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Major depressive disorder (MDD) is a highly prevalent psychiatric disorder, but chances for remission largely decrease with each failed treatment attempt. It is therefore desirable to assign a given patient to the most promising individual treatment option as early as possible. We used a polygenic score (PGS) informed electroencephalography (EEG) data-driven approach to identify potential predictors for MDD treatment outcome. Post-hoc we conducted exploratory analyses in order to understand the results in depth. First, an EEG independent component analysis produced 54 functional brain networks in a large heterogeneous cohort of psychiatric patients (n = 4,045; 5–84 yrs.). Next, the network that was associated to PGS for antidepressant-response (PRS-AR) in an independent sample (n = 722) was selected: an age-related posterior alpha network that explained >60 % of EEG variance, and was highly stable over recording time. Translational analyses were performed in two other independent datasets to examine if the network was predictive of psychopharmacotherapy (n = 535) and/or repetitive transcranial magnetic stimulation (rTMS) and concomitant psychotherapy (PT; n = 186) outcome. The network predicted remission to venlafaxine (p = 0.015), resulting in a normalized positive predicted value (nPPV) of 138 %, and rTMS + PT – but in opposite direction for women (p = 0.002) relative to men (p = 0.018) – yielding a nPPV of 131 %. Blinded out-of-sample validations for venlafaxine (n = 29) and rTMS + PT (n = 36) confirmed the findings for venlafaxine, while results for rTMS + PT could not be replicated. These data suggest the existence of a relatively stable EEG posterior alpha aging network related to PGS-AR that has potential as MDD treatment predictor. [ABSTRACT FROM AUTHOR]

Knowledge about brain source localizations for religious states of mind is still limited. Previous studies have usually not set a direct emphasis on experience. The present study investigated the phenomenon of religious experience using inverse solution calculations, and it is one of the first to measure the dimension of experience directly. A total of 60 evangelical Christians participated in an experiment where they were asked to engage in worship and try to connect with God. Using a bar slider, the participants continuously rated how strongly they sensed God's presence at any given moment. A selection of songs helped to induce the desired experience. Measurements were made using EEG with 64 electrodes and inverse solutions were calculated with sLORETA. We appropriated two mutually compatible hypotheses from the literature pertaining to religious experiences: the executive inhibition hypothesis (reformulated as the frontal relaxation hypothesis) and the temporal involvement hypothesis. Our results did not yield any information about the frontal areas; however, they indicated that the right temporal cortex appeared to be involved during the experience. [ABSTRACT FROM AUTHOR]

Operators are often subjected to a high working memory load as far as any possibly useful information must always be available and presented to the operator. Thus, we assumed that they may have developed adaptations in mechanisms of working memory realization that help them to be more efficient in information overload conditions. Our aim was to define differences in visual working memory functioning in radar station operators (RSO) and other military profession representatives. For this purpose, in parallel with the performance of original computer tests for the visual working memory identification, which had two levels of complexity, we recorded an electroencephalogram with subsequent coherent and LORETA analysis and electrocardiogram with subsequent determining of stress index of the regulatory systems. It was found that reaction time, as well as the number of errors in both tests, didn't differ significantly for the two groups. At the same time, the control group had a significantly higher number of θ-band coherent connections in the frontal lobe in both tests, which could indicate a higher level of mental stress and emotional involvement. This assumption was confirmed by the stress index dynamic in the control group. LORETA analysis showed that in the RSO group, the degree of fronto-parietal, cingulo-opercular networks, cuneus and precuneus involvement was at a high level from the very first tasks, while in the control group, it increased with task complexity, that is the evidence of adaptive changes in the working memory of RSO, due to which they successfully cope with information overload. [ABSTRACT FROM AUTHOR]

Subjective chronic tinnitus is a prevalent auditory perception characterized by an absence of a corresponding acoustic source. It is often accompanied by hearing deficits and may lead to various psychological problems including sleep disorder, depression and anxiety. To investigate the differential neuronal profile of patients with severe and less severe chronic tinnitus, 34 tinnitus patients were distributed in two groups and their EEG resting state activity was compared. Using standardized Low Resolution Electromagnetic Tomography (sLORETA) a significant and substantial frontal increase in theta wave activity was found in the group with severe tinnitus (p =.013). The correlated severity of depression and anxiety had no influence on the electrophysiological metric. These results support a tinnitus-related global network change in which prefrontal areas are part of a network which exerts a top-down influence on the auditory cortices. The demonstrated slowing of oscillations in the responsible network may constitute a neuronal marker for the prefrontal brain network lacking the capacity to inhibit overexcitation. The magnitude of this influence is linked to the subjective strength of the tinnitus distress. • Brain mechanisms responsible for severe tinnitus reside in a large prefrontal network. • The network lacks the capacity to inhibit overexcitation of the central auditory system. • The neurophysiological basis of tinnitus is not related to psychological disturbances. • Mood disorders are a secondary consequence of the primary neurophysiological pathology. [ABSTRACT FROM AUTHOR]

The treatment of major depressive disorder (MDD) is hampered by low chances of treatment response in each treatment step, which is partly due to a lack of firmly established outcome-predictive biomarkers. Here, we hypothesize that polygenic-informed EEG signatures may help predict antidepressant treatment response. Using a polygenic-informed electroencephalography (EEG) data-driven, data-reduction approach, we identify a brain network in a large cohort (N=1,123), and discover it is sex-specifically (male patients, N=617) associated with polygenic risk score (PRS) of antidepressant response. Subsequently, we demonstrate in three independent datasets the utility of the network in predicting response to antidepressant medication (male, N=232) as well as repetitive transcranial magnetic stimulation (rTMS) and concurrent psychotherapy (male, N=95). This network significantly improves a treatment response prediction model with age and baseline severity data (area under the curve, AUC=0.623 for medicaton; AUC=0.719 for rTMS). A predictive model for MDD patients, aimed at increasing the likelihood of being a responder to antidepressants or rTMS and concurrent psychotherapy based on only this network, yields a positive predictive value (PPV) of 69% for medication and 77% for rTMS. Finally, blinded out-of-sample validation of the network as predictor for psychotherapy response in another independent dataset (male, N=50) results in a within-subsample response rate of 50% (improvement of 56%). Overall, the findings provide a first proof-of-concept of a combined genetic and neurophysiological approach in the search for clinically-relevant biomarkers in psychiatric disorders, and should encourage researchers to incorporate genetic information, such as PRS, in their search for clinically relevant neuroimaging biomarkers. [ABSTRACT FROM AUTHOR]

• Spatial accuracy of 6 linear distributed inverse solutions for interictal high-density EEG source localisation was evaluated. • Low-Resolution Electromagnetic Tomography and Local Autoregressive Average best localised both patients' and simulated sources. • These two algorithms' superiority over newer inverse solutions was due to their relative robustness towards noise. To compare the spatial accuracy of 6 linear distributed inverse solutions for EEG source localisation of interictal epileptic discharges: Minimum Norm, Weighted Minimum Norm, Low-Resolution Electromagnetic Tomography (LORETA), Local Autoregressive Average (LAURA), Standardised LORETA, and Exact LORETA. Spatial accuracy was assessed clinically by retrospectively comparing the maximum source of averaged interictal discharges to the resected brain area in 30 patients with successful epilepsy surgery, based on 204-channel EEG. Additionally, localisation errors of the inverse solutions were assessed in computer simulations, with different levels of noise added to the signal in both sensor space and source space. In the clinical evaluations, the source maximum was located inside the resected brain area in 50–57% of patients when using LORETA or LAURA, while all other inverse solutions performed significantly worse (17–30%; corrected p < 0.01). In the simulation studies, when noise levels exceeded 10%, LORETA and LAURA had substantially smaller localisation errors than the other inverse solutions. LORETA and LAURA provided the highest spatial accuracy both in clinical and simulated data, alongside with a comparably high robustness towards noise. Among the different linear inverse solution algorithms tested, LORETA and LAURA might be preferred for interictal EEG source localisation. [ABSTRACT FROM AUTHOR]

Introduction/aims: The hand is a sophisticated tool which allows humans to interact with the external world mainly via the sense of touch. Previous evidences demonstrated that electrical stimulations of the nerve trunks governing the hand are able to restore touch perception in transradial amputees. The aim of this study was to evaluate the neurological correlates of restored perception by the evaluation of network characteristics of the brain connectome via EEG recordings in amputees utilizing a fully sensorized bionic hand. Methods: A 48-year-old female with a left wrist traumatic disarticulation incurred 23 years prior to the study was enrolled for 6 months, during which experimental sessions were randomized. The control group included 12 healthy subjects performing a similar protocol. Results: Results showed that in both amputee and control group, a trend of SW in delta and beta 1 is recognizable (Delta and Beta 1 opposite spread) selectively in the hemisphere contralateral to the stimulus. Discussion: Delta increases (less orderly network) while Beta 1 decreases (more ordered network). It could be seen as a sign of higher attention and concentration of subjects to understand the perception and this monolateral modulation is similar to the bilateral attention given to the mathematical task difficulty's increment. [ABSTRACT FROM AUTHOR]

