Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 67.125
Filtrar
1.
Nat Commun ; 11(1): 5115, 2020 10 09.
Artigo em Inglês | MEDLINE | ID: mdl-33037228

RESUMO

Recurrent neural networks have led to breakthroughs in natural language processing and speech recognition. Here we show that recurrent networks, specifically long short-term memory networks can also capture the temporal evolution of chemical/biophysical trajectories. Our character-level language model learns a probabilistic model of 1-dimensional stochastic trajectories generated from higher-dimensional dynamics. The model captures Boltzmann statistics and also reproduces kinetics across a spectrum of timescales. We demonstrate how training the long short-term memory network is equivalent to learning a path entropy, and that its embedding layer, instead of representing contextual meaning of characters, here exhibits a nontrivial connectivity between different metastable states in the underlying physical system. We demonstrate our model's reliability through different benchmark systems and a force spectroscopy trajectory for multi-state riboswitch. We anticipate that our work represents a stepping stone in the understanding and use of recurrent neural networks for understanding the dynamics of complex stochastic molecular systems.


Assuntos
Idioma , Memória , Modelos Estatísticos , Redes Neurais de Computação , Inteligência Artificial , Dipeptídeos/química , Cinética , Cadeias de Markov , Simulação de Dinâmica Molecular , Imagem Individual de Molécula
2.
Nat Commun ; 11(1): 5207, 2020 10 15.
Artigo em Inglês | MEDLINE | ID: mdl-33060630

RESUMO

Fear conditioning is a form of associative learning that is known to involve different brain areas, notably the amygdala, the prefrontal cortex and the periaqueductal grey (PAG). Here, we describe the functional role of pathways that link the cerebellum with the fear network. We found that the cerebellar fastigial nucleus (FN) sends glutamatergic projections to vlPAG that synapse onto glutamatergic and GABAergic vlPAG neurons. Chemogenetic and optogenetic manipulations revealed that the FN-vlPAG pathway controls bi-directionally the strength of the fear memories, indicating an important role in the association of the conditioned and unconditioned stimuli, a function consistent with vlPAG encoding of fear prediction error. Moreover, FN-vlPAG projections also modulate extinction learning. We also found a FN-parafascicular thalamus pathway, which may relay cerebellar influence to the amygdala and modulates anxiety behaviors. Overall, our results reveal multiple contributions of the cerebellum to the emotional system.


Assuntos
Sistema Nervoso Central/fisiologia , Medo/fisiologia , Memória/fisiologia , Vias Neurais/fisiologia , Substância Cinzenta Periaquedutal/fisiologia , Tonsila do Cerebelo/fisiologia , Animais , Sistema Nervoso Central/patologia , Cerebelo/diagnóstico por imagem , Cerebelo/fisiologia , Condicionamento Clássico/fisiologia , Condicionamento Operante/fisiologia , Aprendizagem , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Neurônios/metabolismo , Optogenética
3.
Artigo em Chinês | MEDLINE | ID: mdl-33036525

