[Preliminary study on the functional localization of auditory cortex in the healthy young subjects using magnetic source imaging].
OBJECTIVE
To evaluate the value of magnetic source imaging (MSI) in the functional localization of the primary auditory cortex.


METHODS
The M100 waves of cortical auditory evoked magnetic fields (AEFs) evoked by 0.5, 1, 2, 4 and 8 kHz pure tones in 5 subjects and by 2 kHz pure tones in 25 healthy young subjects were measured respectively (16 males and 14 females, with the age from 20 to 32 years old) using a whole head 306 channel magnetoencephalography (MEG) system. The MSI obtained by superimposing functional MEG data on structural magnetic resonance image (MRI) was used to localize the M100 sources on the auditory cortex.


RESULTS
The M100 waves of AEFs were clear and replicable in both hemispheres. The M100 sources were localized on the bilateral transverse temporal gyri in all 30 subjects. The localization of M100 on transverse temporal gyri varied with the changes of stimulus frequency. The localization of primary auditory cortex was asymmetrical between bilateral hemispheres, and the left hemisphere M100 dipoles were significantly posterior compared to the right M100 dipoles. The M100 responses appeared significantly earlier to the contralateral stimuli than that to the ipsilateral stimuli in both hemispheres. The dipole positions of M100 were independent of the side of the stimuli.


CONCLUSIONS
The functional localization of the primary auditory cortex could be determined precisely by magnetic source imaging (MSI) with high spatiotemporal resolution. MSI would hold great promise as a noninvasive tool for the fundamental and clinical research in otology.
Miao
Ying-zhang
YZ
Department of Otorhinolaryngology, Hebei Provincial People's Hospital, Shijiazhuang 050051, China. miaoyz65@hotmail.com
Sun
Ji-lin
JL
Bu
Gui-qing
GQ
Rong
Hong
H
Wu
Jie
J
Li
Su-min
SM
Liang
Heng-ren
HR
D000328:Adult; D001303:Auditory Cortex / Q000502:physiology*; D005260:Female; D006801:Humans; D060526:Magnetic Fields; D008279:Magnetic Resonance Imaging / Q000379:methods; D015225:Magnetoencephalography; D008297:Male; D055815:Young Adult