Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 3.045
Filtrar
1.
Adv Exp Med Biol ; 1185: 365-370, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31884639

RESUMO

Glia play important roles in neural function, including but not limited to amino acid recycling, ion homeostasis, glucose metabolism, and waste removal. During retinal degeneration and subsequent retinal remodeling, Müller cells (MCs) are the first cells to show metabolic and morphological alterations in response to stress. Metabolic alterations in MCs chaotically progress in retina undergoing photoreceptor degeneration; however, what relationship these alterations have with neuronal stress, synapse maintenance, or glia-glia interactions is currently unknown. The work described here reconstructs a MC from a pathoconnectome of early retinal remodeling retinal pathoconnectome 1 (RPC1) and explores relationships between MC structural and metabolic phenotypes in the context of neighboring neurons and glia. Here we find variations in intensity of osmication inter- and intracellularly, variation in small molecule metabolic content of MCs, as well as morphological alterations of glial endfeet. RPC1 provides a framework to analyze these relationships in early retinal remodeling through ultrastructural reconstructions of both neurons and glia. These reconstructions, informed by quantitative metabolite labeling via computational molecular phenotyping (CMP), allow us to evaluate neural-glial interactions in early retinal degeneration with unprecedented resolution and sensitivity.


Assuntos
Conectoma , Células Ependimogliais/patologia , Neurônios/citologia , Degeneração Retiniana/fisiopatologia , Humanos , Retina/citologia , Retina/patologia
2.
Adv Exp Med Biol ; 1192: 139-158, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31705494

RESUMO

Neuroimaging-based personalized medicine is emerging to characterize brain disorders and their evolution at the patient level. In this chapter, we present the most classic methods used to infer large-scale brain connectivity based on functional MRI. We adopt a modeling perspective where every connectivity measure is linked to a specific model that allows to interpret the connectivity estimate. This perspective allows to analyze the quality of retrieved connectivity profiles in terms of modeling error and estimation error. In the first part of the chapter, we present undirected functional connectivity (Pearson's correlation and MI) and effective connectivity (partial correlation), as well as directed effective connectivity (VAR, MOU, Granger causality, DCM). In addition, some of these measures correspond to fully connected graphs (Pearson's correlation) while others to sparse ones (MOU, DCM), where the sparsity can come from the integration of functional and structural data. In the second part, we claim that machine learning tools are better suited than null-hypothesis testing to link the estimated connectomes with diagnosis and prognosis of neuropsychiatric diseases. Finally, we propose that linear models and features selection are preferable to more complex and nonlinear tools (when prediction performance is on a par) for building interpretable algorithms to predict clinical variables.


Assuntos
Encefalopatias , Conectoma , Encéfalo , Humanos , Modelos Lineares , Imagem por Ressonância Magnética
3.
Medicine (Baltimore) ; 98(40): e17127, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31577703

RESUMO

To investigate the functional connectome alterations in cerebral small-vessel disease (CSVD) patients with thalamus lacunes and its relation to cognitive impairment.This case-control study was approved by the local research ethics committee, and all participants provided informed consent. There were 14 CSVD patients with thalamus lacunes (CSVDw.), 27 without (CSVDwo.), and 34 healthy controls (HC) recruited matched for age, sex, and education to undergo a 3T resting-state functional MR examination. The whole-brain functional connectome was constructed by thresholding the Pearson correlation matrices of 90 brain regions, and the topologic properties were analyzed by using graph theory approaches. Networks were compared between CSVD patients and HC, and associations between network measures and cognitive function were tested.Compared with HC, the functional connectome in CSVDw. patients showed abnormalities at the global level and at the nodal level (P < .05, false discovery rate corrected). The network-based statistics method identified a significantly altered network consisting 6 nodes and 13 connections. Among all the 13 connections, only two connections had significant correlation with episodic memory (EM) and processing speed (PS) respectively (P < .05). The CSVDwo. patients showed no significant network alterations relative to controls (P > .05).The configurations of brain functional connectome in CSVDw. patients were perturbed but not obvious for those without, and correlated with the mild cognitive impairment, especially for EM and PS. This study suggested that lacunes on thalamus played a vital role in mediating the neural functional changes of CSVD patients.


