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1.
Natl Sci Rev ; 11(5): nwae124, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38778818

RESUMO

The human brain is a complex system, whose activity exhibits flexible and continuous reorganization across space and time. The decomposition of whole-brain recordings into harmonic modes has revealed a repertoire of gradient-like activity patterns associated with distinct brain functions. However, the way these activity patterns are expressed over time with their changes in various brain states remains unclear. Here, we investigate healthy participants taking the serotonergic psychedelic N,N-dimethyltryptamine (DMT) with the Harmonic Decomposition of Spacetime (HADES) framework that can characterize how different harmonic modes defined in space are expressed over time. HADES demonstrates significant decreases in contributions across most low-frequency harmonic modes in the DMT-induced brain state. When normalizing the contributions by condition (DMT and non-DMT), we detect a decrease specifically in the second functional harmonic, which represents the uni- to transmodal functional hierarchy of the brain, supporting the leading hypothesis that functional hierarchy is changed in psychedelics. Moreover, HADES' dynamic spacetime measures of fractional occupancy, life time and latent space provide a precise description of the significant changes of the spacetime hierarchical organization of brain activity in the psychedelic state.

2.
Geriatrics (Basel) ; 9(2)2024 Apr 19.
Artigo em Inglês | MEDLINE | ID: mdl-38667520

RESUMO

This qualitative study aimed to understand men's social connectedness in later life in Portugal focusing on their perceptions, obstacles, strategies, and impact on well-being. The sample included 104 older Portuguese men over 65 years of age (Mage = 70.76 years). The qualitative data were the direct transcriptions of the answers given by participants to the electronic interview using thematic analysis. Findings revealed six overarching themes encompassing 18 subcategories: definitions of social connectedness (social support, community identity, mental health promotion, use of community structures), difficulties/obstacles in maintaining social connectedness (ageism, lack of initiative, physical limitations, psychological traits, resources), strategies/actions or resources to establish social connections (use of technology, use of community groups, leisure and sport activities, church/religion), negative impact of difficulties in establishing relevant social connections (mental health, physical health, relationships), positive actions from being socially connected (positive prescriptions to promote social connectedness), and concerns from being socially disconnected (health risks). These findings indicate that the lack of social connectedness creates social vulnerability in later life, and social support is needed to ensure safer aging among older men.

3.
Brain Commun ; 6(2): fcae049, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38515439

RESUMO

Psilocybin therapy for depression has started to show promise, yet the underlying causal mechanisms are not currently known. Here, we leveraged the differential outcome in responders and non-responders to psilocybin (10 and 25 mg, 7 days apart) therapy for depression-to gain new insights into regions and networks implicated in the restoration of healthy brain dynamics. We used large-scale brain modelling to fit the spatiotemporal brain dynamics at rest in both responders and non-responders before treatment. Dynamic sensitivity analysis of systematic perturbation of these models enabled us to identify specific brain regions implicated in a transition from a depressive brain state to a healthy one. Binarizing the sample into treatment responders (>50% reduction in depressive symptoms) versus non-responders enabled us to identify a subset of regions implicated in this change. Interestingly, these regions correlate with in vivo density maps of serotonin receptors 5-hydroxytryptamine 2a and 5-hydroxytryptamine 1a, which psilocin, the active metabolite of psilocybin, has an appreciable affinity for, and where it acts as a full-to-partial agonist. Serotonergic transmission has long been associated with depression, and our findings provide causal mechanistic evidence for the role of brain regions in the recovery from depression via psilocybin.

4.
Neuroimage ; 285: 120470, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38016527

RESUMO

Resting-state fMRI can be used to identify recurrent oscillatory patterns of functional connectivity within the human brain, also known as dynamic brain states. Alterations in dynamic brain states are highly likely to occur following pediatric mild traumatic brain injury (pmTBI) due to the active developmental changes. The current study used resting-state fMRI to investigate dynamic brain states in 200 patients with pmTBI (ages 8-18 years, median = 14 years) at the subacute (∼1-week post-injury) and early chronic (∼ 4 months post-injury) stages, and in 179 age- and sex-matched healthy controls (HC). A k-means clustering analysis was applied to the dominant time-varying phase coherence patterns to obtain dynamic brain states. In addition, correlations between brain signals were computed as measures of static functional connectivity. Dynamic connectivity analyses showed that patients with pmTBI spend less time in a frontotemporal default mode/limbic brain state, with no evidence of change as a function of recovery post-injury. Consistent with models showing traumatic strain convergence in deep grey matter and midline regions, static interhemispheric connectivity was affected between the left and right precuneus and thalamus, and between the right supplementary motor area and contralateral cerebellum. Changes in static or dynamic connectivity were not related to symptom burden or injury severity measures, such as loss of consciousness and post-traumatic amnesia. In aggregate, our study shows that brain dynamics are altered up to 4 months after pmTBI, in brain areas that are known to be vulnerable to TBI. Future longitudinal studies are warranted to examine the significance of our findings in terms of long-term neurodevelopment.


