Gamma electroencephalographic coherence and theory of mind in healthy subjects

PURPOSE

Structural brain imaging has revealed that damage to different brain regions may impair theory of mind (ToM) while functional imaging has shown that distributed neural circuits are activated by ToM and empathy. However, the coherence of the electroencephalogram (EEG) frequencies in a definite time span may change during these processes, indicating different neurophysiological correlates. This study evaluated the changes of EEG coherence during ToM tasks in comparison with Empathy, Physical causality, and baseline conditions, aiming to determine the neurophysiological correlates of ToM.

METHODS

Sixteen healthy adults underwent a visual activation paradigm using 30 comic strips concerning ToM, Empathy, or Physical causality during EEG recording. The interhemispheric coherence was estimated using a bivariate autoregressive (AR) parametric model. The coherence spectra were analyzed in the alpha, beta, and gamma frequency EEG bands.

RESULTS

Coherence analysis taking all of the responses showed that in the gamma band, in comparison with the Empathy, Physical causality, and baseline conditions, ToM was associated with significantly higher peaks between the frontal and parietal areas in the right hemisphere and, in comparison with the Physical causality and baseline conditions, in the left hemisphere. Analysis taking the correct responses confirmed these results.

CONCLUSIONS

In healthy adults, ToM processes are associated with immediate specific changes of brain connectivity, as expressed by high cortical coherence within the right frontal and parietal areas. These previously unexplored aspects indicate an online involvement of the right hemisphere networks in normal ToM. In patients with epilepsy, the study of EEG coherence during specific tasks may help determine the neural dysfunctions associated with impaired ToM. This article is part of the Special Issue "Epilepsy and social cognition across the lifespan".

Connectivity measures suggest a sub-cortical generator of myoclonus in Angelman syndrome

OBJECTIVE

The clinical and neurophysiological characteristics of myoclonus in Angelman syndrome (AS) have been evaluated in single case or small cohorts, with contrasting results. We evaluated the features of myoclonus in a wide cohort of AS patients.

METHODS

We performed polygraphic EEG-EMG recording in 24 patients with genetically confirmed AS and myoclonus. Neurophysiological investigations included jerk-locked back-averaging (JLBA), cortico-muscular coherence (CMC) and generalised partial directed coherence (GPDC). CMC and GPDC analyses were compared to those obtained from 10 healthy controls (HC).

RESULTS

Twenty-four patients (aged 3-35 years, median 20) were evaluated. Sequences of quasi-continuous rhythmic jerks mostly occurred at alpha frequency or just below (mean 8.4 ± 1.4 Hz), without EEG correlate. JLBA did not show any clear transient preceding the jerks. CMC showed bilateral over-threshold CMC in alpha band that was prominent on the contralateral hemisphere in the patient group as compared to HC group. GPDC showed a significantly higher alpha outflow from both hemispheres toward activated muscles in the patient group, and a significantly higher beta outflow from contralateral hemisphere in the HC group.

CONCLUSIONS

These neurophysiological findings suggest a subcortical generator of myoclonus in AS.

SIGNIFICANCE

Myoclonus in AS has not a cortical origin as previously hypothesised.

Beta and gamma synchronous oscillations in neural network activity in mice-induced by food deprivation

Food deprivation is known to trigger hunger sensation and motivation to eat for energy replenishing. However, brain mechanisms associated with hunger and neural circuitries that mediate hunger driven responses remained to be investigated. To understand neural signaling of hunger, local field potentials (LFPs) in the lateral hypothalamus (LHa), nucleus accumbens (NAc), dorsal hippocampus (HP) and olfactory bulb (OB) and their interconnectivities were studied in freely moving adult male Albino mice during 18-20 h food deprivation and fed periods. Raw LFP signals were recorded and analyzed for mean values of spectral frequency power and coherence values. One-way repeated measures ANOVA revealed significant increases in spectral powers of beta and gamma frequency ranges induced by food deprivation in the LHa, HP, NAc but not OB. No change of spectral power in these brain regions was induced by food feeding. The analyses of coherent activity between brain regions also deliniated some distributed neural network activities correlated with hunger. In particular, coherent function indicated the increased beta and gamma phase synchrony between the pairs of LHa-HP and NAc-OB regions, and decreased gamma synchrony between the pairs of LHa-NAc and NAc-HP induced by food deprivation. It was found that plasma glucose level, locomotor count, travelled distance and time spent on moving were not altered by food deprivation. These results suggest that changes in LFP hallmarks in these brain regions were associated with hunger driven by negative energy balance.

Brain Connectivity Reflected in Electroencephalogram Coherence in Individuals With Autism: A Meta-Analysis

INTRODUCTION

Many theories have been proposed about the etiology of autism. One is related to brain connectivity in patients with autism. Several studies have reported brain connectivity changes in autism disease. This study was performed on Electroencephalogram (EEG) studies that evaluated patients with autism, using functional brain connectivity, and compared them with typically-developing individuals.

METHODS

Three scientific databases of ScienceDirect, Medline (PubMed), and BioMed Central were systematically searched through their online search engines. Comprehensive Meta-analysis software analyzed the obtained data.

RESULTS

The systematic search led to 10 papers, in which EEG coherence was used to obtain the brain connectivity of people with autism. To determine the effect size, Cohen's d parameter was used. In the first meta-analysis, the study of the maximum effect size was considered, and all significant effect sizes were evaluated in the second meta-analysis. The effect size was assessed using a random-effects model in both meta-analyses. The results of the first meta-analysis indicated that heterogeneity was not present among the studies (Q=13.345, P>0.1). The evaluation of all effect sizes in the second meta-analysis showed a significant lack of homogeneity among the studies (Q=56.984, P=0.0001).

CONCLUSION

On the whole, autism was found to be related to neural connectivity, and the present research showed the difference in the EEG coherence of people with autism and healthy people. These conclusions require further studies with more extensive data, considering different brain regions, and novel analysis techniques for assessing brain connectivity.

Spatial and temporal variation of ecosystem properties at macroscales

Although spatial and temporal variation in ecological properties has been well-studied, crucial knowledge gaps remain for studies conducted at macroscales and for ecosystem properties related to material and energy. We test four propositions of spatial and temporal variation in ecosystem properties within a macroscale (1000 km's) extent. We fit Bayesian hierarchical models to thousands of observations from over two decades to quantify four components of variation - spatial (local and regional) and temporal (local and coherent); and to model their drivers. We found strong support for three propositions: (1) spatial variation at local and regional scales are large and roughly equal, (2) annual temporal variation is mostly local rather than coherent, and, (3) spatial variation exceeds temporal variation. Our findings imply that predicting ecosystem responses to environmental changes at macroscales requires consideration of the dominant spatial signals at both local and regional scales that may overwhelm temporal signals.

Cognitive effort decreases beta, alpha, and theta coherence and ends afterdischarges in human brain

OBJECTIVE

Mental activation has been reported to modify the occurrence of epileptiform activity. We studied its effect on afterdischarges.

METHOD

In 15 patients with implanted electrodes we presented cognitive tasks when afterdischarges occurred. We developed a wavelet cross-coherence function to analyze the electrocorticography before and after the tasks and compared findings when cognitive tasks did or did not result in afterdischarge termination. Six patients returned for functional MRI (fMRI) testing, using similar tasks.

RESULTS

Cognitive tasks often could terminate afterdischarges when direct abortive stimulation could not. Wavelet cross-coherence analysis showed that, when afterdischarges stopped, there was decreased coherence throughout the brain in the 7.13-22.53 Hz frequency ranges (p values 0.008-0.034). This occurred a) regardless of whether an area activated on fMRI and b) regardless of whether there were afterdischarges in the area.

CONCLUSIONS

It is known that cognitive tasks can alter localized or network synchronization. Our results show that they can change activity throughout the brain. These changes in turn can terminate localized epileptiform activity.

SIGNIFICANCE

Cognitive tasks result in diffuse brain changes that can modify focal brain activity. Combined with a seizure detection device, cognitive activation might provide a non-invasive method of terminating or modifying seizures.

