COOPERATIVE DYNAMICS IN AUDITORY BRAIN RESPONSE

Simultaneous estimates of activity in the left and right auditory cort ex of Ave normal human subjects were extracted from multichannel magne toencephalography recordings. Left, right, and binaural stimulations w ere used, in separate runs, for each subject. The resulting time serie s of left and right auditory cortex activity were analyzed using the c oncept of mutual information. The analysis constitutes an objective me thod to address the nature of interhemispheric correlations in respons e to auditory stimulations. The results provide clear evidence of the occurrence of such correlations mediated by a direct information trans port, with clear laterality effects: as a rule, the contralateral hemi sphere leads by 10-20 ms, as can be seen in the average signal. The st rength of the interhemispheric coupling, which cannot be extracted fro m the average data, is found to be highly variable from subject to sub ject, but remarkably stable for each subject. [S1063-651X(98)07511-4].