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The perception and imagery of landmarks activate similar content-dependent brain areas, including occipital and temporo-medial brain regions. However, how these areas interact during visual perception and imagery of scenes, especially when recollecting their spatial location, remains unknown. Here, we combined functional magnetic resonance imaging (fMRI), resting-state functional connectivity (rs-fc), and effective connectivity to assess spontaneous fluctuations and task-induced modulation of signals among regions entailing scene-processing, the primary visual area and the hippocampus (HC), responsible for the retrieval of stored information. First, we functionally defined the scene-selective regions, that is, the occipital place area (OPA), the retrosplenial complex (RSC) and the parahippocampal place area (PPA), by using the face/scene localizer, observing that two portions of the PPA-anterior and posterior PPA-were consistently activated in all subjects. Second, the rs-fc analysis (n = 77) revealed a connectivity pathway similar to the one described in macaques, showing separate connectivity routes linking the anterior PPA with RSC and HC, and the posterior PPA with OPA. Third, we used dynamic causal modelling to evaluate whether the dynamic couplings among these regions differ between perception and imagery of familiar landmarks during a fMRI task (n = 16). We found a positive effect of HC on RSC during the retrieval of imagined places and an effect of occipital regions on both RSC and pPPA during the perception of scenes. Overall, we propose that under similar functional architecture at rest, different neural interactions take place between regions in the occipito-temporal higher-level visual cortex and the HC, subserving scene perception and imagery.
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Mapeo Encefálico , Neocórtex , Mapeo Encefálico/métodos , Lóbulo Occipital/fisiología , Lóbulo Temporal/fisiología , Percepción Visual/fisiología , Imagen por Resonancia Magnética , Estimulación LuminosaRESUMEN
During resting-state EEG recordings, alpha activity is more prominent over the posterior cortex in eyes-closed (EC) conditions compared to eyes-open (EO). In this study, we characterized the difference in spectra between EO and EC conditions using dynamic causal modelling. Specifically, we investigated the role of intrinsic and extrinsic connectivity-within the visual cortex-in generating EC-EO alpha power differences over posterior electrodes. The primary visual cortex (V1) and the bilateral middle temporal visual areas (V5) were equipped with bidirectional extrinsic connections using a canonical microcircuit. The states of four intrinsically coupled subpopulations-within each occipital source-were also modelled. Using Bayesian model selection, we tested whether modulations of the intrinsic connections in V1, V5 or extrinsic connections (or a combination thereof) provided the best evidence for the data. In addition, using parametric empirical Bayes (PEB), we estimated group averages under the winning model. Bayesian model selection showed that the winning model contained both extrinsic connectivity modulations, as well as intrinsic connectivity modulations in all sources. The PEB analysis revealed increased extrinsic connectivity during EC. Overall, we found a reduction in the inhibitory intrinsic connections during EC. The results suggest that the intrinsic modulations in V5 played the most important role in producing EC-EO alpha differences, suggesting an intrinsic disinhibition in higher order visual cortex, during EC resting state.
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Corteza Visual , Teorema de Bayes , Corteza Visual/fisiología , Corteza Cerebral , Ojo , Modelos Teóricos , Imagen por Resonancia Magnética/métodos , Electroencefalografía/métodosRESUMEN
BACKGROUND: Globally, there is a vast mental health treatment gap, whereby the majority of adolescents living in low- and middle-income countries requiring mental health services, do not have access to adequate care. To improve access, the World Health Organization (WHO) developed a range of interventions, designed to be low-cost and delivered by non-specialists. We conducted a two-arm, individually randomised group treatment feasibility trial of a new WHO group intervention for young adolescents with emotional distress ('Early Adolescent Skills for Emotions'; EASE) in Lebanon. METHOD: The aim of this study was to determine the feasibility of the intervention and study procedures. Adolescents aged 10 to 14 years were eligible to take part if they scored above a validated cut-off on the Child Psychosocial Distress Screener. Participants were randomized to EASE or enhanced treatment as usual (ETAU) control using a 1:1 ratio. EASE consisted of seven group sessions with adolescents and three sessions with caregivers. ETAU consisted of a single brief psychoeducation home visit. Child and caregiver outcomes were measured by blind assessors at baseline, endline (8 weeks post-randomisation), and three month follow-up (20 weeks post-randomisation), with the primary outcome measure being child psychological symptoms on the Pediatric Symptom Checklist. Qualitative interviews were conducted with adolescents (n = 13), caregivers (n = 17), facilitators (n = 6), trainers (n = 3), and outreach staff (n = 1) at endline to assess barriers and facilitators related to the feasibility and delivery of EASE and study procedures. RESULTS: Of 154 adolescents screened, 67 (43%) were eligible, completed baseline, and were randomized. Sixty adolescents (90%) completed endline assessments (31 EASE, 29 ETAU), and fifty-nine (88%) completed three-month assessments (29 EASE, 30 ETAU). Qualitatively, participants provided overall positive feedback about the intervention. Several challenges and suggestions for improvement were raised around logistics, intervention content, and acceptability of assessment measures. Implementation data highlighted challenges with intervention uptake and attendance. Outcome measures generally had strong psychometric properties (range: α = 0.77 to α = 87), however did not demonstrate change over time in either group. CONCLUSIONS: The EASE intervention and study procedures are acceptable and feasible for implementation with vulnerable adolescents in Lebanon, however several improvements are necessary prior to full-scale evaluation. TRIAL REGISTRATION: #ISRCTN60799626, retrospectively registered on 04/10/2022.
