At the end of the recording period (typically 4–6 weeks after the implant surgery), a terminal experiment was performed in five of the animals under pentobarbitone anesthesia (60 mg/kg, i.p.). The olivary neurotoxin 3-acetylpyridine (3-AP; 75 mg/kg in 1 ml/kg saline; Aldrich) or saline was injected intraperitoneally. CFPs were evoked at ∼1.5 × T once every 3 s, and responses were recorded for up to 4 h. A single-channel data acquisition system (Neurolog) was used in conjunction with a Micro 1401 interface (Cambridge Electronic Design) and Spike 2 version 7 (Cambridge Electronic Design) software to capture evoked and spontaneous local field potential (LFP) data (30 Hz to 5 kHz, gain of 1 k Hz, sample rate of 5 kHz). The peak-to-peak amplitude of responses evoked by 20 stimulus trials were averaged every 30 min to study changes in the size of the evoked CFP over time. The same data were also sampled for 30 s at 30 min intervals to investigate changes in the power spectral density (square millivolts per Hertz) in the 200–300 Hz frequency band of the LFP signal (sampled at 0.5 Hz, frequency resolution of ∼1Hz). Spike 2 software was used to analyze both CFP and LFP data, and the results were normalized to baseline at t = −30 min. For LFP data, spectrograms were created using the mtspecgramc.m script from the chronux toolbox in MATLAB (MathWorks; Bokil et al., 2010 (link)).
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