Wiktionary
theta rhythm
n. A type of electrical activity in the brain, brain waves with a frequency 4-8 hertz.
WordNet
theta rhythm
n. the normal brainwave in the encephalogram of a person who is awake but relaxed and drowsy; occurs with low frequency and low amplitude [syn: theta wave]
Usage examples of "theta rhythm".
Now the pons was active, and the trace from the hippocampus showed a five-second cycle, the theta rhythm, which had not showed up clearly in this subject.