Neuroanatomical Predictors of Transcranial Direct Current Stimulation (tDCS)-Induced Modifications in Neurocognitive Task Performance in Typically Developing Individuals.

Transcranial direct current stimulation (tDCS) is a noninvasive neuromodulation technique gaining more attention in neurodevelopmental disorders (NDDs). Due to the phenotypic heterogeneity of NDDs, tDCS is unlikely to be equally effective in all individuals. The present study aimed to establish neuroanatomical markers in typically developing (TD) individuals that may be used for the prediction of individual responses to tDCS. Fifty-seven male and female children received 2 mA anodal and sham tDCS, targeting the left dorsolateral prefrontal cortex (DLPFCleft), right inferior frontal gyrus, and bilateral temporoparietal junction. Response to tDCS was assessed based on task performance differences between anodal and sham tDCS in different neurocognitive tasks (N-back, flanker, Mooney faces detection, attentional emotional recognition task). Measures of cortical thickness (CT) and surface area (SA) were derived from 3 Tesla structural MRI scans. Associations between neuroanatomy and task performance were assessed using general linear models (GLM). Machine learning (ML) algorithms were employed to predict responses to tDCS. Vertex-wise estimates of SA were more closely linked to differences in task performance than measures of CT. Across ML algorithms, highest accuracies were observed for the prediction of N-back task performance differences following stimulation of the DLPFCleft, where 65% of behavioral variance was explained by variability in SA. Lower accuracies were observed for all other tasks and stimulated regions. This suggests that it may be possible to predict individual responses to tDCS for some behavioral measures and target regions. In the future, these models might be extended to predict treatment outcome in individuals with NDDs.

Segregated Dynamical Networks for Biological Motion Perception in the Mu and Beta Range Underlie Social Deficits in Autism.

OBJECTIVE: Biological motion perception (BMP) correlating with a mirror neuron system (MNS) is attenuated in underage individuals with autism spectrum disorder (ASD). While BMP in typically-developing controls (TDCs) encompasses interconnected MNS structures, ASD data hint at segregated form and motion processing. This coincides with less fewer long-range connections in ASD than TDC. Using BMP and electroencephalography (EEG) in ASD, we characterized directionality and coherence (mu and beta frequencies). Deficient BMP may stem from desynchronization thereof in MNS and may predict social-communicative deficits in ASD. Clinical considerations thus profit from brain-behavior associations. METHODS: Point-like walkers elicited BMP using 15 white dots (walker vs. scramble in 21 ASD (mean: 11.3 ± 2.3 years) vs. 23 TDC (mean: 11.9 ± 2.5 years). Dynamic Imaging of Coherent Sources (DICS) characterized the underlying EEG time-frequency causality through time-resolved Partial Directed Coherence (tPDC). Support Vector Machine (SVM) classification validated the group effects (ASD vs. TDC). RESULTS: TDC showed MNS sources and long-distance paths (both feedback and bidirectional); ASD demonstrated distinct from and motion sources, predominantly local feedforward connectivity, and weaker coherence. Brain-behavior correlations point towards dysfunctional networks. SVM successfully classified ASD regarding EEG and performance. CONCLUSION: ASD participants showed segregated local networks for BMP potentially underlying thwarted complex social interactions. Alternative explanations include selective attention and global-local processing deficits. SIGNIFICANCE: This is the first study applying source-based connectivity to reveal segregated BMP networks in ASD regarding structure, cognition, frequencies, and temporal dynamics that may explain socio-communicative aberrancies.

Mobile applications in adolescent psychotherapy during the COVID-19 pandemic: a systematic review.

