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The knowledge that brain functional connectomes are unique and reliable has enabled behaviourally relevant inferences at a subject level. However, whether such "fingerprints" persist under altered states of consciousness is unknown. Ayahuasca is a potent serotonergic psychedelic which produces a widespread dysregulation of functional connectivity. Used communally in religious ceremonies, its shared use may highlight relevant novel interactions between mental state and functional connectome (FC) idiosyncrasy. Using 7T fMRI, we assessed resting-state static and dynamic FCs for 21 Santo Daime members after collective ayahuasca intake in an acute, within-subject study. Here, connectome fingerprinting revealed FCs showed reduced idiosyncrasy, accompanied by a spatiotemporal reallocation of keypoint edges. Importantly, we show that interindividual differences in higher-order FC motifs are relevant to experiential phenotypes, given that they can predict perceptual drug effects. Collectively, our findings offer an example of how individualised connectivity markers can be used to trace a subject's FC across altered states of consciousness.
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Banisteriopsis , Conectoma , Humanos , Encéfalo/fisiologia , Estado de Consciência , Imageamento por Ressonância MagnéticaRESUMO
The discovery that human brain connectivity data can be used as a "fingerprint" to identify a given individual from a population, has become a burgeoning research area in the neuroscience field. Recent studies have identified the possibility to extract these brain signatures from the temporal rich dynamics of resting-state magneto encephalography (MEG) recordings. Nevertheless, it is still uncertain to what extent MEG signatures can serve as an indicator of human identifiability during task-related conduct. Here, using MEG data from naturalistic and neurophysiological tasks, we show that identification improves in tasks relative to resting-state, providing compelling evidence for a task dependent axis of MEG signatures. Notably, improvements in identifiability were more prominent in strictly controlled tasks. Lastly, the brain regions contributing most towards individual identification were also modified when engaged in task activities. We hope that this investigation advances our understanding of the driving factors behind brain identification from MEG signals.
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Imageamento por Ressonância Magnética , Magnetoencefalografia , Humanos , Encéfalo/fisiologia , Mapeamento Encefálico , NeurofisiologiaRESUMO
Moving from association to causal analysis of neuroimaging data is crucial to advance our understanding of brain function. The arrow-of-time (AoT), that is, the known asymmetric nature of the passage of time, is the bedrock of causal structures shaping physical phenomena. However, almost all current time series metrics do not exploit this asymmetry, probably due to the difficulty to account for it in modeling frameworks. Here, we introduce an AoT-sensitive metric that captures the intensity of causal effects in multivariate time series, and apply it to high-resolution functional neuroimaging data. We find that causal effects underlying brain function are more distinctively localized in space and time than functional activity or connectivity, thereby allowing us to trace neural pathways recruited in different conditions. Overall, we provide a mapping of the causal brain that challenges the association paradigm of brain function.
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Encéfalo , Neuroimagem , Humanos , Fatores de Tempo , Encéfalo/diagnóstico por imagem , Causalidade , Neuroimagem Funcional , Mapeamento Encefálico , Imageamento por Ressonância MagnéticaRESUMO
The clinical connectome fingerprint (CCF) was recently introduced as a way to assess brain dynamics. It is an approach able to recognize individuals, based on the brain network. It showed its applicability providing network features used to predict the cognitive decline in preclinical Alzheimer's disease. In this article, we explore the performance of CCF in 47 Parkinson's disease (PD) patients and 47 healthy controls, under the hypothesis that patients would show reduced identifiability as compared to controls, and that such reduction could be used to predict motor impairment. We used source-reconstructed magnetoencephalography signals to build two functional connectomes for 47 patients with PD and 47 healthy controls. Then, exploiting the two connectomes per individual, we investigated the identifiability characteristics of each subject in each group. We observed reduced identifiability in patients compared to healthy individuals in the beta band. Furthermore, we found that the reduction in identifiability was proportional to the motor impairment, assessed through the Unified Parkinson's Disease Rating Scale, and, interestingly, able to predict it (at the subject level), through a cross-validated regression model. Along with previous evidence, this article shows that CCF captures disrupted dynamics in neurodegenerative diseases and is particularly effective in predicting motor clinical impairment in PD.