EEG coherence in theta, alpha, and beta bands in frontal regions and executive functions

Executive functions are higdevel cognitive processes that make possible the formation of flexible and adaptive goal-directed behaviors and the frontal lobes regulate these functions. The purpose of this study was to investigate the relationship between frontal EEG coherence in theta, alpha, and beta bands and executive functions in adults. A sample of 168 students (M_age = 25.44 years, SD = 4.52) were included in this study. EEG records were recorded at the psychology laboratory of Mohaghegh Ardabili University (Iran), then intrahemispheric and interhemispheric coherence of frontal regions were analyzed using the NeuroGuide software. The participants were asked to fill in the Adult Executive Skills Questionnaire. Correlational results showed that there is a positive relationship between executive functions and EEG coherence in theta, alpha, and beta bands in frontal regions of the left hemisphere, EEG coherence of alpha and beta bands in frontal regions of the right hemisphere and EEG coherence of alpha band between frontal regions of the two hemispheres. The results of the regression analysis also revealed that coherence of alpha, beta, and theta bands between left and right frontal regions and coherence of beta and theta bands in the left frontal regions predict executive functions. These results indicate that the common activity of frontal cortex, especially the left hemisphere, is associated with executive functions and cognitive control.

A Scenario Approach to the Simonshaven Case

In this paper, we present a scenario approach and apply it to the Simonshaven case. We offer an outline in which we spell out the core notions of the scenario approach. Next, we give a summing up of criteria to assess and compare scenarios. We use examples of the Simonshaven case to illustrate how the scenario‐approach works. The last section contains a discussion of the main strengths and weaknesses of the scenario approach and a brief comparison with argumentation‐based and probabilistic approaches.

Van Koppen and Mackor offer a scenario‐approach analysis of the case. They first explicate their approach, linking it to inference to the best explanation and theories of explanatory coherence. An important distinction in their analysis is between explaining known facts and predicting novel facts. They claim that their approach is cognitively feasible and stays close to descriptive theories of evidential reasoning. They want to keep it informal, so that legal professionals can apply it.

Functional brain connectivity in a rodent seizure model of autistic-like behavior

OBJECTIVE

There is increasing evidence that Autism Spectrum Disorder (ASD) is a disorder of functional connectivity with both human and rodent studies demonstrating alterations in connectivity. Here, we hypothesized that early-life seizures (ELS) in rats would interrupt normal brain connectivity and result in autistic-like behavior (ALB).

METHODS

Following 50 seizures, adult rats were tested in the social interaction and social novelty tests and then underwent qualitative and quantitative intracranial electroencephalography (EEG) monitoring in the medial prefrontal cortex (PFC) and the hippocampal subfields, CA3 and CA1.

RESULTS

Rats with ELS showed deficits in social interaction and novelty, and compared with control, rats had marked increases in coherence within the hippocampus (CA3-CA1) and between the hippocampus and PFC during the awake and sleep states indicating hyperconnectivity. In addition, sleep spindle density was significantly reduced in rats with ELS. There were no differences in voltage correlations and power spectral densities between the ELS and control rats in any bandwidths.

CONCLUSION

Taken together, these findings indicate that ELS can result in ALB and alter functional connectivity as measured by coherence and sleep spindle density. These findings implicate altered connectivity as a robust neural signature for ALB following ELS.

The Coherence of Evolutionary Theory with Its Neighboring Theories

Evolutionary theory coheres with its neighboring theories, such as the theory of plate tectonics, molecular biology, electromagnetic theory, and the germ theory of disease. These neighboring theories were previously unconceived, but they were later conceived, and then they cohered with evolutionary theory. Since evolutionary theory has been strengthened by its several neighboring theories that were previously unconceived, it will be strengthened by infinitely many hitherto unconceived neighboring theories. This argument for evolutionary theory echoes the problem of unconceived alternatives. Ironically, however, the former recommends that we take the realist attitude toward evolutionary theory, while the latter recommends that we take the antirealist attitude toward it.

Trade and nutrition policy coherence: a framing analysis and Australian case study

OBJECTIVE

Maximising synergies and minimising conflicts (i.e. building policy coherence) between trade and nutrition policy is an important objective. One understudied driver of policy coherence is the alignment in the frames, discourses and values of actors involved in the respective sectors. In the present analysis, we aim to understand how such actors interpret (i.e. 'frame') nutrition and the implications for building trade-nutrition policy coherence.

DESIGN

We adopted a qualitative single case study design, drawing on key informant interviews with those involved in trade policy.

SETTING

We focused on the Australian trade policy sub-system, which has historically emphasised achieving market growth and export opportunities for Australian food producers.

PARTICIPANTS

Nineteen key informants involved in trade policy spanning the government, civil society, business and academic sectors.

RESULTS

Nutrition had low 'salience' in Australian trade policy for several reasons. First, it was not a domestic political priority in Australia nor among its trading partners; few advocacy groups were advocating for nutrition in trade policy. Second, a 'productivist' policy paradigm in the food and trade policy sectors strongly emphasised market growth, export opportunities and deregulation over nutrition and other social objectives. Third, few opportunities existed for health advocates to influence trade policy, largely because of limited consultation processes. Fourth, the complexity of nutrition and its inter-linkages with trade presented difficulties for developing a 'broader discourse' for engaging the public and political leaders on the topic.

CONCLUSIONS

Overcoming these 'ideational challenges' is likely to be important to building greater coherence between trade and nutrition policy going forward.

Functional Connectivity in Term Neonates With Hypoxic-Ischemic Encephalopathy Undergoing Therapeutic Hypothermia

BACKGROUND

We investigated whether therapeutic hypothermia and rewarming impact functional connectivity using electroencephalography (EEG) as a measure in neonates with hypoxic-ischemic encephalopathy. We hypothesized that EEG coherence and voltage correlations would be lower and phase lag greater in infants with hypoxic-ischemic encephalopathy than control subjects and that functional connectivity would evolve during therapeutic hypothermia with the greatest improvement occurring during rewarming.

METHODS

This study was a retrospective study of 14 term neonates (greater than 37 weeks) with moderate hypoxic-ischemic encephalopathy who underwent therapeutic hypothermia and rewarming. Continuous EEG and video monitoring was conducted for 96 hours during therapeutic hypothermia and rewarming. The primary quantitative EEG measures of functional connectivity were coherence, phase lag, and voltage correlations. These EEG parameters were compared with a cohort of normal age-matched neonates.

RESULTS

Neonates with hypoxic-ischemic encephalopathy had marked decreases in power, coherences, and voltage correlation and increases in phase lag when compared with control neonates. However, there were no significant changes in these measures between therapeutic hypothermia and rewarming.

CONCLUSIONS

Neonates with hypoxic-ischemic encephalopathy demonstrate significant abnormalities in functional connectivity compared with control subjects. These abnormalities persist through therapeutic hypothermia and rewarming and are not altered after rewarming. Although hypoxic-ischemic encephalopathy is associated with impaired functional brain connectivity, there is no evidence, using quantitative EEG measures, that therapeutic hypothermia or rewarming either improves or exacerbates these abnormalities in connectivity.

The development of functional and directed corticomuscular connectivity during tonic ankle muscle contraction across childhood and adolescence

In adults, oscillatory activity in the sensorimotor cortex is coherent with contralateral muscle activity at beta frequencies (15-35 Hz) during tonic contraction. This functional coupling reflects the involvement of the sensorimotor cortex, the corticospinal pathway, and likely also ascending sensory feedback in the task at hand. However, little is known about the developmental trajectory of task-related corticomuscular connectivity relating to the voluntary control of the ankle muscles. To address this, we recorded electroencephalography (EEG) from the vertex (Cz) and electromyography (EMG) from ankle muscles (proximal and distal anterior tibial, TA; soleus, SOL; gastrocnemius medialis, GM) in 33 participants aged 7-23 yr during tonic dorsi- and plantar flexion requiring precise maintenance of a submaximal torque level. Coherence was calculated for Cz-TA, Cz-SOL, TA-TA, and SOL-GM signal pairs. We found strong, positive associations between age and beta band coherence for Cz-TA, Cz-SOL, and TA-TA, suggesting that oscillatory corticomuscular connectivity is strengthened during childhood development and adolescence. Directionality analysis indicated that the primary interaction underlying this age-related increase was in the descending direction. In addition, performance during dorsi- and plantar flexion tasks was positively associated with age, indicating more precise control of the ankle joint in older participants. Performance was also positively associated with beta band coherence, suggesting that participants with greater coherence also exhibited greater precision. We propose that these results indicate an age-related increase in oscillatory corticospinal input to the ankle muscle motoneuron pools during childhood development and adolescence, with possible implications for maturation of precision force control. Within the theoretical framework of predictive coding, we suggest that our results may reflect an age-related increase in reliance on feedforward control as the developing nervous system becomes better at predicting the sensory consequences of movement. These findings may contribute to the development of novel intervention strategies targeting improved sensorimotor control in children and adolescents with central motor disorders.