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Distrés Psicológico , Intervención Psicosocial , Adolescente , Humanos , Niño , Estudios de Factibilidad , Líbano , EmocionesRESUMEN
BACKGROUND: There is a need for scalable evidence-based psychological interventions for young adolescents experiencing high levels of psychological distress in humanitarian settings and low- and middle-income countries. Poor mental health during adolescence presents a serious public health concern as it is a known predictor of persistent mental disorders in adulthood. This study evaluates the effectiveness of a new group-based intervention developed by the World Health Organization (Early Adolescent Skills for Emotions; EASE), implemented by non-specialists, to reduce young adolescents' psychological distress among mostly Syrian refugees in Lebanon. METHODS: We conducted a two-arm, single-blind, individually randomized group treatment trial. Adolescents aged 10 to 14 years who screened positive for psychological distress using the Pediatric Symptom Checklist (PSC) were randomly allocated to EASE or enhanced treatment as usual (ETAU) (1:1.6). ETAU consisted of a single scripted psycho-education home-visit session with the adolescent and their caregivers. EASE consists of seven group sessions with adolescents and three sessions with caregivers. The primary outcome was adolescent-reported psychological distress as measured with the PSC (internalizing, externalizing, and attentional symptoms). Secondary outcomes included depression, posttraumatic stress, well-being, functioning, and caregivers' parenting and distress. All outcomes were assessed at baseline, endline, and 3 months (primary time point) and 12 months follow-up. RESULTS: Due to the COVID-19 pandemic and other adversities in Lebanon at the time of this research, the study was prematurely terminated, resulting in an under-powered trial sample (n = 198 enrolled compared to n = 445 targeted). We screened 604 children for eligibility. The 198 enrolled adolescents were assigned to EASE (n = 80) and ETAU (n = 118), with retention rates between 76.1 and 88.4% across all timepoints. Intent-to-treat analyses demonstrated no between-group differences on any of the outcome measures between the EASE and ETAU. We did observe a significant improvement on the primary outcome equally in the EASE and ETAU groups (-0.90, 95% CI: -3.6, 1.8; p = .52), - a trend that was sustained at three months follow-up. Sub-group analyses, for those with higher depression symptoms at baseline, showed ETAU outperformed EASE on reducing depression symptoms (difference in mean change = 2.7, 95% CI: 0.1, 5.3; p = .04; d = 0.59) and internalizing problems (difference in mean change 1.0, 95% CI: 0.08, 1.9; p = .03; d = 0.56) . CONCLUSION: No conclusions can be drawn about the comparative effectiveness of the intervention given that the sample was underpowered as a result of early termination. Both EASE and single session psycho-education home visits resulted in meaningful improvements in reducing psychological distress. We did not identify any indications in the data suggesting that EASE was more effective than a single session family intervention in the context of the COVID-19 pandemic and other crises in Lebanon. Fully powered research is needed to evaluate the effectiveness of EASE.
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COVID-19 , Distrés Psicológico , Humanos , Adolescente , Niño , Líbano/epidemiología , Método Simple Ciego , Pandemias , COVID-19/epidemiologíaRESUMEN
In recent years, specific cortical networks have been proposed to be crucial for sustaining consciousness, including the posterior hot zone and frontoparietal resting state networks (RSN). Here, we computationally evaluate the relative contributions of three RSNs - the default mode network (DMN), the salience network (SAL), and the central executive network (CEN) - to consciousness and its loss during propofol anaesthesia. Specifically, we use dynamic causal modelling (DCM) of 10 min of high-density EEG recordings (N = 10, 4 males) obtained during behavioural responsiveness, unconsciousness and post-anaesthetic recovery to characterise differences in effective connectivity within frontal areas, the posterior 'hot zone', frontoparietal connections, and between-RSN connections. We estimate - for the first time - a large DCM model (LAR) of resting EEG, combining the three RSNs into a rich club of interconnectivity. Consistent with the hot zone theory, our findings demonstrate reductions in inter-RSN connectivity in the parietal cortex. Within the DMN itself, the strongest reductions are in feed-forward frontoparietal and parietal connections at the precuneus node. Within the SAL and CEN, loss of consciousness generates small increases in bidirectional connectivity. Using novel DCM leave-one-out cross-validation, we show that the most consistent out-of-sample predictions of the state of consciousness come from a key set of frontoparietal connections. This finding also generalises to unseen data collected during post-anaesthetic recovery. Our findings provide new, computational evidence for the importance of the posterior hot zone in explaining the loss of consciousness, highlighting also the distinct role of frontoparietal connectivity in underpinning conscious responsiveness, and consequently, suggest a dissociation between the mechanisms most prominently associated with explaining the contrast between conscious awareness and unconsciousness, and those maintaining consciousness.