Assuntos
Doenças de Pequenos Vasos Cerebrais/patologia , Disfunção Cognitiva/patologia , Conectoma , Leucoencefalopatias/patologia , Tálamo/patologia , Fatores Etários , Idoso , Idoso de 80 Anos ou mais , Estudos de Casos e Controles , Doenças de Pequenos Vasos Cerebrais/complicações , Doenças de Pequenos Vasos Cerebrais/diagnóstico por imagem , Disfunção Cognitiva/diagnóstico por imagem , Disfunção Cognitiva/etiologia , Estudos Transversais , Escolaridade , Feminino , Humanos , Processamento de Imagem Assistida por Computador , Leucoencefalopatias/complicações , Masculino , Pessoa de Meia-Idade , Avaliação Nutricional , Índice de Gravidade de Doença , Fatores Sexuais , Tálamo/diagnóstico por imagem
4.
Sheng Wu Yi Xue Gong Cheng Xue Za Zhi ; 36(5): 810-817, 2019 Oct 25.
Artigo em Chinês | MEDLINE | ID: mdl-31631630

RESUMO

As a complex system, the topology of human's brain network has an important effect on further study of brain's structural and functional mechanism. Graph theory, a kind of sophisticated analytic strategies, is widely used for analyzing complex brain networks effectively and comparing difference of topological structure alteration in normal development and pathological condition. For the purpose of using this analysis methodology efficiently, it is necessary to develop graph-based visualization software. Thus, we developed VisConnectome, which displays analysis results of the brain network friendly and intuitively. It provides an original graphical user interface (GUI) including the tool window, tool bar and innovative double slider filter, brain region bar, runs in any Windows operating system and doesn't rely on any platform such as Matlab. When importing the user-defined script file that initializes the brain network, VisConnectome abstracts the brain network to the ball-and-stick model and render it. VisConnectome allows a series of visual operations, such as identifying nodes and connection, modifying properties of nodes and connection such as color and size with the color palette and size double slider, imaging the brain regions, filtering the brain network according to its size property in a specific domain as simplification and blending with the brain surface as a context of the brain network. Through experiment and analysis, we conclude that VisConnectome is an effective visualization software with high speed and quality, which helps researchers to visualize and compare the structural and functional brain networks flexibly.


Assuntos
Encéfalo/fisiologia , Conectoma , Software , Humanos
5.
Top Magn Reson Imaging ; 28(5): 265-273, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31592993

RESUMO

The white matter structure of the human brain undergoes critical developmental milestones in utero, which we can observe noninvasively using diffusion-weighted magnetic resonance imaging. In order to understand this fascinating developmental process, we must establish the variability inherent in such a challenging imaging environment and how measurable quantities can be transformed into meaningful connectomes. We review techniques for reconstructing and studying the brain connectome and explore promising opportunities for in utero studies that could lead to more accurate measurement of structural properties and allow for more refined and insightful analyses of the fetal brain. Opportunities for more sophisticated analyses of the properties of the brain and its dynamic changes have emerged in recent years, based on the development of iterative techniques to reconstruct motion-corrupted diffusion-weighted data. Although reconstruction quality is greatly improved, the treatment of fundamental quantities like edge strength requires careful treatment because of the specific challenges of imaging in utero. There are intriguing challenges to overcome, from those in analysis due to both imaging limitations and the significant changes in structural connectivity, to further image processing to address the specific properties of the target anatomy and quantification into a developmental connectome.


Assuntos
Encéfalo/embriologia , Conectoma/métodos , Imagem de Difusão por Ressonância Magnética/métodos , Encéfalo/anatomia & histologia , Humanos , Processamento de Imagem Assistida por Computador
6.
Top Magn Reson Imaging ; 28(5): 275-284, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31592994