From adagio to allegretto: The changing tempo of theta frequencies in epilepsy and its relation to interneuron function

Despite decades of research, our understanding of epilepsy, including how seizures are generated and propagate, is incomplete. However, there is growing recognition that epilepsy is more than just the occurrence of seizures, with patients often experiencing comorbid deficits in cognition that are poorly understood. In addition, the available therapies for treatment of epilepsy, from pharmaceutical treatment to surgical resection and seizure prevention devices, often exacerbate deficits in cognitive function. In this review, we discuss the hypothesis that seizure generation and cognitive deficits have a similar pathological source characterized by, but not limited to, deficits in theta oscillations and their influence on interneurons. We present a new framework that describes oscillatory states in epilepsy as alternating between hyper- and hypo-synchrony rather than solely the spontaneous transition to hyper-excitability characterized by the seizures. This framework suggests that as neural oscillations, specifically in the theta range, vary their tempo from a slowed almost adagio tempo during interictal periods to faster, more rhythmic allegretto tempo preictally, they impact the function of interneurons, modulating their ability to control seizures and their role in cognitive processing. This slow wave oscillatory framework may help explain why current therapies that work to reduce hyper-excitability do not completely eliminate seizures and often lead to exacerbated cognitive deficits.

A fiber coherence index for quality control of B-table orientation in diffusion MRI scans

PURPOSE

The diffusion MRI "b-vector" table describing the diffusion sensitization direction can be flipped and permuted in dimension due to different orientation conventions used in scanners and incorrect or improperly utilized file formats. This can lead to incorrect fiber orientation estimates and subsequent tractography failure. Here, we present an automated quality control procedure to detect when the b-table is flipped and/or permuted incorrectly.

METHODS

We define a "fiber coherence index" to describe how well fibers are connected to each other, and use it to automatically detect the correct configuration of b-vectors. We examined the performance on 3981 research subject scans (Baltimore Longitudinal Study of Aging), 1065 normal subject scans of high image quality (Human Connectome Project), and 202 patient scans (Vanderbilt University Medical Center), as well as 9 in-vivo and 9 ex-vivo animal data.

RESULTS

The coherence index resulted in a 99.9% (3979/3981) and 100% (1065/1065) success rate in normal subject scans, 98% (198/202) in patient scans, and 100% (18/18) in both in-vivo and ex-vivo animal data in detecting the correct gradient table in datasets without severe image artifacts. The four failing cases (4/202) in patient scans, and two failures in healthy subject scans (2/3981), all showed prominent motion or signal dropout artifacts.

CONCLUSIONS

The fiber coherence measure can be used as an automatic quality assurance check in any diffusion analysis pipeline. Additionally, the success of this fiber coherence measure suggests potential broader applications, including evaluating data quality, or even providing diagnostic value as a biomarker of white matter integrity.

Using Corticomuscular and Intermuscular Coherence to Assess Cortical Contribution to Ankle Plantar Flexor Activity During Gait

The present study used coherence and directionality analyses to explore whether the motor cortex contributes to plantar flexor muscle activity during the stance phase and push-off phase during gait. Subjects walked on a treadmill, while EEG over the leg motorcortex area and EMG from the medial gastrocnemius and soleus muscles was recorded. Corticomuscular and intermuscular coherence were calculated from pair-wise recordings. Significant EEG-EMG and EMG-EMG coherence in the beta and gamma frequency bands was found throughout the stance phase with the largest coherence towards push-off. Analysis of directionality revealed that EEG activity preceded EMG activity throughout the stance phase until the time of push-off. These findings suggest that the motor cortex contributes to ankle plantar flexor muscle activity and forward propulsion during gait.

Coherence and congruency mediate medial temporal and medial prefrontal activity during event construction

The precise roles of the hippocampus (HPC) and medial prefrontal cortex (mPFC) in initially constructing imagined events remains unclear. HPC activity during imagination may be modulated by mnemonic load, given its role in working memory for complex materials, and/or by the semantic relatedness (i.e. congruency) between items and their context. MPFC activation may track with congruency or mnemonic load, given the role of ventral mPFC in schema processing and the dorsal mPFC in working memory for social information. Sixteen healthy adults (M age = 22.3) underwent an event construction task, wherein participants were provided with a context and item words and imagined an event, forming as many inter-item associations as possible among the items. The stimuli varied by set size and by normatively-defined congruence (normative congruency) to explore their effects on HPC and mPFC activity and functional connectivity. We observed HPC connectivity during event construction in general, whereas dorsal mPFC connectivity occurred during imagining only at higher set sizes. Moreover, anterior hippocampal activity correlated positively with increasing coherence between items during imagining, suggesting that the anterior HPC is sensitive to the relational demands of constructing a novel event. Parahippocampal, hippocampal, temporal pole, and mPFC activity tracked only with individual differences in subjective ratings of congruency of imagined events, which may contribute to construction by retrieving existing schema-related information. Collectively, these findings provide new insights into the factors that modulate HPC and mPFC activity when constructing mental simulations.

Increased EMG intermuscular coherence and reduced signal complexity in Parkinson's disease

OBJECTIVES

To investigate differences in surface electromyography (EMG) features in individuals with idiopathic Parkinson's disease (PD) and aged-matched controls.

METHODS

Surface EMG was recorded during isometric leg extension in PD patients prior to, and after undergoing a locomotor training programme, and in aged-matched controls. Differences in EMG structure were quantified using determinism (%DET), sample entropy (SampEn) and intermuscular coherence.

RESULTS

%DET was significantly higher, and SampEn significantly lower, in PD patients. Intermuscular coherence was also significantly higher in the PD group in theta, alpha and beta frequency bands. %DET increased and SampEn decreased with increasing Movement-Disorder-Society UPDRS scores, while theta band coherence was significantly correlated with total MDS-UPDRS scores and torque variance. Neither %DET, SampEn nor intermuscular coherence changed in response to training.

CONCLUSIONS

The differences observed are consistent with increased synchrony among motor units within and across leg muscles in PD. Differences between EMG signals recorded from the PD and control groups persisted post-therapy, after improvements in walking capacity occurred.

SIGNIFICANCE

These results provide insight into changes in motoneuron activity in PD, demonstrate increased beta band intramuscular coherence in PD for the first time, and support the development of quantitative biomarkers for PD based on advanced surface EMG features.

Theta band network supporting human episodic memory is not activated in the seizure onset zone

Episodic memory, everyday memory for events, is frequently impaired in patients with epilepsy. We tested patients undergoing intracranial electroencephalography (intracranial EEG) monitoring for the treatment of medically-refractory epilepsy on a well-characterized paradigm that requires episodic memory. We report that an anatomically diffuse network characterized by theta-band (4-7 Hz) coherence is activated at the time of target selection in a task that requires episodic memory. This distinct network of oscillatory activity is absent when episodic memory is not required. Further, the theta band synchronous network was absent in electrodes within the patient's seizure onset zone (SOZ). Our data provide novel empirical evidence for a set of brain areas that supports episodic memory in humans, and it provides a pathophysiologic mechanism for the memory deficits observed in patients with epilepsy.

