Transient and phase-locked evoked magnetic fields in response to periodic acoustic signals

• Published in: Neuroreport Vol. 15; no. 10; p. 1687
• Main Authors: Hertrich, Ingo, Mathiak, Klaus, Lutzenberger, Werner, Ackermann, Hermann
• Format: Journal Article
• Language: English
• Published: England 19.07.2004
• Subjects: Acoustic Stimulation - methods; Adult; Auditory Cortex - physiology; Auditory Cortex - radiation effects; Brain Mapping; Evoked Potentials, Auditory - physiology; Evoked Potentials, Auditory - radiation effects; Female; Functional Laterality - physiology; Humans; Magnetoencephalography; Male; Periodicity; Spectrum Analysis; Speech Perception - physiology
• ISSN: 0959-4965
• DOI: 10.1097/01.wnr.0000134930.04561.b2

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.