RESUMO

Developmental pathoconnectomics is an emerging field that aims to unravel the events leading to and outcome from disrupted brain connectivity development. Advanced magnetic resonance imaging (MRI) technology enables the portrayal of human brain connectivity before birth and has the potential to offer novel insights into normal and pathological human brain development. This review gives an overview of the currently used MRI techniques for connectomic imaging, with a particular focus on recent studies that have successfully translated these to the in utero or postmortem fetal setting. Possible mechanisms of how pathologies, maternal, or environmental factors may interfere with the emergence of the connectome are considered. The review highlights the importance of advanced image post processing and the need for reproducibility studies for connectomic imaging. Further work and novel data-sharing efforts would be required to validate or disprove recent observations from in utero connectomic studies, which are typically limited by low case numbers and high data drop out. Novel knowledge with regard to the ontogenesis, architecture, and temporal dynamics of the human brain connectome would lead to the more precise understanding of the etiological background of neurodevelopmental and mental disorders. To achieve this goal, this review considers the growing evidence from advanced fetal connectomic imaging for the increased vulnerability of the human brain during late gestation for pathologies that might lead to impaired connectome development and subsequently interfere with the development of neural substrates serving higher cognition.


Assuntos
Encéfalo/diagnóstico por imagem , Encéfalo/embriologia , Conectoma/métodos , Imagem por Ressonância Magnética/métodos , Feminino , Humanos , Gravidez , Reprodutibilidade dos Testes
7.
Nat Commun ; 10(1): 4289, 2019 09 19.
Artigo em Inglês | MEDLINE | ID: mdl-31537787

RESUMO

Neural information flow is inherently directional. To date, investigation of directional communication in the human structural connectome has been precluded by the inability of non-invasive neuroimaging methods to resolve axonal directionality. Here, we demonstrate that decentralized measures of network communication, applied to the undirected topology and geometry of brain networks, can infer putative directions of large-scale neural signalling. We propose the concept of send-receive communication asymmetry to characterize cortical regions as senders, receivers or neutral, based on differences between their incoming and outgoing communication efficiencies. Our results reveal a send-receive cortical hierarchy that recapitulates established organizational gradients differentiating sensory-motor and multimodal areas. We find that send-receive asymmetries are significantly associated with the directionality of effective connectivity derived from spectral dynamic causal modeling. Finally, using fruit fly, mouse and macaque connectomes, we provide further evidence suggesting that directionality of neural signalling is significantly encoded in the undirected architecture of nervous systems.


Assuntos
Encéfalo/fisiologia , Comunicação Celular/fisiologia , Rede Nervosa/fisiologia , Vias Neurais/fisiologia , Adulto , Animais , Conectoma , Drosophila/fisiologia , Feminino , Humanos , Macaca/fisiologia , Masculino , Camundongos , Modelos Neurológicos , Transdução de Sinais/fisiologia , Adulto Jovem
8.
Phys Rev Lett ; 123(3): 038301, 2019 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-31386449

RESUMO

The brain requires diverse segregated and integrated processing to perform normal functions in terms of anatomical structure and self-organized dynamics with critical features, but the fundamental relationships between the complex structural connectome, critical state, and functional diversity remain unknown. Herein, we extend the eigenmode analysis to investigate the joint contribution of hierarchical modular structural organization and critical state to brain functional diversity. We show that the structural modes inherent to the hierarchical modular structural connectome allow a nested functional segregation and integration across multiple spatiotemporal scales. The real brain hierarchical modular organization provides large structural capacity for diverse functional interactions, which are generated by sequentially activating and recruiting the hierarchical connectome modes, and the critical state can best explore the capacity to maximize the functional diversity. Our results reveal structural and dynamical mechanisms that jointly support a balanced segregated and integrated brain processing with diverse functional interactions, and they also shed light on dysfunctional segregation and integration in neurodegenerative diseases and neuropsychiatric disorders.


Assuntos
Encéfalo/fisiologia , Conectoma/métodos , Modelos Neurológicos , Encéfalo/diagnóstico por imagem , Humanos , Imagem por Ressonância Magnética
9.
Neurology ; 93(11): e1112-e1122, 2019 09 10.
Artigo em Inglês | MEDLINE | ID: mdl-31405905

