Enhanced neural synchronization during social communications between dyads with high autistic traits.

Autism is characterized by atypical social communication styles. To investigate whether individuals with high autistic traits could still have effective social communication among each other, we compared the behavioral patterns and communication quality within 64 dyads of college students paired with both high, both low, and mixed high-low (HL) autistic traits, with their gender matched. Results revealed that the high-high (HH) autistic dyads exhibited atypical behavioral patterns during conversations, including reduced mutual gaze, communicational turns, and emotional sharing compared with the low-low and/or HL autistic dyads. However, the HH autistic dyads displayed enhanced interpersonal neural synchronization during social communications measured by functional near-infrared spectroscopy, suggesting an effective communication style. Besides, they also provided more positive subjective evaluations of the conversations. These findings highlight the potential for alternative pathways to effectively communicate with the autistic community, contribute to a deeper understanding of how high autistic traits influence social communication dynamics among autistic individuals, and provide important insights for the clinical practices for supporting autistic people.

Vicarious punishment of moral violations in naturalistic drama narratives predicts cortical synchronization.

Punishment of moral norm violators is instrumental for human cooperation. Yet, social and affective neuroscience research has primarily focused on second- and third-party norm enforcement, neglecting the neural architecture underlying observed (vicarious) punishment of moral wrongdoers. We used naturalistic television drama as a sampling space for observing outcomes of morally-relevant behaviors to assess how individuals cognitively process dynamically evolving moral actions and their consequences. Drawing on Affective Disposition Theory, we derived hypotheses linking character morality with viewers' neural processing of characters' rewards and punishments. We used functional magnetic resonance imaging (fMRI) to examine neural responses of 28 female participants while free-viewing 15 short story summary video clips of episodes from a popular US television soap opera. Each summary included a complete narrative structure, fully crossing main character behaviors (moral/immoral) and the consequences (reward/punishment) characters faced for their actions. Narrative engagement was examined via intersubject correlation and representational similarity analysis. Highest cortical synchronization in 9 specifically selected regions previously implicated in processing moral information was observed when characters who act immorally are punished for their actions with participants' empathy as an important moderator. The results advance our understanding of the moral brain and the role of normative considerations and character outcomes in viewers' engagement with popular narratives.

Event-related desynchronization and synchronization in multiple sclerosis.

BACKGROUND: Motor preparation and execution can be impaired in patients with multiple sclerosis (pwMS). These neural processes can be assessed using electroencephalography (EEG). During a self-paced movement, EEG signal amplitude decreases before movement (event-related desynchronization, ERD) and increases after movement (event-related synchronization, ERS). OBJECTIVE: To reappraise ERD/ERS changes in pwMS compared to healthy controls (HC). METHODS: This single-center study included 13 pwMS and 10 sex/age-matched HC. 60-channel EEG was recorded during two self-paced movements of the right hand: a simple index finger extension task and a more complex finger tapping task. Clinical variables included MS type, sex, age, disease duration, disability, grip strength, fatigue and attentional performance. EEG variables included ERD and ERS onset latency, duration, and amplitude determined using two methods of signal analyses (based on visual or automated determination) in the alpha and beta frequency bands in five cortical regions: right and left frontocentral and centroparietal regions and a midline region. Neuroimaging variables included the volumes of four deep brain structures (thalamus, putamen, pallidum and caudate nucleus) and the relative lesion load. RESULTS: ERD/ERS changes in pwMS compared to HC were observed only in the beta band. In pwMS, beta-ERD had a delayed onset in the midline and right parietocentral regions and a shortened duration or increased amplitude in the parietocentral region; beta-ERS had a shorter duration, delayed onset, or reduced amplitude in the left parieto/frontocentral region. In addition, pwMS with a more delayed beta-ERD in the midline region had less impaired executive functions but increased caudate nuclei volume, while pwMS with a more delayed beta-ERS in the parietocentral region contralateral to the movement had less fatigue but increased thalami volume. CONCLUSION: This study confirms an alteration of movement preparation and execution in pwMS, mainly characterized by a delayed cortical activation (ERD) and a delayed and reduced post-movement inhibition (ERS) in the beta band. Compensatory mechanisms could be involved in these changes, associating more preserved clinical performance and overactivation of deep brain structures.

