Left frontal EEG coherence reflects modality independent language processes.

Previous studies showed that distinct components of higher cognitive processes like memorizing of words could be correlated with changes in different frequency bands of the human EEG. This study was designed in order to find out if 1) some frequency bands show power and coherence changes only due to the modality of presented stimuli (either auditory or visual) and 2) if other frequency bands show modality independent effects which should reflect real cognitive-linguistic differences between word classes (either concrete and abstract nouns). EEG was recorded from sixteen right-handed females which had to memorize auditorily and visually presented concrete and abstract nouns. Results show the alpha-1 band to reveal no differences between word classes but demonstrate an influence of modality of stimulus presentation. The only modality independent differences between concrete and abstract noun processing were found in the delta, theta and beta-1 band at left frontal electrodes.