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Doença de Alzheimer , Disfunção Cognitiva , Doença de Parkinson , Humanos , Doença de Parkinson/complicações , Doença de Parkinson/diagnóstico por imagem , Encéfalo/diagnóstico por imagem , Magnetoencefalografia , Disfunção Cognitiva/diagnóstico por imagem , Disfunção Cognitiva/etiologiaRESUMO
Brain signatures of functional activity have shown promising results in both decoding brain states, meaning distinguishing between different tasks, and fingerprinting, that is identifying individuals within a large group. Importantly, these brain signatures do not account for the underlying brain anatomy on which brain function takes place. Structure-function coupling based on graph signal processing (GSP) has recently revealed a meaningful spatial gradient from unimodal to transmodal regions, on average in healthy subjects during resting-state. Here, we explore the specificity of structure-function coupling to distinct brain states (tasks) and to individual subjects. We used multimodal magnetic resonance imaging of 100 unrelated healthy subjects from the Human Connectome Project both during rest and seven different tasks and adopted a support vector machine classification approach for both decoding and fingerprinting, with various cross-validation settings. We found that structure-function coupling measures allow accurate classifications for both task decoding and fingerprinting. In particular, key information for fingerprinting is found in the more liberal portion of functional signals, with contributions strikingly localized to the fronto-parietal network. Moreover, the liberal portion of functional signals showed a strong correlation with cognitive traits, assessed with partial least square analysis, corroborating its relevance for fingerprinting. By introducing a new perspective on GSP-based signal filtering and FC decomposition, these results show that brain structure-function coupling provides a new class of signatures of cognition and individual brain organization at rest and during tasks. Further, they provide insights on clarifying the role of low and high spatial frequencies of the structural connectome, leading to new understanding of where key structure-function information for characterizing individuals can be found across the structural connectome graph spectrum.
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Conectoma/métodos , Imageamento por Ressonância Magnética/métodos , Fenômenos Fisiológicos do Sistema Nervoso , Adulto , Feminino , Humanos , Masculino , Processamento de Sinais Assistido por Computador , Máquina de Vetores de SuporteRESUMO
Measuring the temporal complexity of functional MRI (fMRI) time series is one approach to assess how brain activity changes over time. In fact, hemodynamic response of the brain is known to exhibit critical behaviour at the edge between order and disorder. In this study, we aimed to revisit the spatial distribution of temporal complexity in resting state and task fMRI of 100 unrelated subjects from the Human Connectome Project (HCP). First, we compared two common choices of complexity measures, i.e., Hurst exponent and multiscale entropy, and observed a high spatial similarity between them. Second, we considered four tasks in the HCP dataset (Language, Motor, Social, and Working Memory) and found high task-specific complexity, even when the task design was regressed out. For the significance thresholding of brain complexity maps, we used a statistical framework based on graph signal processing that incorporates the structural connectome to develop the null distributions of fMRI complexity. The results suggest that the frontoparietal, dorsal attention, visual, and default mode networks represent stronger complex behaviour than the rest of the brain, irrespective of the task engagement. In sum, the findings support the hypothesis of fMRI temporal complexity as a marker of cognition.
