Discharge of identified orexin/hypocretin neurons across the sleep-waking cycle - PubMed (original) (raw)
Discharge of Nb+/Orx+ neurons across sleep-wake states. A, Bar graph showing mean spike rate (in blue with SEM) that varied significantly as a function of sleep-wake stage across cells (n = 6; F = 16.05; df = 5, 25; p = 0.007). The rate during aW was significantly higher than that during qW and all sleep stages, including PS (p < 0.05). The line graph (in red) shows the discharge rate of the Nb+/Orx+ neuron (#c32u10) shown in B and C. B, Hypnogram, spike rate histogram, and EMG amplitude and EEG frequency spectra (split for different scaling from blue to red over the lower frequency range, 0-30 Hz from 1 to 100 uV, and gamma range, 30-60 Hz from 0 to 25 uV) over the recording session (of 400 s corresponding to 40 10 s epochs). C, Four 1 min segments (as indicated by time below) of unit, EEG, and EMG activity during state transitions: from qW through aW, tSWS to SWS (supplemental video 1, available at
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) (1), from tPS to PS (supplemental video 2, available at
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) (2), from PS through aW back to PS (supplemental video 3, available at
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) (3), and from PS to aW (supplemental video 4, available at
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) (4). Stages were scored per 10 s epoch as indicated by the stage names between dots marking the epochs. Note that the unit fires during aW (in 1) becomes quiet during SWS (in 1) and PS (in 2 and 3), except for occasional spikes sometimes associated with twitches (in 2) or a brief arousal (in 3). The increase in firing before arousal from PS (in 3 and 4) anticipates the transition from PS to aW judged by EEG (open arrowhead) and also EMG (filled arrowhead). Calibration: horizontal, 10 s; vertical, 1 mV for EEG, 0.5 mV for EMG, and 2 mV for unit. OB, Olfactory bulb; PF, prefrontal cortex; RS, retrosplenial cortex.