RESUMO

Objective: To study the effects on learning and memory, mitochondrial energy metabolism and ATPase activity of hippocampus in mice with subacute exposure to n-hexane. Methods: The SPF 40 Kunming mice were randomly divided into low, middle and high dose groups and control groups according to different dosages. Each group consisted of 10 mice. The mice were given n-hexane by gavage, the mice in the low, middle and high dose groups were given 0.2 ml/d of n-hexane at concentrations of 500, 1000 and 2000 mg/kg respectively, while the mice in the control group were given 0.2 ml/d of cooking oil once a day for 28 days. The y-type maze test, the activity of ATP Enzyme, mitochondrial respiratory chain enzyme complex Ⅰ-IV, the mrna of mitochondrial fusion gene (MFn1, Mfn2) and fission gene (FIs1) in brain tissues were performed. Results: Except for the wrong reaction times of low-dose exposure group in the first test, there existed significantly different in the first and second Y-maze tests in exposure groups and control group (P<0.05) ; in low, middle and high-dose group, the Na(+)-K(+)-ATPase activities were (8.27±2.65) , (5.38±1.55) , (3.55±1.69) µmol/gprot/h, and Ca(2+)-Mg(2+)-ATPase activities were (10.32±2.96) , (7.19±1.94) and (4.49±1.33) µmol/gprot/h, respectively. Compared with those in control group, the activities of Na(+)-K(+)-ATPase and Ca(2+)-Mg(2+)-ATPase decreased significantly in middle-dose group and high-dose group (P<0.05) . Compared with those in control group, the activities of mitochondrial respiratory chain enzyme complex I-IV in each dose group were significantly decreased (P<0.05) . The expressions of Mfn1mRNA and Mfn2mRNA in each dose group was significantly lower than those in control group (P<0.05) . Conclusion: Subacute exposure to n-hexane can result in the decrease of activities of mitochondrial respiratory chain enzyme complex in hippocampus of mice, which may lead to the disorder of mitochondrial energy metabolism by the decrease of ATPase activity and the imbalance of mitochondrial fusion-division, which must be one of the mechanisms of impairment of learning and memory of mice induced by n-hexane.


Assuntos
Hipocampo , Memória , Animais , Metabolismo Energético , Hexanos , Camundongos
4.
Sci Rep ; 10(1): 18241, 2020 10 26.
Artigo em Inglês | MEDLINE | ID: mdl-33106506

RESUMO

This study examines publicly available online search data in China to investigate the spread of public awareness of the 2019 novel coronavirus (SARS-CoV-2) outbreak. We found that cities that had previously suffered from SARS (in 2003-04) and have greater migration ties to Wuhan had earlier, stronger and more durable public awareness of the outbreak. Our data indicate that 48 such cities developed awareness up to 19 days earlier than 255 comparable cities, giving them an opportunity to better prepare. This study suggests that it is important to consider memory of prior catastrophic events as they will influence the public response to emerging threats.


Assuntos
Conscientização , Infecções por Coronavirus/patologia , Relações Interpessoais , Pneumonia Viral/patologia , Betacoronavirus/isolamento & purificação , Blogging , China/epidemiologia , Infecções por Coronavirus/epidemiologia , Infecções por Coronavirus/virologia , Surtos de Doenças , Humanos , Memória , Pandemias , Pneumonia Viral/epidemiologia , Pneumonia Viral/virologia , Mídias Sociais
5.
Ideggyogy Sz ; 73(9-10): 327-337, 2020 Sep 30.
Artigo em Húngaro | MEDLINE | ID: mdl-33035416

RESUMO

Background and purpose: A growing body of evidence suggests that sleep plays an essential role in the consolidation of different memory systems, but less is known about the beneficial effect of sleep on relational memory processes and the recognition of emotional facial expressions, however, it is a fundamental cognitive skill in human everyday life. Thus, the study aims to investigate the effect of timing of learning and the role of sleep in relational memory processes. Methods: 84 young adults (average age: 22.36 (SD: 3.22), 21 male/63 female) participated in our study, divided into two groups: evening group and morning group indicating the time of learning. We used the face-name task to measure relational memory and facial expression recognition. There were two sessions for both groups: the immediate testing phase and the delayed retesting phase, separated by 24 hours. Results: 84 young adults (average age: 22.36 (SD: 3.22), 21 male/63 female) participated in our study, divided into two groups: evening group and morning group indicating the time of learning. We used the face-name task to measure relational memory and facial expression recognition. There were two sessions for both groups: the immediate testing phase and the delayed retesting phase, separated by 24 hours. Conclusion: Our results suggest that the timing of learning and sleep plays an important role in the stabilizing process of memory representation to resist against forgetting.


