Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 4.839
Filtrar
1.
Philos Trans A Math Phys Eng Sci ; 379(2212): 20200256, 2021 Dec 13.
Artigo em Inglês | MEDLINE | ID: mdl-34689621

RESUMO

While Granger causality (GC) has been often employed in network neuroscience, most GC applications are based on linear multivariate autoregressive (MVAR) models. However, real-life systems like biological networks exhibit notable nonlinear behaviour, hence undermining the validity of MVAR-based GC (MVAR-GC). Most nonlinear GC estimators only cater for additive nonlinearities or, alternatively, are based on recurrent neural networks or long short-term memory networks, which present considerable training difficulties and tailoring needs. We reformulate the GC framework in terms of echo-state networks-based models for arbitrarily complex networks, and characterize its ability to capture nonlinear causal relations in a network of noisy Duffing oscillators, showing a net advantage of echo state GC (ES-GC) in detecting nonlinear, causal links. We then explore the structure of ES-GC networks in the human brain employing functional MRI data from 1003 healthy subjects drawn from the human connectome project, demonstrating the existence of previously unknown directed within-brain interactions. In addition, we examine joint brain-heart signals in 15 subjects where we explore directed interaction between brain networks and central vagal cardiac control in order to investigate the so-called central autonomic network in a causal manner. This article is part of the theme issue 'Advanced computation in cardiovascular physiology: new challenges and opportunities'.


Assuntos
Conectoma , Redes Neurais de Computação , Encéfalo/diagnóstico por imagem , Humanos , Imageamento por Ressonância Magnética , Rede Nervosa/diagnóstico por imagem
2.
Isr Med Assoc J ; 23(10): 625-630, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34672443

RESUMO

BACKGROUND: Only a small proportion of schizophrenia patients present with catatonic symptoms. Imaging studies suggest that brain motor circuits are involved in the underlying pathology of catatonia. However, data about diffusivity dysregulation of these circuits in catatonic schizophrenia are scarce. OBJECTIVES: To assess the involvement of brain motor circuits in schizophrenia patients with catatonia. METHODS: Diffusion tensor imaging (DTI) was used to measure white matter signals in selected brain regions linked to motor circuits. Relevant DTI data of seven catatonic schizophrenia patients were compared to those of seven non-catatonic schizophrenia patients, matched for sex, age, and education level. RESULTS: Significantly elevated fractional anisotropy values were found in the splenium of the corpus callosum, the right peduncle of the cerebellum, and the right internal capsule of the schizophrenia patients with catatonia compared to those without catatonia. This finding showed altered diffusivity in selected motor-related brain areas. CONCLUSIONS: Catatonic schizophrenia is associated with dysregulation of the connectivity in specific motoric brain regions and corresponding circuits. Future DTI studies are needed to address the neural correlates of motor abnormalities in schizophrenia-related catatonia during the acute and remitted state of the illness to identify the specific pathophysiology of this disorder.


Assuntos
Imagem de Tensor de Difusão/métodos , Córtex Motor , Esquizofrenia Catatônica , Adulto , Anisotropia , Cerebelo/diagnóstico por imagem , Cerebelo/fisiopatologia , Conectoma/métodos , Corpo Caloso/diagnóstico por imagem , Corpo Caloso/fisiopatologia , Correlação de Dados , Manual Diagnóstico e Estatístico de Transtornos Mentais , Feminino , Humanos , Cápsula Interna/diagnóstico por imagem , Cápsula Interna/fisiopatologia , Masculino , Córtex Motor/diagnóstico por imagem , Córtex Motor/fisiopatologia , Escalas de Graduação Psiquiátrica , Esquizofrenia Catatônica/diagnóstico , Esquizofrenia Catatônica/fisiopatologia
3.
Transl Psychiatry ; 11(1): 511, 2021 10 07.
Artigo em Inglês | MEDLINE | ID: mdl-34620830