Prediction error connectivity: A new method for EEG state analysis

Several models have been proposed to explain brain regional and interregional communication, the majority of them using methods that tap the frequency domain, like spectral coherence. Considering brain interareal communication as binary interactions, we describe a novel method devised to predict dynamics and thus highlight abrupt changes marked by unpredictability. Based on a variable-order Markov model algorithm developed in-house for data compression, the prediction error connectivity (PEC) estimates network transitions by calculating error matrices (EMs). We analysed 20 h of EEG signals of virtual networks generated with a neural mass model. Subnetworks changed through time (2 of 5 signals), from normal to normal or pathological states. PEC was superior to spectral coherence in detecting all considered transitions, especially in broad and ripple bands. Subsequently, EMs of real data were classified using a support vector machine in order to capture the transition from interictal to preictal state and calculate seizure risk. A single seizure was randomly selected for training. Through this approach it was possible to establish a threshold that the calculated risk consistently overcame minutes before the events. Using either spectral coherence or PEC we created 1000 models that successfully predicted 6 seizures (100% sensibility), a whole cluster recorded in a patient with hippocampal epilepsy. However, PEC resulted superior to coherence in terms of true seizure free time and amount of false warnings. Indeed, the best PEC model predicted 96% of interictal time (vs. 83% of coherence) of about 20 h of stereo-EEG. This analysis was extended to patients with neo/mesocortical temporal, neocortical frontal, parietal and occipital lobe epilepsy. Again PEC showed high performance, allowing the prediction of 31 events distributed across 10 days with ROC AUCs that reached 98% (average 93 ± 5%) in 6 different patients. Moreover, considering another state transition, PEC could classify and forecast up to 88% (average 85 ± 3%) of the REM phase both in deep and scalp EEG. In conclusion, PEC is a novel approach that relies on pattern analysis in the time-domain. We believe that this method can be successfully employed both for the study of brain connectivity, and also implemented in real-life solutions for seizure detection and prediction.

The Electrical Brain Activity in Men with Different Alpha-Rhythm Characteristics during Manual Movements Executed by the Subdominant Hand

Background

The ability to control motor actions and flexibly interact with the environment is considered one of the main components of the human brain executive functions. The spontaneous electroencephalogram (EEG) is among the physiological techniques making it possible to formulate a direct estimation of specific features of the activity of the human brain during manual movements.

Purpose

This study is devoted to an investigation of brain processes in men with a high or a low individual α-frequency determined during manual movements executed by the subdominant hand.

Methods

A test group consisting of 104 right-handed healthy men from the ages of 19 to 21 was divided into 2 groups in terms of the average magnitude of their individual α-frequency (ІαF) - groups with high (n = 53, IαF ≥10.04 Hz) and low (n = 51, IαF ≤10.04 Hz) values of ІαF. The power and coherence of the electrical activity of the cerebral cortex as well as the differences between the groups were evaluated by the testees during manual movements executed by the subdominant hand.

Results

Manual movements executed by the subdominant hand in response to the sensory signals are generally accompanied by the increased coherence of the EEG frequency components, especially, in the frontal, anterior temporal and central brain regions in men with different α-activity characteristics. Under these conditions, it has been found some electrogenesis power lowering in the cortical areas responsible for the sensory analysis, motor programming, sensory and motor information integration. Such changes have been combined with the local power increase of θ-, α1-oscillations in the frontal leads. Additionally, men with a low IαF were characterized by the local growth of α3-activity in the frontal areas of their cortex. Men from both groups also had the generalized increase in the capacity of the high-frequency β2- and γ-oscillations. Some higher power and coherence of the EEG frequency components have been registered in men with the low IαF in comparison with men having some high α-frequency.

Conclusion

The functional content of the established differences may generally reflect some relatively lower tone of the cortex activation in men with a low IαF and can be specifically compensated by some increased "intensity" and the redundancy of brain processes.

Do scalp-recorded slow potentials during neuro-feedback training reflect the cortical activity?

OBJECTIVE

Neuro-feedback (NFB) training by the self-regulation of slow potentials (SPs) <0.5 Hz recorded from the vertex scalp has been applied for seizure suppression in patients with epilepsy. However, SP is highly susceptible to artifact contamination, such as the galvanic skin response (GSR). This study aimed to evaluate the correlation between SPs recorded from the scalp and intracranial electroencephalography (EEG) by event-related coherence analysis.

METHODS

The scalp and subdural SPs were simultaneously recorded during NFB training by the DC-EEG machine while undergoing invasive recordings before epilepsy surgery in 10 patients with refractory partial epilepsy. The SPs at the vertex electrode were used as a reference for coherence analysis.

RESULTS

The coherence of SPs negatively correlated with the distance between the subdural and scalp electrodes. A significant negative correlation was noted between the linear subdural-scalp electrode distance and the coherence value (r =  - 0.916, p < 0.001).

CONCLUSION

Scalp-recorded SPs from the vertex area primarily reflect the cortical activity of high lateral convexity.

SIGNIFICANCE

Our results strongly suggest that SPs in NFB recorded from the vertex scalp electrode is derived from the cortices of high lateral convexity but not from the artifacts, such as GSR.

Rhythms of the body, rhythms of the brain: Respiration, neural oscillations, and embodied cognition

In spite of its importance as a life-defining rhythmic movement and its constant rhythmic contraction and relaxation of the body, respiration has not received attention in Embodied Cognition (EC) literature. Our paper aims to show that (1) respiration exerts significant and unexpected influence on cognitive processes, and (2) it does so by modulating neural synchronization that underlies specific cognitive processes. Then, (3) we suggest that the particular example of respiration may function as a model for a general mechanism through which the body influences cognitive functioning. Finally, (4) we work out the implications for EC, draw a parallel to the role of gesture, and argue that respiration sometimes plays a double, pragmatic and epistemic, role, which reduces the cognitive load. In such cases, consistent with EC, the overall cognitive activity includes a loop-like interaction between neural and non-neural elements.

Characterization of network structure in stereoEEG data using consensus-based partial coherence

Coherence is a widely used measure to determine the frequency-resolved functional connectivity between pairs of recording sites, but this measure is confounded by shared inputs to the pair. To remove shared inputs, the 'partial coherence' can be computed by conditioning the spectral matrices of the pair on all other recorded channels, which involves the calculation of a matrix (pseudo-) inverse. It has so far remained a challenge to use the time-resolved partial coherence to analyze intracranial recordings with a large number of recording sites. For instance, calculating the partial coherence using a pseudoinverse method produces a high number of false positives when it is applied to a large number of channels. To address this challenge, we developed a new method that randomly aggregated channels into a smaller number of effective channels on which the calculation of partial coherence was based. We obtained a 'consensus' partial coherence (cPCOH) by repeating this approach for several random aggregations of channels (permutations) and only accepting those activations in time and frequency with a high enough consensus. Using model data we show that the cPCOH method effectively filters out the effect of shared inputs and performs substantially better than the pseudo-inverse. We successfully applied the cPCOH procedure to human stereotactic EEG data and demonstrated three key advantages of this method relative to alternative procedures. First, it reduces the number of false positives relative to the pseudo-inverse method. Second, it allows for titration of the amount of false positives relative to the false negatives by adjusting the consensus threshold, thus allowing the data-analyst to prioritize one over the other to meet specific analysis demands. Third, it substantially reduced the number of identified interactions compared to coherence, providing a sparser network of connections from which clear spatial patterns emerged. These patterns can serve as a starting point of further analyses that provide insight into network dynamics during cognitive processes. These advantages likely generalize to other modalities in which shared inputs introduce confounds, such as electroencephalography (EEG) and magneto-encephalography (MEG).

Event related potential analysis techniques for autism spectrum disorders: A review

Autism Spectrum Disorders (ASD) comprise all pervasive neurodevelopmental diseases marked by deficits in social and communication skills, delayed cognitive development, restricted and repetitive behaviors. The core symptoms begin in early childhood, may continue life-long resulting in poor performance in adult stage. Event-related potential (ERP) is basically a time-locked electroencephalogram signal elicited by various stimuli, related to sensory and cognitive processes. The various ERP based techniques used for the study of ASD are considered in this review. ERP based study offers the advantage of being a non-invasive technique to measure the brain activity precisely. The techniques are categorized into three based on the processing domain: time, frequency and time-frequency. Power spectral density, coherence, phase synchrony, multiscale entropy, modified multiscale entropy, sum of signed differences, synchrostates and variance are some of the measures that have been widely used to study the abnormalities in frequency bands and brain connectivity. Various signal processing techniques such as Fast Fourier Transform, Discrete Fourier Transform, Short-Time Fourier Transform, Principal Component Analysis, Wavelet Transform, Directed Transfer Function etc. have been used to analyze the recorded signals so as to unravel the distinctive event-related potential patterns in individuals with ASD. The review concludes that ERP proves to be an efficient tool in detecting the brain abnormalities and connectivity issues, indicating the heterogeneity of ASD. Many advanced techniques are utilized to decipher the underlying neural circuitry so as to aid in therapeutic interventions for improving the core areas of deficits.

