The implanted microdrive assembly was produced in-house and consisted of 8 individually drivable stereotrodes (25 μm nichrome wires, A-M Systems, Inc., Carlsborg, WA). A 2.0 mm craniotomy was prepared at −0.1 mm anterior to and 5.0 mm lateral to lambda, allowing for visualization of the transverse sinus. The electrodes were inserted 300–500 μm anterior to the transverse sinus

at a 22° angle along the mediolateral axis with tip pointed Ruxolitinib in the lateral direction. The electrodes were lowered 300 μm from the cortical surface and secured with dental cement, dental acrylic, and anchor screws. Rats were allowed 7 days to recover prior to behavioral training. At the end of the experiment, animals were given an overdose of Beuthanasia-D (100 mg/kg, i.p.), electrode tip placements were marked with a small lesion, the animals were perfused, and the brains were extracted and prepared for histology and subsequent localization of electrodes. The locations of electrode Ulixertinib cell line tips were reconstructed with a light microscope and localized in POR as defined by Burwell (2001). During recording, microdrivers were generally advanced about 1/6 turn or 55.5 μm. Total distance advanced ranged from 333 to 610.5 μm. Given this short distance and the trajectory of electrodes, we assumed that all cells recorded

from a particular stereotrode were in the layer in which the tip was histologically located. See Supplemental Experimental Procedures for details. Neuronal activity recorded from stereotrodes (McNaughton et al., 1983) was multiplied by 20 with an operational amplifier at the head stage (HST/8o50-G20-GR, Plexon, Inc., Dallas, TX). Signals were Rebamipide then passed through a differential preamplifier with a gain of 50 (PBX2/16sp-r-G50, Plexon, Inc.). Also at this stage, single-unit activity was filtered between 154–8,800 Hz and LFPs were filtered between 0.7–170 Hz (PBX2/16sp-r-G50, Plexon, Inc.). The signal was then digitized at 40 kHz for single-unit activity and 1 kHz for LFP activity and further amplified for a total gain of 10,000 (MAP system, Plexon, Inc.). Waveforms with signal-to-noise ratios greater

than ∼3:1 were extracted by real-time thresholding (Sort Client, Plexon, Inc.) and stored along with time stamps of behaviorally relevant events for offline analysis. Spikes associated with putative individual cells were isolated offline for each session using a variety of manual and partially automated techniques for classification based on waveform characteristics (Offline Sorter, Plexon, Inc). Separation of sorted spikes by at least 1 ms was verified by autocorrelograms. Sorted files were corrected for an identified issue of time alignment between spike data and field potential data using FPAlignV1 (Plexon, Inc.) (Nelson et al., 2008). Timestamps for spikes and behaviorally relevant event markers were extracted from sorted files using Neuroexplorer (NEX, Plexon, Inc.).