Neural correlates tracking different aspects of the emerging representation of novel visual categories.

Current studies investigating electroencephalogram correlates associated with categorization of sensory stimuli (P300 event-related potential, alpha event-related desynchronization, theta event-related synchronization) typically use an oddball paradigm with few, familiar, highly distinct stimuli providing limited insight about the aspects of categorization (e.g. difficulty, membership, uncertainty) that the correlates are linked to. Using a more complex task, we investigated whether such more specific links could be established between correlates and learning and how these links change during the emergence of new categories. In our study, participants learned to categorize novel stimuli varying continuously on multiple integral feature dimensions, while electroencephalogram was recorded from the beginning of the learning process. While there was no significant P300 event-related potential modulation, both alpha event-related desynchronization and theta event-related synchronization followed a characteristic trajectory in proportion with the gradual acquisition of the two categories. Moreover, the two correlates were modulated by different aspects of categorization, alpha event-related desynchronization by the difficulty of the task, whereas the magnitude of theta -related synchronization by the identity and possibly the strength of category membership. Thus, neural signals commonly related to categorization are appropriate for tracking both the dynamic emergence of internal representation of categories, and different meaningful aspects of the categorization process.

Cross-frequency and inter-regional phase synchronization in explicit transitive inference.

Explicit logical reasoning, like transitive inference, is a hallmark of human intelligence. This study investigated cortical oscillations and their interactions in transitive inference with EEG. Participants viewed premises describing abstract relations among items. They accurately recalled the relationship between old pairs of items, effectively inferred the relationship between new pairs of items, and discriminated between true and false relationships for new pairs. First, theta (4-7 Hz) and alpha oscillations (8-15 Hz) had distinct functional roles. Frontal theta oscillations distinguished between new and old pairs, reflecting the inference of new information. Parietal alpha oscillations changed with serial position and symbolic distance of the pairs, representing the underlying relational structure. Frontal alpha oscillations distinguished between true and false pairs, linking the new information with the underlying relational structure. Second, theta and alpha oscillations interacted through cross-frequency and inter-regional phase synchronization. Frontal theta-alpha 1:2 phase locking appeared to coordinate spectrally diverse neural activity, enhanced for new versus old pairs and true versus false pairs. Alpha-band frontal-parietal phase coherence appeared to coordinate anatomically distributed neural activity, enhanced for new versus old pairs and false versus true pairs. It suggests that cross-frequency and inter-regional phase synchronization among theta and alpha oscillations supports human transitive inference.

Hemispheric synchronization patterns linked with shooting performance in archers.

Sustainable attention, effective visual-spatial perception, and motor control skills are considered highly important for achieving superior athletic performance. The aim of the current study was to investigate hemispheric synchronization patterns of brain electrical activation related to successful and unsuccessful shots of archers using electroencephalography (EEG). This study involved 16 elite archers, each shooting 36 arrows. The 10 shots closest to the target's center were successful, while the 10 farthest shots were unsuccessful. The transformed EEG data, obtained through surface Laplacian filtering, were divided into 5 sub-bands (theta, alpha1, alpha2, beta1, beta2) by calculating the alpha peak frequencies. The synchronization values of the electrode pairs were calculated using the Phase Locking Value (PLV) method. To compare the EEG data for successful and unsuccessful shots in all frequency bands, the linear mixed models were fitted. Perceived fatigue levels were quantified using a visual analog scale (VAS). Spearman's correlation analysis was conducted to examine the relationship between fatigue and shooting performance. The results showed significantly higher coupling strength for C3-O1, C4-O2, O1-O2, F3-F4, C4-T8, T7-O2, F4-C4, C3-O2 and F4-T8 pairs during successful shooting. Moreover, the coupling strengths for F3-O2, F4-T7, C3-C4, C3-T8, T7-T8, C4-O1, F3-T8, and F4-O2 were significantly higher in unsuccessful shooting. The current findings revealed differences in the synchronization patterns associated with shooting performance. It is observed that visual-motor performance is correlated with an increase in cortical synchronization values during successful shots. These findings have the potential to serve as a theoretical reference that contributes to superior performance.