Assuntos
Aprendizagem/fisiologia , Memória/fisiologia , Sono/fisiologia , Adulto , Emoções , Expressão Facial , Reconhecimento Facial , Feminino , Humanos , Masculino , Adulto Jovem
6.
Ideggyogy Sz ; 73(9-10): 295-301, 2020 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-33035420

RESUMO

Interest in the hippocampal formation and its role in navigation and memory arose in the second part of the 20th century, at least in part due to the curious case of Henry G. Molaison, who underwent brain surgery for intractable epilepsy. The temporal association observed between the removal of his entorhinal cortex along with a significant part of hippocampus and the developing severe memory deficit inspired scientists to focus on these regions. The subsequent discovery of the so-called place cells in the hippocampus launched the description of many other functional cell types and neuronal networks throughout the Papez-circuit that has a key role in memory processes and spatial information coding (speed, head direction, border, grid, object-vector etc). Each of these cell types has its own unique characteristics, and together they form the so-called "Brain GPS". The aim of this short survey is to highlight for practicing neurologists the types of cells and neuronal networks that represent the anatomical substrates and physiological correlates of pathological entities affecting the limbic system, especially in the temporal lobe. For that purpose, we survey early discoveries along with the most relevant neuroscience observations from the recent literature. By this brief survey, we highlight main cell types in the hippocampal formation, and describe their roles in spatial navigation and memory processes. In recent decades, an array of new and functionally unique neuron types has been recognized in the hippocampal formation, but likely more remain to be discovered. For a better understanding of the heterogeneous presentations of neurological disorders affecting this anatomical region, insights into the constantly evolving neuroscience behind may be helpful. The public health consequences of diseases that affect memory and spatial navigation are high, and grow as the population ages, prompting scientist to focus on further exploring this brain region.


Assuntos
Memória , Neurociências , Navegação Espacial , Córtex Entorrinal , Hipocampo , Humanos
7.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 5657-5660, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33019260

RESUMO

The Clock Drawing Test, where the participant is asked to draw a clock from memory and copy a model clock, is widely used for screening of cognitive impairment. The digital version of the clock test, the digital clock drawing test (dCDT), employs accelerometer and pressure sensors of a digital pen to capture time and pressure information from a participant's performance in a granular digital format. While visual features of the clock drawing test have previously been studied, little is known about the relationship between demographic and cognitive impairment characteristics with dCDT latency and graphomotor features. Here, we examine dCDT feature clusters with respect to sociodemographic and cognitive impairment outcomes. Our results show that the clusters are not significantly different in terms of age and gender, but did significantly differ in terms of education, Mini-Mental State Exam scores, and cognitive impairment diagnoses.This study shows that features extracted from digital clock drawings can provide important information regarding cognitive reserve and cognitive impairments.


Assuntos
Disfunção Cognitiva , Reserva Cognitiva , Disfunção Cognitiva/diagnóstico , Humanos , Programas de Rastreamento , Memória , Testes Neuropsicológicos
8.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 3363-3366, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33018725

RESUMO

Many studies have explored brain signals during the performance of a memory task to predict later remembered items. However, prediction methods are still poorly used in real life and are not practical due to the use of electroencephalography (EEG) recorded from the scalp. Ear-EEG has been recently used to measure brain signals due to its flexibility when applying it to real world environments. In this study, we attempt to predict whether a shown stimulus is going to be remembered or forgotten using ear-EEG and compared its performance with scalp-EEG. Our results showed that there was no significant difference between ear-EEG and scalp-EEG. In addition, the higher prediction accuracy was obtained using a convolutional neural network (pre-stimulus: 74.06%, on-going stimulus: 69.53%) and it was compared to other baseline methods. These results showed that it is possible to predict performance of a memory task using ear-EEG signals and it could be used for predicting memory retrieval in a practical brain-computer interface.