RESUMO

Major depressive disorder (MDD) is associated with abnormal neural circuitry. It can be measured by assessing functional connectivity (FC) at resting-state functional MRI, that may help identifying neural markers of MDD and provide further efficient diagnosis and monitor treatment outcomes. The main aim of the present study is to investigate, in an unbiased way, functional alterations in patients with MDD using a large multi-center dataset from the PsyMRI consortium including 1546 participants from 19 centers ( www.psymri.com ). After applying strict exclusion criteria, the final sample consisted of 606 MDD patients (age: 35.8 ± 11.9 y.o.; females: 60.7%) and 476 healthy participants (age: 33.3 ± 11.0 y.o.; females: 56.7%). We found significant relative hypoconnectivity within somatosensory motor (SMN), salience (SN) networks and between SMN, SN, dorsal attention (DAN), and visual (VN) networks in MDD patients. No significant differences were detected within the default mode (DMN) and frontoparietal networks (FPN). In addition, alterations in network organization were observed in terms of significantly lower network segregation of SMN in MDD patients. Although medicated patients showed significantly lower FC within DMN, FPN, and SN than unmedicated patients, there were no differences between medicated and unmedicated groups in terms of network organization in SMN. We conclude that the network organization of cortical networks, involved in processing of sensory information, might be a more stable neuroimaging marker for MDD than previously assumed alterations in higher-order neural networks like DMN and FPN.


Assuntos
Conectoma , Transtorno Depressivo Maior , Adulto , Encéfalo/diagnóstico por imagem , Mapeamento Encefálico , Transtorno Depressivo Maior/diagnóstico por imagem , Transtorno Depressivo Maior/tratamento farmacológico , Feminino , Humanos , Imageamento por Ressonância Magnética , Pessoa de Meia-Idade , Vias Neurais/diagnóstico por imagem , Descanso , Adulto Jovem
4.
Transl Psychiatry ; 11(1): 526, 2021 10 13.
Artigo em Inglês | MEDLINE | ID: mdl-34645783

RESUMO

Brain function relies on efficient communications between distinct brain systems. The pathology of major depressive disorder (MDD) damages functional brain networks, resulting in cognitive impairment. Here, we reviewed the associations between brain functional connectome changes and MDD pathogenesis. We also highlighted the utility of brain functional connectome for differentiating MDD from other similar psychiatric disorders, predicting recurrence and suicide attempts in MDD, and evaluating treatment responses. Converging evidence has now linked aberrant brain functional network organization in MDD to the dysregulation of neurotransmitter signaling and neuroplasticity, providing insights into the neurobiological mechanisms of the disease and antidepressant efficacy. Widespread connectome dysfunctions in MDD patients include multiple, large-scale brain networks as well as local disturbances in brain circuits associated with negative and positive valence systems and cognitive functions. Although the clinical utility of the brain functional connectome remains to be realized, recent findings provide further promise that research in this area may lead to improved diagnosis, treatments, and clinical outcomes of MDD.


Assuntos
Conectoma , Transtorno Depressivo Maior , Encéfalo/diagnóstico por imagem , Humanos , Imageamento por Ressonância Magnética , Rede Nervosa/diagnóstico por imagem
5.
PLoS One ; 16(10): e0258992, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34673832

RESUMO

Systematic evaluation of cortical differences between humans and macaques calls for inter-species registration of the cortex that matches homologous regions across species. For establishing homology across brains, structural landmarks and biological features have been used without paying sufficient attention to functional homology. The present study aimed to determine functional homology between the human and macaque cortices, defined in terms of functional network properties, by proposing an iterative functional network-based registration scheme using surface-based spherical demons. The functional connectivity matrix of resting-state functional magnetic resonance imaging (rs-fMRI) among cortical parcellations was iteratively calculated for humans and macaques. From the functional connectivity matrix, the functional network properties such as principal network components were derived to estimate a deformation field between the human and macaque cortices. The iterative registration procedure updates the parcellation map of macaques, corresponding to the human connectome project's multimodal parcellation atlas, which was used to derive the macaque's functional connectivity matrix. To test the plausibility of the functional network-based registration, we compared cortical registration using structural versus functional features in terms of cortical regional areal change. We also evaluated the interhemispheric asymmetry of regional area and its inter-subject variability in humans and macaques as an indirect validation of the proposed method. Higher inter-subject variability and interhemispheric asymmetry were found in functional homology than in structural homology, and the assessed asymmetry and variations were higher in humans than in macaques. The results emphasize the significance of functional network-based cortical registration across individuals within a species and across species.