Background: To bridge the gap in adolescent psychotherapy created by the increasing need for mental health interventions and the limited possibilities of in-person treatment during the pandemic, many health care providers opted to offer online mental health care programs. As a result, the number of mental health apps available in app stores experienced a sharp increase during the COVID-19 pandemic. Objective: The aim of the current review is to provide an overview of feasibility and effectiveness studies testing mobile applications in adolescent psychotherapy during the peak phase of the COVID-19 pandemic. Methods: We conducted a literature search in Pubmed, PsychInfo, Google Scholar, OpenSIGLE and OpenGREY for papers published from June 2020 to June 2023. Studies were included if they evaluated app-based interventions intended for psychotherapeutic treatment and targeted adolescents between 12 and 27 years of age with symptoms of psychological disorders. The quality of each study was assessed using the Systematic Assessment of Quality in Observational Research (SAQOR). Effectiveness outcomes were analyzed by vote counting and calculating a binomial probability test. Results: The search yielded 31 relevant studies that examined 27 different apps with a total of 1,578 adolescent participants. Nine articles were primary effectiveness studies and 22 focused on feasibility measures as primary outcome. There was evidence that mental health apps influenced adolescents' psychotherapy, with 83% of the studies with effectiveness outcomes favoring the intervention (p = 0.002). Sixty-one percent of the included studies were rated at low or very low quality. Conclusions: The pandemic has given apps a firm and important role in healthcare that will probably continue to expand in the future. To ensure that mental health apps are truly effective and beneficial for adolescents' psychotherapy, we need a standardized measurement of quality features of mental health apps and higher quality app evaluation studies. Systematic review registration: https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=406455, PROSPERO International Prospective Register of Systematic Reviews [CRD42023406455].

Safety of noninvasive brain stimulation in children.

PURPOSE OF REVIEW: Noninvasive brain stimulation (NIBS) is a promising method for altering cortical excitability with clinical implications. It has been increasingly used in children, especially in neurodevelopmental disorders. Yet, its safety and applications in the developing brain require further investigation. This review aims to provide an overview of the safety of commonly used NIBS techniques in children, including transcranial electrical stimulation (tES) and transcranial magnetic stimulation (TMS). Safety data for other NIBS methods is not reported in this review. RECENT FINDINGS: In line with studies from the last decade, findings in the last 2 years (2022-2023) support the safety of NIBS in children and adolescents within the currently applied protocols. Both tES and TMS are well tolerated, if safety rules, including exclusion criteria, are applied. SUMMARY: We briefly discussed developmental aspects of stimulation parameters that need to be considered in the developing brain and provided an up-to-date overview of tES/TMS applications in children and adolescents. Overall, the safety profile of tES/TMS in children is good. For both the tES and TMS applications, epilepsy and active seizure disorder should be exclusion criteria to prevent potential seizures. Using child-sized earplugs is required for TMS applications. We lack large randomized double-blind trialsand longitudinal studies to establish the safety of NIBS in children. VIDEO ABSTRACT: http://links.lww.com/YCO/A78 .

Offline 20 Hz transcranial alternating current stimulation over the right inferior frontal gyrus increases theta activity during a motor response inhibition task.

OBJECTIVES: Previous studies have shown that the right inferior frontal gyrus (rIFG) and the pre-supplementary motor area (preSMA) play an important role in motor inhibitory control. The aim of the study was to use theta frequency transcranial alternating current stimulation (tACS) to modulate brain activity in the rIFG and preSMA and to test the effects of stimulation using a motor response inhibition task. METHODS: In four sessions, 20 healthy participants received tACS at 6 Hz over preSMA or rIFG, or 20 Hz over rIFG (to test frequency specificity), or sham stimulation before task processing. After each type of stimulation, the participants performed the Go/NoGo task with simultaneous electroencephalogram (EEG) recording. RESULTS: By stimulating rIFG and preSMA with 6 Hz tACS, we were not able to modulate either behavioral performance nor the EEG correlate. Interestingly, 20 Hz tACS over the rIFG significantly increased theta activity, however without behavioral effects. This increased theta activity did not coincide with the stimulation area and was localized in the fronto-central and centro-parietal areas. CONCLUSIONS: The inclusion of a control frequency is crucial to test for frequency specificity. Our findings are in accordance with previous studies showing that after effects of tACS are not restricted to the stimulation frequency but can also occur in other frequency bands.

Stratification of responses to tDCS intervention in a healthy pediatric population based on resting-state EEG profiles.

