Electrical stimulation of the rostral ventrolateral medulla promotes wakefulness in rats.

Chen CY, Kuo TB, Hsieh IT, Yang CC.
Sleep Med. 2013 Aug 21. [Epub ahead of print]. PMID: 24047536

Objective:   Because people suffering from hypertension often have corresponding sleep disorders, it has been thought that the RVLM plays a role in regulating sleep activity through the regulation of blood pressure or through stimulation of other nuclei involved in wakefulness and sleep.  Indeed, the RVLM’s activity decreases during non-REM sleep, and stimulation of the RVLM during sleep causes arousal.  In this paper, the authors examine the role of RVLM activity in the transition states between wakefulness and sleep.

Results:

·         When the rats were subjected to pre-determined stimulation of the RVLM, they experienced an increase in blood pressure and in the number of transitions between active waking (AW) and non-REM sleep (NREM).  When the stimulus occurred during NREM, the rats transitioned to AW, but stimulus during REM sleep did not cause the same transition.

·         Because increases in blood pressure are sufficient to cause a NREM state animal to transition to AW, they used EEG and EMG to examine the latency between the change in wakefulness and the change in blood pressure.  They found that the brain and muscle changed activity state within 1.5 seconds, while the initial increase in blood pressure took 2.27 seconds.  This indicates that activation of the RVLM causes changes in wakefulness before it causes the changes in blood pressure.

-DH