The main goals of the present study were to replicate and extend current knowledge related to paralimbic dysfunctions associated with psychopathy. The research evaluated the quantitative electroencephalography, current density (CD) source and synchronization likelihood analysis during the rest condition and structural magnetic resonance imaging images to compare volumetric and cortical thickness, in inmates recruited from two prisons located in Havana City. The Psychopathy Checklist‐Revised (PCL‐R) was used as a quantitative measure of psychopathy. This study showed most beta energy and less alpha activity in male psychopath offenders. Low‐resolution electromagnetic tomography signified an increase of beta activity in psychopath offender groups within paralimbic regions. The superior temporal gyrus volume was associated with the F1 factor while the fusiform, anterior cingulate and associative occipital areas were primarily associated with the F2 factor of PCL‐R scale. Cortical thickness in the left dorsal anterior cingulate cortex and the temporal pole was negatively associated with PCL‐R total score. [ABSTRACT FROM AUTHOR]

Background: Most common progressive brain diseases in the elderly are Alzheimer's disease (AD) and vascular dementia (VaD). They present with relatively similar clinical symptoms of cognitive decline, but the underlying pathophysiological mechanisms are different.Objective: The aim is to explore the brain connectivity differences between AD and VaD patients compared to mild cognitive impairment (MCI) and normal elderly (Nold) subjects applying graph theory, in particular the Small World (SW) analysis.Methods: 274 resting state EEGs were analyzed in 100 AD, 80 MCI, 40 VaD, and 54 Nold subjects. Graph theory analyses were applied to undirected and weighted networks obtained by lagged linear coherence evaluated by eLORETA tool.Results: VaD and AD patients presented more ordered low frequency structure (lower value of SW) than Nold and MCI subjects, and more random organization (higher value of SW) in low and high frequency alpha rhythms. Differences between patients have been found in high frequency alpha rhythms in VaD (higher value of SW) with respect to AD, and in theta band with a trend which is more similar to MCI and Nold than to AD. MCI subjects presented a network organization which is intermediate, in low frequency bands, between Nold and patients.Conclusion: Graph theory applied to EEG data has proved very useful in identifying differences in brain network patterns in subjects with dementia, proving to be a valid tool for differential diagnosis. Future studies will aim to validate this method to diagnose especially in the early stages of the disease and at single subject level. [ABSTRACT FROM AUTHOR]

Pain arises from the integration of sensory and cognitive processes in the brain, resulting in specific patterns of neural oscillations that can be characterized by measuring electrical brain activity. Current source density (CSD) estimation from low‐resolution brain electromagnetic tomography (LORETA) and its standardized (sLORETA) and exact (eLORETA) variants, is a common approach to identify the spatiotemporal dynamics of the brain sources in physiological and pathological pain‐related conditions. However, there is no consensus on the magnitude and variability of clinically or experimentally relevant effects for CSD estimations. Here, we systematically examined reports of sample size calculations and effect size estimations in all studies that included the keywords pain, and LORETA, sLORETA, or eLORETA in Scopus and PubMed. We also assessed the reliability of LORETA CSD estimations during non‐painful and painful conditions to estimate hypothetical sample sizes for future experiments using CSD estimations. We found that none of the studies included in the systematic review reported sample size calculations, and less than 20% reported measures of central tendency and dispersion, which are necessary to estimate effect sizes. Based on these data and our experimental results, we determined that sample sizes commonly used in pain studies using CSD estimations are suitable to detect medium and large effect sizes in crossover designs and only large effects in parallel designs. These results provide a comprehensive summary of the effect sizes observed using LORETA in pain research, and this information can be used by clinicians and researchers to improve settings and designs of future pain studies. [ABSTRACT FROM AUTHOR]

• Combined and inattentive subtypes of attention deficit hyperactivity disorder (ADHD) exhibit elevated theta/beta power ratio in resting state EEG. • ADHD shows increasing theta power in fronto-central and temporal areas with increasing age. • Inattentive ADHD is characterized by widespread increased theta source power, while combined type ADHD displays diffuse decrease in beta source power. This study investigated age-dependent and subtype-related alterations in electroencephalography (EEG) power spectra and current source densities (CSD) in children with attention deficit and hyperactivity disorder (ADHD). We performed spectral and cortical source (exact low-resolution electromagnetic tomography, eLORETA) analyses using resting state EEG recordings from 40 children (8–16 years) with combined and inattentive subtypes of ADHD and 41 age-matched healthy controls (HC). Group differences in EEG spectra and CSD were investigated at each scalp location, voxel and cortical region in delta, theta, alpha and beta bands. We also explored associations between topographic changes in EEG power and CSD and age. Compared to healthy controls, combined ADHD subtype was characterized with significantly increased diffuse theta/beta power ratios (TBR) with a widespread decrease in beta CSD. Inattentive ADHD subtype presented increased TBR in all brain regions except in posterior areas with a global increase in theta source power. In both ADHD and HC, older age groups showed significantly lower delta source power and TBR and higher alpha and beta source power than younger age groups. Compared to HC, ADHD was characterized with increases in theta fronto-central and temporal source power with increasing age. Our results confirm that TBR can be used as a neurophysiological biomarker to differentiate ADHD from healthy children at both the source and sensor levels. Our findings emphasize the importance of performing the source imaging analysis in order to better characterize age-related changes in resting-state EEG activity in ADHD and controls. [ABSTRACT FROM AUTHOR]

Background: Several studies investigated clinical and instrumental differences to make diagnosis of dementia in general and in Alzheimer's disease (AD) in particular with the aim to classify, at the individual level, AD patients and healthy controls cooperating with neuropsychological tests for an early diagnosis. Advanced network analysis of electroencephalographic (EEG) rhythms provides information on dynamic brain connectivity and could be used in classification processes. If successfully reached, this goal would add a low-cost, easily accessible, and non-invasive technique with neuropsychological tests.Objective: To investigate the possibility to automatically classify physiological versus pathological aging from cortical sources' connectivity based on a support vector machine (SVM) applied to EEG small-world parameter.Methods: A total of 295 subjects were recruited: 120 healthy volunteers and 175 AD. Graph theory functions were applied to undirected and weighted networks obtained by lagged linear coherence evaluated by eLORETA. A machine-learning classifier (SVM) was applied. EEG frequency bands were: delta (2-4 Hz), theta (4-8 Hz), alpha1 (8-10.5 Hz), alpha2 (10.5-13 Hz), beta1 (13-20 Hz), beta2 (20-30 Hz), and gamma (30-40 Hz).Results: The receiver operating characteristic curve showed AUC of 0.97±0.03 (indicating very high classification accuracy). The classifier showed 95% ±5% sensitivity, 96% ±3% specificity, and 95% ±3% accuracy for the classification.Conclusion: EEG connectivity analysis via a combination of source/connectivity biomarkers, highly correlating with neuropsychological AD diagnosis, could represent a promising tool in identification of AD patients. This approach represents a low-cost and non-invasive method, one that utilizes widely available techniques which, when combined, reach high sensitivity/specificity and optimal classification accuracy on an individual basis (0.97 of AUC). [ABSTRACT FROM AUTHOR]

We examined times (latencies) of two types of the sensorimotor (visuomotor) reactions, simple sensorimotor reaction (SSMR) and choice motor reaction (ChMR), in men (combatants) suffering from the consequences of mild traumatic brain injury (mTBI) during the Joint Forces Operation in the East of Ukraine (17 right-handed volunteers aged 27–43 years) and compared the respective values with those demonstrated by healthy control men (16 right-handed volunteers, 18–21 years). Combatants with mTBI were characterized by significantly greater values of the latency in the ChMR, mostly determined by considerably longer times necessary for decision-making processes. Results of the analysis of cerebral network connectivity based on the data of EEG recording, coherence measurements, and LORETA neurovisualization gave reasons to suppose that a large-scale synchronized frontoparietal neuronetwork functions in control subjects; this network is responsible for decision making according to the results of control, analysis of information, and coordination of various alternatives. Unlike this, an associative decision-making system mostly functions in combatants with mTBI; this system uses coding networks in the primary and secondary visual cortices; functioning of the above associative system is followed by the creation of imaginary phenomena and associations, which are then realized in motor acts. [ABSTRACT FROM AUTHOR]

