Electrophysiological signatures of resting state networks under new environmental conditions.

It is assumed that cognitive processes are provided by the regulatory interactions of different brain networks. The three most stable resting state networks, among which the default mode network (DMN), the central executive network (CEN) and the salience network (SN) are considered to be the key neurocognitive networks for understanding higher cognitive functions. Peculiarities of changes in the connectivity of resting state networks of an individual entering a new environment and after a year of adaptation in this environment remain poorly studied. The aim of this study was to investigate the peculiarities of the connectivity of resting state networks calculated in EEG data in students right after moving to an unfamiliar environment and one year after moving. 128-channel EEGs were recorded in the resting state in 45 students (all men) aged from 18 to 29 years, who moved to the North region of Russia (Yakutsk, Republic of Sakha (Yakutia)). Resting state networks were calculated by the seed-based method. The subjects had increased SN connectivity with the sensorimotor cortex and the posterior node of DMN (posterior cingulate cortex and precuneus) in the condition when they were exposed to a new unfamiliar environment, compared to the condition after a year in the same environment. In general, the obtained data are consistent with the notion of increased SN functioning when encountering new significant stimuli and tasks, i.e. new environmental conditions, and the representation of SN as closely related to the function of homeostasis regulation according to organism's internal goals and environmental requirements.

Associations of Hyperactivity and Inattention Scores with Theta and Beta Oscillatory Dynamics of EEG in Stop-Signal Task in Healthy Children 7-10 Years Old.

In the current study, we aimed to investigate the associations between the natural variability in hyperactivity and inattention scores, as well as their combination with EEG oscillatory responses in the Stop-Signal task in a sample of healthy children. During performance, the Stop-Signal task EEGs were recorded in 94 Caucasian children (40 girls) from 7 to 10 years. Hyperactivity/inattention and inattention scores positively correlated with RT variability. Hyperactivity/inattention and inattention scores negatively correlated with an increase in beta spectral power in the first 200 ms after presentation of the Go stimulus. Such results are in line with the lack of arousal model in ADHD children and can be associated with less sensory arousal in the early stages of perception in children with symptoms of inattention. The subsequent greater increase in theta rhythm at about 300 ms after presentation of the Go stimulus in children with higher inattention scores may be associated with increased attention processes and compensation for insufficient vigilance in the early stages of perception.

Oscillatory dynamics of perception of emotional sentences in healthy subjects with different severity of depressive symptoms.

The aim of the study was to investigate the characteristics of the oscillatory dynamics of brain activity during the perception of negative, positive, and neutral sentences in healthy individuals with differing severity of depressive symptoms at the preclinical stage. The study involved 34 healthy people (22 women). The severity of the symptoms of depression was assessed using Beck's Depression Inventory (BDI II). Using independent component analysis and the function of dipfit in the EEGlab software, the EEG was divided into components and their localizations were calculated. To assess the induced responses, event-related spectral perturbations were calculated. The perception of emotional sentences was accompanied by a more pronounced increase in theta rhythm in the group with lower severity of depressive symptoms. The perception of all types of sentences was accompanied by a decrease in beta rhythm in the group with lower severity of depressive symptoms. The effects were localized to the precuneus. The decrease of oscillatory responses in the theta and beta ranges in individuals with a high severity of depressive symptoms suggests a reduction of attention to the emotional content and meaning of the sentences.

Impact of Polymorphisms in the Serotonin Transporter Gene on Oscillatory Dynamics during Inhibition of Planned Movement in Children.

The serotonin transporter plays an important role in serotonergic neuromodulation. It is known that polymorphisms in the serotonin transporter gene are linked to the dysregulation of emotions. In the current study, we aimed to investigate the impact of variation in the gene encoding serotonin transporter polymorphism on oscillatory dynamics during inhibition of planned movement in the stop signal paradigm. During performance the stop signal paradigm, electroencephalograms (EEGs) were recorded in 90 healthy Caucasian children (39 girls) from 7 to 12 years. Buccal epithelium probes were taken from all participants. The La, Lg, and S alleles of serotonin transporter-linked polymorphic region (5-HTTLPR) polymorphism were detected in the DNA samples using PCR. LaLa genotype carriers did not differ from LaS\LgS and LgS\LgLg\SS carriers in a number of successful inhibitions of a prepotent response. Carriers of LaLa exhibit higher alpha and beta event-related spectral perturbations (ERSP) in parietal and occipital cortices after the presentation of signal of inhibition of movement than LaS\LgS and LgS\LgLg\SS carriers. Results are consistent with current literature and confirm that S allele carriers are more predisposed to disturbances in cognitive control.

Cross-Frequency Coupling in Developmental Perspective.

It is generally assumed that different electroencephalogram (EEG) frequency bands are somehow related to different computational modes in the brain. Integration of these computational modes is reflected in the phenomenon of cross-frequency coupling (CFC). On slow temporal scales, CFC may reflect trait-like properties, which posits a question of its developmental trends. This is the first study that explored source-level CFC measures in a developmental perspective using both cross-sectional and longitudinal designs. CFC measures demonstrated good test-retest stability and proved to be higher in adults in cortical areas participating in sensory-motor integration, response inhibition, and attentional control. In children, greater CFC was observed in parietal regions involved in self-centered cognition. Over the period from 7 to 10 years, CFC demonstrated nonlinear growth trajectories. Introversion was associated with higher CFC in cortical areas related to emotion, attention, and social cognition, implying that the association between introversion and CFC appears early in the development.

EEG dynamics of spontaneous stimulus-independent thoughts.

