Oscillatory brain activity in the development and the actualization of semantic categoriesстатьяТезисы
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Дата последнего поиска статьи во внешних источниках: 27 мая 2015 г.
Аннотация:Oscillatory brain activity in the development and the actualization of semantic categories
Nina N. Danilova
Lomonosov Moscow State University, Russia
The interaction of the cortex and subcortical brain structures is the key to understanding the brain mechanisms of semantic categorization. However, the role of oscillatory brain activity providing this communication is understood poorly. Here, we investigated the interaction of human brain structures during tasks imposed on the categorization of visual presented words belonging to two domains: "animals" and "objects." For this aim the author's method — "Microstructural analysis of oscillatory brain activity" (Danilova, 2002-2012) based on the pacemaker hypothesis of the origin of EEG rhythms was used. This method allows to leave from traditionally used total indicators of the main rhythms of EEG and to pay attention to their separate frequency components. The method operates with concepts of frequency-selective generators and reveals their local activity in cortical and subcortical brain structures. For this aim the coordinates of the dipole sources of frequency-selective generators are calculated and localized in brain structures during 1 s after stimulus. The research covered 10 subjects aged 20-23, the group data are presented. Frequency-selective generators removed from the ERPs for two stimulus categories.
This study shows the difference in the processes of categorization for two domains: "animals" and "objects". The recognition of the animals category was performed more effectively with shorter latency for motor response, and caused the greater activity of frequency-selective theta generators in the temporal lobe (Fusiform G.), in extra occipital cortex (Lingual G., BA 19) and in the thalamus anterior nucleus (AN) in the comparison with the identification of the objects category. Our results show that the domain "animals" has a powerful connection with the frontal-striatal-thalamic network which has been identified by fMRI as a network involved in the forming and maintaining categories (Grinband et al. 2006; Tan et al. 2011). The anticipation of the visual presented semantic category was found also. Enhancing activity of frequency-selective theta generators together with decreased activity of alpha generators was appeared only before word presentations — the names of the objects. This indicates the high need in activity of attention and memory processes which are required for semantic categorization of the objects as a more complex domain. The presented results were obtained by localization of the dipole sources of frequency-selective generators in brain structures. Brain regions are estimated from Talairach and Tournoux (1988), after adjustments for differences between BL6 and Talairach coordinates.
The study was supported by the Russian Humanitarian Scientific Foundation, research projects no. 13-06-00312-a and Russian Scientific Foundation, research projects no. 14-18-03253.