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Individual characterization of subjects based on their functional connectome (FC), termed "FC fingerprinting", has become a highly sought-after goal in contemporary neuroscience research. Recent functional magnetic resonance imaging (fMRI) studies have demonstrated unique characterization and accurate identification of individuals as an accomplished task. However, FC fingerprinting in magnetoencephalography (MEG) data is still widely unexplored. Here, we study resting-state MEG data from the Human Connectome Project to assess the MEG FC fingerprinting and its relationship with several factors including amplitude- and phase-coupling functional connectivity measures, spatial leakage correction, frequency bands, and behavioral significance. To this end, we first employ two identification scoring methods, differential identifiability and success rate, to provide quantitative fingerprint scores for each FC measurement. Secondly, we explore the edgewise and nodal MEG fingerprinting patterns across the different frequency bands (delta, theta, alpha, beta, and gamma). Finally, we investigate the cross-modality fingerprinting patterns obtained from MEG and fMRI recordings from the same subjects. We assess the behavioral significance of FC across connectivity measures and imaging modalities using partial least square correlation analyses. Our results suggest that fingerprinting performance is heavily dependent on the functional connectivity measure, frequency band, identification scoring method, and spatial leakage correction. We report higher MEG fingerprinting performances in phase-coupling methods, central frequency bands (alpha and beta), and in the visual, frontoparietal, dorsal-attention, and default-mode networks. Furthermore, cross-modality comparisons reveal a certain degree of spatial concordance in fingerprinting patterns between the MEG and fMRI data, especially in the visual system. Finally, the multivariate correlation analyses show that MEG connectomes have strong behavioral significance, which however depends on the considered connectivity measure and temporal scale. This comprehensive, albeit preliminary investigation of MEG connectome test-retest identifiability offers a first characterization of MEG fingerprinting in relation to different methodological and electrophysiological factors and contributes to the understanding of fingerprinting cross-modal relationships. We hope that this first investigation will contribute to setting the grounds for MEG connectome identification.
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Encéfalo/fisiologia , Conectoma/normas , Imageamento por Ressonância Magnética/normas , Magnetoencefalografia/normas , Rede Nervosa/fisiologia , Adulto , Encéfalo/diagnóstico por imagem , Conectoma/métodos , Feminino , Humanos , Imageamento por Ressonância Magnética/métodos , Magnetoencefalografia/métodos , Masculino , Rede Nervosa/diagnóstico por imagemRESUMO
Brain connectome fingerprinting is rapidly rising as a novel influential field in brain network analysis. Yet, it is still unclear whether connectivity fingerprints could be effectively used for mapping and predicting disease progression from human brain data. We hypothesize that dysregulation of brain activity in disease would reflect in worse subject identification. We propose a novel framework, Clinical Connectome Fingerprinting, to detect individual connectome features from clinical populations. We show that "clinical fingerprints" can map individual variations between elderly healthy subjects and patients with mild cognitive impairment in functional connectomes extracted from magnetoencephalography data. We find that identifiability is reduced in patients as compared to controls, and show that these connectivity features are predictive of the individual Mini-Mental State Examination (MMSE) score in patients. We hope that the proposed methodology can help in bridging the gap between connectivity features and biomarkers of brain dysfunction in large-scale brain networks.
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Encéfalo/fisiopatologia , Cognição/fisiologia , Disfunção Cognitiva/fisiopatologia , Conectoma , Rede Nervosa/fisiopatologia , Disfunção Cognitiva/psicologia , Humanos , Magnetoencefalografia , Testes NeuropsicológicosRESUMO
Functional connectivity, as estimated using resting state functional MRI, has shown potential in bridging the gap between pathophysiology and cognition. However, clinical use of functional connectivity biomarkers is impeded by unreliable estimates of individual functional connectomes and lack of generalizability of models predicting cognitive outcomes from connectivity. To address these issues, we combine the frameworks of connectome predictive modeling and differential identifiability. Using the combined framework, we show that enhancing the individual fingerprint of resting state functional connectomes leads to robust identification of functional networks associated to cognitive outcomes and also improves prediction of cognitive outcomes from functional connectomes. Using a comprehensive spectrum of cognitive outcomes associated to Alzheimer's disease (AD), we identify and characterize functional networks associated to specific cognitive deficits exhibited in AD. This combined framework is an important step in making individual level predictions of cognition from resting state functional connectomes and in understanding the relationship between cognition and connectivity.