Assuntos
Concussão Encefálica , Lesões Encefálicas , Humanos , Criança , Concussão Encefálica/diagnóstico por imagem , Rede Nervosa/diagnóstico por imagem , Encéfalo/diagnóstico por imagem , Mapeamento Encefálico , Imageamento por Ressonância Magnética
5.
Stress ; 27(1): 2275207, 2024 01.
Artigo em Inglês | MEDLINE | ID: mdl-37877207

RESUMO

Maternal prenatal distress (PD), frequently defined as in utero prenatal stress exposure (PSE) to the developing fetus, influences the developing brain and numerous associations between PSE and brain structure have been described both in neonates and in older children. Previous studies addressing PSE-linked alterations in neonates' brain activity have focused on connectivity analyses from predefined seed regions, but the effects of PSE at the level of distributed functional networks remains unclear. In this study, we investigated the impact of prenatal distress on the spatial and temporal properties of functional networks detected in functional MRI data from 20 naturally sleeping, term-born (age 25.85 ± 7.72 days, 11 males), healthy neonates. First, we performed group level independent component analysis (GICA) to evaluate an association between PD and the identified functional networks. Second, we searched for an association with PD at the level of the stability of functional networks over time using leading eigenvector dynamics analysis (LEiDA). No statistically significant associations were detected at the spatial level for the GICA-derived networks. However, at the dynamic level, LEiDA revealed that maternal PD negatively associated with the stability of a frontoparietal network. These results imply that maternal PD may influence the stability of frontoparietal connections in neonatal brain network dynamics and adds to the cumulating evidence that frontal areas are especially sensitive to PSE. We advocate for early preventive intervention strategies regarding pregnant mothers. Nevertheless, future research venues are required to assess optimal intervention timing and methods for maximum benefit.


Assuntos
Encéfalo , Estresse Psicológico , Masculino , Recém-Nascido , Gravidez , Feminino , Criança , Humanos , Encéfalo/diagnóstico por imagem , Mapeamento Encefálico , Imageamento por Ressonância Magnética , Mães
6.
PLoS One ; 18(12): e0295984, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-38100479

RESUMO

Research has shown that maladaptive personality characteristics, such as Neuroticism, are associated with poor outcome after mild traumatic brain injury (mTBI). The current exploratory study investigated the neural underpinnings of this process using dynamic functional network connectivity (dFNC) analyses of resting-state (rs) fMRI, and diffusion MRI (dMRI). Twenty-seven mTBI patients and 21 healthy controls (HC) were included. After measuring the Big Five personality dimensions, principal component analysis (PCA) was used to obtain a superordinate factor representing emotional instability, consisting of high Neuroticism, moderate Openness, and low Extraversion, Agreeableness, and Conscientiousness. Persistent symptoms were measured using the head injury symptom checklist at six months post-injury; symptom severity (i.e., sum of all items) was used for further analyses. For patients, brain MRI was performed in the sub-acute phase (~1 month) post-injury. Following parcellation of rs-fMRI using independent component analysis, leading eigenvector dynamic analysis (LEiDA) was performed to compute dynamic phase-locking brain states. Main patterns of brain diffusion were computed using tract-based spatial statistics followed by PCA. No differences in phase-locking state measures were found between patients and HC. Regarding dMRI, a trend significant decrease in fractional anisotropy was found in patients relative to HC, particularly in the fornix, genu of the corpus callosum, anterior and posterior corona radiata. Visiting one specific phase-locking state was associated with lower symptom severity after mTBI. This state was characterized by two clearly delineated communities (each community consisting of areas with synchronized phases): one representing an executive/saliency system, with a strong contribution of the insulae and basal ganglia; the other representing the canonical default mode network. In patients who scored high on emotional instability, this relationship was even more pronounced. Dynamic phase-locking states were not related to findings on dMRI. Altogether, our results provide preliminary evidence for the coupling between personality and dFNC in the development of long-term symptoms after mTBI.