Induced synchronization by endogenous noise modulation in finite-size random neural networks: A stochastic mean-field study.

Event-related synchronization and desynchronization (ERS/ERD) are well-known features found experimentally in brain signals during cognitive tasks. Their understanding promises to have much better insights into neural information processes in cognition. Under the hypothesis that neural information affects the endogenous neural noise level in populations, we propose to employ a stochastic mean-field model to explain ERS/ERD in the γ-frequency range. The work extends previous mean-field studies by deriving novel effects from finite network size. Moreover, numerical simulations of ERS/ERD and their analytical explanation by the mean-field model suggest several endogenous noise modulation schemes, which may modulate the system's synchronization.

Reaction time and brain oscillations in Go/No-go tasks with different meanings of stimulus color.

Color has meaning in particular contexts, and the meaning of color can impact behavioral performance. For example, the meaning of color about traffic rules (blue/green and red mean "go" and "stop" respectively) influences reaction times (RTs) to signals. Specifically, in a Go/No-go task, RTs have been reported to be longer when responding to a red signal and withholding the response to a blue signal (Red Go/Blue No-go task) than when responding to a blue signal and withholding the response to a red signal (Blue Go/Red No-go task). However, the neurophysiological background of this phenomenon has not been fully understood. The purpose of this study was to investigate the brain oscillatory activity associated with the effect of meaning of color on RTs in the Go/No-go task. Twenty participants performed a Blue simple reaction task, a Red simple reaction task, a Blue Go/Red No-go task, and a Red Go/Blue No-go task. We recorded responses to signals and electroencephalogram (EEG) during the tasks and evaluated RTs and changes in spectral power over time, referred to as event-related synchronization (ERS) and event-related desynchronization (ERD). The behavioral results were similar to previous studies. The EEG results showed that frontal beta ERD and theta ERS were greater when signals were presented in blue than red color in both simple reaction and Go/No-go tasks. In addition, the onset of theta ERS was delayed in the Red Go than Blue Go trial in the Go/No-go task. The enhanced beta ERD may indicate that blue signals facilitate motor response, and the delayed onset of theta ERS may indicate the delayed onset of cognitive process when responding to red signals as compared to blue signals in the Go/No-go task. Thus, this delay in cognitive process can be involved in the slow response in the Red Go/Blue No-go task.

Enhanced behavioral performance through interareal gamma and beta synchronization.

Cognitive functioning requires coordination between brain areas. Between visual areas, feedforward gamma synchronization improves behavioral performance. Here, we investigate whether similar principles hold across brain regions and frequency bands, using simultaneous electrocorticographic recordings from 15 areas of two macaque monkeys during performance of a selective attention task. Short behavioral reaction times (RTs), suggesting efficient interareal communication, occurred when occipital areas V1, V2, V4, and DP showed gamma synchronization, and fronto-central areas S1, 5, F1, F2, and F4 showed beta synchronization. For both area clusters and corresponding frequency bands, deviations from the typically observed phase relations increased RTs. Across clusters and frequency bands, good phase relations occurred in a correlated manner specifically when they processed the behaviorally relevant stimulus. Furthermore, the fronto-central cluster exerted a beta-band influence onto the occipital cluster whose strength predicted short RTs. These results suggest that local gamma and beta synchronization and their inter-regional coordination jointly improve behavioral performance.

Cortical temporal integration can account for limits of temporal perception: investigations in the binaural system.

The auditory system has exquisite temporal coding in the periphery which is transformed into a rate-based code in central auditory structures, like auditory cortex. However, the cortex is still able to synchronize, albeit at lower modulation rates, to acoustic fluctuations. The perceptual significance of this cortical synchronization is unknown. We estimated physiological synchronization limits of cortex (in humans with electroencephalography) and brainstem neurons (in chinchillas) to dynamic binaural cues using a novel system-identification technique, along with parallel perceptual measurements. We find that cortex can synchronize to dynamic binaural cues up to approximately 10 Hz, which aligns well with our measured limits of perceiving dynamic spatial information and utilizing dynamic binaural cues for spatial unmasking, i.e. measures of binaural sluggishness. We also find that the tracking limit for frequency modulation (FM) is similar to the limit for spatial tracking, demonstrating that this sluggish tracking is a more general perceptual limit that can be accounted for by cortical temporal integration limits.