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Doença de Alzheimer/diagnóstico por imagem , Disfunção Cognitiva/diagnóstico por imagem , Conectoma/métodos , Rede Nervosa/diagnóstico por imagem , Idoso , Idoso de 80 Anos ou mais , Doença de Alzheimer/fisiopatologia , Disfunção Cognitiva/fisiopatologia , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino , Rede Nervosa/fisiopatologiaRESUMO
Human functional brain connectivity is usually measured either at "rest" or during cognitive tasks, ignoring life's moments of mental transition. We propose a different approach to understanding brain network transitions. We applied a novel independent component analysis of functional connectivity during motor inhibition (stop signal task) and during the continuous transition to an immediately ensuing rest. A functional network reconfiguration process emerged that: (i) was most prominent in those without familial alcoholism risk, (ii) encompassed brain areas engaged by the task, yet (iii) appeared only transiently after task cessation. The pattern was not present in a pre-task rest scan or in the remaining minutes of post-task rest. Finally, this transient network reconfiguration related to a key behavioral trait of addiction risk: reward delay discounting. These novel findings illustrate how dynamic brain functional reconfiguration during normally unstudied periods of cognitive transition might reflect addiction vulnerability, and potentially other forms of brain dysfunction.
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Alcoolismo/fisiopatologia , Córtex Cerebral/fisiopatologia , Conectoma , Desvalorização pelo Atraso/fisiologia , Predisposição Genética para Doença , Inibição Psicológica , Atividade Motora/fisiologia , Rede Nervosa/fisiologia , Recompensa , Adulto , Alcoolismo/diagnóstico por imagem , Córtex Cerebral/diagnóstico por imagem , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino , Rede Nervosa/diagnóstico por imagem , Fatores de Tempo , Adulto JovemRESUMO
It has been well established that Functional Connectomes (FCs), as estimated from functional MRI (fMRI) data, have an individual fingerprint that can be used to identify an individual from a population (subject-identification). Although identification rate is high when using resting-state FCs, other tasks show moderate to low values. Furthermore, identification rate is task-dependent, and is low when distinct cognitive states, as captured by different fMRI tasks, are compared. Here we propose an embedding framework, GEFF (Graph Embedding for Functional Fingerprinting), based on group-level decomposition of FCs into eigenvectors. GEFF creates an eigenspace representation of a group of subjects using one or more task FCs (Learning Stage). In the Identification Stage, we compare new instances of FCs from the Learning subjects within this eigenspace (validation dataset). The validation dataset contains FCs either from the same tasks as the Learning dataset or from the remaining tasks that were not included in Learning. Assessment of validation FCs within the eigenspace results in significantly increased subject-identification rates for all fMRI tasks tested and potentially task-independent fingerprinting process. It is noteworthy that combining resting-state with one fMRI task for GEFF Learning Stage covers most of the cognitive space for subject identification. Thus, while designing an experiment, one could choose a task fMRI to ask a specific question and combine it with resting-state fMRI to extract maximum subject differentiability using GEFF. In addition to subject-identification, GEFF was also used for identification of cognitive states, i.e. to identify the task associated to a given FC, regardless of the subject being already in the Learning dataset or not (subject-independent task-identification). In addition, we also show that eigenvectors from the Learning Stage can be characterized as task- and subject-dominant, subject-dominant or neither, using two-way ANOVA of their corresponding loadings, providing a deeper insight into the extent of variance in functional connectivity across individuals and cognitive states.