Assuntos
Concussão Encefálica , Humanos , Concussão Encefálica/diagnóstico por imagem , Encéfalo/diagnóstico por imagem , Imageamento por Ressonância Magnética/métodos , Mapeamento Encefálico , Personalidade
7.
Front Hum Neurosci ; 17: 1275387, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37886692

RESUMO

[This corrects the article DOI: 10.3389/fnhum.2022.958706.].

8.
Hum Brain Mapp ; 44(17): 5770-5783, 2023 12 01.
Artigo em Inglês | MEDLINE | ID: mdl-37672593

RESUMO

Recurrence in major depressive disorder (MDD) is common, but neurobiological models capturing vulnerability for recurrences are scarce. Disturbances in multiple resting-state networks have been linked to MDD, but most approaches focus on stable (vs. dynamic) network characteristics. We investigated how the brain's dynamical repertoire changes after patients transition from remission to recurrence of a new depressive episode. Sixty two drug-free, MDD-patients with ≥2 episodes underwent a baseline resting-state fMRI scan when in remission. Over 30-months follow-up, 11 patients with a recurrence and 17 matched-remitted MDD-patients without a recurrence underwent a second fMRI scan. Recurrent patterns of functional connectivity were characterized by applying Leading Eigenvector Dynamics Analysis (LEiDA). Differences between baseline and follow-up were identified for the 11 non-remitted patients, while data from the 17 matched-remitted patients was used as a validation dataset. After the transition into a depressive state, basal ganglia-anterior cingulate cortex (ACC) and visuo-attentional networks were detected significantly more often, whereas default mode network activity was found to have a longer duration. Additionally, the fMRI signal in the basal ganglia-ACC areas underlying the reward network, were significantly less synchronized with the rest of the brain after recurrence (compared to a state of remission). No significant changes were observed in the matched-remitted patients who were scanned twice while in remission. These findings characterize changes that may be associated with the transition from remission to recurrence and provide initial evidence of altered dynamical exploration of the brain's repertoire of functional networks when a recurrent depressive episode occurs.


Assuntos
Transtorno Depressivo Maior , Humanos , Transtorno Depressivo Maior/diagnóstico por imagem , Depressão , Encéfalo/diagnóstico por imagem , Imageamento por Ressonância Magnética , Recompensa , Mapeamento Encefálico
9.
J Youth Adolesc ; 52(12): 2545-2558, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-37620682

RESUMO

The literature shows that impulsivity, prevalent in adolescence, is negatively linked with a variety of psychosocial factors (e.g., positive interpersonal relationships, emotion regulation); however, there is limited research examining the relative contribution of multiple factors for this trait nor exploring how these factors influence the associations between impulsivity and risk-related outcomes. Drawing on multiple components of the unified theory of development (i.e., psychological variables, peers subsystem, community subsystem, family processes subsystem), this cross-sectional study aims to identify explanatory psychosocial variables (i.e., early memories of warmth and safeness, rational decision-making style, resilience, emotion regulation, coping, parental attachment, social group attachment, satisfaction with school and family-related variables) that are negatively related with impulsivity, in younger (13-15) and older (16-19 years) adolescents, and explore their moderating role in the associations between this trait and some risk-related outcomes (i.e., verbal aggression, anger, self-harm, other high-risk behaviors). A representative sample of 6894 adolescents (52.9% female) living in the Azores (Portugal), with ages ranging from 13 to 19 (M = 15.4), was used. Two stepwise multiple regressions, one for each age group, revealed that only emotion regulation, parental attachment, and social group attachment had a negative effect on impulsivity in both age groups; additionally, satisfaction with teachers also had this effect in younger adolescents. The first three variables weakened the positive associations between impulsivity and the risk-related outcomes. These results suggest that the psychological system and all subsystems of the social context measured play a relevant role in explaining adolescent impulsivity and that it may be reduced by promoting emotion regulation, positive parenting practices, healthier relationships with peers, and healthier relationships with teachers.