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Anestésicos/administración & dosificación , Red en Modo Predeterminado/fisiología , Lóbulo Frontal/fisiología , Redes Neurales de la Computación , Lóbulo Parietal/fisiología , Inconsciencia/fisiopatología , Estado de Conciencia/efectos de los fármacos , Estado de Conciencia/fisiología , Red en Modo Predeterminado/efectos de los fármacos , Electroencefalografía/efectos de los fármacos , Electroencefalografía/métodos , Femenino , Lóbulo Frontal/efectos de los fármacos , Humanos , Masculino , Lóbulo Parietal/efectos de los fármacos , Propofol/administración & dosificación , Inconsciencia/inducido químicamente , Adulto JovenRESUMEN
The influence of global BOLD fluctuations on resting state functional connectivity in fMRI data remains a topic of debate, with little consensus. In this study, we assessed the effects of global signal regression (GSR) on effective connectivity within and between resting state networks (RSNs) - as estimated with dynamic causal modelling (DCM) for resting state fMRI (rsfMRI). DCM incorporates a forward (generative) model that quantifies the contribution of different types of noise (including global measurement noise), effective connectivity, and (neuro)vascular processes to functional connectivity measurements. DCM analyses were applied to two different designs; namely, longitudinal and cross-sectional designs. In the modelling of longitudinal designs, we considered four extensive longitudinal resting state fMRI datasets with a total number of 20 subjects. In the analysis of cross-sectional designs, we used rsfMRI data from 361 subjects from the Human Connectome Project. We hypothesized that (1) GSR would have no discernible impact on effective connectivity estimated with DCM, and (2) GSR would be reflected in the parameters representing global measurement noise. Additionally, we performed comparative analyses of information gain with and without GSR. Our results showed negligible to small effects of GSR on effective connectivity within small (separately estimated) RSNs. However, although the effect sizes were small, there was substantial to conclusive evidence for an effect of GSR on connectivity parameters. For between-network connectivity, we found two important effects: the effect of GSR on between-network effective connectivity (averaged over all connections) was negligible to small, while the effect of GSR on individual connections was non-negligible. In the cross-sectional (but not in the longitudinal) data, some connections showed substantial to conclusive evidence for an effect of GSR. Contrary to our expectations, we found either no effect (in the longitudinal designs) or a non-specific (cross-sectional design) effect of GSR on parameters characterising (global) measurement noise. Data without GSR were found to be more informative than data with GSR; however, in small resting state networks the precision of posterior estimates was greater after GSR. In conclusion, GSR is a minor concern in DCM studies; however, quantitative interpretation of between-network connections (as opposed to average between-network connectivity) and noise parameters should be treated with some caution. The Kullback-Leibler divergence of the posterior from the prior (i.e., information gain) - together with the precision of posterior estimates - might offer a useful measure to assess the appropriateness of GSR in resting state fMRI.
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Corteza Cerebral/fisiología , Conectoma/métodos , Imagen por Resonancia Magnética/métodos , Red Nerviosa/fisiología , Adulto , Corteza Cerebral/diagnóstico por imagen , Conectoma/normas , Estudios Transversales , Femenino , Humanos , Estudios Longitudinales , Imagen por Resonancia Magnética/normas , Masculino , Red Nerviosa/diagnóstico por imagen , Adulto JovenRESUMEN
This analysis explores the effective connectivity of the cerebellum with the cerebral cortex during the generation of correct sequences of social and non-social events, using dynamic causal modelling (DCM). Our hypothesis is that during human evolution, the cerebellum's function evolved from a mere coordinator of fluent sequences of motions and actions, to an interpreter of action sequences without overt movements that are important for social understanding. This requires efficient neural communication between the cerebellum and cerebral cortex. In a functional magnetic resonance imaging (fMRI) study, participants generated the correct chronological order of (non-)social events, including stories involving mechanical and social scripts, and true or false beliefs. Across all stories, a DCM analysis of these data revealed, as predicted, bidirectional (closed-loop) connections linking the bilateral posterior cerebellum with the bilateral temporo-parietal junction (TPJ) associated with behavior understanding, and this connectivity pattern was almost entirely significant. There was also a unidirectional connection from the right posterior cerebellum to the precuneus, but no direct connections with the dorsomedial prefrontal cortex (dmPFC). Moreover, all connections emanating from the bilateral posterior cerebellum were negative, indicative of some kind of error signal. Within the cerebral cortex, there were unidirectional connections from the bilateral TPJ to the dmPFC, as well as bidirectional connections between the precuneus and dmPFC, and between the bilateral TPJ. These results confirm that the effective connectivity between the posterior cerebellum and mentalizing areas in the cerebral cortex play a critical role in the understanding and construction of the correct order of social and non-social action sequences.