RESUMO

OBJECTIVE: To study the intrinsic organization of the thalamocortical circuitry in patients with generalized epilepsy with tonic-clonic seizures (GTCS) via resting-state fMRI (rs-fMRI) connectome analysis and to evaluate its relation to drug response. METHODS: In a prospectively followed-up sample of 41 patients and 27 healthy controls, we obtained rs-fMRI and structural MRI. After 1 year of follow-up, 27 patients were classified as seizure-free and 14 as drug-resistant. We examined connectivity within and between resting-state communities in cortical and thalamic subregions. In addition to comparing patients to controls, we examined associations with seizure control. We assessed reproducibility in an independent cohort of 21 patients. RESULTS: Compared to controls, patients showed a more constrained network embedding of the thalamus, while frontocentral neocortical regions expressed increased functional diversity. Findings remained significant after regressing out thalamic volume and cortical thickness, suggesting independence from structural alterations. We observed more marked network imbalances in drug-resistant compared to seizure-free patients. Findings were similar in the reproducibility dataset. CONCLUSIONS: Our findings suggest a pathoconnectomic mechanism of generalized epilepsy centered on diverging changes in cortical and thalamic connectivity. More restricted thalamic connectivity could reflect the tendency to engage in recursive thalamocortical loops, which may contribute to hyperexcitability. Conversely, increased connectional diversity of frontocentral networks may relay abnormal activity to an extended bilateral territory. Network imbalances were observed shortly after diagnosis and related to future drug response, suggesting clinical utility.


Assuntos
Córtex Cerebral/diagnóstico por imagem , Conectoma/métodos , Epilepsia Generalizada/diagnóstico por imagem , Imagem por Ressonância Magnética/métodos , Rede Nervosa/diagnóstico por imagem , Tálamo/diagnóstico por imagem , Adolescente , Adulto , Córtex Cerebral/fisiopatologia , Epilepsia Generalizada/fisiopatologia , Feminino , Seguimentos , Humanos , Masculino , Rede Nervosa/fisiopatologia , Estudos Prospectivos , Tálamo/fisiopatologia , Adulto Jovem
10.
11.
Nat Commun ; 10(1): 3903, 2019 08 29.
Artigo em Inglês | MEDLINE | ID: mdl-31467291

RESUMO

In connectomics, the study of the network structure of connected neurons, great advances are being made on two different scales: that of macro- and meso-scale connectomics, studying the connectivity between populations of neurons, and that of micro-scale connectomics, studying connectivity between individual neurons. We combine these two complementary views of connectomics to build a first draft statistical model of the micro-connectome of a whole mouse neocortex based on available data on region-to-region connectivity and individual whole-brain axon reconstructions. This process reveals a targeting principle that allows us to predict the innervation logic of individual axons from meso-scale data. The resulting connectome recreates biological trends of targeting on all scales and predicts that an established principle of scale invariant topological organization of connectivity can be extended down to the level of individual neurons. It can serve as a powerful null model and as a substrate for whole-brain simulations.


Assuntos
Conectoma/métodos , Neocórtex/fisiologia , Animais , Encéfalo/fisiologia , Camundongos , Modelos Animais , Modelos Estatísticos , Rede Nervosa/fisiologia , Neurônios/fisiologia
12.
J Clin Neurosci ; 68: 235-242, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31420273

RESUMO

This study used Voxel-based morphometry (VBM) and resting-state functional magnetic resonance imaging (rs-fMRI) to investigate changes in brain structure and networks functional connectivity, respectively. We tried to identify the potential biomarkers in Parkinson's disease (PD) progression. We recruited nine idiopathic PD patients and seven healthy control participants (HC group) who were age-matched to undergo T1-weighted images and rs-fMRI on 1.5 T. Brain structure differences were analyzed by VBM. Topological properties of networks functional connectivity were analyzed by graph theory. Thirty-two nodes of 8 networks and 133 nodes of interest then were identified with graph theory approaches. VBM examinations showed significant decreases of brain gray matter regions including the left temporal lobe, left middle temporal, middle temporal gyrus, parietal lobe, postcentral gyrus, left inferior parietal gyrus, medial frontal gyrus and supplement motor area in PD patients compared to the HC group. The 32 ROI of networks topological metrics measurement in PD demonstrated increases of global efficiency, cost, and degree in frontoparietal PPC (R) network, but decreases of local efficiency, clustering coefficient, and average path length in salience ACC, dorsal attention FEF (L), and salience aInsula (R) networks, respectively. All 165 ROI connectomes showed eight connections intensity changes, that decrease in OP r to frontoparietal PPC, putamen r to cereb11, and SFG l to Ver8 in PD. These results suggest that the graph theory and the network topological metrics measurement may be the potential biomarkers in PD to evaluate the disease progress and to monitor the therapeutic results.