Transcranial Direct Current Stimulation (tDCS) is a non-invasive neuromodulation technique with a wide variety of clinical and research applications. As increasingly acknowledged, its effectiveness is subject dependent, which may lead to time consuming and cost ineffective treatment development phases. We propose the combination of electroencephalography (EEG) and unsupervised learning for the stratification and prediction of individual responses to tDCS. A randomized, sham-controlled, double-blind crossover study design was conducted within a clinical trial for the development of pediatric treatments based on tDCS. The tDCS stimulation (sham and active) was applied either in the left dorsolateral prefrontal cortex or in the right inferior frontal gyrus. Following the stimulation session, participants performed 3 cognitive tasks to assess the response to the intervention: the Flanker Task, N-Back Task and Continuous Performance Test (CPT). We used data from 56 healthy children and adolescents to implement an unsupervised clustering approach that stratify participants based on their resting-state EEG spectral features before the tDCS intervention. We then applied a correlational analysis to characterize the clusters of EEG profiles in terms of participant's difference in the behavioral outcome (accuracy and response time) of the cognitive tasks when performed after a tDCS-sham or a tDCS-active session. Better behavioral performance following the active tDCS session compared to the sham tDCS session is considered a positive intervention response, whilst the reverse is considered a negative one. Optimal results in terms of validity measures was obtained for 4 clusters. These results show that specific EEG-based digital phenotypes can be associated to particular responses. While one cluster presents neurotypical EEG activity, the remaining clusters present non-typical EEG characteristics, which seem to be associated with a positive response. Findings suggest that unsupervised machine learning can be successfully used to stratify and eventually predict responses of individuals to a tDCS treatment.

How Does Dietary Intake Relate to Dispositional Optimism and Health-Related Quality of Life in Germline BRCA1/2 Mutation Carriers?

Background: The Mediterranean diet (MD) is an anti-inflammatory diet linked to improved health-related quality of life (HRQoL). Germline (g)BRCA1/2 mutation carriers have an increased risk of developing breast cancer and are often exposed to severe cancer treatments, thus the improvement of HRQoL is important. Little is known about the associations between dietary intake and HRQoL in this population. Methods: We included 312 gBRCA1/2 mutation carriers from an ongoing prospective randomized controlled lifestyle intervention trial. Baseline data from the EPIC food frequency questionnaire was used to calculate the dietary inflammatory index (DII), and adherence to MD was captured by the 14-item PREDIMED questionnaire. HRQoL was measured by the EORTC QLQ-C30 and LOT-R questionnaires. The presence of metabolic syndrome (MetS) was determined using anthropometric measurements, blood samples and vital parameters. Linear and logistic regression models were performed to assess the possible impact of diet and metabolic syndrome on HRQoL. Results: Women with a prior history of cancer (59.6%) reported lower DIIs than women without it (p = 0.011). A greater adherence to MD was associated with lower DII scores (p < 0.001) and reduced odds for metabolic syndrome (MetS) (p = 0.024). Women with a more optimistic outlook on life reported greater adherence to MD (p < 0.001), whereas a more pessimistic outlook on life increased the odds for MetS (OR = 1.15; p = 0.023). Conclusions: This is the first study in gBRCA1/2 mutation carriers that has linked MD, DII, and MetS to HRQoL. The long-term clinical implications of these findings are yet to be determined.

Heart Rate Variability's Association with Positive and Negative Affect in Daily Life: An Experience Sampling Study with Continuous Daytime Electrocardiography over Seven Days.

Heart rate variability has been found to be related to emotional processing and emotional responses. Studies that investigated these relationships were mostly lab-based or cross-sectional. Only limited research used intensive longitudinal data, in particular investigating within-individual processes in real-life settings. This study addresses the applicability of ambulatory-assessed electrocardiograms in combination with the experience sampling methodology by investigating the associations of various HRV measures with affective states on within- and between-individual levels. A total of 26 participants aged 18-29 years (23 females) wore electrocardiograms continuously for seven days. The participants received seven prompts per day and answered questions about their affective wellbeing. The heart rate and heart rate variability measures differed between body positions and activity classes. The heart rate and ratio of low-to-high-frequency heart rate variability were consistently associated with positive affect on a within-individual (state-like) level. These associations were mainly driven by the items of feeling "enthusiastic" and "happy". No associations were found with negative affect. Overall, we found evidence that the dominance of the sympathetic nervous system over the parasympathetic nervous system was associated with higher levels of positive affect on a within-individual (state-like) level. Suggestions for the application of ambulatory electrocardiogram assessment in the study of the association between autonomous nervous system activity and ecological momentary assessment-based variables are discussed.

Child and adolescent psychiatry staff's knowledge on pain management.