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Encéfalo/fisiologia , Cognição/fisiologia , Conectoma/métodos , Imageamento por Ressonância Magnética/métodos , Modelos Teóricos , Adulto , Encéfalo/diagnóstico por imagem , Feminino , Humanos , Processamento de Imagem Assistida por Computador , Masculino , Adulto JovemRESUMO
Huntington's disease (HD) is the most common neurodegenerative disorder for which no effective cure is yet available. Although several agents have been identified to provide benefits so far, the number of therapeutic options remains limited with only symptomatic treatment available. Over the past few years, we have demonstrated that sphingolipid-based approaches may open the door to new and more targeted treatments for the disease. In this study, we investigated the therapeutic potential of stimulating sphingosine-1-phosphate (S1P) receptor 5 by the new selective agonist A-971432 (provided by AbbVie) in R6/2 mice, a widely used HD animal model. Chronic administration of low-dose (0.1 mg/kg) A-971432 slowed down the progression of the disease and significantly prolonged lifespan in symptomatic R6/2 mice. Such beneficial effects were associated with activation of pro-survival pathways (BDNF, AKT and ERK) and with reduction of mutant huntingtin aggregation. A-971432 also protected blood-brain barrier (BBB) homeostasis in the same mice. Interestingly, when administered early in the disease, before any overt symptoms, A-971432 completely protected HD mice from the classic progressive motor deficit and preserved BBB integrity. Beside representing a promising strategy to take into consideration for the development of alternative therapeutic options for HD, selective stimulation of S1P receptor 5 may be also seen as an effective approach to target brain vasculature defects in the disease.
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Barreira Hematoencefálica/efeitos dos fármacos , Proteína Huntingtina/genética , Doença de Huntington/tratamento farmacológico , Agregação Patológica de Proteínas/tratamento farmacológico , Receptores de Lisoesfingolipídeo/genética , Animais , Encéfalo/efeitos dos fármacos , Encéfalo/patologia , Fator Neurotrófico Derivado do Encéfalo/genética , Modelos Animais de Doenças , MAP Quinases Reguladas por Sinal Extracelular/genética , Regulação da Expressão Gênica/efeitos dos fármacos , Humanos , Doença de Huntington/genética , Doença de Huntington/patologia , Camundongos , Camundongos Transgênicos , Atividade Motora/efeitos dos fármacos , Agregação Patológica de Proteínas/fisiopatologia , Proteínas Proto-Oncogênicas c-akt/genética , Receptores de Lisoesfingolipídeo/agonistasRESUMO
Multi-site studies are becoming important to increase statistical power, enhance generalizability, and to improve the likelihood of pooling relevant subgroups together-activities which are otherwise limited by the availability of subjects or funds at a single site. Even with harmonized imaging sequences, site-dependent variability can mask the advantages of these multi-site studies. The aim of this study was to assess multi-site reproducibility in resting-state functional connectivity "fingerprints", and to improve identifiability of functional connectomes. The individual fingerprinting of functional connectivity profiles is promising due to its potential as a robust neuroimaging biomarker with which to draw single-subject inferences. We evaluated, on two independent multi-site datasets, individual fingerprints in test-retest visit pairs within and across two sites and present a generalized framework based on principal component analysis to improve identifiability. Those principal components that maximized differential identifiability of a training dataset were used as an orthogonal connectivity basis to reconstruct the individual functional connectomes of training and validation sets. The optimally reconstructed functional connectomes showed a substantial improvement in individual fingerprinting of the subjects within and across the two sites and test-retest visit pairs relative to the original data. A notable increase in ICC values for functional edges and resting-state networks were also observed for reconstructed functional connectomes. Improvements in identifiability were not found to be affected by global signal regression. Post-hoc analyses assessed the effect of the number of fMRI volumes on identifiability and showed that multi-site differential identifiability was for all cases maximized after optimal reconstruction. Finally, the generalizability of the optimal set of orthogonal basis of each dataset was evaluated through a leave-one-out procedure. Overall, results demonstrate that the data-driven framework presented in this study systematically improves identifiability in resting-state functional connectomes in multi-site studies.