Abnormal coherence and sleep composition in children with Angelman syndrome: a retrospective EEG study

Background

Angelman syndrome (AS) is a neurodevelopmental disorder characterized by intellectual disability, speech and motor impairments, epilepsy, abnormal sleep, and phenotypic overlap with autism. Individuals with AS display characteristic EEG patterns including high-amplitude rhythmic delta waves. Here, we sought to quantitatively explore EEG architecture in AS beyond known spectral power phenotypes. We were motivated by studies of functional connectivity and sleep spindles in autism to study these EEG readouts in children with AS.

Methods

We analyzed retrospective wake and sleep EEGs from children with AS (age 4-11) and age-matched neurotypical controls. We assessed long-range and short-range functional connectivity by measuring coherence across multiple frequencies during wake and sleep. We quantified sleep spindles using automated and manual approaches.

Results

During wakefulness, children with AS showed enhanced long-range EEG coherence across a wide range of frequencies. During sleep, children with AS showed increased long-range EEG coherence specifically in the gamma band. EEGs from children with AS contained fewer sleep spindles, and these spindles were shorter in duration than their neurotypical counterparts.

Conclusions

We demonstrate two quantitative readouts of dysregulated sleep composition in children with AS-gamma coherence and spindles-and describe how functional connectivity patterns may be disrupted during wakefulness. Quantitative EEG phenotypes have potential as biomarkers and readouts of target engagement for future clinical trials and provide clues into how neural circuits are dysregulated in children with AS.

EEG findings and outcomes of continuous video-EEG monitoring started prior to initiation of seizure treatment in the perinatal stroke

BACKGROUND

To analyze the findings in the background EEG activity of infants who suffered perinatal stroke.

METHODS

Eleven neonates born 2009-2014 diagnosed of ischemic stroke by MRI (three of them with multistroke) underwent continuous video-EEG monitoring. Visual and spectral (power spectrum and coherence) analyses of the background EEG was performed in three moments: 1) Onset of EEG recording (prior to initiate seizure treatment), 2) Post-ictal epoch (1-2 h after the last seizure), and 3) one-two days after seizure control. All children aged 2-6 years underwent neurodevelopmental assessment.

RESULTS

Discontinuity, asymmetry, asynchrony, transients, and relative power spectrum in δ and θ frequency bands increased significantly (p < 0.05) in the post-ictal epoch with respect to onset of EEG recording. After seizure control, discontinuity, asynchrony, and θ power spectrum no longer had significant differences with those found at onset of EEG recording. Significant differences between the ischemic and unaffected hemispheres were found in transients and in β coherence (p = 0.002; p = 0.001, respectively) exclusively in the post-ictal epoch. Seizure burden and time-to-control ranged 5-38 min and 0.5-40 h respectively. Currently, only one child is affected by spastic monoparesis. The intelligence quotients ranged 96-123.

CONCLUSIONS

The background EEG can undergo significant changes in the post-ictal epoch due to the seizure activity triggered by the perinatal stroke. Most of these EEG changes involve all brain activity and not exclusively the ischemic hemisphere. Many of these modifications in the EEG background reverse following the seizure control. Video-EEG monitoring allows accurate/immediate diagnosis and rapid/intensive treatment of the stroke-associated seizures.

Abnormal coherence and sleep composition in children with Angelman syndrome: a retrospective EEG study

Background

Angelman syndrome (AS) is a neurodevelopmental disorder characterized by intellectual disability, speech and motor impairments, epilepsy, abnormal sleep, and phenotypic overlap with autism. Individuals with AS display characteristic EEG patterns including high-amplitude rhythmic delta waves. Here, we sought to quantitatively explore EEG architecture in AS beyond known spectral power phenotypes. We were motivated by studies of functional connectivity and sleep spindles in autism to study these EEG readouts in children with AS.

Methods

We analyzed retrospective wake and sleep EEGs from children with AS (age 4–11) and age-matched neurotypical controls. We assessed long-range and short-range functional connectivity by measuring coherence across multiple frequencies during wake and sleep. We quantified sleep spindles using automated and manual approaches.

Results

During wakefulness, children with AS showed enhanced long-range EEG coherence across a wide range of frequencies. During sleep, children with AS showed increased long-range EEG coherence specifically in the gamma band. EEGs from children with AS contained fewer sleep spindles, and these spindles were shorter in duration than their neurotypical counterparts.

Conclusions

We demonstrate two quantitative readouts of dysregulated sleep composition in children with AS—gamma coherence and spindles—and describe how functional connectivity patterns may be disrupted during wakefulness. Quantitative EEG phenotypes have potential as biomarkers and readouts of target engagement for future clinical trials and provide clues into how neural circuits are dysregulated in children with AS.

Electronic supplementary material

The online version of this article (10.1186/s13229-018-0214-8) contains supplementary material, which is available to authorized users.

Kindergarteners' Narrative Competence Across Tasks and Time

The authors investigated children's narrative competence by analyzing the development of the reciprocal relationship between storytelling and story retelling performances over a school year through a cross-lagged panel design. The participants in this study were 170 Italian kindergarten pupils (M age = 4.98 ± 0.31 years). Children were asked to produce oral narratives in two different tasks: a storytelling and a story retelling task. Narrative competence was assessed in terms of structure and coherence. The cross-lagged panel analyses showed that both storytelling and story retelling tasks are stable constructs, but they differ in the emphasis on coherence. Data confirmed the pivotal role played by storytelling as a task, and structure as a component in fostering the development of children's narrative competence. Overall, results from this study suggest that storytelling and story retelling are tasks that involve interrelated but not overlapping processes, and trigger different aspects of narrative competence.

Coherence in the Visual Imagination

An incoherent visualization is when aspects of different senses of a word (e.g., the biological "mouse" vs. the computer "mouse") are present in the same visualization (e.g., a visualization of a biological mouse in the same image with a computer tower). We describe and implement a new model of creating contextual coherence in the visual imagination called Coherencer, based on the SOILIE model of imagination. We show that Coherencer is able to generate scene descriptions that are more coherent than SOILIE's original approach as well as a parallel connectionist algorithm that is considered competitive in the literature on general coherence. We also show that co-occurrence probabilities are a better association representation than holographic vectors and that better models of coherence improve the resulting output independent of the association type that is used. Theoretically, we show that Coherencer is consistent with other models of cognitive generation. In particular, Coherencer is a similar, but more cognitively plausible model than the C3 model of concept combination created by Costello and Keane (2000). We show that Coherencer is also consistent with both the modal schematic indices of perceptual symbol systems theory (Barsalou, 1999) and the amodal contextual constraints of Thagard's (2002) theory of coherence. Finally, we describe how Coherencer is consistent with contemporary research on the hippocampus, and we show evidence that the process of making a visualization coherent is serial.

User Systems Architectures - Two studies in design and assessment

The concept of User System Architectures (USA) is introduced as part of the overall systems architecture. A USA is defined as a set of ergonomics information and knowledge assembled to represent system structure and content. It is described in the context of the system development lifecycle. The characteristics associated with a USA are outlined. These include layers of description, viewpoints, coherency and traceability. The concept of coherency between layers and the techniques for tracing the design characteristics back to the requirements (i.e. traceability) are discussed with their implications for ergonomics. Two studies (one design and one assessment) are used to demonstrate the use of USA techniques. The benefits, shortfalls and costs of using the USA technique are outlined for each case, and in a more general range of applications. The validity and reliability of the representations are discussed.

