The cognitive correlates of human brain oscillations.

This mini-symposium summarizes recent findings concerning the role of brain oscillations in human cognition. Two rhythms that show particularly strong behavioral correlates are the 4 – 8 Hz theta rhythm and the 30 – 80 Hz gamma rhythm. The former rhythm has been studied extensively in rodents, in which it is especially prominent in the hippocampus during locomotion, orienting, and other voluntary behaviors. The higher-frequency gamma rhythm has been linked recently to increased hemodynamic activity (as measured using functional magnetic resonance imaging) in cat, monkey, and human. Recent analyses of intracranial electroencephalographic (iEEG) recordings, taken from neurosurgical patients, have provided evidence for locally generated brain oscillations in human hippocampus and neocortex. Along with scalp EEG and magnetoencephalographic (MEG) recordings, these studies reveal evidence of synchronous oscillations in the thetaand gamma-frequency bands that are modulated by behavioral and task variables. The convergence of recent evidence suggests that brain oscillations are generated in almost every part of the brain and that they play a wide range of functions in both human and animal cognition.