Differential outcomes from magneto- and electroencephalography for the analysis of human cognition.

Theoretical considerations show that magnetoencephalography (MEG) and electroencephalography (EEG) provide different information about ongoing human brain activity. The paper presents simultaneously measured MEG and EEG data showing that these measures may lead to different conclusions about cognitive models under investigation. This was demonstrated for amplitude results of the P300/N400 complex in a study of the secondary processing of lexical and non-verbal information in visual stimuli. As both methods provide different information about ongoing brain activity, their combined analysis is valuable. This seems particularly true for studies of higher order cognitive processing.