Assuntos
Pais , Grupo Associado , Humanos , Adolescente , Feminino , Masculino , Estudos Transversais , Pais/psicologia , Comportamento Impulsivo/fisiologia , Relações Familiares
10.
Netw Neurosci ; 7(2): 478-495, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37397890

RESUMO

Beyond the established effects of subthalamic nucleus deep brain stimulation (STN-DBS) in reducing motor symptoms in Parkinson's disease, recent evidence has highlighted the effect on non-motor symptoms. However, the impact of STN-DBS on disseminated networks remains unclear. This study aimed to perform a quantitative evaluation of network-specific modulation induced by STN-DBS using Leading Eigenvector Dynamics Analysis (LEiDA). We calculated the occupancy of resting-state networks (RSNs) in functional MRI data from 10 patients with Parkinson's disease implanted with STN-DBS and statistically compared between ON and OFF conditions. STN-DBS was found to specifically modulate the occupancy of networks overlapping with limbic RSNs. STN-DBS significantly increased the occupancy of an orbitofrontal limbic subsystem with respect to both DBS OFF (p = 0.0057) and 49 age-matched healthy controls (p = 0.0033). Occupancy of a diffuse limbic RSN was increased with STN-DBS OFF when compared with healthy controls (p = 0.021), but not when STN-DBS was ON, which indicates rebalancing of this network. These results highlight the modulatory effect of STN-DBS on components of the limbic system, particularly within the orbitofrontal cortex, a structure associated with reward processing. These results reinforce the value of quantitative biomarkers of RSN activity in evaluating the disseminated impact of brain stimulation techniques and the personalization of therapeutic strategies.

11.
Neuroimage ; 277: 120236, 2023 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-37355200

RESUMO

Existing whole-brain models are generally tailored to the modelling of a particular data modality (e.g., fMRI or MEG/EEG). We propose that despite the differing aspects of neural activity each modality captures, they originate from shared network dynamics. Building on the universal principles of self-organising delay-coupled nonlinear systems, we aim to link distinct features of brain activity - captured across modalities - to the dynamics unfolding on a macroscopic structural connectome. To jointly predict connectivity, spatiotemporal and transient features of distinct signal modalities, we consider two large-scale models - the Stuart Landau and Wilson and Cowan models - which generate short-lived 40 Hz oscillations with varying levels of realism. To this end, we measure features of functional connectivity and metastable oscillatory modes (MOMs) in fMRI and MEG signals - and compare them against simulated data. We show that both models can represent MEG functional connectivity (FC), functional connectivity dynamics (FCD) and generate MOMs to a comparable degree. This is achieved by adjusting the global coupling and mean conduction time delay and, in the WC model, through the inclusion of balance between excitation and inhibition. For both models, the omission of delays dramatically decreased the performance. For fMRI, the SL model performed worse for FCD and MOMs, highlighting the importance of balanced dynamics for the emergence of spatiotemporal and transient patterns of ultra-slow dynamics. Notably, optimal working points varied across modalities and no model was able to achieve a correlation with empirical FC higher than 0.4 across modalities for the same set of parameters. Nonetheless, both displayed the emergence of FC patterns that extended beyond the constraints of the anatomical structure. Finally, we show that both models can generate MOMs with empirical-like properties such as size (number of brain regions engaging in a mode) and duration (continuous time interval during which a mode appears). Our results demonstrate the emergence of static and dynamic properties of neural activity at different timescales from networks of delay-coupled oscillators at 40 Hz. Given the higher dependence of simulated FC on the underlying structural connectivity, we suggest that mesoscale heterogeneities in neural circuitry may be critical for the emergence of parallel cross-modal functional networks and should be accounted for in future modelling endeavours.


Assuntos
Conectoma , Rede Nervosa , Humanos , Rede Nervosa/diagnóstico por imagem , Rede Nervosa/fisiologia , Encéfalo/diagnóstico por imagem , Encéfalo/fisiologia , Imageamento por Ressonância Magnética/métodos , Conectoma/métodos , Frequência Cardíaca
12.
Cureus ; 15(5): e38526, 2023 May.
Artigo em Inglês | MEDLINE | ID: mdl-37273294