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Cerebelo/diagnóstico por imagen , Corteza Cerebral/diagnóstico por imagen , Percepción Social , Teorema de Bayes , Cerebelo/fisiología , Corteza Cerebral/fisiología , Femenino , Neuroimagen Funcional , Humanos , Imagen por Resonancia Magnética , Masculino , Mentalización , Vías Nerviosas , Lóbulo Parietal/diagnóstico por imagen , Lóbulo Parietal/fisiología , Corteza Prefrontal/diagnóstico por imagen , Corteza Prefrontal/fisiología , Lóbulo Temporal/diagnóstico por imagen , Lóbulo Temporal/fisiologíaRESUMEN
Previous studies have characterized the brain regions involved in encoding monetary reward and punishment outcomes. The question of how this information is integrated across brain regions has received less attention. Here, we investigated changes in effective connectivity related to the processing of positive and negative monetary outcomes using functional magnetic resonance imaging data from the Human Connectome Project. Specifically, subjects engaged in a card guessing game which could yield win, loss, or neutral outcomes. A general linear model was used to define a network of regions involved in win and loss outcome processing, including anterior insula, anterior cingulate cortex, and ventral striatum. Dynamic causal modelling (DCM) was implemented to study between-region couplings and outcome-related modulations thereof within this network. In addition, we explored the relation between effective connectivity patterns and choice behavior in the gambling task. Parametric empirical Bayesian modelling was conducted for group-level inferences of both DCM and the choice behavior. Behaviorally, both win and loss outcomes increased the probability of choice switches in subsequent gambles. In terms of connectivity, win outcomes were associated with increased extrinsic connectivity across the network, while loss outcomes featured a balance between increased and decreased extrinsic connectivity. Moreover, self-inhibitory connections tended to decrease for both win and loss outcomes. Interestingly, a substantial discrepancy was observed for occipital cortex connectivity, which was characterized by intrinsic disinhibition in loss but not in win trials. The observed differences in effective connectivity during the processing of positive and negative outcomes, despite similarities in average regional activity and choice behavior, highlight the value of exploring network dynamics in the context of incentive manipulations.
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Conducta/fisiología , Red Nerviosa/fisiología , Recompensa , Estriado Ventral/fisiología , Adulto , Conectoma/métodos , Femenino , Juego de Azar , Humanos , Imagen por Resonancia Magnética/métodos , MasculinoRESUMEN
Global signal (GS) is an ubiquitous construct in resting state functional magnetic resonance imaging (rs-fMRI), associated to nuisance, but containing by definition most of the neuronal signal. Global signal regression (GSR) effectively removes the impact of physiological noise and other artifacts, but at the same time it alters correlational patterns in unpredicted ways. Performing GSR taking into account the underlying physiology (mainly the blood arrival time) has been proven to be beneficial. From these observations we aimed to: 1) characterize the effect of GSR on network-level functional connectivity in a large dataset; 2) assess the complementary role of global signal and vessels; and 3) use the framework of partial information decomposition to further look into the joint dynamics of the global signal and vessels, and their respective influence on the dynamics of cortical areas. We observe that GSR affects intrinsic connectivity networks in the connectome in a non-uniform way. Furthermore, by estimating the predictive information of blood flow and the global signal using partial information decomposition, we observe that both signals are present in different amounts across intrinsic connectivity networks. Simulations showed that differences in blood arrival time can largely explain this phenomenon, while using hemodynamic and calcium mouse recordings we were able to confirm the presence of vascular effects, as calcium recordings lack hemodynamic information. With these results we confirm network-specific effects of GSR and the importance of taking blood flow into account for improving de-noising methods. Additionally, and beyond the mere issue of data denoising, we quantify the diverse and complementary effect of global and vessel BOLD signals on the dynamics of cortical areas.