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Encéfalo/diagnóstico por imagem , Conectoma/normas , Imageamento por Ressonância Magnética/normas , Estudos Multicêntricos como Assunto/normas , Rede Nervosa/diagnóstico por imagem , Adolescente , Adulto , Encéfalo/fisiologia , Estudos de Coortes , Conectoma/métodos , Feminino , Humanos , Imageamento por Ressonância Magnética/métodos , Masculino , Estudos Multicêntricos como Assunto/métodos , Rede Nervosa/fisiologia , Adulto JovemRESUMO
INTRODUCTION: Given that recent research has shown that functional connectivity is not a static phenomenon, we aim to investigate the dynamic properties of the default mode network's (DMN) connectivity in patients with disorders of consciousness. METHODS: Resting-state fMRI volumes of a convenience sample of 17 patients in unresponsive wakefulness syndrome (UWS) and controls were reduced to a spatiotemporal point process by selecting critical time points in the posterior cingulate cortex (PCC). Spatial clustering was performed on the extracted PCC time frames to obtain 8 different co-activation patterns (CAPs). We investigated spatial connectivity patterns positively and negatively correlated with PCC using both CAPs and standard stationary method. We calculated CAPs occurrences and the total number of frames. RESULTS: Compared to controls, patients showed (i) decreased within-network positive correlations and between-network negative correlations, (ii) emergence of "pathological" within-network negative correlations and between-network positive correlations (better defined with CAPs), and (iii) "pathological" increases in within-network positive correlations and between-network negative correlations (only detectable using CAPs). Patients showed decreased occurrence of DMN-like CAPs (1-2) compared to controls. No between-group differences were observed in the total number of frames CONCLUSION: CAPs reveal at a more fine-grained level the multifaceted spatial connectivity reconfiguration following the DMN disruption in UWS patients, which is more complex than previously thought and suggests alternative anatomical substrates for consciousness. BOLD fluctuations do not seem to differ between patients and controls, suggesting that BOLD response represents an intrinsic feature of the signal, and therefore that spatial configuration is more important for consciousness than BOLD activation itself. Hum Brain Mapp 39:89-103, 2018. © 2017 Wiley Periodicals, Inc.
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Encéfalo/fisiopatologia , Transtornos da Consciência/fisiopatologia , Adulto , Encéfalo/diagnóstico por imagem , Circulação Cerebrovascular/fisiologia , Transtornos da Consciência/diagnóstico por imagem , Estudos Transversais , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino , Vias Neurais/diagnóstico por imagem , Vias Neurais/fisiopatologia , Oxigênio/sangueRESUMO
Examining task-free functional connectivity (FC) in the human brain offers insights on how spontaneous integration and segregation of information relate to human cognition, and how this organization may be altered in different conditions, and neurological disorders. This is particularly relevant for patients in disorders of consciousness (DOC) following severe acquired brain damage and coma, one of the most devastating conditions in modern medical care. We present a novel data-driven methodology, connICA, which implements Independent Component Analysis (ICA) for the extraction of robust independent FC patterns (FC-traits) from a set of individual functional connectomes, without imposing any a priori data stratification into groups. We here apply connICA to investigate associations between network traits derived from task-free FC and cognitive/clinical features that define levels of consciousness. Three main independent FC-traits were identified and linked to consciousness-related clinical features. The first one represents the functional configuration of a "resting" human brain, and it is associated to a sedative (sevoflurane), the overall effect of the pathology and the level of arousal. The second FC-trait reflects the disconnection of the visual and sensory-motor connectivity patterns. It also relates to the time since the insult and to the ability of communicating with the external environment. The third FC-trait isolates the connectivity pattern encompassing the fronto-parietal and the default-mode network areas as well as the interaction between left and right hemispheres, which are also associated to the awareness of the self and its surroundings. Each FC-trait represents a distinct functional process with a role in the degradation of conscious states of functional brain networks, shedding further light on the functional sub-circuits that get disrupted in severe brain-damage.
