The Role of Slow-Wave Electroencephalographic Activity in Reading

Abstract

Background. Although slow-wave EEG activity has traditionally been associated with either deep sleep or brain pathology, recent studies have revealed a relationship between this neuronal activity and cognitive functions. The present study explored the slow-wave EEG amplitude differences between resting and reading states in a group of 19 non-clinical young adults. Methods. EEG was recorded during an eyes-open resting baseline, and three different reading tasks selectively engaging the visual, phonetic, and semantic reading modalities. Frequency spectra between 1 and 8 Hz were analyzed in two frequency bands, 1-4 Hz (delta) and 4-8 Hz (theta). Results. Multiple t-test analyses comparing the three reading tasks with the baseline showed significant amplitude increases during reading mostly in the 1-4 Hz and some in the 4-8 Hz band. These changes were topographically different among the three reading tasks. During visual reading, amplitude increased at C3, C4, T3, T4, and T5 for the 1-4 Hz band, and at T5 and T6 for the 4-8 Hz band. During phonetic reading, amplitude increased at T3, T4, F3 and F7 for the 1-4 Hz band, and at T5 and FP1 for the 4-8 Hz band. During semantic reading, amplitude increased at T3, T4, C3, C4, F3, F7, F8, CZ and FZ for the 1-4 Hz band and at T5 for the 4-8 Hz band. Conclusions. Amplitude increases in slow-wave EEG are part of the normal reading process and it appears at scalp electrodes close to cortical areas expected to be involved according to different reading modalities. Implications for neurofeedback involve tentative models for cognitive processes.