Parietofrontal network upregulation after motor stroke

Objective

Motor recovery after stroke shows a high inter-subject variability. The brain's potential to form new connections determines individual levels of recovery of motor function. Most of our daily activities require visuomotor integration, which engages parietal areas. Compared to the frontal motor system, less is known about the parietal motor system's reconfiguration related to stroke recovery. Here, we tested if functional connectivity among parietal and frontal motor areas undergoes plastic changes after stroke and assessed the behavioral relevance for motor function after stroke.

Methods

We investigated stroke lesion-induced changes in functional connectivity by measuring high-density electroencephalography (EEG) and assessing task-related changes in coherence during a visually guided grip task with the paretic hand in 30 chronic stroke patients with variable motor deficits and 19 healthy control subjects. Quantitative changes in task-related coherence in sensorimotor rhythms were compared to the residual motor deficit.

Results

Parietofrontal coupling was significantly stronger in patients compared to controls. Whereas motor network coupling generally increased during the task in both groups, the task-related coherence between the parietal and primary motor cortex in the stroke lesioned hemisphere showed increased connectivity across a broad range of sensorimotor rhythms. Particularly the parietofrontal task-induced coupling pattern was significantly and positively related to residual impairment in the Nine-Hole Peg Test performance and grip force.

Interpretation

These results demonstrate that parietofrontal motor system integration during visually guided movements is stronger in the stroke-lesioned brain. The correlation with the residual motor deficit could either indicate an unspecific marker of motor network damage or it might indicate that upregulated parietofrontal connectivity has some impact on post-stroke motor function.

Development of a SEM-based low-energy in-line electron holography microscope for individual particle imaging

A new SEM-based in-line electron holography microscope has been under development. The microscope utilizes conventional SEM and BF-STEM functionality to allow for rapid searching of the specimen of interest, seamless interchange between SEM, BF-STEM and holographic imaging modes, and makes use of coherent low-energy in-line electron holography to obtain low-dose, high-contrast images of light element materials. We report here an overview of the instrumentation and first experimental results on gold nano-particles and carbon nano-fibers for system performance tests. Reconstructed images obtained from the holographic imaging mode of the new microscope show substantial image contrast and resolution compared to those acquired by SEM and BF-STEM modes, demonstrating the feasibility of high-contrast imaging via low-energy in-line electron holography. The prospect of utilizing the new microscope to image purified biological specimens at the individual particle level is discussed and electron optical issues and challenges to further improve resolution and contrast are considered.

Coherence and interlimb force control: Effects of visual gain

Neural coupling across hemispheres and homologous muscles often appears during bimanual motor control. Force coupling in a specific frequency domain may indicate specific bimanual force coordination patterns. This study investigated coherence on pairs of bimanual isometric index finger force while manipulating visual gain and task asymmetry conditions. We used two visual gain conditions (low and high gain = 8 and 512 pixels/N), and created task asymmetry by manipulating coefficient ratios imposed on the left and right index finger forces (0.4:1.6; 1:1; 1.6:0.4, respectively). Unequal coefficient ratios required different contributions from each hand to the bimanual force task resulting in force asymmetry. Fourteen healthy young adults performed bimanual isometric force control at 20% of their maximal level of the summed force of both fingers. We quantified peak coherence and relative phase angle between hands at 0-4, 4-8, and 8-12 Hz, and estimated a signal-to-noise ratio of bimanual forces. The findings revealed higher peak coherence and relative phase angle at 0-4 Hz than at 4-8 and 8-12 Hz for both visual gain conditions. Further, peak coherence and relative phase angle values at 0-4 Hz were larger at the high gain than at the low gain. At the high gain, higher peak coherence at 0-4 Hz collapsed across task asymmetry conditions significantly predicted greater signal-to-noise ratio. These findings indicate that a greater level of visual information facilitates bimanual force coupling at a specific frequency range related to sensorimotor processing.

Movement Kinematics Dynamically Modulates the Rolandic ~ 20-Hz Rhythm During Goal-Directed Executed and Observed Hand Actions

This study investigates whether movement kinematics modulates similarly the rolandic α and β rhythm amplitude during executed and observed goal-directed hand movements. It also assesses if this modulation relates to the corticokinematic coherence (CKC), which is the coupling observed between cortical activity and movement kinematics during such motor actions. Magnetoencephalography (MEG) signals were recorded from 11 right-handed healthy subjects while they performed or observed an actor performing the same repetitive hand pinching action. Subjects' and actor's forefinger movements were monitored with an accelerometer. Coherence was computed between acceleration signals and the amplitude of α (8-12 Hz) or β (15-25 Hz) oscillations. The coherence was also evaluated between source-projected MEG signals and their β amplitude. Coherence was mainly observed between acceleration and the amplitude of β oscillations at movement frequency within bilateral primary sensorimotor (SM1) cortex with no difference between executed and observed movements. Cross-correlation between the amplitude of β oscillations at the SM1 cortex and movement acceleration was maximal when acceleration was delayed by ~ 100 ms, both during movement execution and observation. Coherence between source-projected MEG signals and their β amplitude during movement observation and execution was not significantly different from that during rest. This study shows that observing others' actions engages in the viewer's brain similar dynamic modulations of SM1 cortex β rhythm as during action execution. Results support the view that different neural mechanisms might account for this modulation and CKC. These two kinematic-related phenomena might help humans to understand how observed motor actions are actually performed.

Readability and Coherence of Department/Ministry of Health HPV Information

BACKGROUND

Human papilloma virus (HPV) is a prime factor in the development of many cancers and genital warts in Canada. A majority of sexually active Canadians are likely to have an HPV infection during their lifetime. Information provided online by each specific provincial department/ministry of health in regard to HPV and vaccination may not be at an ideal standard for the lay population to understand and should be evaluated.

PURPOSE

The purpose of this study is to assess the readability and coherence of provincial department/ministry of health HPV information to determine if it is adequate for the Canadian lay population to understand.

METHODS AND RESULTS

Seven of ten Canadian provincial department/ministry of health's HPV information websites were evaluated for readability and coherence. The readability tools Gunning-Fog index and Simple Measure of Gobbledygook (SMOG) both found that approximately 60 % of the population for each of the provinces evaluated may be able to understand the information. The coherence measures of latent semantic analysis (LSA) and computerized propositional idea density rater (CPIDR) both concluded that relative to the benchmark that represents the lay population, the coherence level is not appropriate (LSA, p < 0.001and CPIDR, p < 0.001).

INTERPRETATION

HPV information provided by the Canadian provincial department/ministry of health websites may not be adequate for the lay population to understand. Readability and coherence are important factors that should be considered to improve the quality and adequacy of the information provided so the message reaches the Canadian population.

A coherentist conception of ad hoc hypotheses

What does it mean for a hypothesis to be ad hoc? One prominent account has it that ad hoc hypotheses have no independent empirical support. Others have viewed ad hoc judgements as stemming from a lack of unifiedness of the amended theory. Still others view them as merely subjective. Here I critically review these views and defend my own Coherentist Conception of Ad hocness by working out its conceptual and descriptive attractions.

Applying GRADE-CERQual to qualitative evidence synthesis findings-paper 4: how to assess coherence

BACKGROUND

The GRADE-CERQual (Grading of Recommendations Assessment, Development and Evaluation-Confidence in Evidence from Reviews of Qualitative research) approach has been developed by the GRADE working group. The approach has been developed to support the use of findings from qualitative evidence syntheses in decision-making, including guideline development and policy formulation. CERQual includes four components for assessing how much confidence to place in findings from reviews of qualitative research (also referred to as qualitative evidence syntheses): (1) methodological limitations, (2) relevance, (3) coherence and (4) adequacy of data. This paper is part of a series providing guidance on how to apply CERQual and focuses on CERQual's coherence component.

METHODS

We developed the coherence component by searching the literature for definitions, gathering feedback from relevant research communities and developing consensus through project group meetings. We tested the CERQual coherence component within several qualitative evidence syntheses before agreeing on the current definition and principles for application.