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Mapeamento Encefálico/métodos , Transtornos da Consciência/psicologia , Estado de Consciência/fisiologia , Vias Neurais/fisiologia , Adulto , Anestésicos Inalatórios/farmacologia , Nível de Alerta/efeitos dos fármacos , Cognição/fisiologia , Estudos de Coortes , Estado de Consciência/efeitos dos fármacos , Transtornos da Consciência/induzido quimicamente , Transtornos da Consciência/diagnóstico por imagem , Feminino , Lobo Frontal/diagnóstico por imagem , Lobo Frontal/fisiologia , Humanos , Imageamento por Ressonância Magnética , Masculino , Processos Mentais/fisiologia , Éteres Metílicos/farmacologia , Pessoa de Meia-Idade , Vias Neurais/diagnóstico por imagem , Vias Neurais/efeitos dos fármacos , Lobo Parietal/diagnóstico por imagem , Lobo Parietal/fisiologia , Sensação/efeitos dos fármacos , Sevoflurano , Percepção Visual/efeitos dos fármacosRESUMO
When a monkey selects a piece of food lying on the ground from among other viable objects in the near vicinity, only the desired item governs the particular pattern and direction of the animal's reaching action. It would seem then that selection is an important component controlling the animal's action. But, we may ask, is the selection process in such cases impervious to the presence of other objects that could constitute potential obstacles to or constraints on movement execution? And if it is, in fact, pervious to other objects, do they have a direct influence on the organization of the response? The kinematics of macaques' reaching movements were examined by the current study that analysed some exemplars as they selectively reached to grasp a food item in the absence as well as in the presence of potential obstacles (i.e., stones) that could affect the arm trajectory. Changes in movement parameterization were noted in temporal measures, such as movement time, as well as in spatial ones, such as paths of trajectory. Generally speaking, the presence of stones in the vicinity of the acting hand stalled the reaching movement and affected the arm trajectory as the hand veered away from the stone even when it was not a physical obstacle. We concluded that nearby objects evoke a motor response in macaques, and the attentional mechanisms that allow for a successful action selection are revealed in the reaching path. The data outlined here concur with human studies indicating that potential obstacles are internally represented, a finding implying basic cognitive operations allowing for action selection in macaques.
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Atenção , Macaca , Movimento , Animais , Mãos , Força da Mão , Humanos , Desempenho PsicomotorRESUMO
Huntington disease (HD) is a genetic neurodegenerative disorder for which there is currently no cure and no way to stop or even slow the brain changes it causes. In the present study, we aimed to investigate whether FTY720, the first approved oral therapy for multiple sclerosis, may be effective in HD models and eventually constitute an alternative therapeutic approach for the treatment of the disease. Here, we utilized preclinical target validation paradigms and examined the in vivo efficacy of chronic administration of FTY720 in R6/2 HD mouse model. Our findings indicate that FTY720 improved motor function, prolonged survival and reduced brain atrophy in R6/2 mice. The beneficial effect of FTY720 administration was associated with a significant strengthening of neuronal activity and connectivity and, with reduction of mutant huntingtin aggregates, and it was also paralleled by increased phosphorylation of mutant huntingtin at serine 13/16 residues that are predicted to attenuate protein toxicity.
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Doença de Huntington/tratamento farmacológico , Doenças Neurodegenerativas/tratamento farmacológico , Propilenoglicóis/uso terapêutico , Esfingosina/análogos & derivados , Animais , Encéfalo/efeitos dos fármacos , Encéfalo/metabolismo , Encéfalo/patologia , Linhagem Celular , Modelos Animais de Doenças , Cloridrato de Fingolimode , Doença de Huntington/metabolismo , Immunoblotting , Imuno-Histoquímica , Masculino , Camundongos , Camundongos Transgênicos , Doenças Neurodegenerativas/metabolismo , Fosfotransferases (Aceptor do Grupo Álcool)/metabolismo , Reação em Cadeia da Polimerase em Tempo Real , Esfingosina/uso terapêuticoRESUMO
Huntington disease (HD) is a neurodegenerative disorder for which new treatments are urgently needed. Pridopidine is a new dopaminergic stabilizer, recently developed for the treatment of motor symptoms associated with HD. The therapeutic effect of pridopidine in patients with HD has been determined in two double-blind randomized clinical trials, however, whether pridopidine exerts neuroprotection remains to be addressed. The main goal of this study was to define the potential neuroprotective effect of pridopidine, in HD in vivo and in vitro models, thus providing evidence that might support a potential disease-modifying action of the drug and possibly clarifying other aspects of pridopidine mode-of-action. Our data corroborated the hypothesis of neuroprotective action of pridopidine in HD experimental models. Administration of pridopidine protected cells from apoptosis, and resulted in highly improved motor performance in R6/2 mice. The anti-apoptotic effect observed in the in vitro system highlighted neuroprotective properties of the drug, and advanced the idea of sigma-1-receptor as an additional molecular target implicated in the mechanism of action of pridopidine. Coherent with protective effects, pridopidine-mediated beneficial effects in R6/2 mice were associated with an increased expression of pro-survival and neurostimulatory molecules, such as brain derived neurotrophic factor and DARPP32, and with a reduction in the size of mHtt aggregates in striatal tissues. Taken together, these findings support the theory of pridopidine as molecule with disease-modifying properties in HD and advance the idea of a valuable therapeutic strategy for effectively treating the disease.
