Event-related EEG/MEG synchronization and desynchronization: basic principles.

http://download.neurosky.com/docs/papers/bcq/Klimesch_1999_EEG_alpha_and_theta_oscillations_reflect_cognitive_and_memory_performance.pdf

EEG alpha and theta oscillations reflect cognitive and memory performance: a review and analysis

The mismatch negativity (MMN) in basic research of central auditory processing: a review.

In the present article, the basic research using the mismatch negativity (MMN) and analogous results obtained by using the magnetoencephalography (MEG) and other brain-imaging technologies is reviewed. This response is elicited by any discriminable change in auditory stimulation but recent studies extended the notion of the MMN even to higher-order cognitive processes such as those involving grammar and semantic meaning. Moreover, MMN data also show the presence of automatic intelligent processes such as stimulus anticipation at the level of auditory cortex. In addition, the MMN enables one to establish the brain processes underlying the initiation of attention switch to, conscious perception of, sound change in an unattended stimulus stream. 2007 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

/pdf/invited-review-the-mismatch-negativity-mmn-in-basic-research-4qrhy54ph5.pdf

Invited review The mismatch negativity (MMN) in basic research of central auditory processing: A review

To study the role of brain oscillations in working memory, we recorded the scalp electroencephalogram (EEG) during the retention interval of a modified Sternberg task. A power spectral analysis of the EEG during the retention interval revealed a clear peak at 9−12 Hz, a frequency in the alpha band (8−13 Hz). In apparent conflict with previous ideas according to which alpha band oscillations represent brain ‘idling’, we found that the alpha peak systematically increased with the number of items held in working memory. The enhancement was prominent over the posterior and bilateral central regions. The enhancement over posterior regions is most likely explained by the well known alpha rhythm produced close to the parietal-occipital fissure, whereas the lateral enhancement could be explained by sources in somato-motor cortex. A time-frequency analysis revealed that the enhancement was present throughout the last 2.5 s of the 2.8 s retention interval and that alpha power rapidly diminished following the probe. The load dependence and the tight temporal regulation of alpha provide strong evidence that the alpha generating system is directly or indirectly linked to the circuits responsible for working memory. Although a clear peak in the theta band (5−8 Hz) was only detectable in one subject, other lines of evidence indicate that theta occurs and also has a role in working memory. Hypotheses concerning the role of alpha band activity in working memory are discussed.

/pdf/oscillations-in-the-alpha-band-9-12-hz-increase-with-memory-1giq2l7a25.pdf

Oscillations in the Alpha Band (9–12 Hz) Increase with Memory Load during Retention in a Short-term Memory Task

Early and Late Mismatch Negativity Elicited by Words and Speech-Like Stimuli in Children

Event-related. EEG desynchronization and synchronization during an auditory memory task

Relative alpha desynchronization and synchronization during speech perception.

Event-related desynchronization and synchronization during an auditory lexical matching task

Relative desynchronization (ERD) and synchronization (ERS) of the 8–10 Hz and 10–12 Hz alpha freqency bands elicited by music were studied in ten musically untrained right-handed subjects. The subjects listened to two five-minute musical excerpts representing two different musical genres, popular and classical, presented both foward and backward. ERD/ERS of the two alpha frequency bands was examined during the first four minutes of stimulus presentation using one-minute time windows. The results demonstrated that both the 8–10 Hz and the 10–12Hz frequency band exhibited reactivity to musical stimuli. The responses of the 8–10Hz and 10–12 Hz alpha frequency bands were dissimilar, dymanic and dependent on both time and stimulation type. The dynamics of these changes over time may explain some discrepancies in earlier EEG studies during listening to music.

A.Heikki Lang

Papers

Early and Late Mismatch Negativity Elicited by Words and Speech-Like Stimuli in Children

Event-related. EEG desynchronization and synchronization during an auditory memory task

Relative alpha desynchronization and synchronization during speech perception.

Event-related desynchronization and synchronization during an auditory lexical matching task

Relative alpha desynchronization and synchronization during perception of music