title: The auditory evoked-gamma response and its relation with the N1m.
abstract: This study explored the patterns of oscillatory activity that underpin the N1m auditory evoked response. Evoked gamma activity is a small and relatively rarely-reported component of the auditory evoked response, and the objective of this work was to determine how this component relates to the larger and more prolonged changes in lower frequency bands. An event-related beamformer analysis of MEG data from monaural click stimulation was used to reconstruct volumetric images and virtual electrode time series. Group analysis of localisations showed that activity in the gamma band originated from a source that was more medial than those for activity in the theta-to-beta band, and virtual-electrode analysis showed that the source of the gamma activity could be statistically dissociated from the lower-frequency response. These findings are in accordance with separate functional roles for the activity in each frequency band, and provide evidence that the oscillatory activity that underpins the auditory evoked response may contain important information about the physiological basis of the macroscopic signals recorded by MEG in response to auditory stimulation.
authors.affiliation: Aston Brain Centre, Aston University, Birmingham, B4 7ET, UK. Electronic address: c.witton@aston.ac.uk.
authors.forename: Caroline
authors.initials: C
authors.lastname: Witton
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Medical University of South Carolina, Charleston, SC, USA.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Eckert
authors.affiliation: Aston Brain Centre, Aston University, Birmingham, B4 7ET, UK.
authors.forename: Ian M
authors.initials: IM
authors.lastname: Stanford
authors.affiliation: Aston Brain Centre, Aston University, Birmingham, B4 7ET, UK.
authors.forename: Lauren E
authors.initials: LE
authors.lastname: Gascoyne
authors.affiliation: Aston Brain Centre, Aston University, Birmingham, B4 7ET, UK.
authors.forename: Paul L
authors.initials: PL
authors.lastname: Furlong
authors.affiliation: Aston Brain Centre, Aston University, Birmingham, B4 7ET, UK.
authors.forename: Siân F
authors.initials: SF
authors.lastname: Worthen
authors.affiliation: Department of Clinical Neurophysiology and Magnetoencephalography Center, VU University Medical Center, 1081 HV, Amsterdam, The Netherlands.
authors.forename: Arjan
authors.initials: A
authors.lastname: Hillebrand
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D000368:Aged; D001303:Auditory Cortex / Q000473:pathology / Q000502:physiology*; D001931:Brain Mapping; D015331:Cohort Studies; D004566:Electrodes; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D005260:Female; D006801:Humans; D007802:Language; D007806:Language Disorders / Q000175:diagnosis / Q000473:pathology; D015225:Magnetoencephalography; D008297:Male; D008875:Middle Aged; D009991:Oscillometry; D013060:Speech / Q000502:physiology
keywords: Beamformer; Cortex; Magnetoencephalography; Oscillations