Assuntos
Encéfalo/fisiopatologia , Interpretação de Imagem Assistida por Computador/métodos , Imagem por Ressonância Magnética/métodos , Modelos Teóricos , Doença de Parkinson/fisiopatologia , Idoso , Encéfalo/diagnóstico por imagem , Encéfalo/patologia , Conectoma/métodos , Feminino , Humanos , Pessoa de Meia-Idade , Modelos Neurológicos , Doença de Parkinson/diagnóstico por imagem , Doença de Parkinson/patologia
13.
Neuron ; 103(4): 554-556, 2019 08 21.
Artigo em Inglês | MEDLINE | ID: mdl-31437450

RESUMO

How does the noradrenergic nucleus locus coeruleus act on target networks to regulate behavior? In this issue of Neuron, Zerbi et al. (2019) combine functional neuroimaging and pharmacogenetics in mice to tackle that question, uncovering a network action underlying stress. And providing insight for cognition?


Assuntos
Conectoma , Locus Cerúleo , Animais , Camundongos , Neurônios , Norepinefrina
14.
Nat Commun ; 10(1): 3497, 2019 08 02.
Artigo em Inglês | MEDLINE | ID: mdl-31375668

RESUMO

Human memory is thought to depend on a circuit of connected brain regions, but this hypothesis has not been directly tested. We derive a human memory circuit using 53 case reports of strokes causing amnesia and a map of the human connectome (n = 1000). This circuit is reproducible across discovery (n = 27) and replication (n = 26) cohorts and specific to lesions causing amnesia. Its hub is at the junction of the presubiculum and retrosplenial cortex. Connectivity with this single location defines a human brain circuit that incorporates > 95% of lesions causing amnesia. Lesion intersection with this circuit predicts memory scores in two independent datasets (N1 = 97, N2 = 176). This network aligns with neuroimaging correlates of episodic memory, abnormalities in Alzheimer's disease, and brain stimulation sites reported to enhance memory in humans.


Assuntos
Amnésia/patologia , Encéfalo/patologia , Conectoma , Memória/fisiologia , Rede Nervosa/patologia , Adulto , Idoso , Doença de Alzheimer/complicações , Doença de Alzheimer/diagnóstico por imagem , Doença de Alzheimer/patologia , Amnésia/diagnóstico por imagem , Amnésia/etiologia , Encéfalo/diagnóstico por imagem , Conjuntos de Dados como Assunto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Acidente Vascular Cerebral/complicações , Acidente Vascular Cerebral/diagnóstico por imagem , Acidente Vascular Cerebral/patologia
15.
Philos Trans A Math Phys Eng Sci ; 377(2153): 20180132, 2019 Sep 09.
Artigo em Inglês | MEDLINE | ID: mdl-31329065

RESUMO

The timing of activity across brain regions can be described by its phases for oscillatory processes, and is of crucial importance for brain functioning. The structure of the brain constrains its dynamics through the delays due to propagation and the strengths of the white matter tracts. We use self-sustained delay-coupled, non-isochronous, nonlinearly damped and chaotic oscillators to study how spatio-temporal organization of the brain governs phase lags between the coherent activity of its regions. In silico results for the brain network model demonstrate a robust switching from in- to anti-phase synchronization by increasing the frequency, with a consistent lagging of the stronger connected regions. Relative phases are well predicted by an earlier analysis of Kuramoto oscillators, confirming the spatial heterogeneity of time delays as a crucial mechanism in shaping the functional brain architecture. Increased frequency and coupling are also shown to distort the oscillators by decreasing their amplitude, and stronger regions have lower, but more synchronized activity. These results indicate specific features in the phase relationships within the brain that need to hold for a wide range of local oscillatory dynamics, given that the time delays of the connectome are proportional to the lengths of the structural pathways. This article is part of the theme issue 'Nonlinear dynamics of delay systems'.


