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Involuntary auditory attention: Measurements of electromagnetic brain activity and behavior

Kimmo Alho

Department of Psychology, University of Helsinki, 00014 Helsinki, Finland and BioMag Laboratory, Helsinki University Central Hospital

Physically deviant sounds occurring in a sequence of repetitive standard sounds presented to a subject concentrating on a visual discrimination task occasionally catch the subject's attention. This is seen as increased reaction times and errors in discriminating visual stimuli preceded by deviant sounds [1, 2]. The mismatch nega-tivity (MMN) and the subsequent positive P3a event-related potentials (ERPs), and their magnetoencephalographic (MEG) counterparts, elicited by deviant sounds, are probably generated by brain mechanisms involved in such involuntary attention. The MMN has generators in the auditory and frontal cortices [3 - 5]. The frontal MMN component might be generated by frontal mechanisms initiating involuntary attention to sound change, while the P3a might be associated with the actual orienting of attention. According to MEG recordings, the early part of P3a originates from the supratemporal auditory cortex [6]. It might be involved in triggering temporo-parietal and frontal P3a genera-tors indicated by recent scalp current den-sity mapping [7] of the large P3a to widely deviant novel sounds occurring among standard and de-viant tones. This temporo-parietal and frontal activity might be as-sociated with orienting of attention or with further evaluation of the novel sounds. Work supported by the Academy of Finland.

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5. Giard, M., Perrin, F., Pernier, J., and Bouchet, P. Psychophysiol. 27, 627-640, 1990
6. Alho, K., Winkler, I., Escera, C., Huotilainen, M., Virtanen, J., Jääskeläinen, I., Pekkonen, E., and Ilmoniemi, R. Psychophysiol. 35: 211-224, 1998
7. Escera, C., Serra, J., Giard, M., Yago, E., and Alho, K. (in preparation)

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