The pedunculopontine tegmental (PPT) and laterodorsal tegmental (LDT) nuclei are cholinergic brainstem nuclei critical for REM sleep generation. Which of the following best describes their firing pattern across sleep-wake states?
- A Active during wakefulness and REM sleep, relatively silent during NREM sleep ✓
- B Active only during NREM sleep
- C Active only during REM sleep
- D Active during wakefulness and NREM sleep, silent during REM sleep
Correct answer: A. Active during wakefulness and REM sleep, relatively silent during NREM sleep
Explanation
PPT/LDT cholinergic neurons are REM-on cells that fire during both wakefulness and REM sleep, promoting cortical activation and EEG desynchronization. They are relatively silent during NREM sleep. In contrast, monoaminergic neurons in the raphe and locus coeruleus are active during wakefulness, reduce firing during NREM, and become virtually silent during REM sleep. This reciprocal interaction between cholinergic and monoaminergic systems regulates sleep-wake cycling.
Reference: Principles of Neural Science, 6th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.