Event-related EEG synchronization and desynchronization in patients with obsessive-compulsive disorder.

Symptoms in patients with obsessive-compulsive disorder (OCD) are associated with impairment in cognitive control, attention, and action inhibition. We investigated OCD group differences relative to healthy subjects in terms of event-related alpha and beta range synchronization (ERS) and desynchronization (ERD) during a visually cued Go/NoGo task. Subjects were 62 OCD patients and 296 healthy controls (HC). The OCD group in comparison with HC, showed a changed value of alpha/beta oscillatory power over the central cortex, in particular, an increase in the alpha/beta ERD over the central-parietal cortex during the interstimulus interval (Cue condition) as well as changes in the postmovement beta synchronization topography and frequency. Over the frontal cortex, the OCD group showed an increase in magnitude of the beta ERS in NoGo condition. Within the parietal-occipital ERS/ERD modulations, the OCD group showed an increase in the alpha/beta ERD over the parietal cortex after the presentation of the visual stimuli as well as a decrease in the beta ERD over the occipital cortex after the presentation of the Cue and Go stimuli. The specific properties in the ERS/ERD patterns observed in the OCD group may reflect high involvement of the frontal and central cortex in action preparation and action inhibition processes and, possibly, in maintaining the motor program, which might be a result of the dysfunction of the cortico-striato-thalamo-cortical circuits involving prefrontal cortex. The data about enhanced involvement of the parietal cortex in the evaluation of the visual stimuli are in line with the assumption about overfocused attention in OCD.

Rapid thalamocortical network switching mediated by cortical synchronization underlies propofol-induced EEG signatures: a biophysical model.

Propofol-mediated unconsciousness elicits strong alpha/low-beta and slow oscillations in the electroencephalogram (EEG) of patients. As anesthetic dose increases, the EEG signal changes in ways that give clues to the level of unconsciousness; the network mechanisms of these changes are only partially understood. Here, we construct a biophysical thalamocortical network involving brain stem influences that reproduces transitions in dynamics seen in the EEG involving the evolution of the power and frequency of alpha/low-beta and slow rhythm, as well as their interactions. Our model suggests that propofol engages thalamic spindle and cortical sleep mechanisms to elicit persistent alpha/low-beta and slow rhythms, respectively. The thalamocortical network fluctuates between two mutually exclusive states on the timescale of seconds. One state is characterized by continuous alpha/low-beta-frequency spiking in thalamus (C-state), whereas in the other, thalamic alpha spiking is interrupted by periods of co-occurring thalamic and cortical silence (I-state). In the I-state, alpha colocalizes to the peak of the slow oscillation; in the C-state, there is a variable relationship between an alpha/beta rhythm and the slow oscillation. The C-state predominates near loss of consciousness; with increasing dose, the proportion of time spent in the I-state increases, recapitulating EEG phenomenology. Cortical synchrony drives the switch to the I-state by changing the nature of the thalamocortical feedback. Brain stem influence on the strength of thalamocortical feedback mediates the amount of cortical synchrony. Our model implicates loss of low-beta, cortical synchrony, and coordinated thalamocortical silent periods as contributing to the unconscious state.NEW & NOTEWORTHY GABAergic anesthetics induce alpha/low-beta and slow oscillations in the EEG, which interact in dose-dependent ways. We constructed a thalamocortical model to investigate how these interdependent oscillations change with propofol dose. We find two dynamic states of thalamocortical coordination, which change on the timescale of seconds and dose-dependently mirror known changes in EEG. Thalamocortical feedback determines the oscillatory coupling and power seen in each state, and this is primarily driven by cortical synchrony and brain stem neuromodulation.

From Motivation to Action: Action Cost Better Predicts Changes in Premovement Beta-Band Activity than Speed.

