Transient and phase-locked evoked magnetic fields in response to periodic acoustic signals.
Using whole-head MEG, time course and hemispheric lateralization effects of phase-locked brain responses to complex periodic acoustic signals (stimulus frequency 13, 22, 40, 67, or 111 Hz) were determined based on a dipole analysis approach. Apart from systematic rate-induced changes in amplitude and shape of the transient evoked magnetic fields (M50, M100), phase-locked brain activity emerged, being more pronounced over the right as compared to the left hemisphere. Furthermore, this MEG component showed a consistent phase angle across subjects, indicating active synchronization mechanisms within auditory cortex that operate upon afferent input. Conceivably, these early side-differences in periodicity encoding contribute to or even snowball into hemispheric lateralization effects of higher-order aspects of central-auditory processing such as melody perception.
Hertrich
Ingo
I
Department of General Neurology, Hertie-Institute for Clinical Brain Research, University of Tübingen, Hoppe-Seyler-Strasse 3, D-72076 Tübingen, Germany. ingo.hertrich@uni-tuebingen.de
Mathiak
Klaus
K
Lutzenberger
Werner
W
Ackermann
Hermann
H
D000161:Acoustic Stimulation / Q000379:methods; D000328:Adult; D001303:Auditory Cortex / Q000502:physiology* / Q000528:radiation effects; D001931:Brain Mapping; D005072:Evoked Potentials, Auditory / Q000502:physiology* / Q000528:radiation effects; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D015225:Magnetoencephalography; D008297:Male; D010507:Periodicity; D013057:Spectrum Analysis; D013067:Speech Perception / Q000502:physiology*