, broadband signals (0.07 Hz 8 kHz) were amplified (×1000) (HST/32V-G20 and PBX3, Plexon) relative to a cerebellar bone screw and were digitized at 20 kHz (PXI, National Instruments). Once spiking activity was detected, optical pulses (50 ms pulse width at 2 Hz repetition rate) were delivered from either the optical fiber or μLED to assess whether neurons could be activated by optical stimulation, after which recording sessions were initiated. Each recording session typically consisted of a non-stimulation period (up to 2 min), optrode and μLED stimulation periods (up to 3 min) and another non-stimulation period (up to 2 min). The μLED was driven by a current source (Yokogawa, Source Measure Unit GS610) from 0.1 mA up to 6 mA (Corresponding to intensities at the probe/neural tissue interface from 0.5 mW/mm² up to 52 mW/mm²). In the experiment in Figure 3, the μLED was supplied with 4 mA (40 mW/mm²) current pulses. The light source of the optrode was a commercial GaN LED (450 nm, PlexBright, Plexon) with 58.9 mW/mm² output at tip of the probe. This light level was used as standard for all cortical experiments as it allow for stimulation along the full length of the optrode.