Assuntos
Córtex Cerebral/diagnóstico por imagem , Rede Nervosa/diagnóstico por imagem , Algoritmos , Animais , Mapeamento Encefálico , Conectoma , Humanos , Processamento de Imagem Assistida por Computador , Macaca mulatta , Imageamento por Ressonância Magnética , Especificidade da Espécie
6.
Nat Commun ; 12(1): 5728, 2021 09 30.
Artigo em Inglês | MEDLINE | ID: mdl-34593791

RESUMO

Our thoughts arise from coordinated patterns of interactions between brain structures that change with our ongoing experiences. High-order dynamic correlations in neural activity patterns reflect different subgraphs of the brain's functional connectome that display homologous lower-level dynamic correlations. Here we test the hypothesis that high-level cognition is reflected in high-order dynamic correlations in brain activity patterns. We develop an approach to estimating high-order dynamic correlations in timeseries data, and we apply the approach to neuroimaging data collected as human participants either listen to a ten-minute story or listen to a temporally scrambled version of the story. We train across-participant pattern classifiers to decode (in held-out data) when in the session each neural activity snapshot was collected. We find that classifiers trained to decode from high-order dynamic correlations yield the best performance on data collected as participants listened to the (unscrambled) story. By contrast, classifiers trained to decode data from scrambled versions of the story yielded the best performance when they were trained using first-order dynamic correlations or non-correlational activity patterns. We suggest that as our thoughts become more complex, they are reflected in higher-order patterns of dynamic network interactions throughout the brain.


Assuntos
Percepção Auditiva/fisiologia , Encéfalo/fisiologia , Cognição/fisiologia , Modelos Neurológicos , Encéfalo/diagnóstico por imagem , Conectoma , Conjuntos de Dados como Assunto , Imageamento por Ressonância Magnética , Rede Nervosa/fisiologia , Neuroimagem/métodos , Fatores de Tempo
7.
Sci Rep ; 11(1): 20803, 2021 10 21.
Artigo em Inglês | MEDLINE | ID: mdl-34675312

RESUMO

The interaction of acute exercise and the central nervous system evokes increasing interest in interdisciplinary research fields of neuroscience. Novel approaches allow to monitor large-scale brain networks from mobile electroencephalography (EEG) applying graph theory, but it is yet uncertain whether brain graphs extracted after exercise are reliable. We therefore aimed to investigate brain graph reliability extracted from resting state EEG data before and after submaximal exercise twice within one week in male participants. To obtain graph measures, we extracted global small-world-index (SWI), clustering coefficient (CC) and characteristic path length (PL) based on weighted phase leg index (wPLI) and spectral coherence (Coh) calculation. For reliability analysis, Intraclass-Correlation-Coefficient (ICC) and Coefficient of Variation (CoV) were computed for graph measures before (REST) and after POST) exercise. Overall results revealed poor to excellent measures at PRE and good to excellent ICCs at POST in the theta, alpha-1 and alpha-2, beta-1 and beta-2 frequency band. Based on bootstrap-analysis, a positive effect of exercise on reliability of wPLI based measures was observed, while exercise induced a negative effect on reliability of Coh-based graph measures. Findings indicate that brain graphs are a reliable tool to analyze brain networks in exercise contexts, which might be related to the neuroregulating effect of exercise inducing functional connections within the connectome. Relative and absolute reliability demonstrated good to excellent reliability after exercise. Chosen graph measures may not only allow analysis of acute, but also longitudinal studies in exercise-scientific contexts.


