Processing of complex sounds in the human auditory cortex as revealed by magnetic brain responses

Authors


  • This research was supported by the Academy of Finland, the Jenny and Antti Wihuri Foundation, the Emil Aaltonen Foundation, and the Finnish Cultural Foundation.

  • We are grateful to Robert T. Knight, Patrick May, Göte Nyman, Jukka Saarinen, and Veijo Virsu for their constructive comments during the preparation of this manuscript.

Address reprint requests to: Kimmo Alho, Department of Psychology, P. O. Box 11, FIN-00014 University of Helsinki, Finland.

Abstract

Processing of simple and complex sounds in the human brain was compared by recording extracranial magnetic mismatch responses (MMNm; the magnetic counterpart of the mismatch negativity, or MMN) to frequency changes in these sounds. Generator sources, modeled as equivalent current dipoles (ECDs), of MMNm responses to a change in one frequency element of complex sounds (a chord and a serial tone pattern) were located in supratemporal auditory cortex, on average, 10 mm medially to the source of an MMNm elicited by an identical frequency change in a simple tone. These results suggest that at least partially different supratemporal neuron populations are invovled in processing changes in simple and complex sounds and that sensory-memory representations for these sounds may be located in different fields of the auditory cortex.

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