Frequency-selective generators of oscillatory brain activity allow identifying processes of a working memory

Danilova, N.N.; Strabykina, E.A.

Авторы: Danilova Nina N., Strabykina Elena A.
Журнал: International Journal of Psychophysiology
Том: 77
Номер: 3
Год издания: 2010
Издательство: Elsevier BV
Местоположение издательства: Netherlands
Первая страница: 208
Последняя страница: 208
DOI: 10.1016/j.ijpsycho.2010.06.011
Аннотация: The aim of this study to investigate processes of visual working memory by a new method of micro structural analysis of event-related oscillations based on the pacemaker hypothesis of rhythm genesis (Danilova, 2006, 2008). Computation of equivalent current dipoles based on multichannel EEC data and their superposition onto slices of structural MRI for an individual human brain was used to identify localization of activated frequency-selective gamma (30-75 Hz), beta (14-29 Hz) and theta (4-7 Hz) generators. In experiments with working memory (10 participants), the subject has to memorize four pairs of two-digit numbers that are visually-presented and retain them during a delay interval for the subsequent comparison with target and no-target stimuli and performing motor reaction on target stimuli. The similarity of activated brain structures was found for the perception stage and retention interval. High-frequency generators were localized in frontal, associative (temporal, parietal) cortex, visual cortex, and cerebellum. Activity level in the frontal area during the perception and number memorization was higher than during the retention interval. However, during the delay period, the maximum activity of high-frequency generators was shifting from a frontal to an associative cortex and the cerebellum. The growth of cerebellum activity and the activation of visual cortex may be attributed to a motor readiness, the ability to predict the moment of stimulus presentation, and activating sensory memory traces. The investigation of the dynamic of memory retention showed that frequency-selective gamma and beta genera¬tors operating at different frequencies form bursts of join activity which periodically appears and disappears. The join activity of the frontal brain area with the visual and temporal cortex occurs during the delay interval and is absent at the perception stages. This suggests that during the retention interval, there is the interaction of local neuron networks represented by activated high-frequency generators. It facilitates rewriting the numerical information (LT-memory traces) from associative brain areas into prefrontal cortex, where it assumes an active form for subsequent use in behavior. Because theta rhythm is connected with encoding function, we have investigated the integration rrequency-seiective tneta generators witn nign-rrequency gamma and beta generators. For this aim, we used weighed centroid method for clusterization of neural sources in the dipole model of the brain. Results supported periodic fluctuations of join activity of gamma, beta, and theta generators. Localization of centroids showed repeated join activity in the prefrontal and/or cingular cortex, temporal, visual-parietal cortex, cerebellum and thalamus. Our finding highlights the role of frequency-selective generators in the sub-function of visual working memory - the retention of memory traces in active form for future use in behavior. Research was supported by Russian Humanitarian Scientific Fund project No 10-06 00481a.
Добавил в систему: Данилова Нина Николаевна

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