OBJECTIVE: To assess the level of child and adolescent psychiatric staff's knowledge regarding pain management, to determine group differences between the medically more educated (physicians, nurses) and the less educated (psychologists, educators, special therapists) and to investigate the influence of gender, age, or professional experience as well as staff's own pain experiences. METHODS: A total of 193 staff members from different professional backgrounds from three independent child and adolescent psychiatry clinics in Northern Germany were tested using the German version of the Pediatric Nurses' Knowledge and Attitudes Survey Regarding Pain Shriner's revision (PNKAS-Sr). RESULTS: In total, the staff scored correctly 66% of the inventory questions. There was no difference between medically more educated and less educated staff members regarding the knowledge of pain management. The main factors influencing PNKAS score were age, profession, and pain education training. CONCLUSIONS: Although chronic pain is not one of the main aspects of continuing education in child and adolescent psychiatry, the resulting level of knowledge was comparable to results of similar surveys with paediatric staffs. Nevertheless, further education is needed to enhance knowledge and understanding of children's pain in child psychiatry staff in order to professionally treat patients with chronic somatic and mental illnesses.

No effects of prefrontal multichannel tACS at individual alpha frequency on phonological decisions.

OBJECTIVE: Alpha oscillations are linked to inhibitory capabilities in higher cognitive processing. Transcranial alternating current stimulation (tACS) at 10 Hz can enhance alpha oscillations and modulate behaviour. One possibility to increase the efficacy of tACS may be stimulating at the individual alpha frequency (IAF). The present work addresses this issue (among others) to increase the current understanding of the functional role of alpha oscillations in higher cognitive tasks. METHODS: Twenty-two healthy and 13 dyslexic participants performed two word decision tasks while receiving IAF-tACS over the left prefrontal cortex. Resting EEG was recorded to detect electrophysiological changes. Cortical excitability was assessed with TMS. RESULTS: Dyslexic participants performed worse in the phonological task. However, no significant tACS effects were found. Interestingly, higher cortical excitability was correlated with faster responses in healthy controls. In dyslexics this association significantly differed in the phonological task. CONCLUSION: The non-significant modulation by tACS might be explained by methodological limitations. Alternatively, it may indicate that alpha oscillations do not play a functional role in phonological decisions. The findings on cortical excitability expands the existing literature and may reflect the specific phonological deficit in dyslexics. SIGNIFICANCE: Our critical discussion of these null findings expands the systematic knowledge on alpha-tACS for future studies.

Multichannel anodal tDCS over the left dorsolateral prefrontal cortex in a paediatric population.

Methodological studies investigating transcranial direct current stimulation (tDCS) over the left dorsolateral prefrontal cortex (lDLPFC) in paediatric populations are limited. Therefore, we investigated in a paediatric population whether stimulation success of multichannel tDCS over the lDLPFC depends on concurrent task performance and individual head anatomy. In a randomised, sham-controlled, double-blind crossover study 22 healthy participants (10-17 years) received 2 mA multichannel anodal tDCS (atDCS) over the lDLPFC with and without a 2-back working memory (WM) task. After stimulation, the 2-back task and a Flanker task were performed. Resting state and task-related EEG were recorded. In 16 participants we calculated the individual electric field (E-field) distribution. Performance and neurophysiological activity in the 2-back task were not affected by atDCS. atDCS reduced reaction times in the Flanker task, independent of whether atDCS had been combined with the 2-back task. Flanker task related beta oscillation increased following stimulation without 2-back task performance. atDCS effects were not correlated with the E-field. We found no effect of multichannel atDCS over the lDLPFC on WM in children/adolescents but a transfer effect on interference control. While this effect on behaviour was independent of concurrent task performance, neurophysiological activity might be more sensitive to cognitive activation during stimulation. However, our results are limited by the small sample size, the lack of an active control group and variations in WM performance.

Transcranial direct-current stimulation and pediatric attention deficit hyperactivity disorder (ADHD)-Findings from an interview ethics study with children, adolescents, and their parents.

INTRODUCTION: Transcranial direct current stimulation (tDCS) is a brain stimulation technique for an alternative or complementary treatment for various neurological disorders, including pediatric ADHD. However, little is known about the experiences of participants undergoing tDCS treatments in clinical trials. Exploration of their views on the matter is an important contribution to the societal debate on ethical issues of tDCS, allowing for a responsible translation into clinical practice and timely identification of potential challenges. METHODS: in-depth interviews study with children with ADHD undertaking tDCS and their parents (n=32). RESULTS: Children reported overall good experiences with the stimulation, although they found participation in the clinical study very tiring and time consuming. Their responses to the actual effects of the stimulation were mixed. Parents were very keen for their children to participate in the study as they saw it as a promising and safe alternative to medication. Even though many of them understood the techniques, they often did not see the link between the (current) lack of side effects and an absence of longitudinal studies. Unlike children, interviewed parents were cautious about using tDCS for non-medical/enhancement purposes. DISCUSSION: There is a need for more transparent information about the state of the art of tDCS, its function and what it actually might be able to offer. It is especially important in order to prevent unrealistic hopes and to make sure that future pediatric patients and their carers are more aware of the potential side-effects and long-term effects of tDCS.