Although premovement beta-band event-related desynchronization (ß-ERD; 13-30 Hz) from sensorimotor regions is modulated by movement speed, current evidence does not support a strict monotonic association between the two. Given that ß-ERD is thought to increase information encoding capacity, we tested the hypothesis that it might be related to the expected neurocomputational cost of movement, here referred to as action cost. Critically, action cost is greater both for slow and fast movements compared with a medium or "preferred" speed. Thirty-one right-handed participants performed a speed-controlled reaching task while recording their EEG. Results revealed potent modulations of beta power as a function of speed, with ß-ERD being significantly greater both for movements performed at high and low speeds compared with medium speed. Interestingly, medium-speed movements were more often chosen by participants than low-speed and high-speed movements, suggesting that they were evaluated as less costly. In line with this, modeling of action cost revealed a pattern of modulation across speed conditions that strikingly resembled the one found for ß-ERD. Indeed, linear mixed models showed that estimated action cost predicted variations of ß-ERD significantly better than speed. This relationship with action cost was specific to beta power, as it was not found when averaging activity in the mu band (8-12 Hz) and gamma band (31-49 Hz) bands. These results demonstrate that increasing ß-ERD may not merely speed up movements, but instead facilitate the preparation of high-speed and low-speed movements through the allocation of additional neural resources, thereby enabling flexible motor control.SIGNIFICANCE STATEMENT Heightened beta activity has been associated with movement slowing in Parkinson's disease, and modulations of beta activity are commonly used to decode movement parameters in brain-computer interfaces. Here we show that premovement beta activity is better explained by the neurocomputational cost of the action rather than its speed. Instead of being interpreted as a mere reflection of changes in movement speed, premovement changes in beta activity might therefore be used to infer the amount of neural resources that are allocated for motor planning.

Parabolic avalanche scaling in the synchronization of cortical cell assemblies.

Neurons in the cerebral cortex fire coincident action potentials during ongoing activity and in response to sensory inputs. These synchronized cell assemblies are fundamental to cortex function, yet basic dynamical aspects of their size and duration are largely unknown. Using 2-photon imaging of neurons in the superficial cortex of awake mice, we show that synchronized cell assemblies organize as scale-invariant avalanches that quadratically grow with duration. The quadratic avalanche scaling was only found for correlated neurons, required temporal coarse-graining to compensate for spatial subsampling of the imaged cortex, and suggested cortical dynamics to be critical as demonstrated in simulations of balanced E/I-networks. The corresponding time course of an inverted parabola with exponent of χ = 2 described cortical avalanches of coincident firing for up to 5 s duration over an area of 1 mm2. These parabolic avalanches maximized temporal complexity in the ongoing activity of prefrontal and somatosensory cortex and in visual responses of primary visual cortex. Our results identify a scale-invariant temporal order in the synchronization of highly diverse cortical cell assemblies in the form of parabolic avalanches.

Symmetrical Contralaterally Controlled Functional Electrical Stimulation Enhanced Cortical Activity and Synchronization of Stroke Survivors.

Contralaterally controlled functional electrical stimulation (CCFES) is a rehabilitation method whose efficacy has been proved in several randomized controlled trials. Symmetrical CCFES (S-CCFES) and asymmetrical CCFES (A-CCFES) are two basic strategies of CCFES. The cortical response can reflect the instant efficacy of CCFES. However, it is still unclear of the difference on cortical responses of these different strategies. Therefore, the aim of the study is to determine what cortical response CCFES may engage. Thirteen stroke survivors were recruited to complete three training sessions with S-CCFES, A-CCFES and unilateral functional electrical stimulation (U-FES), in which the affected arm was stimulated. The electroencephalogram (EEG) signals were recorded during the experiment. The event-related desynchronization (ERD) value of stimulation-induced EEG and phase synchronization index (PSI) for resting EEG were calculated and compared in different tasks. We found that S-CCFES induced significantly stronger ERD at affected MAI(motor area of interest) in alpha-rhythm (8-15Hz), which indicated stronger cortical activity. Meanwhile, S-CCFES also increased intensity of cortical synchronization within the affected hemisphere and between hemispheres, and the significantly increased PSI occurred in a wider area after S-CCFES. Our results suggested that S-CCFES could enhance cortical activity during stimulation and cortical synchronization after stimulation in stroke survivors. S-CCFES seems to have better prospects for stroke recovery.

Response outcome gates the effect of spontaneous cortical state fluctuations on perceptual decisions.