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Artefactos , Encéfalo/fisiología , Circulación Cerebrovascular/fisiología , Conectoma/métodos , Procesamiento de Imagen Asistido por Computador/métodos , Humanos , Imagen por Resonancia Magnética/métodosRESUMEN
Functional and effective connectivity are known to change systematically over time. These changes might be explained by several factors, including intrinsic fluctuations in activity-dependent neuronal coupling and contextual factors, like experimental condition and time. Furthermore, contextual effects may be subject-specific or conserved over subjects. To characterize fluctuations in effective connectivity, we used dynamic causal modelling (DCM) of cross spectral responses over 1-â¯min of electroencephalogram (EEG) recordings during rest, divided into 1-sec windows. We focused on two intrinsic networks: the default mode and the saliency network. DCM was applied to estimate connectivity in each time-window for both networks. Fluctuations in DCM connectivity parameters were assessed using hierarchical parametric empirical Bayes (PEB). Within-subject, between-window effects were modelled with a second-level linear model with temporal basis functions as regressors. This procedure was conducted for every subject separately. Bayesian model reduction was then used to assess which (combination of) temporal basis functions best explain dynamic connectivity over windows. A third (between-subject) level model was used to infer which dynamic connectivity parameters are conserved over subjects. Our results indicate that connectivity fluctuations in the default mode network and to a lesser extent the saliency network comprised both subject-specific components and a common component. For both networks, connections to higher order regions appear to monotonically increase during the 1-â¯min period. These results not only establish the predictive validity of dynamic connectivity estimates - in virtue of detecting systematic changes over subjects - they also suggest a network-specific dissociation in the relative contribution of fluctuations in connectivity that depend upon experimental context. We envisage these procedures could be useful for characterizing brain state transitions that may be explained by their cognitive or neuropathological underpinnings.
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Corteza Cerebral/fisiología , Conectoma/métodos , Electroencefalografía/métodos , Modelos Teóricos , Red Nerviosa/fisiología , Adulto , Corteza Cerebral/diagnóstico por imagen , HumanosRESUMEN
In this analysis we explored the effective connectivity of the cerebellum with the cerebrum in social mentalizing, across five studies (n = 91) involving abstract and complex forms of mentalizing, such as (a) person and group impression formation, based on behavioral descriptions, and (b) constructing personal counterfactual events. Connectivity was analyzed by applying dynamic causal model analysis, which revealed effective connectivity between the mentalizing areas of the cerebellum and cerebrum. The results revealed a significant pattern of bidirectional (closed-loop) connectivity linking the right posterior cerebellum with bilateral temporo-parietal junction (TPJ), associated with behavior understanding. These connections are consistent with known anatomical data on closed loops between the cerebellum and cerebrum, although contralateral closed loops typically dominate. This analysis improves on an earlier psychophysiological interaction analysis of this dataset, which had failed to reveal such evidence of closed loops. Within the cerebrum, there were connections between the bilateral areas of TPJ, as well as connections between bilateral TPJ and the (ventral and dorsal) medial prefrontal cortex. The discussion centers on the function of cerebro-cerebellar connections in generating internal cerebellar "forward" models, potentially serving the automatic understanding, prediction, and error correction of behavioral sequences.
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Cognición/fisiología , Mentalización/fisiología , Vías Nerviosas/fisiología , Conducta/fisiología , Mapeo Encefálico/métodos , Cerebelo/fisiología , Cerebro/fisiología , Femenino , Humanos , Imagen por Resonancia Magnética/métodos , Masculino , Corteza Prefrontal/fisiologíaRESUMEN
Electrical activity recorded on the scalp using electroencephalography (EEG) results from the mixing of signals originating from different regions of the brain as well as from artifactual sources. In order to investigate the role of distinct brain areas in a given experiment, the signal recorded on the sensors is typically projected back into the brain (source reconstruction) using algorithms that address the so-called EEG "inverse problem". Once the activity of sources located inside of the brain has been reconstructed, it is often desirable to study the statistical dependencies among them, in particular to quantify directional dynamical interactions between brain areas. Unfortunately, even when performing source reconstruction, the superposition of signals that is due to the propagation of activity from sources to sensors cannot be completely undone, resulting in potentially biased estimates of directional functional connectivity. Here we perform a set of simulations involving interacting sources to quantify source connectivity estimation performance as a function of the location of the sources, their distance to each other, the noise level, the source reconstruction algorithm, and the connectivity estimator. The generated source activity was projected onto the scalp and projected back to the cortical level using two source reconstruction algorithms, linearly constrained minimum variance beamforming and 'Exact' low-resolution tomography (eLORETA). In source space, directed connectivity was estimated using multi-variate Granger causality and time-reversed Granger causality, and compared with the imposed ground truth. Our results demonstrate that all considered factors significantly affect the connectivity estimation performance.