Cortical current density magnitudes during transcranial direct current stimulation correlate with skull thickness in children, adolescent and young adults.

Transcranial direct current stimulation protocols are often applied with a fixed parameter set to all subjects participating in an interventional study. This might lead to considerable effect variation in inhomogeneous subject groups or when transferring stimulation protocols to different age groups. The aim of this study was to evaluate magnitude differences of the electric current density distribution on the gray matter surface in children, adolescent and adults in correlation with the individual volume conductor geometry. We generated individual six compartment finite element models from structural magnetic resonance images of four children (age: 10.95 a±1.32 a), eight adolescents (age: 15.10 a±1.16 a) and eight young adults (age: 21.62 a±2.45 a). We determined the skull thickness in the models as Euclidean distance between the surface of the cerebrospinal fluid compartment and outer skull boundary. For tDCS simulations, we modeled 5×7cm patch electrodes impressing 1mA current intensity as anode and cathode over the left M1 and the right fronto-polar orbit, respectively. The resulting current density was analyzed on the gray matter surface. Our results demonstrate higher cortical current density magnitudes in children compared to adults for a given tDCS current strength. Above the evaluated cortex, the skull thickness increased with age. In conclusion, we underline the importance of age-dependent and individual models in tDCS simulations.

Phase-IIa randomized, double-blind, sham-controlled, parallel group trial on anodal transcranial direct current stimulation (tDCS) over the left and right tempo-parietal junction in autism spectrum disorder-StimAT: study protocol for a clinical trial.

BACKGROUND: Autism spectrum disorder (ASD) is characterized by impaired social communication and interaction, and stereotyped, repetitive behaviour and sensory interests. To date, there is no effective medication that can improve social communication and interaction in ASD, and effect sizes of behaviour-based psychotherapy remain in the low to medium range. Consequently, there is a clear need for new treatment options. ASD is associated with altered activation and connectivity patterns in brain areas which process social information. Transcranial direct current stimulation (tDCS) is a technique that applies a weak electrical current to the brain in order to modulate neural excitability and alter connectivity. Combined with specific cognitive tasks, it allows to facilitate and consolidate the respective training effects. Therefore, application of tDCS in brain areas relevant to social cognition in combination with a specific cognitive training is a promising treatment approach for ASD. METHODS: A phase-IIa pilot randomized, double-blind, sham-controlled, parallel-group clinical study is presented, which aims at investigating if 10 days of 20-min multi-channel tDCS stimulation of the bilateral tempo-parietal junction (TPJ) at 2.0 mA in combination with a computer-based cognitive training on perspective taking, intention and emotion understanding, can improve social cognitive abilities in children and adolescents with ASD. The main objectives are to describe the change in parent-rated social responsiveness from baseline (within 1 week before first stimulation) to post-intervention (within 7 days after last stimulation) and to monitor safety and tolerability of the intervention. Secondary objectives include the evaluation of change in parent-rated social responsiveness at follow-up (4 weeks after end of intervention), change in other ASD core symptoms and psychopathology, social cognitive abilities and neural functioning post-intervention and at follow-up in order to explore underlying neural and cognitive mechanisms. DISCUSSION: If shown, positive results regarding change in parent-rated social cognition and favourable safety and tolerability of the intervention will confirm tDCS as a promising treatment for ASD core-symptoms. This may be a first step in establishing a new and cost-efficient intervention for individuals with ASD. TRIAL REGISTRATION: The trial is registered with the German Clinical Trials Register (DRKS), DRKS00014732 . Registered on 15 August 2018. PROTOCOL VERSION: This study protocol refers to protocol version 1.2 from 24 May 2019.

Online Effects of Beta-tACS Over the Left Prefrontal Cortex on Phonological Decisions.

