Excitation of the genioglossus in REM sleep

Abstract

Although attention has focused on atonia of the genioglossus (GG) in rapid eye movement (REM) sleep, the fact is that, as shown here in the rat, the overall level of activity of the muscle is greater in REM than in NREM sleep. Three Wistar rats were anesthetized and electrodes were implanted to record electroencephalogram (EEG) and electromyograms (EMG) of the diaphragm, GG and neck muscle. After recovery and adaptation, the animals were recorded during REM sleep. GG activity emerged on an atonic background an average of 20s (±2 SEM) after the onset of REM sleep and was present for 71% (±6 SEM) of the REM duration. This activity developed to a peak 2‐3 fold higher than the average level of activity present during the preceding NREM period. The profile of GG activity, obtain from 88 REM periods, was unimodal with a peak in the second half of the REM period. GG activity correlated with an increased diaphragmatic muscle activity. However, nuchal activity did not present a similar pattern of activity. These results indicate that there is an excitatory drive affecting specifically the respiratory system, including the genioglossus muscle, during REM sleep in rat.