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Mapeo Encefálico/métodos , Electroencefalografía/métodos , Algoritmos , Encéfalo , Humanos , Procesamiento de Señales Asistido por ComputadorRESUMEN
Many different analysis techniques have been developed and applied to EEG recordings that allow one to investigate how different brain areas interact. One particular class of methods, based on the linear parametric representation of multiple interacting time series, is widely used to study causal connectivity in the brain. However, the results obtained by these methods should be interpreted with great care. The goal of this paper is to show, both theoretically and using simulations, that results obtained by applying causal connectivity measures on the sensor (scalp) time series do not allow interpretation in terms of interacting brain sources. This is because (1) the channel locations cannot be seen as an approximation of a source's anatomical location and (2) spurious connectivity can occur between sensors. Although many measures of causal connectivity derived from EEG sensor time series are affected by the latter, here we will focus on the well-known time domain index of Granger causality (GC) and on the frequency domain directed transfer function (DTF). Using the state-space framework and designing two simulation studies we show that mixing effects caused by volume conduction can lead to spurious connections, detected either by time domain GC or by DTF. Therefore, GC/DTF causal connectivity measures should be computed at the source level, or derived within analysis frameworks that model the effects of volume conduction. Since mixing effects can also occur in the source space, it is advised to combine source space analysis with connectivity measures that are robust to mixing.
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Electroencefalografía/métodos , Mapeo Encefálico/métodos , Simulación por Computador , HumanosRESUMEN
Dynamic causal modelling (DCM) for resting state fMRI - namely spectral DCM - is a recently developed and widely adopted method for inferring effective connectivity in intrinsic brain networks. Most applications of spectral DCM have focused on group-averaged connectivity within large-scale intrinsic brain networks; however, the consistency of subject- and session-specific estimates of effective connectivity has not been evaluated. Establishing reliability (within subjects) is crucial for its clinical use; e.g., as a neurophysiological phenotype of disease progression. Effective connectivity during rest is likely to vary due to changes in cognitive, and physiological states. Quantifying these variations may help understand functional brain architectures - and inform clinical applications. In the present study, we investigated the consistency of effective connectivity within and between subjects, as well as potential sources of variability (e.g., hemispheric asymmetry). We also addressed the effects on consistency of standard data processing procedures. DCM analyses were applied to four longitudinal resting state fMRI datasets. Our sample comprised 17 subjects with 589 resting state fMRI sessions in total. These data allowed us to quantify the robustness of connectivity estimates for each subject, and to generalise our conclusions beyond specific data features. We found that subjects showed systematic and reliable patterns of hemispheric asymmetry. When asymmetry was taken into account, subjects showed very similar connectivity patterns. We also found that various processing procedures (e.g. global signal regression and ROI size) had little effect on inference and the reliability of connectivity estimates for the majority of subjects. Finally, Bayesian model reduction significantly increased the consistency of connectivity patterns.
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Mapeo Encefálico/métodos , Encéfalo/fisiología , Procesamiento de Imagen Asistido por Computador/métodos , Red Nerviosa/fisiología , Adulto , Teorema de Bayes , Encéfalo/anatomía & histología , Femenino , Humanos , Estudios Longitudinales , Imagen por Resonancia Magnética/métodos , Masculino , Persona de Mediana Edad , Red Nerviosa/anatomía & histología , Reproducibilidad de los Resultados , Adulto JovenRESUMEN
BACKGROUND: In humanitarian settings, brief screening instruments for child psychological distress have potential to assist in assessing prevalence, monitoring outcomes, and identifying children and adolescents in most need of scarce resources, given few mental health professionals for diagnostic services. Yet, there are few validated screening tools available, particularly in Arabic. METHODS: We translated and adapted the Child Psychosocial Distress Screener (CPDS) and the Pediatric Symptom Checklist (PSC) and conducted a validation study with 85 adolescents (aged 10-15) in Lebanon. We assessed internal consistency; test-retest reliability; convergent validity between adolescent- and caregiver-report and between the two measures; ability to distinguish between clinical and non-clinical samples; and concurrent validity against psychiatrist interview using the Kiddie Schedule for Affective Disorders and Schizophrenia. RESULTS: The translated and adapted child-reported PSC-17 and PSC-35, and caregiver-reported PSC-35 all showed adequate internal consistency and test-retest reliability and high concurrent validity with psychiatrist interview and were able to distinguish between clinical and non-clinical samples. However, the caregiver-reported PSC-17 did not demonstrate adequate performance in this setting. Child-reported versions of the PSC outperformed caregiver-reported versions and the 35-item PSC scales showed stronger performance than 17-item scales. The CPDS showed adequate convergent validity with the PSC, ability to distinguish between clinical and non-clinical samples, and concurrent validity with psychiatrist interview. Internal consistency was low for the CPDS, likely due to the nature of the brief risk-screening tool. There were discrepancies between caregiver and child-reports, worthy of future investigation. For indication of any diagnosis requiring treatment, we recommend cut-offs of 5 for CPDS, 12 for child-reported PSC-17, 21 for child-reported PSC-35, and 26 for caregiver-reported PSC-35. CONCLUSIONS: The Arabic PSC and CPDS are reliable and valid instruments for use as primary screening tools in Lebanon. Further research is needed to understand discrepancies between adolescent and caregiver reports, and optimal methods of using multiple informants.