RESULTS

When applying CERQual, we define coherence as how clear and cogent the fit is between the data from the primary studies and a review finding that synthesises that data. In this paper, we describe the coherence component and its rationale and offer guidance on how to assess coherence in the context of a review finding as part of the CERQual approach. This guidance outlines the information required to assess coherence, the steps that need to be taken to assess coherence and examples of coherence assessments.

CONCLUSIONS

This paper provides guidance for review authors and others on undertaking an assessment of coherence in the context of the CERQual approach. We suggest that threats to coherence may arise when the data supporting a review finding are contradictory, ambiguous or incomplete or where competing theories exist that could be used to synthesise the data. We expect the CERQual approach, and its individual components, to develop further as our experiences with the practical implementation of the approach increase.

Characterization of corticospinal activation of finger motor neurons during precision and power grip in humans

Direct and indirect corticospinal pathways to finger muscles may play a different role in control of the upper extremity. We used transcranial magnetic stimulation (TMS) and coherence analysis to characterize the corticospinal drive to the first dorsal interosseous (FDI) and abductor pollicis brevis (APB) when active during a precision and power grip task. In experiment 1, single motor units were recorded during precision grip and power grip in 20 adults (25.2 ± 7.1 years). Post-stimulus time histograms (PSTH) were obtained following TMS. In experiment 2, coherence and cross-correlation analysis of the FDI and APB surface EMG were used to investigate the temporal organization of corticospinal drive during precision grip and power grip in 15 adults (27.4 ± 8.1 years). We found no significant differences in PSTH peak onset (26.6 ± 1.9 vs. 26.7 ± 2.0 ms, p = 0.75), maximal peak (27.4 ± 1.9 vs. 27.4 ± 1.9 ms, p = 1.0) or peak duration (2.3 ± 1.1 vs. 2.3 ± 1.0 ms, p = 0.75) for the 11 recovered motor units during precision grip and power grip. Also, no significant difference in coherence or the width of the synchronization peaks during precision grip (7.2 ± 3.7 ms) and power grip (7.9 ± 3.1 ms) could be observed (p = 0.59). The short duration of peaks elicited in the PSTH of single motor units following TMS and central synchronization peaks of voluntarily activated motor units during precision and power grip suggests that the direct corticospinal pathway (the corticomotoneuronal system) is equally involved in the control of both tasks. The data do not support that indirect pathways would make a larger contribution to power grip.

How context features modulate the involvement of the working memory system during discourse comprehension

Using functional magnetic resonance imaging (fMRI), we investigated the effects of context features on the involvement of the working memory (WM) system during discourse comprehension. During the fMRI scan, participants were asked to read two-sentence discourses in which the topic of the second sentence was either maintained, or was shifted from, the topic of the first. Changes in the level of coherence between the two sentences as well as context length were also investigated across discourse items. The WM system was identified with a verbal N-back task. Analysis of the reading comprehension task revealed that within the WM system, stronger activation in the left inferior frontal gyrus corresponded with increased bridging coherence demands between sentences, while greater activation in the left inferior and middle frontal gyri, bilateral superior frontal gyri, and bilateral inferior parietal lobules corresponded with increased context length. Topic variation showed no effect on activation of the WM system. These results provide new insights into understanding how different levels of context features modulate activation of the subcomponents of the WM system and indicate a role for the left inferior frontal gyrus as a core component of the WM system supporting discourse processing.

Associations among mothers' representations of their relationship with their toddlers, maternal parenting stress, and toddlers' internalizing and externalizing behaviors

This study examined the array of associations among the emotional valence and the coherence of mothers' representations of their relationship with their toddlers, mothers' reported parenting stress, and toddlers' internalizing and externalizing behaviors. To evaluate maternal representations, 55 mothers were interviewed using the Five Minute Speech Sample procedure (FMSS; Magaña et al., 1986), which was coded for criticism and positive comments (Magaňa-Amato, 1993), as well as coherence (Sher-Censor & Yates, 2015). Mothers also completed the Parenting Stress Index - Short Form (PSI; Abidin, 1997) to evaluate their parenting stress and the Child Behavior Checklist (CBCL/1.5-5; Achenbach & Rescorla, 2000) to assess their toddlers' internalizing and externalizing behaviors. Results indicated that parenting stress was associated with maternal criticism and fewer positive comments in the FMSS, but not with the coherence of mothers' FMSS. Parenting stress, criticism, and lower coherence in the FMSS were associated with maternal reports of externalizing behaviors. Only parenting stress and lower coherence in the FMSS were related to mothers' reports of internalizing behaviors of the child. Thus, the emotional valence and the coherence of mothers' representations of their relationship with their child and parenting stress may each constitute a distinct aspect of parenting and contribute to the understanding of individual differences in toddlers' internalizing and externalizing behaviors. Implications for research and practice with families of toddlers are discussed.

A review on EEG-based methods for screening and diagnosing alcohol use disorder

The screening test for alcohol use disorder (AUD) patients has been of subjective nature and could be misleading in particular cases such as a misreporting the actual quantity of alcohol intake. Although the neuroimaging modality such as electroencephalography (EEG) has shown promising research results in achieving objectivity during the screening and diagnosis of AUD patients. However, the translation of these findings for clinical applications has been largely understudied and hence less clear. This study advocates the use of EEG as a diagnostic and screening tool for AUD patients that may help the clinicians during clinical decision making. In this context, a comprehensive review on EEG-based methods is provided including related electrophysiological techniques reported in the literature. More specifically, the EEG abnormalities associated with the conditions of AUD patients are summarized. The aim is to explore the potentials of objective techniques involving quantities/features derived from resting EEG, event-related potentials or event-related oscillations data.

The temporal dynamics involved in object representation updating to predict change

The synchronization of cortically disparate neural assemblies at frequencies in the gamma-band range (30-70Hz) is considered to be involved in the perceptual organization of the environment. In support of this Elliott (2014) demonstrated improved detection of a target stimulus when this target was primed in a matrix that flickered at specific frequencies in the gamma-band range, each found to be separated by regular intervals which correspond with a 6.69Hz period. This can be explained in terms of the interaction of the stimulus (and stimulus-induced) rhythm with a slow endogenous theta rhythm. When the interaction is in phase between these rhythms and target presentation time is slightly ahead of the priming stimulus presentation, improved detection times are recorded indicating an anticipatory response. However, when these rhythms are out of phase and the target is presented during or slightly after priming stimulus presentation, improved responding also occurs, suggesting a retroactive response is facilitated. Research in the auditory domain supports these findings (Aksentijevic et al., 2011). The conclusions of this research suggest that synchronization of neural assemblies contributes to the temporal code necessary to facilitate representation updating in order to respond to a dynamic environment and anticipate the logical next event.

Alterations of Effective Connectivity Patterns in Mild Cognitive Impairment: An MEG Study

Neuroimaging techniques have demonstrated over the years their ability to characterize the brain abnormalities associated with different neurodegenerative diseases. Among all these techniques, magnetoencephalography (MEG) stands out by its high temporal resolution and noninvasiveness. The aim of the present study is to explore the coupling patterns of resting-state MEG activity in subjects with mild cognitive impairment (MCI). To achieve this goal, five minutes of spontaneous MEG activity were acquired with a 148-channel whole-head magnetometer from 18 MCI patients and 26 healthy controls. Inter-channel relationships were investigated by means of two complementary coupling measures: coherence and Granger causality. Coherence is a classical method of functional connectivity, while Granger causality quantifies effective (or causal) connectivity. Both measures were calculated in the five conventional frequency bands: delta (δ, 1-4 Hz), theta (θ, 4-8 Hz), alpha (α, 8-13 Hz), beta (β, 13-30 Hz), and gamma (γ, 30-45 Hz). Our results showed that connectivity values were lower for MCI patients than for controls in all frequency bands. However, only Granger causality revealed statistically significant differences between groups (p-values < 0.05, FDR corrected Mann-Whitney U-test), mainly in the beta band. Our results support the role of MCI as a disconnection syndrome, which elicits early alterations in effective connectivity patterns. These findings can be helpful to identify the neural substrates involved in prodromal stages of dementia.

Yes, The Precautionary Principle Is Incoherent

This article is a reply to Thomas Boyer-Kassem's discussion of my criticism of the precautionary principle published in this journal about a decade ago. Boyer-Kassem does not question the logical validity of the theorem proved in my original article, but he brings up important questions about its scope. He also challenges the plausibility of some of the assumptions on which it is based. In this comment, I argue that each objection can be adequately dealt with. As a decision rule, the precautionary principle is (still) incoherent.

Early visual analysis tool using magnetoencephalography for treatment and recovery of neuronal dysfunction

Functional neuroimaging modalities play an important role in deciding the diagnosis and course of treatment of neuronal dysfunction and degeneration. This article presents an analytical tool with visualization by exploiting the strengths of the MEG (magnetoencephalographic) neuroimaging technique. The tool automates MEG data import (in tSSS format), channel information extraction, time/frequency decomposition, and circular graph visualization (connectogram) for simple result inspection. For advanced users, the tool also provides magnitude squared coherence (MSC) values allowing personalized threshold levels, and the computation of default model from MEG data of control population. Default model obtained from healthy population data serves as a useful benchmark to diagnose and monitor neuronal recovery during treatment. The proposed tool further provides optional labels with international 10-10 system nomenclature in order to facilitate comparison studies with EEG (electroencephalography) sensor space. Potential applications in epilepsy and traumatic brain injury studies are also discussed.

Abnormalities in Dynamic Brain Activity Caused by Mild Traumatic Brain Injury Are Partially Rescued by the Cannabinoid Type-2 Receptor Inverse Agonist SMM-189

Mild traumatic brain injury (mTBI) can cause severe long-term cognitive and emotional deficits, including impaired memory, depression, and persevering fear, but the neuropathological basis of these deficits is uncertain. As medial prefrontal cortex (mPFC) and hippocampus play important roles in memory and emotion, we used multi-site, multi-electrode recordings of oscillatory neuronal activity in local field potentials (LFPs) in awake, head-fixed mice to determine if the functioning of these regions was abnormal after mTBI, using a closed-skull focal cranial blast model. We evaluated mPFC, hippocampus CA1, and primary somatosensory/visual cortical areas (S1/V1). Although mTBI did not alter the power of oscillations, it did cause increased coherence of θ (4-10 Hz) and β (10-30 Hz) oscillations within mPFC and S1/V1, reduced CA1 sharp-wave ripple (SWR)-evoked LFP activity in mPFC, downshifted SWR frequencies in CA1, and enhanced θ-γ phase-amplitude coupling (PAC) within mPFC. These abnormalities might be linked to the impaired memory, depression, and persevering fear seen after mTBI. Treatment with the cannabinoid type-2 (CB2) receptor inverse agonist SMM-189 has been shown to mitigate functional deficits and neuronal injury after mTBI in mice. We found that SMM-189 also reversed most of the observed neurophysiological abnormalities. This neurophysiological rescue is likely to stem from the previously reported reduction in neuron loss and/or the preservation of neuronal function and connectivity resulting from SMM-189 treatment, which appears to stem from the biasing of microglia from the proinflammatory M1 state to the prohealing M2 state by SMM-189.

Low-beta cortico-pallidal coherence decreases during movement and correlates with overall reaction time

Beta band oscillations (13–30 Hz) are a hallmark of cortical and subcortical structures that are part of the motor system. In addition to local population activity, oscillations also provide a means for synchronization of activity between regions. Here we examined the role of beta band coherence between the internal globus pallidus (GPi) and (motor) cortex during a simple reaction time task performed by nine patients with idiopathic dystonia. We recorded local field potentials from deep brain stimulation (DBS) electrodes implanted in bilateral GPi in combination with simultaneous whole-head magneto-encephalography (MEG). Patients responded to visually presented go or stop-signal cues by pressing a button with left or right hand. Although coherence between signals from DBS electrodes and MEG sensors was observed throughout the entire beta band, a significant movement-related decrease prevailed in lower beta frequencies (∼13–21 Hz). In addition, patients' absolute coherence values in this frequency range significantly correlated with their median reaction time during the task (r = 0.89, p = 0.003). These findings corroborate the recent idea of two functionally distinct frequency ranges within the beta band, as well as the anti-kinetic character of beta oscillations.

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Simultaneous internal pallidum LFP and MEG recordings in dystonia patients.

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Cortico-pallidal coherence was found throughout the beta frequency range.

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Predominantly low-beta coherence (13–21 Hz) decreased with movement.

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Overall level of coherence was indicative of subject's median reaction time.

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No correlations were found between beta coherence measures and clinical scores.

Comparison of Electroencephalography (EEG) Coherence between Major Depressive Disorder (MDD) without Comorbidity and MDD Comorbid with Internet Gaming Disorder

Internet gaming disorder (IGD) has many comorbid psychiatric problems including major depressive disorder (MDD). In the present study, we compared the neurobiological differences between MDD without comorbidity (MDD-only) and MDD comorbid with IGD (MDD+IGD) by analyzing the quantitative electroencephalogram (QEEG) findings. We recruited 14 male MDD+IGD (mean age, 20.0 ± 5.9 years) and 15 male MDD-only (mean age, 20.3 ± 5.5 years) patients. The electroencephalography (EEG) coherences were measured using a 21-channel digital EEG system and computed to assess synchrony in the frequency ranges of alpha (7.5-12.5 Hz) and beta (12.5-35.0 Hz) between the following 12 electrode site pairs: inter-hemispheric (Fp1-Fp2, F7-F8, T3-T4, and P3-P4) and intra-hemispheric (F7-T3, F8-T4, C3-P3, C4-P4, T5-O1, T6-O2, P3-O1, and P4-O2) pairs. Differences in inter- and intra-hemispheric coherence values for the frequency bands between groups were analyzed using the independent t-test. Inter-hemispheric coherence value for the alpha band between Fp1-Fp2 electrodes was significantly lower in MDD+IGD than MDD-only patients. Intra-hemispheric coherence value for the alpha band between P3-O1 electrodes was higher in MDD+IGD than MDD-only patients. Intra-hemispheric coherence values for the beta band between F8-T4, T6-O2, and P4-O2 electrodes were higher in MDD+IGD than MDD-only patients. There appears to be an association between decreased inter-hemispheric connectivity in the frontal region and vulnerability to attention problems in the MDD+IGD group. Increased intra-hemisphere connectivity in the fronto-temporo-parieto-occipital areas may result from excessive online gaming.

Bottom-up gamma and stages of waking

Gamma activity has been proposed to promote the feed forward or "bottom-up" flow of information from lower to higher regions of the brain during perception. The pedunculopontine nucleus (PPN) modulates waking and REM sleep, and is part of the reticular activating system (RAS). The properties of PPN cells are unique in that all PPN neurons fire maximally at gamma band frequency regardless of electrophysiological or transmitter type, thus proposed as one origin of "bottom-up" gamma. This property is based on the presence of intrinsic membrane oscillations subserved by high threshold, voltage-dependent calcium channels. Moreover, some PPN cells are electrically coupled. Assuming that the population of PPN neurons has the capacity to fire at ∼40Hz coherently, then the population as a whole can be expected to generate a stable gamma band signal. But what if not all the neurons are firing at the peaks of the oscillations? That means that some cells may fire only at the peaks of every second oscillation. Therefore, the population as a whole can be expected to be firing at a net ∼20Hz. If some cells are firing at the peaks of every fourth oscillation, then the PPN as a whole would be firing at ∼10Hz. Firing at rates below 10Hz would imply that the system is seldom firing at the peaks of any oscillation, basically asleep, in slow wave sleep, thus the activation of the RAS is insufficient to promote waking. This hypothesis carries certain implications, one of which is that we awaken in stages as more and more cells are recruited to fire at the peaks of more and more oscillations. For this system, it would imply that, as we awaken, we step from ∼10Hz to ∼20Hz to ∼30Hz to ∼40Hz, that is, in stages and presumably at different levels of awareness. A similar process can be expected to take place as we fall asleep. Awakening can then be considered to be stepwise, not linear. That is, the implication is that the process of waking is a stepwise event, not a gradual increase, suggesting that the brain can spend time at each of these different stages of arousal.