Assuntos
Interfaces Cérebro-Computador , Eletroencefalografia , Encéfalo , Cognição , Humanos , Memória
9.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 569-575, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33018053

RESUMO

Classification of seizure type is a key step in the clinical process for evaluating an individual who presents with seizures. It determines the course of clinical diagnosis and treatment, and its impact stretches beyond the clinical domain to epilepsy research and the development of novel therapies. Automated identification of seizure type may facilitate understanding of the disease, and seizure detection and prediction have been the focus of recent research that has sought to exploit the benefits of machine learning and deep learning architectures. Nevertheless, there is not yet a definitive solution for automating the classification of seizure type, a task that must currently be performed by an expert epileptologist. Inspired by recent advances in neural memory networks (NMNs), we introduce a novel approach for the classification of seizure type using electrophysiological data. We first explore the performance of traditional deep learning techniques which use convolutional and recurrent neural networks, and enhance these architectures by using external memory modules with trainable neural plasticity. We show that our model achieves a state-of-the-art weighted F1 score of 0.945 for seizure type classification on the TUH EEG Seizure Corpus with the IBM TUSZ preprocessed data. This work highlights the potential of neural memory networks to support the field of epilepsy research, along with biomedical research and signal analysis more broadly.


Assuntos
Eletroencefalografia , Epilepsia , Epilepsia/diagnóstico , Humanos , Memória , Redes Neurais de Computação , Convulsões/diagnóstico
10.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 2479-2482, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33018509

RESUMO

To build hippocampal memory prosthesis for restoring memory functions, we previously developed and implemented a multi-input multi-output (MIMO) nonlinear dynamic model of the hippocampus. This model can successfully predict hippocampal output spike activities based on input spike activities, and thus be used to drive microstimulation to bypass the damaged hippocampal region. Building such a MIMO model involves estimations of a large number of model coefficients, which typically takes hundreds of hours using a single personal computer. In practice, however, due to the requirement of medical care and clinical trials, the modeling processes must be completed within 72 hours after the recording, so that models can be used to drive stimulations. To solve this problem, we utilized a parallelization strategy to divide the whole MIMO model computation involving iterative estimation and optimization into independent computing tasks that can be performed simultaneously in multiple computer nodes. Such a strategy was implemented on the high-performance computing cluster at the University of Southern California. It reduced the model estimation time to tens of hours and thus allowed us to complete the modeling process within the required time frame to further test model-driven electrical stimulation for the hippocampal memory prosthesis.


Assuntos
Hipocampo , Memória , Estimulação Elétrica , Microcomputadores , Dinâmica não Linear
11.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 3586-3589, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33018778

RESUMO

Sleep spindles are transient oscillations in the brain related to sleep consolidation and memory. We investigated if brief, localized electrical pulses could perturb spindles on five human patients with intracerebral electrodes implanted for clinical purpose. We used a closed-loop setup to specifically detect spindles and stimulate in real-time during these events. Stimulation latency was 200-400 ms following spindle onset. Analyzing the intracranial electro-encephalographic (iEEG) data both locally and globally, we found, in two of the patients, that single pulse stimulation could stop the spindles locally. Spindles were shorter than those without stimulation and a decrease in power at the same frequency as spindles was observed following stimulation.Clinical Relevance- This study shows that brief and precise electrical stimulation may be used to modulate oscillatory behavior of the human brain. Applied to sleep spindles, further studies may establish that single pulses applied in a closed-loop manner could be used to modulate memory and could help understand effect of neuromodulation in sleep disruption.


Assuntos
Eletroencefalografia , Sono , Encéfalo , Estimulação Elétrica , Humanos , Memória
12.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 3625-3628, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33018787

