title: Electrical Brain Responses to an Auditory Illusion and the Impact of Musical Expertise.
abstract: The presentation of two sinusoidal tones, one to each ear, with a slight frequency mismatch yields an auditory illusion of a beating frequency equal to the frequency difference between the two tones; this is known as binaural beat (BB). The effect of brief BB stimulation on scalp EEG is not conclusively demonstrated. Further, no studies have examined the impact of musical training associated with BB stimulation, yet musicians' brains are often associated with enhanced auditory processing. In this study, we analysed EEG brain responses from two groups, musicians and non-musicians, when stimulated by short presentation (1 min) of binaural beats with beat frequency varying from 1 Hz to 48 Hz. We focused our analysis on alpha and gamma band EEG signals, and they were analysed in terms of spectral power, and functional connectivity as measured by two phase synchrony based measures, phase locking value and phase lag index. Finally, these measures were used to characterize the degree of centrality, segregation and integration of the functional brain network. We found that beat frequencies belonging to alpha band produced the most significant steady-state responses across groups. Further, processing of low frequency (delta, theta, alpha) binaural beats had significant impact on cortical network patterns in the alpha band oscillations. Altogether these results provide a neurophysiological account of cortical responses to BB stimulation at varying frequencies, and demonstrate a modulation of cortico-cortical connectivity in musicians' brains, and further suggest a kind of neuronal entrainment of a linear and nonlinear relationship to the beating frequencies.
authors.affiliation: Department of Psychology, Goldsmiths, University of London, London, United Kingdom; Institute of Music Physiology and Musicians' Medicine, Hannover University of Music, Drama and Media, Hanover, Germany.
authors.forename: Christos I
authors.initials: CI
authors.lastname: Ioannou
authors.affiliation: Electrical Engineering and Bioengineering Group, Department of Industrial Engineering, University of La Laguna, Tenerife, Spain; Institute of Biomedical Technology (CIBICAN), University of La Laguna, Tenerife, Spain.
authors.forename: Ernesto
authors.initials: E
authors.lastname: Pereda
authors.affiliation: Department of Psychology, Goldsmiths, University of London, London, United Kingdom.
authors.forename: Job P
authors.initials: JP
authors.lastname: Lindsen
authors.affiliation: Department of Psychology, Goldsmiths, University of London, London, United Kingdom.
authors.forename: Joydeep
authors.initials: J
authors.lastname: Bhattacharya
mesh_terms: D000328:Adult; D001303:Auditory Cortex / Q000502:physiology*; D058256:Brain Waves; D016022:Case-Control Studies; D005072:Evoked Potentials, Auditory; D005260:Female; D006801:Humans; D007088:Illusions; D008297:Male; D009146:Music