Sensory responses of cortical neurons are more discriminable when evoked on a baseline of desynchronized spontaneous activity, but cortical desynchronization has not generally been associated with more accurate perceptual decisions. Here, we show that mice perform more accurate auditory judgments when activity in the auditory cortex is elevated and desynchronized before stimulus onset, but only if the previous trial was an error, and that this relationship is occluded if previous outcome is ignored. We confirmed that the outcome-dependent effect of brain state on performance is neither due to idiosyncratic associations between the slow components of either signal, nor to the existence of specific cortical states evident only after errors. Instead, errors appear to gate the effect of cortical state fluctuations on discrimination accuracy. Neither facial movements nor pupil size during the baseline were associated with accuracy, but they were predictive of measures of responsivity, such as the probability of not responding to the stimulus or of responding prematurely. These results suggest that the functional role of cortical state on behavior is dynamic and constantly regulated by performance monitoring systems.

Analyzing bursting synchronization in structural connectivity matrix of a human brain under external pulsed currents.

Cognitive tasks in the human brain are performed by various cortical areas located in the cerebral cortex. The cerebral cortex is separated into different areas in the right and left hemispheres. We consider one human cerebral cortex according to a network composed of coupled subnetworks with small-world properties. We study the burst synchronization and desynchronization in a human neuronal network under external periodic and random pulsed currents. With and without external perturbations, the emergence of bursting synchronization is observed. Synchronization can contribute to the processing of information, however, there are evidences that it can be related to some neurological disorders. Our results show that synchronous behavior can be suppressed by means of external pulsed currents.

Cortical oscillations and interareal synchronization as a preparatory activity for postural response.

Neural mechanisms of human standing are expected to be elucidated for preventing fallings. Postural response evoked by sudden external perturbation originates from various areas in the central nervous system. Recent studies have revealed that the corticospinal pathway is one of the key nodes for an appropriate postural response. The corticospinal pathway that mediates the early part of the electromyographic response is modulated with prediction before a perturbation occurs. Temporal prediction explicitly exhibiting an onset timing contributes to enhancing corticospinal excitability. However, how the cortical activities in the sensorimotor area with temporal prediction are processed before the corticospinal pathway enhancement remains unclear. In this study, using electroencephalography, we investigated how temporal prediction affects both neural oscillations and synchronization between sensorimotor and distal areas. Our results revealed that desynchronization of cortical oscillation at α- and ß-bands was observed in the sensorimotor and parietooccipital areas (Cz, CPz, Pz and POz), and those are nested in the phase at θ-band frequency. Furthermore, a reduction in the interareal phase synchrony in the α-band was induced after the timing cue for the perturbation onset. The phase synchrony at the low frequency can relay the temporal prediction among the distant areas and initiate the modulation of the local cortical activities. Such modulations contribute to the preparation for sensory processing and motor execution that are necessary for optimal responses.

(Lack of) neural efficiency related to general giftedness and mathematical excellence: An EEG study.

Previous studies on intelligence have demonstrated that higher abilities are associated with lower brain activation, indicating a higher neural efficiency. In other words, more able individuals use fewer brain resources. However, it is unclear whether the neural efficiency phenomenon also appears for mathematical performance, which is influenced by both domain-general giftedness and domain-specific competencies. Therefore, this study examined the effects of general giftedness (G) and excellence in mathematics (EM) on performance and brain activation while solving learning-based mathematical tasks that required translation from graphical to symbolic representations of functions. Overall, 118 high school students (aged 16-18) participated in the present study and were divided according to G and EM using a 2 × 2 study design. Participants worked on a function task requiring translation between symbolic and graphical representations of functions. Analyses of the behavioral data revealed positive effects of both G and EM on the accuracy of solutions and an interaction effect of both factors on reaction times, reflecting a positive effect of EM only among the gifted individuals. EEG analyses focused on oscillatory activity in the theta and alpha frequency bands and showed a significant effect of EM in the upper alpha band (10-12 Hz) event-related desynchronization (ERD) for both graphical and symbolic representations. Specifically, higher (compared to lower) EM was associated with a larger alpha ERD, indicating a higher level of brain activity. This stands in contrast with the neural efficiency phenomenon. These findings suggest that the neural efficiency phenomenon cannot be generalized to higher-order mathematical demands in high-performing individuals. Several explanations for this limitation are offered.