Which neurotransmitter is absent during REM sleep according to the material?

Which neurotransmitter is absent during REM sleep according to the material?

• A. Norepinephrine
• B. Glycine
• C. Acetylcholine
• D. Serotonin

Answer: (C)

REM sleep features a marked drop in monoaminergic signaling, especially from the brainstem neurons that release norepinephrine and serotonin. With these systems largely quiet, the cortex becomes highly activated in a way that resembles wakefulness, which is why you can have vivid dreams and rapid eye movements. At the same time, acetylcholine is active during REM, driving that similar cortical activation and the characteristic REM phenomena. The muscle tone you see during REM is ensured by glycine-mediated inhibition of motor neurons in the spinal cord, producing the dream-associated atonia. So, the neurotransmitters that are absent during REM are norepinephrine and serotonin, not acetylcholine. Acetylcholine is actually elevated during REM, supporting the neural and behavioral features of this sleep stage.

REM sleep features a marked drop in monoaminergic signaling, especially from the brainstem neurons that release norepinephrine and serotonin. With these systems largely quiet, the cortex becomes highly activated in a way that resembles wakefulness, which is why you can have vivid dreams and rapid eye movements. At the same time, acetylcholine is active during REM, driving that similar cortical activation and the characteristic REM phenomena. The muscle tone you see during REM is ensured by glycine-mediated inhibition of motor neurons in the spinal cord, producing the dream-associated atonia.

So, the neurotransmitters that are absent during REM are norepinephrine and serotonin, not acetylcholine. Acetylcholine is actually elevated during REM, supporting the neural and behavioral features of this sleep stage.