This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Sleep Disorders, Subject name: Psychiatry
Pontogeniculo-occipital spike is characteristic of which of the following sleep stage? 
Select and explain. 
A. Stage 1 NREM, B. Stage 2 NREM, C. Stage 3 NREM, D. REM
D: REM
Answer: D: REM 
Explanation: Ponto - geniculo - occipital spikes are large phasic potentials, seen in REM sleep. These orginate from cholinergic neurons in pons and pass rapidly to lateral geniculate body and then to occipital coex.