the coordinated oscillations of cortical populations of neurons at frequencies from 25 to 60 Hz (gamma waves). This pattern of electrical activity, as recorded via intracranial electrodes or scalp electroencephalography, predominates during periods of focused mental activities. Growing evidence suggests that gamma synchrony may be a general mechanism for the integration of cognitive processes. Cross-frequency synchrony, including gamma synchrony, has been suggested as the neural correlate of consciousness. Gamma coherence is gamma synchrony with a brief phase lag.