RESUMO

Several studies have shown that direct brain stimulation can enhance memory in humans and animal models. Investigating the neurophysiological changes induced by brain stimulation is an important step towards understanding the neural processes underlying memory function. Furthermore, it paves the way for developing more efficient neuromodulation approaches for memory enhancement. In this study, we utilized a combination of unsupervised and supervised machine learning approaches to investigate how amygdala stimulation modulated hippocampal network activities during the encoding phase. Using a sliding window in time, we estimated the hippocampal dynamic functional network connectivity (dFNC) after stimulation and during sham trials, based on the covariance of local field potential recordings in 4 subregions of the hippocampus. We extracted different network states by combining the dFNC samples from 5 subjects and applying k-means clustering. Next, we used the between-state transition numbers as the latent features to classify between amygdala stimulation and sham trials across all subjects. By training a logistic regression model, we could differentiate stimulated from sham trials with 67% accuracy across all subjects. Using elastic net regularization as a feature selection method, we identified specific patterns of hippocampal network state transition in response to amygdala stimulation. These results offer a new approach to better understanding of the causal relationship between hippocampal network dynamics and memory-enhancing amygdala stimulation.


Assuntos
Tonsila do Cerebelo , Estimulação Encefálica Profunda , Animais , Hipocampo , Humanos , Memória
13.
Nat Commun ; 11(1): 5418, 2020 10 27.
Artigo em Inglês | MEDLINE | ID: mdl-33110085

RESUMO

Human categorization is one of the most important and successful targets of cognitive modeling, with decades of model development and assessment using simple, low-dimensional artificial stimuli. However, it remains unclear how these findings relate to categorization in more natural settings, involving complex, high-dimensional stimuli. Here, we take a step towards addressing this question by modeling human categorization over a large behavioral dataset, comprising more than 500,000 judgments over 10,000 natural images from ten object categories. We apply a range of machine learning methods to generate candidate representations for these images, and show that combining rich image representations with flexible cognitive models captures human decisions best. We also find that in the high-dimensional representational spaces these methods generate, simple prototype models can perform comparably to the more complex memory-based exemplar models dominant in laboratory settings.


Assuntos
Cognição , Aprendizado Profundo , Reconhecimento Visual de Modelos , Tomada de Decisões , Humanos , Julgamento , Memória , Modelos Psicológicos , Córtex Visual
14.
Neuroscientist ; 26(5-6): 386, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33012258
16.
Obstet Gynecol ; 136(5): 1065, 2020 11.
Artigo em Inglês | MEDLINE | ID: mdl-33093416
17.
Nat Commun ; 11(1): 5247, 2020 10 16.
Artigo em Inglês | MEDLINE | ID: mdl-33067436

RESUMO

Sleep spindle generation classically relies on an interplay between the thalamic reticular nucleus (TRN), thalamo-cortical (TC) relay cells and cortico-thalamic (CT) feedback during non-rapid eye movement (NREM) sleep. Spindles are hypothesized to stabilize sleep, gate sensory processing and consolidate memory. However, the contribution of non-sensory thalamic nuclei in spindle generation and the role of spindles in sleep-state regulation remain unclear. Using multisite thalamic and cortical LFP/unit recordings in freely behaving mice, we show that spike-field coupling within centromedial and anterodorsal (AD) thalamic nuclei is as strong as for TRN during detected spindles. We found that spindle rate significantly increases before the onset of rapid eye movement (REM) sleep, but not wakefulness. The latter observation is consistent with our finding that enhancing spontaneous activity of TRN cells or TRN-AD projections using optogenetics increase spindle rate and transitions to REM sleep. Together, our results extend the classical TRN-TC-CT spindle pathway to include non-sensory thalamic nuclei and implicate spindles in the onset of REM sleep.


Assuntos
Fenômenos Fisiológicos Oculares , Sono REM , Núcleos Talâmicos/fisiologia , Animais , Eletroencefalografia , Olho/química , Feminino , Masculino , Memória , Camundongos Endogâmicos C57BL , Optogenética , Núcleos Talâmicos/química , Tálamo/química , Tálamo/fisiologia , Vigília
18.
Georgian Med News ; (304-305): 80-84, 2020.
Artigo em Russo | MEDLINE | ID: mdl-32965254

RESUMO

The number of elderly and senile people with severe senile asthenia syndrome and cognitive disorders, which eventually develop into dementia, is increasing every year in the world. It is this disease that is the highest priority in the health care of the entire world community.; The article provides a historical overview of the creation of memory clinics that operate in the paradigm of providing community-based psychiatric care. The results of changes in the clinical-dynamic and epidemiological indicators of the prevalence of dementia in the direction of early detection of pre-dementia conditions with mild cognitive decline syndrome are presented. Global trends in the development of memory clinics for outpatient patients are considered.; The purpose of the study: to provide a comprehensive analysis of the available literature data on the feasibility of a multi-faceted approach in the development of the concept of memory clinics.