Assuntos
Encéfalo/diagnóstico por imagem , Teste de Esforço , Exercício Físico , Rede Nervosa/fisiologia , Adulto , Algoritmos , Análise por Conglomerados , Conectoma/métodos , Eletroencefalografia , Voluntários Saudáveis , Humanos , Estudos Longitudinais , Masculino , Reprodutibilidade dos Testes , Adulto Jovem
8.
PLoS One ; 16(10): e0249846, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34705821

RESUMO

Understanding hierarchy and modularity in natural as well as technological networks is of utmost importance. A major aspect of such analysis involves identifying the nodes that are crucial to the overall processing structure of the network. More recently, the approach of hourglass analysis has been developed for the purpose of quantitatively analyzing whether only a few intermediate nodes mediate the information processing between a large number of inputs and outputs of a network. We develop a new framework for hourglass analysis that takes network weights into account while identifying the core nodes and the extent of hourglass effect in a given weighted network. We use this framework to study the structural connectome of the C. elegans and identify intermediate neurons that form the core of sensori-motor pathways in the organism. Our results show that the neurons forming the core of the connectome show significant differences across the male and hermaphrodite sexes, with most core nodes in the male concentrated in sex-organs while they are located in the head for the hermaphrodite. Our work demonstrates that taking weights into account for network analysis framework leads to emergence of different network patterns in terms of identification of core nodes and hourglass structure in the network, which otherwise would be missed by unweighted approaches.


Assuntos
Caenorhabditis elegans/fisiologia , Rede Nervosa/fisiologia , Animais , Conectoma/métodos , Masculino , Modelos Neurológicos , Neurônios/fisiologia , Córtex Sensório-Motor/fisiologia , Sinapses/fisiologia
9.
J Affect Disord ; 295: 759-770, 2021 12 01.
Artigo em Inglês | MEDLINE | ID: mdl-34517250

RESUMO

BACKGROUND: From the perspective of information processing, an integrated understanding of the structural and functional connectomes in depression patients is important, a multimodal meta-analysis is required to detect the robust alterations in graph metrics across studies. METHODS: Following a systematic search, 952 depression patients and 1447 controls in nine diffusion magnetic resonance imaging (dMRI) and twelve rest state functional MRI (rs-fMRI) studies with high methodological quality met the inclusion criteria and were included in the meta-analysis. RESULTS: Regarding the dMRI results, no significant differences of meta-analytic metrics were found; regarding the rs-fMRI results, the modularity and local efficiency were found to be significantly lower in the depression group than in the controls (Hedge's g = -0.330 and -0.349, respectively). CONCLUSION: Our findings suggested a lower modularity and network efficiency in the rs-fMRI network in depression patients, indicating that the pathological imbalances in brain connectomes needs further exploration. LIMITATIONS: Included number of trials was low and heterogeneity should be noted.


Assuntos
Conectoma , Benchmarking , Encéfalo/diagnóstico por imagem , Depressão , Humanos , Imageamento por Ressonância Magnética
10.
Semin Ultrasound CT MR ; 42(5): 507-522, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34537118

RESUMO

A comprehensive mapping of the structural and functional circuitry of the brain is a major unresolved problem in contemporary neuroimaging research. Diffusion-weighted and functional MRI have provided investigators with the capability to assess structural and functional connectivity in-vivo, driven primarily by methods of white matter tractography and resting-state fMRI, respectively. These techniques have paved the way for the construction of the functional and structural connectomes, which are quantitative representations of brain architecture as neural networks, comprised of nodes and edges. The connectomes, typically depicted as matrices or graphs, possess topological properties that inherently characterize the strength, efficiency, and organization of the connections between distinct brain regions. Graph theory, a general mathematical framework for analyzing networks, can be implemented to derive metrics from the connectomes that are sensitive to changes in brain connectivity associated with age, sex, cognitive function, and disease. These quantities can be assessed at either the global (whole brain) or local levels, allowing for the identification of distinct regional connectivity hubs and associated localized brain networks, which together serve crucial roles in establishing the structural and functional architecture of the brain. As a result, structural and functional connectomes have each been employed to study the brain circuitry underlying early brain development, neuroplasticity, developmental disorders, psychopathology, epilepsy, aging, neurodegenerative disorders, and traumatic brain injury. While these studies have yielded important insights into brain structure, function, and pathology, a precise description of the innate relationship between functional and structural networks across the brain remains unachieved. To date, connectome research has merely scratched the surface of potential clinical applications and related characterizations of brain-wide connectivity. Continued advances in diffusion and functional MRI acquisition, the delineation of functional and structural networks, and the quantification of neural network properties in specific brain regions, will be invaluable to future progress in neuroimaging science.