RESUMO

Tuberculosis remains a major cause of death by infection in the world. Disseminated tuberculosis occurs most frequently in the context of reactivation of a previously latent infection and is invariably lethal if untreated. Age, late presentation, and serious underlying disease are strong death predictors. We report the case of a 72-year-old male patient who presented to the emergency room with sudden onset hemiparesis and aphasia, with no acute lesions on contrast CT. Two months prior to the current event, the patient had undergone surgery for a testicular abscess in a different hospital. Since the surgery, he had progressive and unexplained weight loss and dysphagia. The medical team reviewed patient records from this hospital and the one where the surgery took place and concluded that the histopathology results from the surgery were not reviewed in the post-surgery follow-up consult and that the diagnosis of genitourinary tuberculosis was never made. This disease, untreated, evolved into disseminated tuberculosis with central nervous system involvement, causing the neurological deficits the patient presented and leading to his death. Surveillance and notification systems exist for individual and public health safeguarding. In the present case, failure to review the pathology report after surgery, coupled with the absence of notification from the laboratory, delayed the diagnosis and led to patient death. This report suggests a need for continuous system improvement, with integrated healthcare records and interinstitutional communication channels, in order to minimize information loss, diagnostic delays, and public health risks.

13.
Neuroimage ; 275: 120162, 2023 07 15.
Artigo em Inglês | MEDLINE | ID: mdl-37196986

RESUMO

Disorders of consciousness are complex conditions characterised by persistent loss of responsiveness due to brain injury. They present diagnostic challenges and limited options for treatment, and highlight the urgent need for a more thorough understanding of how human consciousness arises from coordinated neural activity. The increasing availability of multimodal neuroimaging data has given rise to a wide range of clinically- and scientifically-motivated modelling efforts, seeking to improve data-driven stratification of patients, to identify causal mechanisms for patient pathophysiology and loss of consciousness more broadly, and to develop simulations as a means of testing in silico potential treatment avenues to restore consciousness. As a dedicated Working Group of clinicians and neuroscientists of the international Curing Coma Campaign, here we provide our framework and vision to understand the diverse statistical and generative computational modelling approaches that are being employed in this fast-growing field. We identify the gaps that exist between the current state-of-the-art in statistical and biophysical computational modelling in human neuroscience, and the aspirational goal of a mature field of modelling disorders of consciousness; which might drive improved treatments and outcomes in the clinic. Finally, we make several recommendations for how the field as a whole can work together to address these challenges.


Assuntos
Lesões Encefálicas , Estado de Consciência , Humanos , Estado de Consciência/fisiologia , Transtornos da Consciência/diagnóstico por imagem , Lesões Encefálicas/complicações , Neuroimagem , Simulação por Computador
14.
J Youth Adolesc ; 52(8): 1738-1752, 2023 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-37178280

RESUMO

Adolescence is a critical developmental period associated with an increased variety of interrelated risks and vulnerabilities. Previous studies have found associations between early memories of warmth and safeness, as well as emotion regulation, and self-harm and suicidal ideation in adolescence. Additionally, these early emotional memories have been found to be positively linked with some indicators of emotion regulation during this period. The present cross-sectional study extends prior research by exploring the moderating role of emotion regulation in the relationships between early memories of warmth and safeness, as well as each of the following risk-related outcomes in adolescence, in younger (i.e., 13-15) and older (i.e., 16-19) adolescents: suicidal ideation and self-harm and its associated functions (i.e., automatic and social reinforcement. Three self-report measures of these early emotional memories, emotion regulation, and risk-related outcomes, and a sample of 7918 Portuguese adolescents (53.3% females), with ages ranging from 13 to 19 (Mage = 15.5), were used. In both age groups, at high levels of emotion regulation, early memories of warmth and safeness had a greater (negative) effect on suicidal ideation and the automatic reinforcement function of self-harm, compared to at average and low levels of emotion regulation. These findings highlight the enhancing role of emotion regulation on the associations between early memories of warmth and safeness and some risk-related outcomes in adolescents, both younger and older, which reveals the relevance of targeting emotion regulation when preventing or tackling these outcomes, regardless of adolescents' levels of early memories of warmth and safeness.