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BACKGROUND: The use of feedback to address gaps and reinforce skills is a key component of successful competency-based mental health and psychosocial support intervention training approaches. Competency-based feedback during training and supervision for personnel delivering psychological interventions is vital for safe and effective care. AIMS: For non-specialists trained in low-resource settings, there is a lack of standardised feedback systems. This study explores perspectives on competency-based feedback, using structured role-plays that are featured on the Ensuring Quality in Psychosocial and Mental Health Care (EQUIP) platform developed by the World Health Organization and United Nations Children's Fund. METHOD: Qualitative data were collected from supervisors, trainers and trainees from multiple EQUIP training sites (Ethiopia, Kenya, Lebanon, Peru and Uganda), from 18 key informant interviews and five focus group discussions (N = 41 participants). Qualitative analysis was conducted in Dedoose, using a codebook with deductively and inductively developed themes. RESULTS: Four main themes demonstrated how a competency-based structure enhanced the feedback process: (a) competency-based feedback was personalised and goal-specific, (b) competency-based feedback supported a feedback loop, (c) competency-based feedback supported a comfortable and objective feedback environment, and (d) competency-based feedback created greater opportunities for flexibility in training and supervision. CONCLUSIONS: A better understanding of the role of feedback supports the implementation of competency-based training that is systematic and effective for trainers and supervisors, which ultimately benefits the learning process for trainees.
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There has been an increase in the evaluation and implementation of non-specialist delivered psychological interventions to address unmet mental health needs in humanitarian emergencies. While randomized controlled trials (RCTs) provide important evidence about intervention impact, complementary qualitative process evaluations are essential to understand key implementation processes and inform future scaling up of the intervention. This study was conducted as part of an RCT of the Early Adolescents Skills for Emotions (EASE) psychological intervention for young adolescents with elevated psychological distress (predominantly with a Syrian refugee background) in Lebanon. Our aims were firstly to conduct a qualitative process evaluation to understand stakeholder experiences and perceived impact of the intervention and identify barriers and facilitators for implementation, and secondly to explore considerations for scaling up. Eleven key informant interviews and seven focus groups were conducted with 39 respondents including adolescent and caregiver participants, trainers, providers, outreach workers, and local stakeholders. Data were analyzed using inductive and deductive thematic analysis. Respondents perceived the intervention to be highly needed and reported improvements in adolescent mental health and wellbeing. Key implementation factors that have potential to influence engagement, adherence, and perceived impact included the socio-economic situation of families, mental health stigma, coordination within and between sectors (particularly for scaling up), embedding the intervention within existing service pathways, having clear quality and accountability processes including training and supervision for non-specialists, and sustainable funding. Our findings provide important context for understanding effectiveness outcomes of the RCT and highlights factors that need to be considered when implementing a mental health intervention on a larger scale in a complex crisis.
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Background: Syrian refugees have a high burden of mental health symptoms and face challenges in accessing mental health and psychosocial support (MHPSS). This study assesses health system responsiveness (HSR) to the MHPSS needs of Syrian refugees, comparing countries in Europe and the Middle East to inform recommendations for strengthening MHPSS systems. Methods: A mixed-methods rapid appraisal methodology guided by an adapted WHO Health System Framework was used to assess HSR in eight countries (Egypt, Germany, Jordan, Lebanon, Netherlands, Sweden, Switzerland, and Türkiye). Quantitative and qualitative analysis of primary and secondary data was used. Data collection and analysis were performed iteratively by multiple researchers. Country reports were used for comparative analysis and synthesis. Results: We found numerous constraints in HSR: i) Too few appropriate mental health providers and services; ii) Travel-related barriers impeding access to services, widening rural-urban inequalities in the distribution of mental health workers; iii) Cultural, language, and knowledge-related barriers to timely care likely caused by insufficient numbers of culturally sensitive providers, costs of professional interpreters, somatic presentations of distress by Syrian refugees, limited mental health awareness, and stigma associated to mental illness; iv) High out-of-pocket costs for psychological treatment and transportation to services reducing affordability, particularly in middle-income countries; v) Long waiting times for specialist mental health services; vi) Information gaps on the mental health needs of refugees and responsiveness of MHPSS systems in all countries. Six recommendations are provided to address these issues. Conclusions: All eight host countries struggle to provide responsive MHPSS to Syrian refugees. Strengthening the mental health workforce (in terms of quantity, quality, diversity, and distribution) is urgently needed to enable Syrian refugees to receive culturally appropriate and timely care and improve mental health outcomes. Increased financial investment in mental health and improved health information systems are crucial.