Assuntos
Conectoma , Substância Branca , Encéfalo/diagnóstico por imagem , Imagem de Tensor de Difusão , Humanos , Imageamento por Ressonância Magnética , Rede Nervosa/diagnóstico por imagem , Vias Neurais/diagnóstico por imagem , Substância Branca/diagnóstico por imagem
11.
Elife ; 102021 09 20.
Artigo em Inglês | MEDLINE | ID: mdl-34542407

RESUMO

The flexible and efficient adaptation to dynamic, rapid changes in the auditory environment likely involves generating and updating of internal models. Such models arguably exploit connections between the neocortex and the cerebellum, supporting proactive adaptation. Here, we tested whether temporo-cerebellar disconnection is associated with the processing of sound at short timescales. First, we identify lesion-specific deficits for the encoding of short timescale spectro-temporal non-speech and speech properties in patients with left posterior temporal cortex stroke. Second, using lesion-guided probabilistic tractography in healthy participants, we revealed bidirectional temporo-cerebellar connectivity with cerebellar dentate nuclei and crura I/II. These findings support the view that the encoding and modeling of rapidly modulated auditory spectro-temporal properties can rely on a temporo-cerebellar interface. We discuss these findings in view of the conjecture that proactive adaptation to a dynamic environment via internal models is a generalizable principle.


Assuntos
Percepção Auditiva , Encéfalo/fisiologia , Cerebelo/diagnóstico por imagem , Conectoma , Lobo Temporal/diagnóstico por imagem , Tempo , Adulto , Estudos de Casos e Controles , Cerebelo/fisiopatologia , Feminino , Humanos , Imageamento por Ressonância Magnética/métodos , Masculino , Pessoa de Meia-Idade , Acidente Vascular Cerebral/fisiopatologia , Análise e Desempenho de Tarefas , Lobo Temporal/fisiopatologia
12.
Philos Trans R Soc Lond B Biol Sci ; 376(1836): 20200256, 2021 10 25.
Artigo em Inglês | MEDLINE | ID: mdl-34482717

RESUMO

Speech production relies on the orchestrated control of multiple brain regions. The specific, directional influences within these networks remain poorly understood. We used regression dynamic causal modelling to infer the whole-brain directed (effective) connectivity from functional magnetic resonance imaging data of 36 healthy individuals during the production of meaningful English sentences and meaningless syllables. We identified that the two dynamic connectomes have distinct architectures that are dependent on the complexity of task production. The speech was regulated by a dynamic neural network, the most influential nodes of which were centred around superior and inferior parietal areas and influenced the whole-brain network activity via long-ranging coupling with primary sensorimotor, prefrontal, temporal and insular regions. By contrast, syllable production was controlled by a more compressed, cost-efficient network structure, involving sensorimotor cortico-subcortical integration via superior parietal and cerebellar network hubs. These data demonstrate the mechanisms by which the neural network reorganizes the connectivity of its influential regions, from supporting the fundamental aspects of simple syllabic vocal motor output to multimodal information processing of speech motor output. This article is part of the theme issue 'Vocal learning in animals and humans'.


Assuntos
Encéfalo/fisiologia , Conectoma , Fala/fisiologia , Adulto , Boston , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade
13.
Biol Psychiatry ; 90(10): 678-688, 2021 11 15.
Artigo em Inglês | MEDLINE | ID: mdl-34482949

RESUMO

Obsessive-compulsive disorder is among the most disabling psychiatric disorders. Although deep brain stimulation is considered an effective treatment, its use in clinical practice is not fully established. This is, at least in part, due to ambiguity about the best suited target and insufficient knowledge about underlying mechanisms. Recent advances suggest that changes in broader brain networks are responsible for improvement of obsessions and compulsions, rather than local impact at the stimulation site. These findings were fueled by innovative methodological approaches using brain connectivity analyses in combination with neuromodulatory interventions. Such a connectomic approach for neuromodulation constitutes an integrative account that aims to characterize optimal target networks. In this critical review, we integrate findings from connectomic studies and deep brain stimulation interventions to characterize a neural network presumably effective in reducing obsessions and compulsions. To this end, we scrutinize methodologies and seemingly conflicting findings with the aim to merge observations to identify common and diverse pathways for treating obsessive-compulsive disorder. Ultimately, we propose a unified network that-when modulated by means of cortical or subcortical interventions-alleviates obsessive-compulsive symptoms.


Assuntos
Conectoma , Estimulação Encefálica Profunda , Transtorno Obsessivo-Compulsivo , Encéfalo/diagnóstico por imagem , Humanos , Transtorno Obsessivo-Compulsivo/terapia , Resultado do Tratamento
14.
Nutrients ; 13(9)2021 Sep 16.
Artigo em Inglês | MEDLINE | ID: mdl-34579106

RESUMO

Intra-cortical myelin is a myelinated part of the cerebral cortex that is responsible for the spread and synchronization of neuronal activity in the cortex. Recent animal studies have established a link between obesity and impaired oligodendrocyte maturation vis-à-vis cells that produce and maintain myelin; however, the association between obesity and intra-cortical myelination remains to be established. To investigate the effects of obesity on intra-cortical myelin in living humans, we employed a large, demographically well-characterized sample of healthy young adults drawn from the Human Connectome Project (n = 1066). Intra-cortical myelin was assessed using a novel T1-w/T2-w ratio method. Linear regression analysis was used to investigate the association between body mass index (BMI), an indicator of obesity, and intra-cortical myelination, adjusting for covariates of no interest. We observed BMI was related to lower intra-cortical myelination in regions previously identified to be involved in reward processing (i.e., medial orbitofrontal cortex, rostral anterior cingulate cortex), attention (i.e., visual cortex, inferior/middle temporal gyrus), and salience detection (i.e., insula, supramarginal gyrus) in response to viewing food cues (corrected p < 0.05). In addition, higher BMIs were associated with more intra-cortical myelination in regions associated with somatosensory processing (i.e., the somatosensory network) and inhibitory control (i.e., lateral inferior frontal gyrus, frontal pole). These findings were also replicated after controlling for key potential confounding factors including total intracranial volume, substance use, and fluid intelligence. Findings suggested that altered intra-cortical myelination may represent a novel microstructure-level substrate underlying prior abnormal obesity-related brain neural activity, and lays a foundation for future investigations designed to evaluate how living habits, such as dietary habit and physical activity, affect intra-cortical myelination.


Assuntos
Índice de Massa Corporal , Córtex Cerebral/fisiologia , Conectoma , Bainha de Mielina/fisiologia , Adulto , Feminino , Humanos , Masculino , Adulto Jovem
15.
Nat Commun ; 12(1): 5713, 2021 09 29.
Artigo em Inglês | MEDLINE | ID: mdl-34588439

RESUMO

Large, openly available datasets and current analytic tools promise the emergence of population neuroscience. The considerable diversity in personality traits and behaviour between individuals is reflected in the statistical variability of neural data collected in such repositories. Recent studies with functional magnetic resonance imaging (fMRI) have concluded that patterns of resting-state functional connectivity can both successfully distinguish individual participants within a cohort and predict some individual traits, yielding the notion of an individual's neural fingerprint. Here, we aim to clarify the neurophysiological foundations of individual differentiation from features of the rich and complex dynamics of resting-state brain activity using magnetoencephalography (MEG) in 158 participants. We show that akin to fMRI approaches, neurophysiological functional connectomes enable the differentiation of individuals, with rates similar to those seen with fMRI. We also show that individual differentiation is equally successful from simpler measures of the spatial distribution of neurophysiological spectral signal power. Our data further indicate that differentiation can be achieved from brain recordings as short as 30 seconds, and that it is robust over time: the neural fingerprint is present in recordings performed weeks after their baseline reference data was collected. This work, thus, extends the notion of a neural or brain fingerprint to fast and large-scale resting-state electrophysiological dynamics.


Assuntos
Encéfalo/fisiologia , Individualidade , Magnetoencefalografia/estatística & dados numéricos , Neurofisiologia/métodos , Descanso/fisiologia , Adolescente , Adulto , Artefatos , Conectoma , Fenômenos Eletrofisiológicos , Feminino , Humanos , Análise dos Mínimos Quadrados , Masculino , Pessoa de Meia-Idade , Adulto Jovem
16.
J Neurol Sci ; 429: 118073, 2021 10 15.
Artigo em Inglês | MEDLINE | ID: mdl-34517228

RESUMO

We do not have an understanding of the fundamental mechanism of how information is stored and retrieved by the brain. A Universal Brain Code utilized for these functions is proposed here. The basic tenent of the Code is that a memory engram is propagated and guided through the connectome by specific proteins/peptides embedded within the pre-synaptic neuronal membrane corresponding to information provided by afferent electrical currents to the pre-synaptic neuron. It is intended to provide a working approach to this central brain activity and begin the process of investigation based on these ideas which are new and unexplored.


Assuntos
Conectoma , Memória , Encéfalo/diagnóstico por imagem , Humanos , Neurônios
17.
Elife ; 102021 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-34523418

RESUMO

Insects have evolved diverse and remarkable strategies for navigating in various ecologies all over the world. Regardless of species, insects share the presence of a group of morphologically conserved neuropils known collectively as the central complex (CX). The CX is a navigational center, involved in sensory integration and coordinated motor activity. Despite the fact that our understanding of navigational behavior comes predominantly from ants and bees, most of what we know about the underlying neural circuitry of such behavior comes from work in fruit flies. Here, we aim to close this gap, by providing the first comprehensive map of all major columnar neurons and their projection patterns in the CX of a bee. We find numerous components of the circuit that appear to be highly conserved between the fly and the bee, but also highlight several key differences which are likely to have important functional ramifications.


Assuntos
Abelhas/fisiologia , Comportamento Animal , Conectoma , Voo Animal , Vias Neurais/fisiologia , Neurópilo/fisiologia , Comportamento Espacial , Animais , Abelhas/ultraestrutura , Drosophila melanogaster/fisiologia , Drosophila melanogaster/ultraestrutura , Vias Neurais/ultraestrutura , Neurópilo/ultraestrutura , Especificidade da Espécie
18.
Rev Neurol (Paris) ; 177(9): 1093-1103, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34563375

RESUMO

Although clinical neurology was mainly erected on the dogma of localizationism, numerous reports have described functional recovery after lesions involving presumed non-compensable areas in an inflexible view of brain processing. Here, the purpose is to review new insights into the functional connectome and the mechanisms underpinning neural plasticity, gained from intraoperative direct electrostimulation mapping and real-time behavioral monitoring in awake patients, combined with perioperative neuropsychological and neuroimaging data. Such longitudinal anatomo-functional correlations resulted in the reappraisal of classical models of cognition, especially by highlighting the dynamic interplay within and between neural circuits, leading to the concept of meta-network (network of networks), as well as by emphasizing that subcortical connectivity is the main limitation of neuroplastic potential. Beyond their contribution to basic neurosciences, these findings might also be helpful for an optimization of care for brain-damaged patients, such as in resective oncological or epilepsy neurosurgery in structures traditionally deemed inoperable (e.g., in Broca's area) as well as for elaborating new programs of functional rehabilitation, eventually combined with transcranial brain stimulation, aiming to change the connectivity patterns in order to enhance cognitive competences following cerebral injury.