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Doença de Huntington/tratamento farmacológico , Atividade Motora/efeitos dos fármacos , Fármacos Neuroprotetores/uso terapêutico , Piperidinas/uso terapêutico , Animais , Apoptose/efeitos dos fármacos , Fator Neurotrófico Derivado do Encéfalo/metabolismo , Linhagem Celular Transformada , Modelos Animais de Doenças , Fosfoproteína 32 Regulada por cAMP e Dopamina/metabolismo , Doença de Huntington/metabolismo , Doença de Huntington/fisiopatologia , CamundongosRESUMO
The emerging neuroscientific frontier of brain fingerprinting has recently established that human functional connectomes (FCs) exhibit fingerprint-like idiosyncratic features, which map onto heterogeneously distributed behavioral traits. Here, we harness brain-fingerprinting tools to extract FC features that predict subjective drug experience induced by the psychedelic psilocybin. Specifically, in neuroimaging data of healthy volunteers under the acute influence of psilocybin or a placebo, we show that, post psilocybin administration, FCs become more idiosyncratic owing to greater intersubject dissimilarity. Moreover, whereas in placebo subjects idiosyncratic features are primarily found in the frontoparietal network, in psilocybin subjects they concentrate in the default mode network (DMN). Crucially, isolating the latter revealed an FC pattern that predicts subjective psilocybin experience and is characterized by reduced within-DMN and DMN-limbic connectivity, as well as increased connectivity between the DMN and attentional systems. Overall, these results contribute to bridging the gap between psilocybin-mediated effects on brain and behavior, while demonstrating the value of a brain-fingerprinting approach to pharmacological neuroimaging.
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Higher-order properties of functional magnetic resonance imaging (fMRI) induced connectivity have been shown to unravel many exclusive topological and dynamical insights beyond pairwise interactions. Nonetheless, whether these fMRI-induced higher-order properties play a role in disentangling other neuroimaging modalities' insights remains largely unexplored and poorly understood. In this work, by analyzing fMRI data from the Human Connectome Project Young Adult dataset using persistent homology, we discovered that the volume-optimal persistence homological scaffolds of fMRI-based functional connectomes exhibited conservative topological reconfigurations from the resting state to attentional task-positive state. Specifically, while reflecting the extent to which each cortical region contributed to functional cycles following different cognitive demands, these reconfigurations were constrained such that the spatial distribution of cavities in the connectome is relatively conserved. Most importantly, such level of contributions covaried with powers of aperiodic activities mostly within the theta-alpha (4-12 Hz) band measured by magnetoencephalography (MEG). This comprehensive result suggests that fMRI-induced hemodynamics and MEG theta-alpha aperiodic activities are governed by the same functional constraints specific to each cortical morpho-structure. Methodologically, our work paves the way toward an innovative computing paradigm in multimodal neuroimaging topological learning. The code for our analyses is provided in https://github.com/ngcaonghi/scaffold_noise.