Guilt is a social emotion that plays a central role in promoting prosocial behavior. Despite its relevance, it remains poorly understood. The present study aimed to fill this gap by verifying and characterizing a frontal negative fluctuation of the event-related brain potentials (ERP) emerging in conditions of interpersonal guilt. Paired participants would earn money if both performed correctly a dot estimation task (both right); otherwise, both would lose a similar amount (self wrong, partner wrong, and both wrong conditions). The reported feeling of guilt was noticeable in the self wrong condition, which yielded a frontal negativity between 300 and 500 ms after the onset of performance feedback. The amplitude of this fluctuation, however, did not correlate with the amount of guilt reported by the participants, whereas both these values did so with standard measures of empathy. Neither anxiety (trait or state) nor arousal (skin conductance response) seemed to relate to this negativity. A neural source (LORETA) analysis established its generators in the dorsal medial prefrontal cortex (mPFC), a region linked to guilt in fMRI studies but also, importantly, to empathy. The frontal negative fluctuation thus might reflect empathic processes contributing to achieve feelings of interpersonal guilt. [ABSTRACT FROM AUTHOR]

Testing the state of associative memory using the paired associates method revealed a significant decrease in the effectiveness of associative memorization in veterans of the Anti-Terrorist Operation (ATO) / Joint Forces Operation (JFO) with traumatic brain injuries, as evidenced by a larger number of errors made by them and a longer duration of their passing the test compared to the subjects of the control group. In the examined control group, the formation of associative memory was provided by a consistent system of top-down and bottom-up control of memorizing associative pairs of words and forming their images in both right and left hemispheres, while in veterans of the ATO/JFO with traumatic brain injuries in the formation of associative memory was more involved the left hemisphere than the right one, which indicated the overwhelming contribution of the semantic analysis of words to the formation of a connection between them. After the presentation of the first word of an associative pair, the retrieval of the second word in the control group provided a balanced neural network in the right and left hemispheres. At the same time, increased activity in the left hemisphere and the corresponding neural network in the low-frequency range were found in the group with traumatic brain injuries, which indicated a greater involvement of verbal semantic analysis of words when reproducing the second word. At the same time, the lack of synchronization in the beta-range in the central-parietal zone may indicate a deterioration of the postretrieval processes that ensure the processes of inhibition after recalling the corresponding words. Thus, in the control group, when memorizing associative pairs of words, coordinated processes of perception of individual words, their recognition, semantic analysis and the formation of semantic connections between them and their connections with the corresponding images were found, which is a reflection of coordinated inter-hemispheric information processes while subjects with traumatic brain injuries predominantly relied on the phonetic and semantic aspects of associative word pairs. [ABSTRACT FROM AUTHOR]

This report describes the scientific, technical, and clinical bases for the use of quantitative EEG (QEEG) in the assessment of clients and in treatment monitoring. Specific attention is directed toward the use of normative databases and z-scores as a form of standardized referencing for reporting and training purposes. Normative databases have general value and are of particular value when connectivity metrics are being used. It is shown that the use of z = 0 as an average over time corresponds to a state of optimum flexibility, adaptability, and readiness. The use of the inverse solution (LORETA) methods is also described, as well as use of those methods within the QEEG and normative model. Advantages as well as shortcomings of this approach are described and discussed. [ABSTRACT FROM AUTHOR]

Background: The study of cerebral underpinnings of schizophrenia may benefit from the high temporal resolution of electromagnetic techniques, but its spatial resolution is low. However, source imaging approaches such as low-resolution brain electromagnetic tomography (LORETA) allow for an acceptable compromise between spatial and temporal resolutions. Methods: We combined LORETA with 32 channels and 3-Tesla diffusion magnetic resonance (Dmr) to study cerebral dysfunction in 38 schizophrenia patients (17 first episodes, FE), compared to 53 healthy controls. The EEG was acquired with subjects performing an odd-ball task. Analyses included an adaptive window of interest to take into account the interindividual variability of P300 latency. We compared source activation patters to distractor (P3a) and target (P3b) tones within- and between-groups. Results: Patients showed a reduced activation in anterior cingulate and lateral and medial prefrontal cortices, as well as inferior/orbital frontal regions. This was also found in the FE patients alone. The activation was directly related to IQ in the patients and controls and to working memory performance in controls. Symptoms were unrelated to source activation. Fractional anisotropy in the tracts connecting lateral prefrontal and anterior cingulate regions predicted source activation in these regions in the patients. Conclusions: These results replicate the source activation deficit found in a previous study with smaller sample size and a lower number of sensors and suggest an association between structural connectivity deficits and functional alterations. [ABSTRACT FROM AUTHOR]

Acts of helping friends and strangers are part of everyday life. However, people vary significantly with respect to how often they help others and with respect to whom they actually help on a day-to-day basis. Despite everyday helping being so pervasive, these individual differences are poorly understood. Here, we used source-localized resting electroencephalography to measure objective and stable individual differences in neural baseline activation in combination with an ecologically valid method that allows assessment of helping behavior in the field. Results revealed that neural baseline activation in the right dorsolateral prefrontal cortex (DLPFC) - a brain region associated with self-control and strategic social behavior - predicts the daily frequency of helping friends, whereas the daily frequency of helping strangers was predicted by neural baseline activation in the dorsomedial prefrontal cortex (DMPFC) - a brain region associated with social cognition processes. These findings offer evidence that distinct neural signatures and associated psychological and cognitive processes may underlie the propensity to help friends and strangers in daily life. [ABSTRACT FROM AUTHOR]

Objectives: eLORETA (exact low-resolution brain electromagnetic tomography) is a technique created by Pascual-Marqui et al. [Int J Psychophysiol. 1994 Oct; 18(1): 49–65] for the 3-dimensional representation of current source density in the brain by electroencephalography (EEG) data. Kurtosis analysis allows for the identification of spiky activity in the brain. In this study, we focused on the evaluation of the reliability of eLORETA kurtosis analysis. For this purpose, the results of eLORETA kurtosis source localization of paroxysmal activity in EEG were compared with those of eLORETA current source density (CSD) analysis of EEG data in 3 epilepsy patients with partial seizures. Methods: EEG was measured using a digital EEG system with 19 channels. We set the bandpass filter at traditional frequency band settings (1–4, 4–8, 8–15, 15–30, and 30–60 Hz) and 5–10 and 20–70 Hz and performed eLORETA kurtosis to compare the source localization of paroxysmal activity with that of visual interpretation of EEG data and CSD analysis of eLORETA in focal epilepsy patients. Results: The eLORETA kurtosis analysis of EEG data preprocessed by bandpass filtering from 20 to 70 Hz and traditional frequency band settings did not show any discrete paroxysmal source activity compatible with the results of CSD analysis of eLORETA. In all 3 cases, eLORETA kurtosis analysis filtered at 5–10 Hz showed paroxysmal activities in the theta band, which were all consistent with the visual inspection results and the CSD analysis results. Discussion: Our findings suggested that eLORETA kurtosis analysis of EEG data might be useful for the identification of spiky paroxysmal activity sources in epilepsy patients. Since EEG is widely used in the clinical practice of epilepsy, eLORETA kurtosis analysis is a promising method that can be applied to epileptic activity mapping. [ABSTRACT FROM AUTHOR]

Abstract In magnetoencephalography (MEG) research there are a variety of inversion methods to transform sensor data into estimates of brain activity. Each new inversion scheme is generally justified against a specific simulated or task scenario. The choice of this scenario will however have a large impact on how well the scheme performs. We describe a method with minimal selection bias to quantify algorithm performance using human resting state data. These recordings provide a generic, heterogeneous, and plentiful functional substrate against which to test different MEG recording and reconstruction approaches. We used a Hidden Markov model to spatio-temporally partition data into self-similar dynamic states. To test the anatomical precision that could be achieved, we then inverted these data onto libraries of systematically distorted subject-specific cortical meshes and compared the quality of the fit using cross validation and a Free energy metric. This revealed which inversion scheme was able to identify the least distorted (most accurate) anatomical models, and allowed us to quantify an upper bound on the mean anatomical distortion accordingly. We used two resting state datasets, one recorded with head-casts and one without. In the head-cast data, the Empirical Bayesian Beamformer (EBB) algorithm showed the best mean anatomical discrimination (3.7 mm) compared with Minimum Norm/LORETA (6.0 mm) and Multiple Sparse Priors (9.4 mm). This pattern was replicated in the second (conventional dataset) although with a marginally poorer (non-significant) prediction of the missing (cross-validated) data. Our findings suggest that the abundant resting state data now commonly available could be used to refine and validate MEG source reconstruction methods and/or recording paradigms. Highlights • Resting state data provides an unbiased dataset for comparing MEG source estimates. • We use a hidden Markov model to break the data into stationary segments. • We reconstruct these data onto a range of distorted cortical surfaces. • The sensitivity of any algorithm to spatial distortion is quantified in millimetres. [ABSTRACT FROM AUTHOR]

