Serial and parallel processing in the human auditory cortex: a magnetoencephalographic study.
Although anatomical, histochemical and electrophysiological findings in both animals and humans have suggested a parallel and serial mode of auditory processing, precise activation timings of each cortical area are not well known, especially in humans. We investigated the timing of arrival of signals to multiple cortical areas using magnetoencephalography in humans. Following click stimuli applied to the left ear, activations were found in six cortical areas in the right hemisphere: the posteromedial part of Heschl's gyrus (HG) corresponding to the primary auditory cortex (PAC), the anterolateral part of the HG region on or posterior to the transverse sulcus, the posterior parietal cortex (PPC), posterior and anterior parts of the superior temporal gyrus (STG), and the planum temporale (PT). The mean onset latencies of each cortical activity were 17.1, 21.2, 25.3, 26.2, 30.9 and 47.6 ms respectively. These results suggested a serial model of auditory processing along the medio-lateral axis of the supratemporal plane and, in addition, implied the existence of several parallel streams running postero-superiorly (from the PAC to the belt region and then to the posterior STG, PPC or PT) and anteriorly (PAC-belt-anterior STG).
Inui
Koji
K
Department of Integrative Physiology, National Institute for Physiological Sciences, Okazaki 444-8585, Japan. inui@nips.ac.jp
Okamoto
Hidehiko
H
Miki
Kensaku
K
Gunji
Atsuko
A
Kakigi
Ryusuke
R
D000328:Adult; D001303:Auditory Cortex / Q000502:physiology*; D001306:Auditory Pathways / Q000502:physiology; D001931:Brain Mapping / Q000379:methods*; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D005260:Female; D006801:Humans; D015225:Magnetoencephalography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009415:Nerve Net / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology*