EEG synchronization characteristics of functional connectivity and complex network properties of memory maintenance in the delta and theta frequency bands

Tóth, Brigitta; Boha, Roland; Pósfai, Márton; Gaál, Zsófia Anna; Kónya, Anikó; Stam, Cornelis J.; Molnár, Mihály

doi:10.1016/j.ijpsycho.2011.11.017

Cited by 40 publications

(28 citation statements)

References 33 publications

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“…Their power depends on the cognitive load. Theta band coherence between frontal and parietal sites has also been described in recent literature [40], [51]. In mental arithmetic tasks, enhancement of frontal theta activity [54], [55] or synchronization in a large number of electrode pairs have also been reported [53].…”

Section: Discussionmentioning

confidence: 66%

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A Graph Theoretical Approach to Study the Organization of the Cortical Networks during Different Mathematical Tasks

et al. 2013

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The two core systems of mathematical processing (subitizing and retrieval) as well as their functionality are already known and published. In this study we have used graph theory to compare the brain network organization of these two core systems in the cortical layer during difficult calculations. We have examined separately all the EEG frequency bands in healthy young individuals and we found that the network organization at rest, as well as during mathematical tasks has the characteristics of Small World Networks for all the bands, which is the optimum organization required for efficient information processing. The different mathematical stimuli provoked changes in the graph parameters of different frequency bands, especially the low frequency bands. More specific, in Delta band the induced network increases it’s local and global efficiency during the transition from subitizing to retrieval system, while results suggest that difficult mathematics provoke networks with higher cliquish organization due to more specific demands. The network of the Theta band follows the same pattern as before, having high nodal and remote organization during difficult mathematics. Also the spatial distribution of the network’s weights revealed more prominent connections in frontoparietal regions, revealing the working memory load due to the engagement of the retrieval system. The cortical networks of the alpha brainwaves were also more efficient, both locally and globally, during difficult mathematics, while the fact that alpha’s network was more dense on the frontparietal regions as well, reveals the engagement of the retrieval system again. Concluding, this study gives more evidences regarding the interaction of the two core systems, exploiting the produced functional networks of the cerebral cortex, especially for the difficult mathematics.

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Section: Discussionmentioning

confidence: 66%

“…Oscillations in delta range are believed to be generated by neocortical and thalamocortical networks [39]. This band is important for large scale cortical integration [40]. During cognitive processes, changes on delta band are produced and their degree depends on the complexity of tasks [41].…”

Section: Discussionmentioning

confidence: 99%

A Graph Theoretical Approach to Study the Organization of the Cortical Networks during Different Mathematical Tasks

et al. 2013

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“…major cortices of the default-mode network including the inferior frontal gyrus, the parietal cortex, and the insula in patients with PSs [6]. More specifically, theta activity is implicated in memory processes, as well as emotional arousal [13,14]. The posterior parietal cortex is related to self-processing [15] and is implicated in autobiographical thinking about past and future events [16].…”

Section: Discussionmentioning

confidence: 99%

Neural generators of psychogenic seizures: Evidence from intracranial and extracranial brain recordings

Arzy

Halje

Schechter

et al. 2014

Epilepsy & Behavior

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Psychogenic seizures (PSs) convincingly mimic seizure phenomena but with no underlying epileptic activity. However, not much is known about their neurophysiological basis. We had the rare opportunity to analyze intracranial brain recordings of PSs occurring besides epileptic seizures (ESs), which identified distinct frequency changes over the parietal cortex. For further validation, we applied topographic frequency analysis to two other patients who presented PSs and ESs during long-term monitoring. The analysis revealed a power decrease in the theta band at the posterior parietal cortex in all three patients during PSs but not during ESs. These changes may reflect disturbed self-referential processing associated with some PSs.

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“…The most significant finding was the increase in FD with the increase in memory frequency is classically used to quantitatively measure the functional relationship between different brain regions involved in various cognitive processes, like STM. In general, synchronous oscillatory cortical electrical activity in the 4-7 Hz theta band and the 8-12 Hz alpha band was reported in numerous studies to be associated with STM (Michels et al 2012;Palomaki et al 2012;Rawle et al 2012;Toth et al 2012;White et al 2012;Hsieh and Ranganath 2014). Furthermore, changes in theta activity were found to be associated with changes in mental load (Jensen and Tesche 2002).…”

Section: Introductionmentioning

confidence: 93%

Memory load effect in auditory–verbal short-term memory task: EEG fractal and spectral analysis

et al. 2015

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The objective of this preliminary study was to quantify changes in complexity of EEG using fractal dimension (FD) alongside linear methods of spectral power, event-related spectral perturbations, coherence, and source localization of EEG generators for theta (4-7 Hz), alpha (8-12 Hz), and beta (13-23 Hz) frequency bands due to a memory load effect in an auditory-verbal short-term memory (AVSTM) task for words. We examined 20 healthy individuals using the Sternberg's paradigm with increasing memory load (three, five, and seven words). The stimuli were four-letter words. Artifact-free 5-s EEG segments during retention period were analyzed. The most significant finding was the increase in FD with the increase in memory load in temporal regions T3 and T4, and in parietal region Pz, while decrease in FD with increase in memory load was registered in frontal midline region Fz. Results point to increase in frontal midline (Fz) theta spectral power, decrease in alpha spectral power in parietal region-Pz, and increase in beta spectral power in T3 and T4 region with increase in memory load. Decrease in theta coherence within right hemisphere due to memory load was obtained. Alpha coherence increased in posterior regions with anterior decrease. Beta coherence increased in fronto-temporal regions. Source localization delineated theta activity increase in frontal midline region, alpha decrease in superior parietal region, and beta increase in superior temporal gyrus with increase in memory load. In conclusion, FD as a nonlinear measure may serve as a sensitive index for quantifying dynamical changes in EEG signals during AVSTM tasks.

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EEG synchronization characteristics of functional connectivity and complex network properties of memory maintenance in the delta and theta frequency bands

Cited by 40 publications

References 33 publications

A Graph Theoretical Approach to Study the Organization of the Cortical Networks during Different Mathematical Tasks

A Graph Theoretical Approach to Study the Organization of the Cortical Networks during Different Mathematical Tasks

Neural generators of psychogenic seizures: Evidence from intracranial and extracranial brain recordings

Memory load effect in auditory–verbal short-term memory task: EEG fractal and spectral analysis

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