Aims: The prevalence of panic disorder (PD) reportedly is up to fivefold higher in people with tinnitus than it is in the general population. The brain networks in the two conditions overlap but the pathophysiological link remains unclear. In this study the electrophysiological brain activity is investigated in adults with non-pulsatile tinnitus with and without concurrent PD.Methods: Resting-state EEGs of 16 participants with non-pulsatile tinnitus and PD were compared with those of 16 peers with non-pulsatile tinnitus without PD and as many healthy controls. The sLORETA technique was used to identify group-specific electrophysiological frequencies in the brain and to approximate the brain regions where differences occurred. The influence of distress was investigated and functional connectivity charted using the Region-of-Interest (ROI) approach (amygdala, anterior cingulate cortex (ACC), insula, precuneus).Results: The comorbid group showed significantly diminished theta activity (p < 0.05) in the precuneus (BA7) compared to the tinnitus group without PD as well as in another region of the precuneus (BA31) as compared to the controls. Higher levels of distress influenced results in the tinnitus group without PD, while in those with PD a diminished connectivity was observed between the dorsal ACC and the other three ROIs as contrasted to the controls.Conclusions: Adults with non-pulsatile tinnitus and concurrent PD show differential brain activity patterns to tinnitus only sufferers and healthy controls. Higher levels of distress may modulate brain activity in the absence of PD. Screening for distress is recommended in both clinical and research settings. [ABSTRACT FROM AUTHOR]

Extensive studies have shown that a sports expert is superior to a sports novice in visually perceptual-cognitive processes of sports scene information, however the attentional and neural basis of it has not been thoroughly explored. The present study examined whether a sport expert has the attentional superiority on scene information relevant to his/her sport skill, and explored what factor drives this superiority. To address this problem, EEGs were recorded as participants passively viewed sport scenes (tennis vs. non-tennis) and negative emotional faces in the context of a visual attention task, where the pictures of sport scenes or of negative emotional faces randomly followed the pictures with overlapping sport scenes and negative emotional faces. ERP results showed that for experts, the evoked potential of attentional competition elicited by the overlap of tennis scene was significantly larger than that evoked by the overlap of non-tennis scene, while this effect was absent for novices. The LORETA showed that the experts’ left medial frontal gyrus (MFG) cortex was significantly more active as compared to the right MFG when processing the overlap of tennis scene, but the lateralization effect was not significant in novices. Those results indicate that experts have attentional superiority on skill-related scene information, despite intruding the scene through negative emotional faces that are prone to cause negativity bias toward their visual field as a strong distractor. This superiority is actuated by the activation of left MFG cortex and probably due to self-reference. [ABSTRACT FROM AUTHOR]

The focus of the present study is on the relationships between illusory and non-illusory auditory perception analyzed at a biological level. To this aim, we investigate neural mechanisms underlying the Deutsch’s illusion, a condition in which both sound identity (“what”) and origin (“where”) are deceptively perceived. We recorded magnetoencephalogram from healthy subjects in three conditions: (a) listening to the acoustic sequence eliciting the illusion (ILL), (b) listening to a monaural acoustic sequence mimicking the illusory percept (MON), and (c) listening to an acoustic sequence similar to (a) but not eliciting the illusion (NIL). Results show that the areas involved in the illusion were the Heschl’s gyrus, the insular cortex, the inferior frontal gyrus, and the medial-frontal gyrus bilaterally, together with the left inferior-parietal lobe. These areas belong to the two main auditory streams known as the what and where pathways. The neural responses there observed indicate that the sound sequence eliciting the illusion is associated to larger activity at early and middle latencies and to a dynamic lateralization pattern net in favor of the left hemisphere. The present findings extend to illusory perception the well-known what–where auditory processing mechanism, especially as regards tardy latency activity. [ABSTRACT FROM AUTHOR]

This study involved 16 male volunteers, right-handers, ages 18-21, without complaints of health - students of Taras Shevchenko National University of Kyiv (control group) and 16 male volunteers, right-handers, aged 27-43, military men who took part in the operations in the east of Ukraine and have craniocerebral injuries (ССI), later - military men with CCI - patients of the Yu. I. Kundiyeva Institute for occupation health NAMS of Ukraine, Kiev. EEG-study, coherent analysis and analysis of brain activity dipoles showed that in the realization of a simple sensorimotor reaction in the control group, the processes of target detection, mental imagery and planning of the motor response, organizing and performing movements that were consistent with the basic processing of visual information, dorsal and ventral visual streams and the integration of separate elements into a integral image. At the same time, verbal decision-making processes, executive control and coordination of behavior were also involved, based on the processing of current sensory information. Thus, the control groups were matched with coordinated front-parietal neural networks of different scales for the target detection, planning and execute volitional movements with the dominant control of the frontal cortex. In the military men with CCI, an interhemispheric relationship was found in the sensorimotor cortex with the dominant role in the realization of a simple sensorimotor reaction of the visual and parietal cortical areas. Since there were no significant differences in the latent periods of a simple sensorimotor reaction between the control group and the group of military men with CCI, it can be assumed that the loss of front-parietal interaction in the military men with CCI was compensated for its realization by more effective inclusion of cortical brain zones associated with verbal processes of semantic analysis of visual information, which came mainly from the dorsal visual stream. In this case, instead of the higher control of such reaction from the frontal cortex, the control of the motor response may be assumed by the higher associative zones of the parietal cortex. [ABSTRACT FROM AUTHOR]

Human brain electric activity can be measured at high temporal and fairly good spatial resolution via electroencephalography (EEG). The EEG microstate analysis is an increasingly popular method used to investigate this activity at a millisecond resolution by segmenting it into quasi-stable states of approximately 100 ms duration. These so-called EEG microstates were postulated to represent atoms of thoughts and emotions and can be classified into four classes of topographies A through D, which explain up to 90% of the variance of continuous EEG. The present study investigated whether these topographies are primarily driven by alpha activity originating from the posterior cingulate cortex (all topographies), left and right posterior cortices, and the anterior cingulate cortex (topographies A, B, and C, respectively). We analyzed two 64-channel resting state EEG datasets (N = 61 and N = 78) of healthy participants. Sources of head-surface signals were determined via exact low resolution electromagnetic tomography (eLORETA). The Hilbert transformation was applied to identify instantaneous source strength of four EEG frequency bands (delta through beta). These source strength values were averaged for each participant across time periods belonging to a particular microstate. For each dataset, these averages of the different microstate classes were compared for each voxel. Consistent differences across datasets were identified via a conjunction analysis. The intracortical strength and spatial distribution of alpha band activity mainly determined whether a head-surface topography of EEG microstate class A, B, C, or D was induced. EEG microstate class C was characterized by stronger alpha activity compared to all other classes in large portions of the cortex. Class A was associated with stronger left posterior alpha activity than classes B and D, and class B was associated with stronger right posterior alpha activity than A and D. Previous results indicated that EEG microstate dynamics reflect a fundamental mechanism of the human brain that is altered in different mental states in health and disease. They are characterized by systematic transitions between four head-surface topographies, the EEG microstate classes. Our results show that intra-cortical alpha oscillations, which likely reflect decreased cortical excitability, primarily account for the emergence of these classes. We suggest that microstate class dynamics reflect transitions between four global attractor states that are characterized by selective inhibition of specific intra-cortical regions. [ABSTRACT FROM AUTHOR]

We applied exact low-resolution brain electromagnetic tomography (eLORETA) method to auditory startle event-related potentials (ERPs) during cold pain (cold-cup-test: CCT). ERPs and startle data were obtained from a published dataset wherein auditory startle stimuli were used as probes of pain processing (De Pascalis & Scacchia, 2016). We wanted to identify (1) sources of cortical current density changes associated with pain/distress reductions to placebo analgesia (PA) treatment, and (2) sources of activity changes that are predictors of the behavioural inhibition system (BIS) and fight/flight/freeze system (FFFS) of the revised Reinforcement Sensitivity Theory (rRST). We administered three treatments: Baseline, CCT-alone (Pain), and CCT plus sham cream (Placebo). PA, as compared to Pain treatment, was effective in pain and distress reduction, and produced a significant current density reduction within right primary somatosensory cortex (S1) and left middle frontal gyrus (MFG). In addition, current density change in the right S1 was a positive predictor of subjective pain and distress reduction, although distress reduction was also associated with decreased activity in the left MFG. We failed to identify regional sources of placebo-related current density changes as predictors of the BIS and FFFS with the exception of current density changes within left MFG that was positively correlated with BIS and a significant predictor of this trait. Findings appear consistent with rRST predictions suggesting BIS and FFFS as separate, but interacting neurobehavioural systems. [ABSTRACT FROM AUTHOR]

Personality traits have been shown to interact with environmental cues to modulate biological responses including placebo effects. We assessed the behavioural approach system (T-BAS) and its facets (goal drive persistence, GDP; reward interest and reactivity, RI and RR; Impulsivity, Imp) using the Reinforcement Sensitivity Theory Personality Questionnaire (RST-PQ; Corr & Cooper, 2016). Participants received three treatments: Baseline, Pain, and Placebo (pain plus a sham cream). Pain was produced by administering the cold-cup-test (CCT). We used exact low-resolution brain electromagnetic tomography (eLORETA) analysis of event-related potentials elicited by auditory-startle probes to identify regional sources of activity changes as predictors of T-BAS and its facets. We calculated pain minus placebo differences for pain and distress ratings and regional current density. We failed to find significant associations of RST-PQ traits with placebo-induced pain and distress reductions. However, multiple regression analyses and covariance analyses showed that, during placebo analgesia as compared to pain treatment, a lower activity in the primary somatosensory cortex (S1) was associated with higher T-BAS, and RI, whereas lower activity in the ACC was associated with higher T-BAS, RR, and Imp. Findings suggest that placebo analgesia may represent a form of reward responding and likely offer paths of identifying BAS traits that are liable to modulate placebo analgesic responses. [ABSTRACT FROM AUTHOR]

