Magnetoencephalography for research of auditory cortex.
CONCLUSIONS
The results could indicate that, during phylogeny and human ontogeny, the central nervous system has enhanced the speech activity from any other activity even though other frequencies could be relevant for survival.


OBJECTIVE
People of all ages can experience alterations of auditory perception that progressively increase with aging. The whole approach to these alterations needs not only peripheral (cochlear) or brainstem studies but also an analysis of the auditory cortex. In fact, auditory evoked fields (AEF) may contribute to the understanding of the neural correlate of sound awareness.


METHODS
The M100 response after pure tone stimulation (five frequencies ranging from 500 to 8000 Hz) was analyzed in a group of nine adult subjects with normal hearing, older than 25 years of age and under 40 years old. Average M100 field intensity was calculated for all magnetoencephalography (MEG) channels in a 60 ms window around the M100 waveform.


RESULTS
The results indicate a more intense cortical response to main speech frequencies (0.5 to 2 kHz) as compared with other frequencies not involved in human conversation.
Poch-Broto
Joaquín
J
Servicio de Otorrinolaringología, Hospital Clínico Universitario San Carlos, Madrid, Spain.
Bhathal
Beatriz
B
Iglesias
Ma Cruz
MC
Santiuste
Marta
M
Fernández
Alberto
A
Ortiz
Tomás
T
Gil-Loyzaga
Pablo
P
D000328:Adult; D000367:Age Factors; D001288:Attention / Q000502:physiology; D001301:Audiometry, Pure-Tone; D001303:Auditory Cortex / Q000502:physiology*; D001364:Awareness / Q000502:physiology; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D005260:Female; D006801:Humans; D015225:Magnetoencephalography; D008297:Male; D010897:Pitch Discrimination / Q000502:physiology*; D012016:Reference Values; D012815:Signal Processing, Computer-Assisted; D013067:Speech Perception / Q000502:physiology*