The left posterior inferior frontal gyrus in the prefrontal cortex is a key region for phonological aspects of language processing. A previous study has shown that alpha-tACS over the prefrontal cortex applied before task processing facilitated phonological decision-making and increased task-related theta power. However, it is unclear how alpha-tACS affects phonological processing when applied directly during the task. Moreover, the frequency specificity of this effect is also unclear since the majority of neurostimulation studies tested a single frequency only. The present study addressed the question whether and how 10 Hz online tACS affects phonological decisions. To this end, 24 healthy participants received tACS at 10 Hz or 16.18 Hz (control frequency) or sham stimulation over the left prefrontal cortex during task processing in three sessions. As an unexpected finding, 16.18 Hz significantly impaired task accuracy relative to sham stimulation, without affecting response speed. There was no significant difference in phonological task performance between 10 Hz and 16.18 Hz tACS or between 10 Hz and sham stimulation. Our results support the functional relevance of the left prefrontal cortex for phonological decisions and suggest that online beta-tACS may modulate language comprehension.

Source imaging of deep-brain activity using the regional spatiotemporal Kalman filter.

BACKGROUND AND OBJECTIVE: The human brain displays rich and complex patterns of interaction within and among brain networks that involve both cortical and subcortical brain regions. Due to the limited spatial resolution of surface electroencephalography (EEG), EEG source imaging is used to reconstruct brain sources and investigate their spatial and temporal dynamics. The majority of EEG source imaging methods fail to detect activity from subcortical brain structures. The reconstruction of subcortical sources is a challenging task because the signal from these sources is weakened and mixed with artifacts and other signals from cortical sources. In this proof-of-principle study we present a novel EEG source imaging method, the regional spatiotemporal Kalman filter (RSTKF), that can detect deep brain activity. METHODS: The regional spatiotemporal Kalman filter (RSTKF) is a generalization of the spatiotemporal Kalman filter (STKF), which allows for the characterization of different regional dynamics in the brain. It is based on state-space modeling with spatially heterogeneous dynamical noise variances, since models with spatial and temporal homogeneity fail to describe the dynamical complexity of brain activity. First, RSTKF is tested using simulated EEG data from sources in the frontal lobe, putamen, and thalamus. After that, it is applied to non-averaged interictal epileptic spikes from a presurgical epilepsy patient with focal epileptic activity in the amygdalo-hippocampal complex. The results of RSTKF are compared to those of low-resolution brain electromagnetic tomography (LORETA) and of standard STKF. RESULTS: Only RSTKF is successful in consistently and accurately localizing the sources in deep brain regions. Additionally, RSTKF shows improved spatial resolution compared to LORETA and STKF. CONCLUSIONS: RSTKF is a generalization of STKF that allows for accurate, focal, and consistent localization of sources, especially in the deeper brain areas. In contrast to standard source imaging methods, RSTKF may find application in the localization of the epileptogenic zone in deeper brain structures, such as mesial frontal and temporal lobe epilepsies, especially in EEG recordings for which no reliable averaged spike shape can be obtained due to lack of the necessary number of spikes required to reach a certain signal-to-noise ratio level after averaging.

Individual Baseline Performance and Electrode Montage Impact on the Effects of Anodal tDCS Over the Left Dorsolateral Prefrontal Cortex.

Anodal transcranial direct current stimulation (tDCS), applied over the left dorsolateral prefrontal cortex (lDLPFC), can produce significant effects on working memory (WM) performance and associated neurophysiological activity. However, results from previous studies are inconsistent and occasionally contradictory. This inconsistency may be attributed to methodological and individual differences during experiments. This study therefore investigated two hypotheses: (1) A multichannel-optimized montage was expected to be more effective than a classical bipolar montage, because of increased focality. (2) The subjects were expected to benefit differently from the stimulation depending on their initial task performance. In a sham-controlled crossover study, 24 healthy participants received bipolar, multichannel, and sham stimulation for 20 min in randomized order, targeting the lDLPFC while performing a 2-back WM task. After stimulation, electroencephalography (EEG) was recorded at rest and during 2-back and nontarget continuous performance task (CPT) performance. Bipolar and multichannel stimulations were both well tolerated and effectively blinded. We found no effect of stimulation on behavioral performance or neuronal oscillations comparing the classical bipolar or multichannel montage with sham stimulation. We did, however, find an interaction between stimulation and initial task performance. For multichannel stimulation, initially low-performing participants tended to improve their WM performance while initially high-performing participants tended to worsen their performance compared to sham stimulation. Both tDCS montages induced changes in neural oscillatory power, which correlated with baseline performance. The worse the participants' initial WM performance was, the more task-related theta power was induced by multichannel and bipolar stimulation. The same effect was observed for alpha power in the nontarget task following multichannel stimulation. Notably, we were not able to show a superiority of multichannel stimulation compared to bipolar stimulation. Still, comparing both montages with sham stimulation, multichannel stimulation led to stronger effects than bipolar stimulation. The current study highlights the importance of investigating different parameters with potential influence on tDCS effects in combination. Our results demonstrate how individual differences in cognitive performance and electrode montages influence effects of tDCS on neuropsychological performance. These findings support the idea of an individualized and optimized stimulation setting, potentially leading to increased tDCS effects.