Introduction Opioids and antidepressants that inhibit serotonin and norepinephrine reuptake (SNRI) are recognized as analgesics to treat moderate to severe pain, but the central mechanisms underlying their analgesia remain unclear. This study investigated how brain activity at rest and exposed to tonic pain is modified by oxycodone (opioid) and venlafaxine (SNRI). Methods Twenty healthy males were included in this randomized, cross-over, double-blinded study. 61-channel electroencephalogram (EEG) was recorded before and after five days of treatment with placebo, oxycodone (10 mg extended release b.i.d) or venlafaxine (37.5 mg extended release b.i.d) at rest and during tonic pain (hand immersed in 2 °C water for 80 s). Subjective pain and unpleasantness scores of tonic pain were recorded. Spectral analysis and sLORETA source localization were done in delta (1–4 Hz), theta (4–8 Hz), alpha (8–12 Hz), beta1 (12–18 Hz) and beta2 (18–32 Hz) frequency bands. Results Oxycodone decreased pain and unpleasantness scores ( P < 0.05), whereas venlafaxine decreased the pain scores ( P < 0.05). None of the treatments changed the spectral indices or brain sources underlying resting EEG. Venlafaxine decreased spectral indices in alpha band of the EEG to tonic pain, whereas oxycodone decreased the spectral indices and brain source activity in delta and theta frequency bands (all P < 0.05). The brain source activity predominantly decreased in the insula and inferior frontal gyrus. Conclusion The decrease of activity within insula and inferior frontal gyrus is likely involved in pain inhibition due to oxycodone treatment, whereas the decrease in alpha activity is likely involved in pain inhibition due to venlafaxine treatment. [ABSTRACT FROM AUTHOR]

Background: Many studies have demonstrated the usefulness of repetitive task practice by using robotic-assisted gait training (RAGT) devices, including Lokomat, for the treatment of lower limb paresis. Virtual reality (VR) has proved to be a valuable tool to improve neurorehabilitation training. The aim of our pilot randomized clinical trial was to understand the neurophysiological basis of motor function recovery induced by the association between RAGT (by using Lokomat device) and VR (an animated avatar in a 2D VR) by studying electroencephalographic (EEG) oscillations.Methods: Twenty-four patients suffering from a first unilateral ischemic stroke in the chronic phase were randomized into two groups. One group performed 40 sessions of Lokomat with VR (RAGT + VR), whereas the other group underwent Lokomat without VR (RAGT-VR). The outcomes (clinical, kinematic, and EEG) were measured before and after the robotic intervention.Results: As compared to the RAGT-VR group, all the patients of the RAGT + VR group improved in the Rivermead Mobility Index and Tinetti Performance Oriented Mobility Assessment. Moreover, they showed stronger event-related spectral perturbations in the high-γ and β bands and larger fronto-central cortical activations in the affected hemisphere.Conclusions: The robotic-based rehabilitation combined with VR in patients with chronic hemiparesis induced an improvement in gait and balance. EEG data suggest that the use of VR may entrain several brain areas (probably encompassing the mirror neuron system) involved in motor planning and learning, thus leading to an enhanced motor performance.Trial Registration: Retrospectively registered in Clinical Trials on 21-11-2016, n. NCT02971371 . [ABSTRACT FROM AUTHOR]

Objective Although it is believed that patients with Unresponsive Wakefulness Syndrome (UWS) do not feel pain, recent neuroimaging and neurophysiologic studies have demonstrated some residual traces of nociceptive processing. Methods To confirm this growing evidence, we evaluated 21 patients suffering from chronic disorders of consciousness (DOC) (both UWS, n = 11, and Minimally Conscious State – MCS –, n = 10), using an Event-Related Potential (ERP) Low-Resolution Brain Electromagnetic Tomography (LORETA) approach, based on nociceptive repeated laser stimulation (RLS). We delivered laser stimuli to the dorsum of both hands and analysed the γ-band LORETA activations and the ERP γ-power magnitude induced by laser stimulation, as well as the heart rate variability (HRV). Results We found partially preserved cortical activations and ERP γ-power magnitude in all MCS and two UWS individuals. These effects were paralleled by a purposeful behaviour, and a reduced HRV concerning nociceptive stimulation, whereas the two UWS individuals showed no more than reflex behaviours, besides a strong limbic activation. Conclusions Some UWS patients may somehow perceive the affective components of nociceptive stimulation. Significance The diagnosis of functional locked-in syndrome should be taken into account when dealing with DOC differential diagnosis. [ABSTRACT FROM AUTHOR]

In the recent Reinforcement Sensitivity Theory Personality Questionnaire (RST-PQ, Corr and Cooper, 2016) the behavioral approach system (BAS) has been conceptualized as multidimensional in which facets of reward interest and reactivity, and goal-drive persistence, are separate from impulsivity. Aim of the present work was to highlight the predictive power of BAS and its facets in differentiating electrocortical responses by using an auditory augmenting/reducing event-related potential (ERP) paradigm during emotional visual stimulation. ERPs were recorded for 5 levels of intensity in 39 women. The RST-PQ was used to measure the total BAS (T-BAS) and its four facets of Goal-Drive Persistence (GDP), Reward Interest (RI), Reward Reactivity (RR), and Impulsivity (IMP). T-BAS and RI, and to a less extent GDP and RR, were significantly associated with higher N1/P2 amplitudes at central sites (C3, Cz, C4) across neutral, positive and negative slides. Similar, but less pronounced relations were found for GDP and RR, but this relation was lacking for Imp facet. In addition, N1/P2 slope at central sites was positively correlated with T-BAS, GDP, RI, RR, but not Imp. Indeed, T-BAS facets failed to maintain a significant correlation with N1/P2 slope, after controlling for T-BAS residual scores, indicating that T-BAS drives these significant correlations. LORETA analysis at 219 ms (P2 wave) from tone onset revealed a significant activation of the right inferior parietal lobule (IPL, BA40) and left anterior cingulate gyrus (BA32) in high T-BAS compared to low T-BAS participants. Results are discussed within a revised RST framework differentiating reward components from impulsivity. [ABSTRACT FROM AUTHOR]

Growing evidence suggests that loudness dependency of auditory evoked potentials (LDAEP) and resting EEG alpha and theta may be biological markers for predicting response to antidepressants. In spite of this promise, little is known about the joint reliability of these markers, and thus their clinical applicability. New standardized procedures were developed to improve the compatibility of data acquired with different EEG platforms, and used to examine test-retest reliability for the three electrophysiological measures selected for a multisite project-Establishing Moderators and Biosignatures of Antidepressant Response for Clinical Care (EMBARC). Thirty-nine healthy controls across four clinical research sites were tested in two sessions separated by about 1 week. Resting EEG (eyes-open and eyes-closed conditions) was recorded and LDAEP measured using binaural tones (1000 Hz, 40 ms) at five intensities (60-100 dB SPL). Principal components analysis of current source density waveforms reduced volume conduction and provided reference-free measures of resting EEG alpha and N1 dipole activity to tones from auditory cortex. Low-resolution electromagnetic tomography (LORETA) extracted resting theta current density measures corresponding to rostral anterior cingulate (rACC), which has been implicated in treatment response. There were no significant differences in posterior alpha, N1 dipole, or rACC theta across sessions. Test-retest reliability was .84 for alpha, .87 for N1 dipole, and .70 for theta rACC current density. The demonstration of good-to-excellent reliability for these measures provides a template for future EEG/ERP studies from multiple testing sites, and an important step for evaluating them as biomarkers for predicting treatment response. [ABSTRACT FROM AUTHOR]

