In male WKY rats, local field potentials (LFPs) and multiunit activity (MUA) were recorded from deep layers of frontal (n=11 rats) and/or parietal (n=9) cortex with 16-ch (2×8) polyimide-insulated tungsten microwire arrays. Rats were housed individually in transparent Plexiglas cages (light:dark 12:12, light on at 10am, 23±1°C; food and water ad libitum and replaced daily at 10am, except for the sugar pellet reaching task; see Supplementary Information ). Animal protocols followed the National Institutes of Health Guide for the Care and Use of Laboratory Animals and were in accordance with institutional guidelines.
Data acquisition and online spike sorting were performed with the Multichannel Neurophysiology Recording and Stimulation System (Tucker-Davis Technologies Inc., TDT). MUA was collected continuously (25 kHz, 300 Hz – 5 kHz), concomitantly with the LFPs from the same electrodes and epidural EEGs (both 256 Hz, 0.1–100 Hz). Amplitude thresholds for online spike detection were set manually and allowed only crossings of spikes below −25uV. LFP power spectra were computed by a Fast Fourier Transform (FFT) routine for 4-sec epochs (Hanning window, 0.25 Hz resolution). Sleep stages were scored off-line by visual inspection of 4-sec epochs, where the EEG, LFP, EMG and spike activity were displayed. Spike sorting was performed by PCA followed by SMEM clustering algorithm. Population OFF periods in wake and NREM sleep were defined as periods with suppressed or absent neuronal activity. Recordings were performed continuously for 2–3 weeks. In each animal 2–4 experiments (at least 5 days apart) with 4h of sleep deprivation were performed, one of which combined with the sugar pellet reaching task. For details about the analysis of firing rates and neuronal population OFF periods, seeSupplementary Information .
Data acquisition and online spike sorting were performed with the Multichannel Neurophysiology Recording and Stimulation System (Tucker-Davis Technologies Inc., TDT). MUA was collected continuously (25 kHz, 300 Hz – 5 kHz), concomitantly with the LFPs from the same electrodes and epidural EEGs (both 256 Hz, 0.1–100 Hz). Amplitude thresholds for online spike detection were set manually and allowed only crossings of spikes below −25uV. LFP power spectra were computed by a Fast Fourier Transform (FFT) routine for 4-sec epochs (Hanning window, 0.25 Hz resolution). Sleep stages were scored off-line by visual inspection of 4-sec epochs, where the EEG, LFP, EMG and spike activity were displayed. Spike sorting was performed by PCA followed by SMEM clustering algorithm. Population OFF periods in wake and NREM sleep were defined as periods with suppressed or absent neuronal activity. Recordings were performed continuously for 2–3 weeks. In each animal 2–4 experiments (at least 5 days apart) with 4h of sleep deprivation were performed, one of which combined with the sugar pellet reaching task. For details about the analysis of firing rates and neuronal population OFF periods, see