The
theta rhythm is an
oscillatory pattern in
electroencephalography (EEG) signals recorded either from inside the brain or from electrodes glued to the scalp. Two types of theta rhythm have been described. The
"hippocampal theta rhythm" is a strong oscillation that can be observed in the
hippocampus and other brain structures in numerous species of
mammals including rodents, rabbits, dogs, cats, bats, and marsupials.
"Cortical theta rhythms" are low-frequency components of scalp EEG, usually recorded from humans. Theta rhythms can be quantified using
Quantitative electroencephalography (qEEG) using freely available toolboxes, such as,
EEGLAB or the Neurophysiological Biomarker Toolbox (NBT).