Assuntos
Neoplasias Encefálicas , Conectoma , Encéfalo/diagnóstico por imagem , Encéfalo/cirurgia , Neoplasias Encefálicas/complicações , Neoplasias Encefálicas/diagnóstico por imagem , Neoplasias Encefálicas/cirurgia , Humanos , Plasticidade Neuronal , Procedimentos Neurocirúrgicos , Vigília
19.
J Clin Invest ; 131(18)2021 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-34523615

RESUMO

Modern research on gastrointestinal behavior has revealed it to be a highly complex bidirectional process in which the gut sends signals to the brain, via spinal and vagal visceral afferent pathways, and receives sympathetic and parasympathetic inputs. Concomitantly, the enteric nervous system within the bowel, which contains intrinsic primary afferent neurons, interneurons, and motor neurons, also senses the enteric environment and controls the detailed patterns of intestinal motility and secretion. The vast microbiome that is resident within the enteric lumen is yet another contributor, not only to gut behavior, but to the bidirectional signaling process, so that the existence of a microbiota-gut-brain "connectome" has become apparent. The interaction between the microbiota, the bowel, and the brain now appears to be neither a top-down nor a bottom-up process. Instead, it is an ongoing, tripartite conversation, the outline of which is beginning to emerge and is the subject of this Review. We emphasize aspects of the exponentially increasing knowledge of the microbiota-gut-brain "connectome" and focus attention on the roles that serotonin, Toll-like receptors, and macrophages play in signaling as exemplars of potentially generalizable mechanisms.


Assuntos
Encéfalo/fisiologia , Microbioma Gastrointestinal/fisiologia , Animais , Conectoma , Sistema Nervoso Entérico/fisiologia , Microbioma Gastrointestinal/imunologia , Trato Gastrointestinal/imunologia , Trato Gastrointestinal/fisiologia , Humanos , Macrófagos/imunologia , Modelos Neurológicos , Vias Neurais/fisiologia
20.
J Neurosci ; 41(40): 8351-8361, 2021 10 06.
Artigo em Inglês | MEDLINE | ID: mdl-34465598

RESUMO

The connectome of the brain has a great impact on the function of the brain as the structure of the connectome affects the speed and efficiency of information transfer. As a highly energy-consuming organ, an efficient network structure is essential. A previous study has shown consistent overall brain connectivity across a large variety of species. This connectivity conservation was explained by a balance between interhemispheric and intrahemispheric connections; that is, spices with highly connected hemispheres appear to have weaker interhemisphere connections. This study examines this connectivity trade-off in the human brain using diffusion-based tractography and network analysis in the Human Connectome Project (970 subjects, 527 female). We explore the biological origins of this phenomenon, heritability, and the effect on cognitive measures.The proportion of commissural fibers in the brain had a negative correlation to hemispheric efficiency, pointing to a trade-off between inner hemispheric and interhemispheric connectivity. Network hubs including anterior and middle cingulate cortex, superior frontal areas, medial occipital areas, the parahippocampal gyrus, post- and precentral gyri, and the precuneus had the strongest contribution to this phenomenon. Other results show a high heritability as well as a strong connection to crystalized intelligence. This work presents cohort-based network analysis research, spanning a large variety of samples and exploring the overall architecture of the human connectome. Our results show a connectivity conservation phenomenon at the base of the overall brain network architecture. This network structure may explain much of the functional, behavioral, and cognitive variability among different brains.SIGNIFICANCE STATEMENT The network structure of the brain is at the basis of every brain function as it dictates the characteristics of information transfer. Understanding the patterns and mechanisms that guide the connectome structure is crucial to understanding the brain itself. Here we unravel the mechanism at the base of the connectivity conservation phenomenon by exploring the interaction between hemispheric and commissural connectivity in a large-scale cohort-based connectivity study. We describe the trade-off between the two components and examine the origins of the trade-off and observe the effect on cognitive abilities and behavior.


Assuntos
Encéfalo/diagnóstico por imagem , Encéfalo/fisiologia , Conectoma/métodos , Rede Nervosa/diagnóstico por imagem , Rede Nervosa/fisiologia , Adulto , Corpo Caloso/diagnóstico por imagem , Corpo Caloso/fisiologia , Imagem de Tensor de Difusão/métodos , Feminino , Humanos , Masculino , Adulto Jovem
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...