Objective Cortical sources of electroencephalographic (EEG) rhythms were investigated in two sub-populations of naïve HIV subjects, grouped based on clinical criteria to receive different combination anti-retroviral therapies (cARTs). These EEG sources were hypothesized to reflect beneficial effects of both regimes. Methods Eyes-closed resting state EEG data were collected in 19 (Group A) and 39 (Group B) naïve HIV subjects at baseline (i.e. pre-treatment; T0) and after 5 months of cART (T5). Compared with the Group A, the Group B was characterized by slightly worse serological parameters and higher cardiovascular risk. At T0, mean viral load (VL) and CD4 count were 87,694 copies/ml and 435 cells/μl in the Group A and 187,370 copies/ml and 331 cells/μl in the Group B. The EEG data were also collected in 50 matched control HIV-negative subjects. Cortical EEG sources were assessed by LORETA software. Results Compared to the Control Group, the HIV Groups showed lower alpha (8–12 Hz) source activity at T0 while the Group B also exhibited higher delta source activity. The treatment partially normalized alpha and delta source activity in the Group A and B, respectively, in association with improved VL, CD4, and cognitive functions. Conclusions Different cART regimens induced diverse beneficial effects in delta or alpha source activity in the two naïve HIV Groups. Significance These sources might unveil different neurophysiological effects of diverse cART on brain function in naïve HIV Groups as a function of clinical status and/or therapeutic compounds. [ABSTRACT FROM AUTHOR]

• The clinical effect of low frequency (LF) rTMS in auditory hallucinations was confirmed. • LF-rTMS (but not sham) decreased the EEG current densities (sLORETA) in the alpha-2, beta-1, and beta-2 bands in the left fronto-temporo-parietal regions. • Active LF-rTMS was followed by a decrease in functional connectivity (eLORETA lagged phase synchronization) in beta oscillations and by a prevailing increase in connectivity in the alpha-2 band. • Results suggest that LF-rTMS relieves auditory hallucinations via a suppression or modulation of the local aberrant electrical activity and connectivity. Low-frequency repetitive transcranial magnetic stimulation (LF-rTMS) diminishes auditory hallucinations (AHs). The aims of our study were a) to assess the efficacy of LF-rTMS in a randomized, sham-controlled double-blind alignment, b) to identify the electrophysiological changes accompanying the LF-rTMS, and c) to identify the influence of LF-rTMS on brain functional connectivity (FC). Nineteen schizophrenia patients with antipsychotic-resistant AHs were randomized to either active (n = 10) or sham (n = 9) LF-rTMS administered over the left temporo-parietal region for ten days. The clinical effect was assessed by the Auditory Hallucination Rating Scale (AHRS). The localization of the differences in electrical activity was identified by standardized low resolution brain electromagnetic tomography (sLORETA) and FC was measured by lagged phase synchronization. AHRS scores were significantly improved for patients receiving active rTMS compared to the sham (median reduction: 40 % vs 12 %; p = 0.01). sLORETA revealed a decrease of alpha-2, beta-1,-2 bands in the left hemisphere in the active group. Active rTMS led to a decrease of the lagged phase connectivity in beta bands originating in areas close to the site of stimulation, and to a prevailing increase of alpha-2 FC. No significant differences in current density or FC were observed in the sham group. Limitations to our study included the small group sizes, and the disability of LORETA to assess subcortical neuronal activity. LF-rTMS attenuated AHs and induced a decrease of higher frequency bands on the left hemisphere. The FC changes support the assumption that LF-rTMS is linked to the modulation of cortico-cortical coupling. [ABSTRACT FROM AUTHOR]

Assessing residual signs of awareness in patients suffering from chronic disorders of consciousness (DOC) is a challenging issue. DOC patient behavioral assessment is often doubtful since some individuals may retain covert traces of awareness; thus, some Unresponsive Wakefulness Syndrome (UWS) patients may be misdiagnosed. The aim of our study was to explore possible differences between the source powers within poly-modal cortices to differentiate Minimally Conscious State (MCS) from UWS. To this end, we recorded an electroencephalogram (EEG) during awake resting state and performed a Low-Resolution Brain Electromagnetic Tomography (LORETA), which is a 3D source localization method allowing the visualization of the most probable neuroanatomical generators of EEG differences. MCS and UWS patients showed significant variations concerning the frontal source power of delta-band, frontal and parietal of theta, parietal and occipital of alpha, central of beta, and parietal of gamma, in correlation with the Coma Recovery Scale-Revised (CRS-R) score. The alpha-band was the most significant LORETA data correlating with the consciousness level. In addition, we observed a significant correlation between central beta-peaks and the motor abilities and a dissociation between theta and gamma bands within parietal regions. Our findings suggest that LORETA analysis may be useful in DOC differential diagnosis since distinct neurophysiological correlates in some UWS patients could be used to assess deeper the residual cerebral activity of brain areas responsible for covert awareness. [ABSTRACT FROM AUTHOR]

Covering the heads of human volunteers with a toque lined with copper mesh compared to no mesh resulted in significant diminishments in quantitative electroencephalographic power within theta and beta-gamma bands over the right caudal hemisphere. The effect was most evident in women compared to men. The significant attenuation of power was verified by LORETA (low resolution electromagnetic tomography) within the parahippocampal region of the right hemisphere. Direct measurements of frequency-dependent voltages of coronal section preserved in ethanol-formalin-acetic acid from our human brain collection revealed consistently elevated power (0.2 μV 2 Hz −1 ) in right hemispheric structures compared to left. The discrepancy was most pronounced in the grey (cortical) matter of the right parahippocampal region. Probing the superficial convexities of the cerebrum in an unsectioned human brain demonstrated rostrocaudal differences in hemispheric spectral power density asymmetries, particularly over caudal and parahippocampal regions, which were altered as a function of the chemical and spatial contexts imposed upon the tissue. These results indicate that the heterogeneous response of the human cerebrum to covering of the head by a thin conductor could reflect an intrinsic structure and unique electrical property of the (entorhinal) cortices of the right caudal hemisphere that persists in fixed tissue. [ABSTRACT FROM AUTHOR]

We tested the hypothesis of a relationship between heart rate variability (HRV) and Rolandic mu rhythms in relaxed condition of resting state. Resting state eyes-closed electroencephalographic (EEG) and electrocardiographic (ECG) data were recorded (10–20 System) in 42 healthy adults. EEG rhythms of interest were high-frequency alpha (10.5–13 Hz) and low-frequency beta (13–20 Hz), which are supposed to form Rolandic mu rhythms. Rolandic and occipital (control) EEG sources were estimated by LORETA software. Results showed a statistically significant (p < 0.05, corrected) negative correlation across all subjects between Rolandic cortical sources of low-frequency beta rhythms and the low-frequency band power (LF, 0.04–0.15 Hz) of tachogram spectrum as an index of HRV. The lower the amplitude of Rolandic sources of low-frequency beta rhythms (as a putative sign of activity of somatomotor cortex), the higher the LF band power of tachogram spectrum (as a putative sign of sympathetic activity). This effect was specific as there was neither a similar correlation between these EEG rhythms and high-frequency band power of tachogram spectrum (as a putative sign of parasympathetic vagal activity) neither between occipital sources of low-frequency beta rhythms (as a putative sign of activity of visual cortex) and LF band power of tachogram spectrum. These results suggest that Rolandic low-frequency beta rhythms are related to sympathetic activity regulating heart rate, as a dynamic neurophysiologic oscillatory mechanism sub-serving the interaction between brain neural populations involved in somatomotor control and brain neural populations regulating ANS signals to heart for on-going homeostatic adaptations. [ABSTRACT FROM AUTHOR]

ABSTRACT Electroencephalography (EEG) is widely used in variety of research and clinical applications which includes the localization of active brain sources. Brain source localization provides useful information to understand the brain's behavior and cognitive analysis. Various source localization algorithms have been developed to determine the exact locations of the active brain sources due to which electromagnetic activity is generated in brain. These algorithms are based on digital filtering, 3D imaging, array signal processing and Bayesian approaches. According to the spatial resolution provided, the algorithms are categorized as either low resolution methods or high resolution methods. In this research study, EEG data is collected by providing visual stimulus to healthy subjects. FDM is used for head modelling to solve forward problem. The low-resolution brain electromagnetic tomography (LORETA) and standardized LORETA (sLORETA) have been used as inverse modelling methods to localize the active regions in the brain during the stimulus provided. The results are produced in the form of MRI images. The tables are also provided to describe the intensity levels for estimated current level for the inverse methods used. The higher current value or intensity level shows the higher electromagnetic activity for a particular source at certain time instant. Thus, the results obtained demonstrate that standardized method which is based on second order Laplacian (sLORETA) in conjunction with finite difference method (FDM) as head modelling technique outperforms other methods in terms of source estimation as it has higher current level and thus, current density (J) for an area as compared to others. [ABSTRACT FROM AUTHOR]

Objective To explore neurophysiological biomarkers of Alzheimer’s disease (AD), we investigated electroencephalography (EEG) of AD patients, and assessed lagged phase synchronization, a measure of brain functional connectivity. Methods Twenty-eight probable AD patients and 30 healthy controls (HC) were enrolled. Forty seconds of artifact-free EEG data were selected and compared between patients with AD and HC. Current source density (CSD) and lagged phase synchronization were analyzed by using eLORETA. Results Patients with AD showed significantly decreased lagged phase synchronization between most cortical regions in delta band relative to controls. There also was a decrease in lagged phase synchronization between the right dorsolateral prefrontal cortex (DLPFC) and the right posterior-inferior parietal lobule (pIPL) in theta band. In addition, some connections in delta band were found to be associated with cognitive function, measured by MMSE. This involved specifically interhemispheric temporal connections as well as left inferior parietal connectivity with the left hippocampus, lateral frontal regions, and the anterior cingulate cortex (aCC). Right temporal connections in delta band were related to global function, as estimated by CDR. No differences were found in CSD analysis between patients and HC. Conclusions Functional connectivity disruptions between certain brain regions, as measured with lagged phase synchronization, may potentially represent a neurophysiological biomarker of AD. Significance Our study indicated that AD and healthy elderly could have the different patterns of lagged phase synchronization. [ABSTRACT FROM AUTHOR]

