ORIGINAL RESEARCH

Cerebral cortex activation during the Sternberg verbal working memory task

Bakulin IS1, Zabirova AH1, Kopnin PN1, Sinitsyn DO1, Poydasheva AG1, Fedorov MV2, Gnedovskaya EV1,2, Suponeva NA1, Piradov MA1
About authors

1 Research Center of Neurology, Moscow, Russia

2 Skoltech, Moscow, Russia

Correspondence should be addressed: Ilya S. Bakulin
Volokolamskoye shosse, 80, Moscow, 125367; ur.ygoloruen@nilukab

About paper

Author contribution: Bakulin IS, Fedorov MV, Gnedovskaya EV, Suponeva NA, Piradov MA — study planning and design; Bakulin IS, Zabirova AH — literature analysis; Bakulin IS, Poydasheva AG — data acquisition; Zabirova AH, Kopnin PN, Sinitsyn DO — data analysis; Bakulin IS, Zabirova AH, Sinitsyn DO, Fedorov MV, Gnedovskaya EV, Suponeva NA, Piradov MA — data interpretation; Bakulin IS, Zabirova AH — manuscript draft preparation; Kopnin PN, Sinitsyn DO, Poydasheva AG, Fedorov MV, Gnedovskaya EV, Suponeva NA, Piradov MA — manuscript draft editing; all the authors — final version of the article preparation.

Received: 2020-01-22 Accepted: 2020-02-22 Published online: 2020-03-01
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Despite intensive study, the data regarding functional role of specific brain regions in the working memory processes still remain controversial. The study was aimed to determine the activation of cerebral cortex regions at different stages of the working memory task (information encoding, maintenance and retrieval). Functional magnetic resonance imaging (fMRI) with the modified Sternberg task was applied to 19 healthy volunteers. The objective of the task was to memorize and retain in memory the sequence of 7 letters with the subsequent comparison of one letter with the sequence. Activation was analyzed during three periods of the task compared to the rest period, as well as temporal dynamics of changes in BOLD signal intensity in three regions: left dorsolateral prefrontal, left posterior parietal and left occipital cortex. According to the results, significant activation of the regions in prefrontal and posterior parietal cortex was observed during all periods of the task (р < 0.05), but there were changes in its localization and lateralization. The activation pattern during the maintenance period corresponded to the fronto-parietal control network components. According to the analysis of temporal dynamics of changes in BOLD signal intensity, the most prominent activation of the dorsolateral prefrontal cortex and parietal cortex was observed in the end of the encoding period, during the maintenance period and in the beginning of the retrieval period, which confirmed the role of those areas in the working memory processes. The maximum of occipital cortex activation was observed during encoding period. The study confirmed the functional role of the dorsolateral prefrontal cortex and posterior parietal cortex in the working memory mechanisms during all stages of the Sternberg task.

Keywords: working memory, functional magnetic resonance imaging, the Sternberg task, delayed-response task, prefrontal cortex, fronto-parietal control network

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