title: Binaural beats increase interhemispheric alpha-band coherence between auditory cortices.
abstract: Binaural beats (BBs) are an auditory illusion occurring when two tones of slightly different frequency are presented separately to each ear. BBs have been suggested to alter physiological and cognitive processes through synchronization of the brain hemispheres. To test this, we recorded electroencephalograms (EEG) at rest and while participants listened to BBs or a monaural control condition during which both tones were presented to both ears. We calculated for each condition the interhemispheric coherence, which expressed the synchrony between neural oscillations of both hemispheres. Compared to monaural beats and resting state, BBs enhanced interhemispheric coherence between the auditory cortices. Beat frequencies in the alpha (10 Hz) and theta (4 Hz) frequency range both increased interhemispheric coherence selectively at alpha frequencies. In a second experiment, we evaluated whether this coherence increase has a behavioral aftereffect on binaural listening. No effects were observed in a dichotic digit task performed immediately after BBs presentation. Our results suggest that BBs enhance alpha-band oscillation synchrony between the auditory cortices during auditory stimulation. This effect seems to reflect binaural integration rather than entrainment.
authors.affiliation: Division of Neurorehabilitation, Department of Clinical Neurosciences, University Hospital and University of Geneva, CH-1211 Geneva 14, Switzerland.
authors.forename: Marco
authors.initials: M
authors.lastname: Solcà
authors.affiliation: Division of Neurorehabilitation, Department of Clinical Neurosciences, University Hospital and University of Geneva, CH-1211 Geneva 14, Switzerland.
authors.forename: Anaïs
authors.initials: A
authors.lastname: Mottaz
authors.affiliation: Division of Neurorehabilitation, Department of Clinical Neurosciences, University Hospital and University of Geneva, CH-1211 Geneva 14, Switzerland. Electronic address: aguggis@gmail.com.
authors.forename: Adrian G
authors.initials: AG
authors.lastname: Guggisberg
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D000513:Alpha Rhythm; D001303:Auditory Cortex / Q000502:physiology*; D001306:Auditory Pathways / Q000502:physiology; D001931:Brain Mapping / Q000379:methods; D016022:Case-Control Studies; D054022:Cerebrum / Q000502:physiology*; D003071:Cognition; D003344:Cortical Synchronization; D004569:Electroencephalography; D005072:Evoked Potentials, Auditory; D005260:Female; D006212:Hallucinations; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests; D013997:Time Factors
keywords: Alpha band; Dichotic digit test; EEG; Functional connectivity; Interhemispheric synchronization; Phase synchrony