Background: Despite the devastating impact of anxiety disorders (ADs) worldwide, long-lasting debates on causes and remedies have not solved the clinician's puzzle: who should be treated and how? Psychiatric classifications conceptualize ADs as distinct entities, with strong support from neuroscience fields. Yet, comorbidity and pharmacological response suggest a single "serotonin dysfunction" dimension. Whether AD is one or several disorders goes beyond academic quarrels, and the distinction has therapeutic relevance. Addressing the underlying dysfunctions should improve treatment response. By its own nature, neurophysiology can be the best tool to address dysfunctional processes. Purpose: To search for neurophysiological dysfunctions and differences among panic disorder (PD), agoraphobia-social-specific phobia, obsessive-compulsive disorder (OCD) and generalized anxiety disorder. Methods: A sample population of 192 unmedicated patients and 30 aged-matched controls partook in this study. Hypothesis-related neurophysiological variables were combined into ten independent factors: 1) dysrhythmic patterns, 2) delta, 3) theta, 4) alpha, 5) beta (whole-head absolute power z-scores), 6) event-related potential (ERP) combined latency, 7) ERP combined amplitude (z-scores), 8) magnitude, 9) site, and 10) site of hyperactive networks. Combining single variables into representative factors was necessary because, as in all real-life phenomena, the complexity of interactive processes cannot be addressed through single variables and the multiplicity of potentially implicated variables would demand an extremely large sample size for statistical analysis. Results: The nonparametric analysis correctly classified 81% of the sample. Dysrhythmic patterns, decreased delta, and increased beta differentiated AD from controls. Shorter ERP latencies were found in several individual patients, mostly from the OCD group. Hyperactivities were found at the right frontorbital-striatal network in OCD and at the panic circuit in PD. Conclusions: Our findings support diffuse cortical instability in AD in general, with individual differences in information processing deficits and regional hyperactivities in OCD and PD. Study limitations and the rationale behind the variable selection and combination strategy will be discussed before addressing the therapeutic implications of our findings. [ABSTRACT FROM AUTHOR]

Background: Few studies have been conducted that have compared electrical source localization (ESL) results obtained by analyzing ictal patterns in scalp electroencephalogram (EEG) with the brain areas that are found to be responsible for seizures using other brain imaging techniques. Additionally, adequate studies have not been performed to confirm the accuracy of ESL methods. Materials and Methods: In this study, ESL was conducted using LORETA (Low Resolution Brain Electromagnetic Tomography) in 9 patients with lesions apparent on magnetic resonance imaging (MRI) and in 6 patients who did not exhibit lesions on their MRIs. EEGs of patients who underwent surgery for epilepsy and had follow-ups for at least 1 year after operations were analyzed for ictal spike, rhythmic, paroxysmal fast, and obscured EEG activities. Epileptogenic zones identified in postoperative MRIs were then compared with localizations obtained by LORETA model we employed. Results: We found that brain areas determined via ESL were in concordance with resected brain areas for 13 of the 15 patients evaluated, and those 13 patients were post-operatively determined as being seizure-free. Conclusion: ESL, which is a noninvasive technique, may contribute to the correct delineation of epileptogenic zones in patients who will eventually undergo surgery to treat epilepsy, (regardless of neuroimaging status). Moreover, ESL may aid in deciding on the number and localization of intracranial electrodes to be used in patients who are candidates for invasive recording. [ABSTRACT FROM AUTHOR]

The present study investigates the neural substrates underlying cognitive processing in schizophrenia (Sz) patients. To this end, an auditory 3-stimulus oddball paradigm was used to identify P3a and P3b components, elicited by rare-distractor and rare-target tones, respectively. Event-related potentials (ERP) were recorded from 31 Sz patients and 38 healthy controls. The P3a and P3b brain-source generators were identified by time-averaging of low-resolution brain electromagnetic tomography (LORETA) current density images. In contrast with the commonly used fixed window of interest (WOI), we proposed to apply an adaptive WOI, which takes into account subjects' P300 latency variability. Our results showed different P3a and P3b source activation patterns in both groups. P3b sources included frontal, parietal and limbic lobes, whereas P3a response generators were localized over bilateral frontal and superior temporal regions. These areas have been related to the discrimination of auditory stimulus and to the inhibition (P3a) or the initiation (P3b) of motor response in a cognitive task. In addition, differences in source localization between Sz and control groups were observed. Sz patients showed lower P3b source activity in bilateral frontal structures and the cingulate. P3a generators were less widespread for Sz patients than for controls in right superior, medial and middle frontal gyrus. Our findings suggest that target and distractor processing involves distinct attentional subsystems, both being altered in Sz. Hence, the study of neuroelectric brain information can provide further insights to understand cognitive processes and underlying mechanisms in Sz. [ABSTRACT FROM AUTHOR]

There are many theories that attempt to explain the mechanisms of the effects of inhalation anesthetics - from simpler, pursuing individual effects of anesthetics on the level of the ion channels, to more complex that are looking for uniform global changes in brain activity common to several agents. However, we still don't have satisfactory and adequate conclusions. We examined a sample of 39 patients undergoing thoracic surgery at the Clinic of Thoracic Surgery under general anesthesia (GA) and we registered their electroencephalographic (EEG) signals before and during operation. After induction of GA by intravenous (i.v.), we used inhalation anesthetics to maintain GA. We used sevoflurane (SEV) in 20 patients and desflurane (DES) in 19 patients. Then we obtained the EEG data and processed them through mathematical and statistical analysis, to discover any changes of electrical activity in the brain during thoracic surgery under GA. The era of digital recording EEG and present possibilities of modern computer techniques allow quantitative analysis of obtained data. We performed the analysis with the software LORETA (low resolution brain electromagnetic tomography). It is a relatively new research method, which in a similar way as computed tomography (CT) or magnetic resonance imaging (MRI) displays even deeper brain electrical activity, which is hiddeen for a classical EEG approach. We described the general changes in brain electrical activity of the deeper cortical structures within the traditional frequency bands (d, q, a, b and g) during GA at 5 mm spatial resolution. We have shown that the source of the well-known cortical EEG changes after the effect of used inhalation anesthetics is caused by changes situated in the deeper brain structures, particularly the limbic system. Significant changes occurred in the cingulate gyrus for most of an EEG frequency ranges. When comparing the data of patients anesthetised with SEV and DES we found similar changes within the d and q rhythms and then the global changes of EEG activity followed during GA. [ABSTRACT FROM AUTHOR]

An array of eight cloistered (completely covered) 470-nm LEDs was attached to the right caudal scalp of subjects while each sat blindfolded within a darkened chamber. The LEDs were activated by a computer-generated complex (frequency-modulated) temporal pattern that, when applied as weak magnetic fields, has elicited sensed presences and changes in LORETA (low-resolution electromagnetic tomography) configurations. Serial 5-min on to 5-min off presentations of the blue light (10,000 lx) resulted in suppression of gamma activity within the right cuneus (including the extrastriate area), beta activity within the left angular and right superior temporal regions, and alpha power within the right parahippocampal region. The effect required about 5 min to emerge followed by a transient asymptote for about 15 to 20 min when diminished current source density was evident even during no light conditions. Subjective experiences, as measured by our standard exit questionnaire, reflected sensations similar to those reported when the pattern was presented as a weak magnetic field. Given previous evidence that photon flux density of this magnitude can penetrate the skull, these results suggest that properly configured LEDs that generate physiologically patterned light sequences might be employed as noninvasive methods to explore the dynamic characteristics of cerebral activity in epileptic and nonepileptic brains. [ABSTRACT FROM AUTHOR]

The identification of the brain regions involved in the neuropharmacological action is a potential procedure for drug development. These regions are commonly determined by the voxels showing significant statistical differences after comparing placebo-induced effects with drug-elicited effects. LORETA is an electroencephalography (EEG) source imaging technique frequently used to identify brain structures affected by the drug. The aim of the present study was to evaluate different methods for the correction of multiple comparisons in the LORETA maps. These methods which have been commonly used in neuroimaging and also simulated studies have been applied on a real case of pharmaco-EEG study where the effects of increasing benzodiazepine doses on the central nervous system measured by LORETA were investigated. Data consisted of EEG recordings obtained from nine volunteers who received single oral doses of alprazolam 0.25, 0.5, and 1 mg, and placebo in a randomized crossover double-blind design. The identification of active regions was highly dependent on the selected multiple test correction procedure. The combined criteria approach known as cluster mass was useful to reveal that increasing drug doses led to higher intensity and spread of the pharmacologically induced changes in intracerebral current density. [ABSTRACT FROM AUTHOR]