Assuntos
Conectoma , Sincronização Cortical , Modelos Neurológicos , Encéfalo/fisiologia , Fatores de Tempo
16.
Magn Reson Imaging ; 62: 220-227, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31323317

RESUMO

PURPOSE: Diffusion-weighted magnetic resonance imaging (DW-MRI) is of critical importance for characterizing in-vivo white matter. Models relating microarchitecture to observed DW-MRI signals as a function of diffusion sensitization are the lens through which DW-MRI data are interpreted. Numerous modern approaches offer opportunities to assess more complex intra-voxel structures. Nevertheless, there remains a substantial gap between intra-voxel estimated structures and ground truth captured by 3-D histology. METHODS: Herein, we propose a novel data-driven approach to model the non-linear mapping between observed DW-MRI signals and ground truth structures using a sequential deep neural network regression using residual block deep neural network (ResDNN). Training was performed on two 3-D histology datasets of squirrel monkey brains and validated on a third. A second validation was performed using scan-rescan datasets of 12 subjects from Human Connectome Project. The ResDNN was compared with multiple micro-structure reconstruction methods and super resolved-constrained spherical deconvolution (sCSD) in particular as baseline for both the validations. RESULTS: Angular correlation coefficient (ACC) is a correlation/similarity measure and can be interpreted as accuracy when compared with a ground truth. The median ACC of ResDNN is 0.82 and median ACC's of different variants of CSD are 0.75, 0.77, 0.79. The mean, median and std. of ResDNN & sCSD ACC across 12 subjects from HCP are 0.74, 0.88, 0.31 and 0.61, 0.71, 0.31 respectively. CONCLUSION: This work highlights the ability of deep learning to capture linkages between ex-vivo ground truth data with feasible MRI sequences. The data-driven approach is applicable to human in-vivo data and results in intriguingly high reproducibility of orientation structure.


Assuntos
Encéfalo/diagnóstico por imagem , Aprendizado Profundo , Imagem de Difusão por Ressonância Magnética , Imagem de Tensor de Difusão , Substância Branca/diagnóstico por imagem , Animais , Encéfalo/patologia , Conectoma , Humanos , Processamento de Imagem Assistida por Computador , Imagem Tridimensional , Reprodutibilidade dos Testes , Saimiri , Substância Branca/patologia
17.
Nat Neurosci ; 22(8): 1248-1257, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31346295

RESUMO

Studies of patients afflicted by neurodegenerative diseases suggest that misfolded proteins spread through the brain along anatomically connected networks, prompting progressive decline. Recently, mouse models have recapitulated the cell-to-cell transmission of pathogenic proteins and neuron death observed in patients. However, the factors regulating the spread of pathogenic proteins remain a matter of debate due to an incomplete understanding of how vulnerability functions in the context of spread. Here we use quantitative pathology mapping in the mouse brain, combined with network modeling to understand the spatiotemporal pattern of spread. Patterns of α-synuclein pathology are well described by a network model that is based on two factors: anatomical connectivity and endogenous α-synuclein expression. The map and model allow the assessment of selective vulnerability to α-synuclein pathology development and neuron death. Finally, we use quantitative pathology to understand how the G2019S LRRK2 genetic risk factor affects the spread and toxicity of α-synuclein pathology.


Assuntos
Encéfalo/patologia , Conectoma/psicologia , alfa-Sinucleína/genética , Animais , Mapeamento Encefálico , Morte Celular , Feminino , Serina-Treonina Proteína Quinase-2 com Repetições Ricas em Leucina/genética , Modelos Lineares , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Modelos Neurológicos , Neurônios/patologia
18.
Nat Commun ; 10(1): 3174, 2019 07 18.
Artigo em Inglês | MEDLINE | ID: mdl-31320643

RESUMO

Whether and how the balance between plasticity and stability varies across the brain is an important open question. Within a processing hierarchy, it is thought that plasticity is increased at higher levels of cortical processing, but direct quantitative comparisons between low- and high-level plasticity have not been made so far. Here, we address this issue for the human cortical visual system. We quantify plasticity as the complement of the heritability of resting-state functional connectivity and thereby demonstrate a non-monotonic relationship between plasticity and hierarchical level, such that plasticity decreases from early to mid-level cortex, and then increases further of the visual hierarchy. This non-monotonic relationship argues against recent theory that the balance between plasticity and stability is governed by the costs of the "coding-catastrophe", and can be explained by a concurrent decline of short-term adaptation and rise of long-term plasticity up the visual processing hierarchy.


