Offline sorter 2

A 32-channel multi-neuron acquisition processor (MAP, Plexon Inc., Dallas, TX, USA) was used for spike recording and sorting in a weekly basis, for 30–45 min in rats freely behaving in their cages. Online spike sorting was conducted with the help of the SortClient 2002 software (Plexon Inc., USA). A maximum of 4 neuronal action potentials per channel were sorted online and validated by offline analysis (Offline Sorter 2.8, Plexon Inc., USA) according to some criteria, as previously described [22 (link)]: voltage thresholds, amplitude distributions, signal-to-noise ratio, waveform shapes, and principal component analysis. The temporal variation of the electrophysiological pattern in each group during its time of implant (increase or decrease of neural signal) was evaluated by comparing neural signal collected in first and last week of recording.

Extracellular single-unit and local field potentials (LFPs) recordings were obtained from an implanted intracranial multielectrode array structure. The 16-channel multielectrode array was connected to a wireless high-frequency headstage transmitter (W16; Triangle Biosystems, Durham, NC, USA) that sent continuous analog signals to a Multineuron Acquisition Processor system (16MAP, Plexon Inc., Dallas, TX, USA). Neural signals were preamplified (10,000–20,000X) and digitized at 40 kHz. Voltage-time threshold windows were used to identify single-unit waveforms online (SortClient 2.6; Plexon) and validated offline using automatic and manual sorting techniques (Offline Sorter 2.8; Plexon Inc., Dallas, TX, USA) according to the cumulative criteria described in detail previously [33 (link)]. Extracellular LFFs signals were obtained by low-frequency (0.2–200 Hz) filtering of the raw signals. LFPs were preamplified and digitized at a 0.5 kHz sampling rate. These data were subsequently processed offline using the NeuroExplorer 4 software (NEX 4, Plexon Inc., Dallas, TX, USA) and exported to MatLab (R17, MathWorks, Natick, MA, USA) to be further analyzed using custom routines.