Background Idiopathic normal-pressure hydrocephalus (iNPH) is a neuropsychiatric syndrome characterized by the clinical triad of gait disturbance, urinary dysfunction, and cognitive impairment. The aim of the present study was to find specific EEG patterns associated with shunt response in iNPH. Methods Twenty five iNPH patients (10 shunt responders and 15 non-responders) were enrolled in this study. We performed current source density (CSD) analysis in several frequency bands (delta: 2-4Hz, theta: 4-8Hz, alpha: 8-13Hz, beta: 13-30Hz, gamma: 30-60Hz) using exact Low Resolution Brain Electromagnetic Tomography (eLORETA). CSD distribution was compared between shunt responders and non-responders for each frequency band before and after CSF tap test. Results Shunt responders showed increased gamma CSD in the left temporal cortex before CSF tapping relative to non-responders. However, after CSF tapping, shunt response was associated with significantly higher CSDs in several frequency bands, specifically theta, alpha, beta and gamma, involving mainly the frontal and temporal areas. Using eLORETA analysis, we were able to identify cortical oscillatory activity before and after CSF tap test related to clinical recovery due to shunt operation in iNPH. Conclusion Our findings support and extend the results of previous studies examining the effects of CSF tap test and shunt operation in patients with iNPH, possibly indicating electrophysiological features of shunt response in this disease. These findings warrant future studies to use EEG for prediction of shunt response in iNPH. [ABSTRACT FROM AUTHOR]

In major depressive disorder (MDD), elevated theta current density in the rostral anterior cingulate (rACC), as estimated by source localization of scalp-recorded electroencenphalogram (EEG), has been associated with response to antidepressant treatments, whereas elevated frontal theta has been linked to non-response. This study used source localization to attempt to integrate these apparently opposite results and test, whether antidepressant response is associated with elevated rACC theta and non-response with elevated frontal theta and whether theta activity is a differential predictor of response to different types of commonly used antidepressants. In the international Study to Predict Optimized Treatment in Depression (iSPOT-D), a multi-center, international, randomized, prospective practical trial, 1008 MDD participants were randomized to escitalopram, sertraline or venlafaxine-XR. The study also recruited 336 healthy controls. Treatment response and remission were established after eight weeks using the 17-item Hamilton Rating Scale for Depression (HRSD 17 ). The resting-state EEG was assessed at baseline with eyes closed and source localization (eLORETA) was employed to extract theta from the rACC and frontal cortex. Patients with MDD had elevated theta in both frontal cortex and rACC, with small effect sizes. High frontal and rACC theta were associated with treatment non-response, but not with non-remission, and this effect was most pronounced in a subgroup with previous treatment failures. Low theta in frontal cortex and rACC are found in responders to antidepressant treatments with a small effect size. Future studies should investigate in more detail the role of previous treatment (failure) in the association between theta and treatment outcome. [ABSTRACT FROM AUTHOR]

Background Although cognitive theories of depression have postulated enhanced processing of negatively valenced information, previous EEG studies have shown both increased and reduced sensitivity for negative performance feedback in MDD. To reconcile these paradoxical findings, it has been speculated that sensitivity for negative feedback is potentiated in moderate MDD, but reduced in highly anhedonic subjects. The goal of this study was to test this hypothesis by analyzing the feedback-related negativity (FRN), frontomedial theta power (FMT), and source-localized anterior midcingulate cortex (aMCC) activity after negative feedback. Methods Fourteen unmedicated participants with Major Depressive Disorder (MDD) and 15 control participants performed a reinforcement learning task while 128-channel Electroencephalogram (EEG) was recorded. FRN, FMT, and LORETA source-localized aMCC activity after negative and positive feedback were compared between groups. Results The MDD group showed higher FRN amplitudes and aMCC activation to negative feedback than controls. Moreover, aMCC activation to negative feedback was inversely related to self-reported anhedonia. In contrast, self-reported anxiety correlated with feedback-evoked frontomedial theta (FMT) within the depression group. Conclusions The present findings suggest that, among depressed and anxious individuals, enhanced processing of negative feedback occurs relatively early in the information processing stream. These results extend prior work and indicate that although moderate depression is associated with elevated sensitivity for negative feedback, high levels of anhedonia may attenuate this effect. [ABSTRACT FROM AUTHOR]

Principles of perceptual grouping can be divided into intrinsic grouping cues , which are based on built-in properties of the grouped elements (e.g., their shape, position, colour, etc.) like most of the classical Gestalt laws, and extrinsic grouping principles, based on relations between the discrete elements and other external stimuli that induce them to group (e.g., common region, connectedness). Several studies have explored the neural correlates of intrinsic grouping factors but, to our knowledge, no previous study has studied the neural correlates of extrinsic principles. The present study aimed to shed light on this issue by exploiting the high temporal resolution of event-related potentials (ERPs) and recent advances in source localization. Specifically, grouping by common region was compared with two comparison conditions, an intrinsic grouping (luminance similarity) and a uniform stimulus condition, in a perceptual discrimination task. We reported three main neural effects associated with grouping by common region. First, a posterior N210 component with a neural origin in the left extrastriate cortex was related to perceptual analysis of extrinsic elements inducing grouping and the formation of a visual group. Second, an enhanced posterior P280, which presumably reflects higher confidence decisions during response selection. Finally, a P550 originated in the right superior parietal cortex that seems to be associated with top-down suppression activity connected with the termination of the processing of the current trial. Overall, our results suggest that common region cues belong to the category of long latency grouping principles that mainly involve activity in extrastriate cortices. [ABSTRACT FROM AUTHOR]

Úvod: Panická porucha je v populaci často zastoupené psychiatrické onemocnění charakterizované náhlými a nečekanými záchvaty panické úzkosti, doprovázené pocitem masivního strachu. Tyto záchvaty bývají asociovány s celou řadou tělesných symptomů. Vzhledem k velkému množství příznaků lze očekvát, že do průběhu panické ataky bude zapojena řada mozkových struktur. EEG (elektroencefalografie) je jednoduchá laboratorní metoda, která může být s výhodou využita k měření mozkové aktivity. V současné chvíli je EEG v psychiatrii užíváno spíše k hodnocení demencí nebo v rámci diferenciální diagnostiky záchvatových onemocnění. Díky pokrokům ve zpracování signálu je však dnes možno využít EEG nejen k hodnocení kortikální aktivity, ale lze získat informace i o aktivitách hlubších mozkových struktur. Cílem článku je nabídnout přehled současných znalostí o EEG nálezech u pacientů s panickou poruchou. Výsledky: Navzdory řadě studií doposud žádná práce neidentifikovala specifický EEG nález pro panickou poruchu. Podařilo se však odhalit asymetrii frontální alfa-aktivity, změny koherence a pomocí LORETA i změny v absolutním výkonu frekvenčních pásem beta 1 a beta 3 v oblasti laterálního prefrontálního kortexu. Navzdory tomu, že stížnosti na kvalitu spánku a noční panické ataky jsou u pacientů s panickou poruchou časté, ani polysomnografické nálezy nejsou jednoznačné a neprokazují žádný specifický nález. Závěr: Ačkoliv existuje větší množství studií věnujících se problematice EEG změn u pacientů s panickou poruchou, zatím nebyl nalezen žádný specifický nález. Nicméně EEG se ukázalo být dobrým nástrojem pro zkoumání neurobiologické podstaty tohoto onemocnění. Introduction: Panic disorder is frequent psychiatric disorder characterized by sudden and unexpected onset of a panic attack, characterized by terror or impending doom, and associated with many somatic symptoms. Variety of symptoms suggests, that there are many brain structures involved in panic reaction. EEG is simple laborathory method, which can be used for measuring of brain activity. Nowdays is EEG in psychiatry rather used for evaluation of dementia or in differential diagnosis of seizures. Due to development of singal processing can be EEG used both to evaluate cortical acitivity and also gives information about activity of deep brain structures. Aim of this article is to review recent informations about EEG findings in patients with panic disorder. Main findings: Up to date, there is no study identifying specific EEG finding in patients with panic disorder. Some studies detect frontal alpha asymmetry, changes in coherence and using LORETA also changes in absolute power of beta 1 and beta 2 frequency bands in lateral prefrontal cortex. Despite complains about dyssomnia and nocturnal panic attacks are frequent in patients with panic disorder, there was no specific changes found using polysomnography. Conclusions: Although there are many studies monitoring changes in EEG of patients with panic disorder, there are no specific findings for panic. Thus EEG proved to be the usefull method that can be used to study neurobiology of panic disorder. [ABSTRACT FROM AUTHOR]