Fig. 3.

A representative polygraph record of a swallow with an AS during sleep in an SCI subject. A: brain electrical activity during sleep in two separate EEG channels, EEG(c) [records brain activity from electrode attached to the scalp near central (top) portion of the brain] and EEG(o) [records brain activity from electrode attached to the scalp near occipital (back) portion of the brain], respectively. A also shows measure of muscle tension in the body during sleep via activity in the chin channel. B: respiratory parameters (flow, volume, and SaO₂) during sleep along with the supraglottic pressure channel, which is the main channel to depict swallow (a positive spike on the supraglottic pressure channel) during sleep. C: magnification of the highlighted portion of the supraglottic pressure channel of B to calculate the delta pressure change (Δ₂ = a–b) for the breath before AS. A and B are representatives of a sleep segment recorded on two separate sleep systems, which are time-matched. AS arousal preceding the swallow; SCI, spinal cord injury; EEG(c), electroencephalogram (central); EEG(o), electroencephalogram (occipital); SaO₂, oxygen saturation.