Physiology · Higher Mental Functions, EEG, Sleep and Limbic System

During REM sleep, which neurotransmitter system is most responsible for the skeletal muscle atonia (paralysis) that prevents dream enactment?

  • A Serotonergic neurons of the raphe nuclei
  • B Noradrenergic neurons of the locus coeruleus
  • C Cholinergic neurons of the pedunculopontine and laterodorsal tegmental nuclei ✓
  • D Glutamatergic neurons of the reticular formation
Correct answer: C. Cholinergic neurons of the pedunculopontine and laterodorsal tegmental nuclei

Explanation

REM sleep is initiated and maintained by cholinergic neurons of the pedunculopontine tegmental (PPT) and laterodorsal tegmental (LDT) nuclei. These neurons activate brainstem circuits that inhibit spinal motor neurons via glycinergic and GABAergic interneurons, producing the characteristic muscle atonia of REM sleep. Serotonergic (raphe) and noradrenergic (locus coeruleus) neurons are maximally active during wakefulness and minimally active during REM sleep — they promote wakefulness, not atonia. Failure of atonia (due to PPT dysfunction) causes REM sleep behaviour disorder.

Reference: Guyton & Hall, Textbook of Medical Physiology, 14th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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