delta rhythm
true
https://emedicine.medscape.com/article/1139332-overview#a1
Delta activity refers to activity with a frequency range of 1 to 3 Hz.
http://www.case.edu/EpSO.owl#DeltaRhythm
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5603104/
normal EEG pattern