Hjärnans elektriska bakgrunds-aktivitet som mått på kognitiva processer

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The short-lasting, event-related amplitude attenuation of the rhythms in EEC alpha band is called event-related desynchronization (ERD). The opposite phenomenon, event-related synchronization (ERS) is the phasic increase in alpha band power. The alpha rhythm of the EEG is characteristic for inactive cortical fields and alpha desynchronization is thus an indicator of cortical activation. This paper discusses recent findings on the ERD/ERS phenomenon in the auditory stimulus modality. Results on ERD/ERS studies, in which complex auditory stimulation has been examined, are presented and discussed from a theoretical framework. The ERD/ERS technique is likely to be an intriguing method for studying brain electric activation patterns related to higher cognitive functions, such as attention and memory, as well as deviances in these functions.