Significance of Beta-Band Oscillations in Autism Spectrum Disorders During Motor Response Inhibition Tasks: A MEG Study.

In Autism Spectrum Disorders (ASD), impaired response inhibition and lack of adaptation are hypothesized to underlie core ASD symptoms, such as social communication and repetitive, stereotyped behavior. Thus, the aim of the present study was to compare neural correlates of inhibition, post-error adaptation, and reaction time variability in ASD and neuro-typical control (NTC) participants by investigating possible differences in error-related changes of oscillatory MEG activity. Twelve male NTC (mean age 20.3 ± 3.7) and fourteen male patients with ASD (mean age 17.8 ± 2.9) were included in the analysis. Subjects with ASD showed increased error-related reaction time variability. MEG analysis revealed decreased beta power in the ASD group in comparison to the NTC group over the centro-parietal channels in both, the pre-stimulus and post-response interval. In the ASD group, mean centro-parietal beta power negatively correlated with dimensional autism symptoms. In both groups, false alarms were followed by an early increase in temporo-frontal theta to alpha power; and by a later decrease in alpha to beta power at central and posterior sensors. Single trial correlations were additionally studied in the ASD group, who showed a positive correlation of pre-stimulus beta power with post-response theta, alpha, and beta power, particularly after hit trials. On a broader scale, the results deliver important insights into top-down control deficits that may relate to core symptoms observed in ASD.

Raising the bar: Can dual scanning improve our understanding of joint action?

Two-person neuroscience (2 â€‹PN) is a recently introduced conceptual and methodological framework used to investigate the neural basis of human social interaction from simultaneous neuroimaging of two or more subjects (hyperscanning). In this study, we adopted a 2 â€‹PN approach and a multiple-brain connectivity model to investigate the neural basis of a form of cooperation called joint action. We hypothesized different intra-brain and inter-brain connectivity patterns when comparing the interpersonal properties of joint action with non-interpersonal conditions, with a focus on co-representation, a core ability at the basis of cooperation. 32 subjects were enrolled in dual-EEG recordings during a computerized joint action task including three conditions: one in which the dyad jointly acted to pursue a common goal (joint), one in which each subject interacted with the PC (PC), and one in which each subject performed the task individually (Solo). A combination of multiple-brain connectivity estimation and specific indices derived from graph theory allowed to compare interpersonal with non-interpersonal conditions in four different frequency bands. Our results indicate that all the indices were modulated by the interaction, and returned a significantly stronger integration of multiple-subject networks in the joint vs. PC and Solo conditions. A subsequent classification analysis showed that features based on multiple-brain indices led to a better discrimination between social and non-social conditions with respect to single-subject indices. Taken together, our results suggest that multiple-brain connectivity can provide a deeper insight into the understanding of the neural basis of cooperation in humans.

Neuropsychological Measures in the Diagnosis of ADHD in Preschool: Can Developmental Research Inform Diagnostic Practice?

Objective: The diagnosis of ADHD in preschool is challenging. Behavioral ratings are less reliable, but the value of neuropsychological tests in the diagnosis of ADHD has been debated. Method: This article provides an overview of neuropsychological measures utilized in preschoolers with ADHD (3-5 years). In addition, the manuscript discusses the extent to which these measures have been tested for their diagnostic capacity. Results: The diagnostic utility of computerized continuous performance tests and working memory subtests from IQ-batteries has been demonstrated in a number of studies by assessing their psychometric properties, sensitivity, and specificity. However, findings from developmental and basic research attempting to describe risk factors that explain variance in ADHD show the most consistent associations of ADHD with measures of delay aversion. Conclusion: Results from developmental research could benefit studies that improve ADHD diagnosis at the individual level. It might be helpful to consider testing as a structured situation for behavioral observation by the clinician.