Assuntos
Plasticidade Neuronal/fisiologia , Córtex Visual/fisiologia , Percepção Visual/fisiologia , Conectoma , Humanos
19.
Exp Brain Res ; 237(9): 2367-2385, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31292696

RESUMO

The posterior cingulate cortex (PCC) has been implicated in a host of cognitive and behavioral processes in addition to serving as a central hub in the default mode network (DMN). Moreover, the PCC has been shown to be involved in a range of psychiatric and neurological disorders. However, very little is known about the specific activated/deactivated functional profiles of the PCC. Here, we employed a dual analytic approach using robust quantitative meta-analytical connectivity modeling (MACM) and ultra-high field, high resolution resting state functional magnetic resonance imaging (rs-fMRI) to identify state-specific functional activity patterns of the human PCC. The MACM results provided evidence for regions of convergence for PCC co-activation and co-deactivation (i.e., left medial frontal gyrus, left amygdala, and left anterior cingulate) as well as regions of divergence specific to either PCC activation (i.e., bilateral inferior frontal gyri) or PCC deactivation (i.e., left parahippocampal gyrus). In addition, exploratory MACMs on dorsal and ventral subregions of the PCC revealed differential functional activity patterns such as greater co-activation of the right PCC and left inferior parietal lobule with the dorsal PCC and greater co-activation of right precuneus with the ventral PCC. Resting state connectivity analyses showed widespread connectivity similar to that of the PCC co-activation-based MACM, but also demonstrated additional regions of activity, including bilateral superior parietal regions and right superior temporal regions. These analyses highlight the diverse neurofunctional repertoire of the human PCC, provide additional insight into its dynamic functional activity patterns as it switches between activated and deactivated states, and elucidates the cognitive processes that may be implicated in clinical populations.


Assuntos
Atenção/fisiologia , Córtex Cerebral/fisiologia , Conectoma , Giro do Cíngulo/fisiologia , Imagem por Ressonância Magnética , Rede Nervosa/fisiologia , Adulto , Córtex Cerebral/diagnóstico por imagem , Conectoma/métodos , Giro do Cíngulo/diagnóstico por imagem , Humanos , Metanálise como Assunto , Modelos Teóricos , Rede Nervosa/diagnóstico por imagem
20.
Exp Brain Res ; 237(9): 2279-2295, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31267218

RESUMO

While several studies have examined attentional reserve (via event-related potentials) and mental effort (via EEG spectral content) from various cortical regions during dual-task walking, none have assessed changes in the magnitude of interregional (cortico-cortical) communication as a measure of mental workload. Therefore, by deploying a traditional montage of electrode sites centered over the motor planning region as well as a more comprehensive graph theory-based approach encompassing the entire scalp, this study aimed to systematically examine changes in the magnitude of functional connectivity underlying cortico-cortical communication to assess changes in mental workload under various levels of challenge. Specifically, the Weighted Phase Lag Index (WPLI) was computed to assess the changes in magnitude of functional connectivity as participants performed a cognitive task under two demands (low and high) and two conditions (seated and walking). The results revealed enhanced fronto-centro-temporo-parietal theta connectivity during dual-task walking relative to being seated as well as a reduced inhibition of fronto-centro-temporo-parieto-occipital alpha networking as the demand on the secondary cognitive task increased. Collectively, these findings may reflect greater recruitment of task relevant processes to respond to increased cognitive-motor demands and thus an elevation of mental workload in an effort to maintain performance under varying levels of challenge. This work has the potential to inform future mental workload assessment applications in patient populations, including those who employ prostheses during cognitive-motor performance under various task demands.


Assuntos
Córtex Cerebral/fisiologia , Conectoma , Função Executiva/fisiologia , Rede Nervosa/fisiologia , Desempenho Psicomotor/fisiologia , Ritmo Teta/fisiologia , Caminhada/fisiologia , Adulto , Ritmo alfa , Percepção de Cores/fisiologia , Feminino , Humanos , Masculino , Reconhecimento Visual de Modelos/fisiologia , Adulto Jovem
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA