The electrophysiological correlates of the working memory subcomponents: evidence from high-density EEG and coherence analysis

Synchronization between prefrontal (executive) and posterior (association) cortices seems a plausible mechanism for temporary maintenance of information. However, while EEG studies reported involvement of (pre)frontal midline structures in synchronization, functional neuroimaging elucidated the impo...

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Bibliographic Details
Published in:Neurological sciences 2015-12, Vol.36 (12), p.2199-2207
Main Authors: Rutar Gorišek, Veronika, Belič, Aleš, Manouilidou, Christina, Koritnik, Blaž, Repovš, Grega, Bon, Jure, Žibert, Janez, Zidar, Janez
Format: Article
Language:English
Subjects:
Adult
Brain Mapping
Cerebral Cortex - physiology
Cortical Synchronization - physiology
Electroencephalography - methods
Electrophysiological Phenomena - physiology
Female
Humans
Male
Medicine
Medicine & Public Health
Memory, Short-Term - physiology
Neurology
Neuropsychological Tests
Neuroradiology
Neurosciences
Neurosurgery
Original Article
Psychiatry
Reaction Time
Theta Rhythm - physiology
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Summary:Synchronization between prefrontal (executive) and posterior (association) cortices seems a plausible mechanism for temporary maintenance of information. However, while EEG studies reported involvement of (pre)frontal midline structures in synchronization, functional neuroimaging elucidated the importance of lateral prefrontal cortex (PFC) in working memory (WM). Verbal and spatial WM rely on lateralized subsystems (phonological loop and visuospatial sketchpad, respectively), yet only trends for hemispheric dissociation of networks supporting rehearsal of verbal and spatial information were identified by EEG. As oscillatory activity is WM load dependent, we applied an individually tailored submaximal load for verbal (V) and spatial (S) task to enhance synchronization in the relevant functional networks. To map these networks, we used high-density EEG and coherence analysis. Our results imply that the synchronized activity is limited to highly specialized areas that correspond well with the areas identified by functional neuroimaging. In both V and S task, two independent networks of theta synchronization involving dorsolateral PFC of each hemisphere were revealed. In V task, left prefrontal and left parietal areas were functionally coupled in gamma frequencies. Theta synchronization thus provides the necessary interface for storage and manipulation of information, while left-lateralized gamma synchronization could represent the EEG correlate of the phonological loop.
ISSN:1590-1874
1590-3478
DOI:10.1007/s10072-015-2337-4