Figure 9.

The excitatory effects of glutamate are rapidly lost during entry into REM sleep but immediately regained in post-REM waking. A, A typical example showing that glutamate perfusion into the left trigeminal motor pool causes a potent activation of left masseter muscle (LM) activity during NREM sleep, but this excitatory effect is immediately abolished during entrance into REM sleep. Note that right masseter muscle (RM) tone is unaffected by glutamate application. B, Group data demonstrating that the excitatory effects of glutamate on trigeminal motoneurons are present in NREM sleep (glutamate vs baseline, p < 0.001) but rapidly lost on entry into tonic REM sleep (glutamate vs baseline, p = 0.916) and immediately regained during post-REM waking (glutamate vs baseline, p < 0.001). All values are means ± SEM; A.U., arbitrary units.