In this study, we aimed to compare the oscillatory dynamics accompanying self-referential and non-self-referential stimulus-independent thoughts. Electroencephalograms were recorded in 30 healthy participants who were asked to press buttons classifying their spontaneous thoughts as self-referential or non-self-referential. EEG data were analyzed using independent component analysis in conjunction with dipole localization. Self-referential thoughts, as compared to non-self-referential thoughts, were accompanied by more pronounced decreases of theta, alpha, and beta spectral power in the anterior hub of the default-mode network, in the left lateral prefrontal, motor/somatosensory, and temporal cortices. These oscillatory dynamics are interpreted as a reflection of autobiographical memory retrieval intrinsic to self-referential thoughts. Abbreviations: BA: Brodmann area; BOLD: blood oxygenation level-dependent; DMN: default mode network; EEG: electroencephalogram; ERSP: event-related spectral perturbations; fMRI: functional magnetic resonance imaging; PCC: posterior cingulate cortex; PET: positron emission tomography; PFC: prefrontal cortex; SIT: stimulus-independent thought; WM: working memory.

Effortful control and resting state networks: A longitudinal EEG study.

Resting state networks' (RSNs) architecture is well delineated in mature brain, but our understanding of their development remains limited. Particularly, there are few longitudinal studies. Besides, all existing evidence is obtained using functional magnetic resonance imaging (fMRI) and there are no data on electrophysiological correlates of RSN maturation. We acquired three yearly waves of resting state EEG data in 80 children between 7 and 9years and in 55 adults. Children's parents filled in the Effortful Control (EC) scale. Seed-based oscillatory power envelope correlation in conjunction with beamformer spatial filtering was used to obtain electrophysiological signatures of the default mode network (DMN) and two task-positive networks (TPN). In line with existing fMRI evidence, both cross-sectional comparison with adults and longitudinal analysis showed that the general pattern of maturation consisted in an increase in long-distance connections with posterior cortical regions and a decrease in short connections within prefrontal cortical areas. Latent growth curve analysis showed that EC scores were predicted by a linear increase over time in DMN integrity in alpha band and an increase in the segregation between DMN and TPN in beta band. These data confirm the neural basis of observed in fMRI research maturation-related changes and show that integrity of the DMN and sufficient level of segregation between DMN and TPN is a prerequisite for appropriate attentional and behavioral control.

Task-positive and task-negative networks and their relation to depression: EEG beamformer analysis.

Major Depressive Disorder (MDD) has been associated with predominance of the default-mode network (DMN) over the task-positive network (TPN), which is considered a neurobiological base for ruminative responding. It is not known whether this predominance is a signature of the full-blown MDD or it already exists at preclinical stages. Besides, all relevant evidence has been obtained using fMRI, which allows for a precise spatial characterization of resting state networks (RSNs), but their neural correlates remain elusive. Here we show that after leakage correction of beamformer-projected resting EEG time series, seed-based oscillatory-power envelope correlation analysis allows revealing RSNs with significant similarity to respective fMRI RSNs. In a non-clinical sample, depressive symptoms, as measured by the Beck Depression Inventory, are associated with predominance of DMN over TPN connectivity in the right insula and the right temporal lobe in the delta frequency band. These findings imply that in individuals with heightened level of depressive symptoms, emotional circuits are stronger connected with DMN than TPN and should be more easily engaged in self-referential rumination than in responding to environmental challenges. The study's findings are in agreement with fMRI evidence, thus confirming the neural base of the observed in fMRI research effects and showing that implicated in depression neural mechanism may already be in action even at preclinical stages.

Oscillatory correlates of moral decision-making: Effect of personality.

The role of emotion in moral decision-making is still a matter of debate. Greene, Sommerville, Nystrom, Darley, and Cohen (2001) argue that 'personal' moral judgments are driven by emotional responses, while 'impersonal' judgments are largely driven by cognitive processes. In this study, oscillatory correlates of decision-making were compared in moral personal, moral impersonal, and nonmoral conditions, as well as in trials associated with utilitarian (i.e., favoring the 'greater good' over individual rights) and non-utilitarian choices. Event-related synchronization in delta and theta bands was greater in the right temporal lobe in personal than in both nonmoral and impersonal moral condition. Graph-theoretical analysis of connectivity patterns showed the prominent role of the orbitofrontal and cingulate cortices in personal moral decision-making, implying greater emotional and self-processing. Higher conscientiousness and intellect and lower behavioral activation were associated with greater difference in oscillatory responses between utilitarian and non-utilitarian choices in personal than in impersonal condition, indicating that sensitivity to moral issues and the ability to grasp the nuances of moral situation are essential for understanding the implications of utilitarian choices in personal and impersonal conditions.

Oscillatory correlates of autobiographical memory.

Recollection of events from one's own life is referred to as autobiographical memory. Autobiographical memory is an important part of our self. Neuroimaging findings link self-referential processes with the default mode network (DMN). Much evidence coming primarily from functional magnetic resonance imaging studies shows that autobiographical memory and DMN have a common neural base. In this study, electroencephalographic data collected in 47 participants during recollection of autobiographical episodes were analyzed using temporal and spatial independent component analyses in combination with source localization. Autobiographical remembering was associated with an increase of spectral power in alpha and beta and a decrease in delta band. The increase of alpha power, as estimated by sLORETA, was most prominent in the posterior DMN, but was also observed in visual and motor cortices, prompting an assumption that it is associated with activation of DMN and inhibition of irrelevant sensory and motor areas. In line with data linking delta oscillations with aversive states, decrease of delta power was more pronounced in episodes associated with positive emotions, whereas episodes associated with negative emotions were accompanied by an increase of delta power. Vividness of recollection correlated positively with theta oscillations. These results highlight the leading role of alpha oscillations and the DMN in the processes accompanying autobiographical remembering.