Assuntos
Regulação Emocional , Comportamento Autodestrutivo , Feminino , Humanos , Adolescente , Masculino , Ideação Suicida , Estudos Transversais , Emoções/fisiologia
15.
Neuroimage ; 272: 120042, 2023 05 15.
Artigo em Inglês | MEDLINE | ID: mdl-36965862

RESUMO

Brain stimulation is an increasingly popular neuromodulatory tool used in both clinical and research settings; however, the effects of brain stimulation, particularly those of non-invasive stimulation, are variable. This variability can be partially explained by an incomplete mechanistic understanding, coupled with a combinatorial explosion of possible stimulation parameters. Computational models constitute a useful tool to explore the vast sea of stimulation parameters and characterise their effects on brain activity. Yet the utility of modelling stimulation in-silico relies on its biophysical relevance, which needs to account for the dynamics of large and diverse neural populations and how underlying networks shape those collective dynamics. The large number of parameters to consider when constructing a model is no less than those needed to consider when planning empirical studies. This piece is centred on the application of phenomenological and biophysical models in non-invasive brain stimulation. We first introduce common forms of brain stimulation and computational models, and provide typical construction choices made when building phenomenological and biophysical models. Through the lens of four case studies, we provide an account of the questions these models can address, commonalities, and limitations across studies. We conclude by proposing future directions to fully realise the potential of computational models of brain stimulation for the design of personalized, efficient, and effective stimulation strategies.


Assuntos
Modelos Neurológicos , Técnicas Estereotáxicas , Humanos , Biofísica , Encéfalo/fisiologia
16.
PLoS One ; 18(3): e0282707, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36952467

RESUMO

The disconnection hypothesis of schizophrenia proposes that symptoms of the disorder arise as a result of aberrant functional integration between segregated areas of the brain. The concept of metastability characterizes the coexistence of competing tendencies for functional integration and functional segregation in the brain, and is therefore well suited for the study of schizophrenia. In this study, we investigate metastability as a candidate neuromechanistic biomarker of schizophrenia pathology, including a demonstration of reliability and face validity. Group-level discrimination, individual-level classification, pathophysiological relevance, and explanatory power were assessed using two independent case-control studies of schizophrenia, the Human Connectome Project Early Psychosis (HCPEP) study (controls n = 53, non-affective psychosis n = 82) and the Cobre study (controls n = 71, cases n = 59). In this work we extend Leading Eigenvector Dynamic Analysis (LEiDA) to capture specific features of dynamic functional connectivity and then implement a novel approach to estimate metastability. We used non-parametric testing to evaluate group-level differences and a naïve Bayes classifier to discriminate cases from controls. Our results show that our new approach is capable of discriminating cases from controls with elevated effect sizes relative to published literature, reflected in an up to 76% area under the curve (AUC) in out-of-sample classification analyses. Additionally, our new metric showed explanatory power of between 81-92% for measures of integration and segregation. Furthermore, our analyses demonstrated that patients with early psychosis exhibit intermittent disconnectivity of subcortical regions with frontal cortex and cerebellar regions, introducing new insights about the mechanistic bases of these conditions. Overall, these findings demonstrate reliability and face validity of metastability as a candidate neuromechanistic biomarker of schizophrenia pathology.


Assuntos
Conectoma , Esquizofrenia , Humanos , Reprodutibilidade dos Testes , Teorema de Bayes , Imageamento por Ressonância Magnética/métodos , Encéfalo/patologia , Conectoma/métodos , Biomarcadores
17.
Nat Commun ; 14(1): 375, 2023 02 06.
Artigo em Inglês | MEDLINE | ID: mdl-36746938

RESUMO

Spontaneous fluctuations in functional magnetic resonance imaging (fMRI) signals correlate across distant brain areas, shaping functionally relevant intrinsic networks. However, the generative mechanism of fMRI signal correlations, and in particular the link with locally-detected ultra-slow oscillations, are not fully understood. To investigate this link, we record ultrafast ultrahigh field fMRI signals (9.4 Tesla, temporal resolution = 38 milliseconds) from female rats across three anesthesia conditions. Power at frequencies extending up to 0.3 Hz is detected consistently across rat brains and is modulated by anesthesia level. Principal component analysis reveals a repertoire of modes, in which transient oscillations organize with fixed phase relationships across distinct cortical and subcortical structures. Oscillatory modes are found to vary between conditions, resonating at faster frequencies under medetomidine sedation and reducing both in number, frequency, and duration with the addition of isoflurane. Peaking in power within clear anatomical boundaries, these oscillatory modes point to an emergent systemic property. This work provides additional insight into the origin of oscillations detected in fMRI and the organizing principles underpinning spontaneous long-range functional connectivity.


