Beta and Gamma Rhythms
Published Online: 30 JAN 2010
Copyright © 2010 John Wiley & Sons, Inc. All rights reserved.
Corsini Encyclopedia of Psychology
How to Cite
Leung, L. S. 2010. Beta and Gamma Rhythms. Corsini Encyclopedia of Psychology. 1–2.
- Published Online: 30 JAN 2010
Beta and gamma rhythms were first studied in the human electroencephalogram (EEG) recorded from the scalp. Beta waves of >13 Hz appear in the occipital EEG when the eyes are open, as first reported by Hans Berger who also named the 8–12 Hz alpha rhythm (Niedermeyer, 2005). As used by neuroscientists, beta typically designates 13 to ∼30 Hz and gamma describes ∼30 to 100 Hz, including the 40-Hz oscillations, while higher frequency activities are called ripples (∼100–500 Hz). Beta, gamma, and ripple EEGs are of relatively low amplitude (<30 μV) in the EEG, and quantification normally requires computer analysis, with careful separation from muscle and 50–60 Hz electrical power artifacts. Other than in the EEG, gamma and beta activities can be found in the magnetoencephalogram (MEG), local field potentials, extracellular neuronal unit firings, and intracellularly recorded membrane potentials. Spontaneous (steady-state), evoked, and induced gamma rhythms are distinguished. Spontaneous rhythm occurs without stimulation, evoked gamma activity is time-locked to the stimulus, and induced gamma is increased by the stimulus but not time-locked to it.
- neural synchrony;
- temporal binding;
- object representation