Background: People who experience war often have increased mental health problems. Those who are forced to flee abroad frequently struggle to access adequate mental health and psychosocial support services. As a result, many refugees often do not seek or use such services.Researchers of the Syrian REfuGees MeNTal HealTH Care Systems (STRENGTHS) consortium carried out rapid appraisals to assess the responsiveness of health systems to the mental health and psychosocial needs of Syrian refugees in eight countries: Egypt, Germany, Jordan, Lebanon, the Netherlands, Sweden, Switzerland, and Türkiye. They used quantitative and qualitative data, including primary and secondary data. This paper summarises and compares findings from the eight countries. What is health system responsiveness?: The ability of a health system to meet the expectations and needs of its people with regards to access, coverage, quality, and safety of services. What are our main findings and recommendations?: We found that all eight host countries struggle to provide responsive mental health and psychosocial support to Syrian refugees. We identified the following key challenges: Insufficient mental health providers and services, including uneven rural-urban distribution;Cultural, language, and knowledge-related barriers to timely care, caused by insufficient culturally sensitive providers and mental health stigma among Syrian refugee communities;Out-of-pocket costs for psychological treatment and transportation to services;Long waiting times for specialist mental health services;Information gaps on the mental health needs of Syrian refugees;We recommend increasing national funding for mental health to help Syrian refugees to receive more culturally appropriate and timely care. Increased funding can reduce out-of-pocket payments by refugees, improve national health information systems, and strengthen the mental health workforce (in terms of quantity, quality, diversity, and distribution). We also recommend investment in cultural competency and mental health training for community-based workers and primary care providers.
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Chronic migraine is characterised by persistent headaches for >15 days per month; the intensity of the pain is fluctuating over time. Here, we explored the dynamic interplay of connectivity patterns between regions known to be related to pain processing and their relation to the ongoing dynamic pain experience. We recorded EEG from 80 sessions (20 chronic migraine patients in 4 separate sessions of 25 min). The patients were asked to continuously rate the intensity of their endogenous headache. On different time-windows, a dynamic causal model (DCM) of cross spectral responses was inverted to estimate connectivity strengths. For each patient and session, the evolving dynamics of effective connectivity were related to pain intensities and to pain intensity changes by using a Bayesian linear model. Hierarchical Bayesian modelling was further used to examine which connectivity-pain relations are consistent across sessions and across patients. The results reflect the multi-facetted clinical picture of the disease. Across all sessions, each patient with chronic migraine exhibited a distinct pattern of pain intensity-related cortical connectivity. The diversity of the individual findings are accompanied by inconsistent relations between the connectivity parameters and pain intensity or pain intensity changes at group level. This suggests a rejection of the idea of a common neuronal core problem for chronic migraine.
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Successful navigation relies on the ability to identify, perceive, and correctly process the spatial structure of a scene. It is well known that visual mental imagery plays a crucial role in navigation. Indeed, cortical regions encoding navigationally relevant information are also active during mental imagery of navigational scenes. However, it remains unknown whether their intrinsic activity and connectivity reflect the individuals' ability to imagine a scene. Here, we primarily investigated the intrinsic causal interactions among scene-selective brain regions such as Parahipoccampal Place Area (PPA), Retrosplenial Complex, and Occipital Place Area (OPA) using Dynamic Causal Modelling for resting-state functional magnetic resonance data. Second, we tested whether resting-state effective connectivity parameters among scene-selective regions could reflect individual differences in mental imagery in our sample, as assessed by the self-reported Vividness of Visual Imagery Questionnaire. We found an inhibitory influence of occipito-medial on temporal regions, and an excitatory influence of more anterior on more medial and posterior brain regions. Moreover, we found that a key role in imagery is played by the connection strength from OPA to PPA, especially in the left hemisphere, since the influence of the signal between these scene-selective regions positively correlated with good mental imagery ability. Our investigation contributes to the understanding of the complexity of the causal interaction among brain regions involved in navigation and provides new insight in understanding how an essential ability, such as mental imagery, can be explained by the intrinsic fluctuation of brain signal.