Assuntos
Anestesia , Isoflurano , Ratos , Feminino , Animais , Imageamento por Ressonância Magnética/métodos , Encéfalo/diagnóstico por imagem , Mapeamento Encefálico/métodos , Rede Nervosa
18.
Neuroimage Clin ; 37: 103351, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36805417

RESUMO

Auditory verbal hallucinations (AVH) are frequently associated with psychotic disorders, yet also occur in non-clinical voice-hearers. AVH in this group are similar to those within clinical voice-hearers in terms of several phenomenological aspects, but non-clinical voice-hearers report to have more control over their AVH and attribute less emotional valence to them. These dissimilarities may stem from differences on the neurobiological level, as it is still under debate whether the mechanisms involved in AVH are the same in clinical and non-clinical voice-hearers. In this study, 21 clinical and 21 non-clinical voice-hearers indicated the onset and offsets of AVH during an fMRI scan. Using a method called leading eigenvector dynamics analysis (LEiDA), we examined time-varying dynamics of functional connectivity involved in AVH with a sub-second temporal resolution. We assessed differences between groups, and between hallucination and rest periods in dwell time, switching frequency, probability of occurrence, and transition probabilities of nine recurrent states of functional connectivity with a permutation ANOVA. Deviations in dwell times, switching frequencies, and switch probabilities in the hallucination period indicated more erratic dynamics during this condition regardless of their clinical status. Post-hoc analyses of the dwell times exhibited the most distinct differences between the rest and hallucination condition for the non-clinical sample, suggesting stronger differences between the two conditions in this group. Overall, these findings suggest that the neurobiological mechanisms involved in AVH are similar in clinical and non-clinical individuals.


Assuntos
Transtornos Psicóticos , Voz , Humanos , Alucinações/diagnóstico por imagem , Alucinações/etiologia , Transtornos Psicóticos/complicações , Imageamento por Ressonância Magnética , Probabilidade
19.
Comput Struct Biotechnol J ; 21: 335-345, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36582443

RESUMO

Traditionally, in neuroimaging, model-free analyses are used to find significant differences between brain states via signal detection theory. Depending on the a priori assumptions about the underlying data, different spatio-temporal features can be analysed. Alternatively, model-based techniques infer features from the data and compare significance from model parameters. However, to assess transitions from one brain state to another remains a challenge in current paradigms. Here, we introduce a "Dynamic Sensitivity Analysis" framework that quantifies transitions between brain states in terms of stimulation ability to rebalance spatio-temporal brain activity towards a target state such as healthy brain dynamics. In practice, it means building a whole-brain model fitted to the spatio-temporal description of brain dynamics, and applying systematic stimulations in-silico to assess the optimal strategy to drive brain dynamics towards a target state. Further, we show how Dynamic Sensitivity Analysis extends to various brain stimulation paradigms, ultimately contributing to improving the efficacy of personalised clinical interventions.

20.
Hum Brain Mapp ; 44(2): 429-446, 2023 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-36069619

RESUMO

Music listening plays a pivotal role for children and adolescents, yet it remains unclear how music modulates brain activity at the level of functional networks in this young population. Analysing the dynamics of brain networks occurring and dissolving over time in response to music can provide a better understanding of the neural underpinning of music listening. We collected functional magnetic resonance imaging (fMRI) data from 17 preadolescents aged 10-11 years while listening to two similar music pieces separated by periods without music. We subsequently tracked the occurrence of functional brain networks over the recording time using a recent method that detects recurrent patterns of phase-locking in the fMRI signals: the leading eigenvector dynamics analysis (LEiDA). The probabilities of occurrence and switching profiles of different functional networks were compared between periods of music and no music. Our results showed significantly increased occurrence of a specific functional network during the two music pieces compared to no music, involving the medial orbitofrontal and ventromedial prefrontal cortices-a brain subsystem associated to reward processing. Moreover, the higher the musical reward sensitivity of the preadolescents, the more this network was preceded by a pattern involving the insula. Our findings highlight the involvement of a brain subsystem associated with hedonic and emotional processing during music listening in the early adolescent brain. These results offer novel insight into the neural underpinnings of musical reward in early adolescence, improving our understanding of the important role and the potential benefits of music at this delicate age.


Assuntos
Música , Criança , Humanos , Adolescente , Música/psicologia , Encéfalo/diagnóstico por imagem , Encéfalo/fisiologia , Mapeamento Encefálico , Percepção Auditiva/fisiologia , Imageamento por Ressonância Magnética , Córtex Pré-Frontal/diagnóstico por imagem , Recompensa
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