Assuntos
Transtornos Cognitivos , Disfunção Cognitiva/diagnóstico , Disfunção Cognitiva/epidemiologia , Idoso , Envelhecimento , Assistência à Saúde , Humanos , Memória
19.
Chemosphere ; 258: 127362, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32947664

RESUMO

Neonicotinoids have been described as toxic to bees. In this context, the A. mellifera foragers were exposed to a sublethal concentration of thiamethoxam (LC50/100: 0,0227 ng de thiamethoxam/µL-1 diet), a neurotoxic insecticide, for 8 days; and it was decided to investigate the insecticide effect on the brain by a shotgun proteomic approach followed by label-free quantitative-based proteomics. A total of 401 proteins were identified in the control group (CG); and a total of 350 proteins in the thiamethoxam exposed group (TMX). Quantitative proteomics data showed up 251 proteins with significant quantitative values in the TMX group. These findings demonstrated the occurrence of shared and unique proteins with altered expression in the TMX group, such as ATP synthase subunit beta, heat shock protein cognate 4, spectrin beta chain-like, mushroom body large-type Kenyon cell-specific protein 1-like, tubulin alpha-1 chain-like, arginine kinase, epidermal growth factor receptor, odorant receptor, glutamine synthetase, glutamate receptor, and cytochrome P450 4c3. Meanwhile, the proteins that were expressed uniquely in the TMX group are involved mainly in the phosphorylation, cellular protein modification, and cell surface receptor signalling processes. Interaction network results showed that identified proteins are present in five different metabolic pathways - oxidative stress, cytoskeleton control, visual process, olfactory memory, and glutamate metabolism. Our scientific outcomes demonstrated that a sublethal concentration of thiamethoxam can impair biological processes and important metabolic pathways, causing damage to the nervous system of bees, and in the long term, can compromise the nutrition and physiology of individuals from the colony.


Assuntos
Abelhas/fisiologia , Encéfalo/efeitos dos fármacos , Inseticidas/toxicidade , Tiametoxam/toxicidade , Animais , Memória , Neonicotinoides , Nitrocompostos , Oxazinas , Proteômica , Tiazóis
20.
Chemosphere ; 254: 126608, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32957262

RESUMO

Al2O3 Nanoparticles (Al2O3-NPs) have been widely used because of their unique physical and chemical properties, and Al2O3-NPs can be released into the environment directly or indirectly. Our previous research found that 13 nm Al2O3-NPs can induce neural cell death and autophagy in primarily cultured neural cells in vitro. The aim of this study was to determine where Al2O3-NPs at 13 nm particle size can cause neural cells in vivo and assess related behavioural changes and involved potential mechanisms. Zebrafish from embryo to adult were selected as animal models. Learning and memory as functional indicators of neural cells in zebrafish were measured during the development from embryo to adult. Our results indicate that Al2O3-NPs treatment in zebrafish embryos stages can cause the accumulation of aluminium content in zebrafish brain tissue, leading to progressive impaired neurodevelopmental behaviours and latent learning and memory performance. Additionally, oxidative stress and disruption of dopaminergic transmission in zebrafish brain tissues are correlated with the dose-dependent and age-dependent accumulation of aluminium content. Moreover, the number of neural cells in the telencephalon tissue treated with Al2O3-NPs significantly declined, and the ultramicroscopic morphology indicated profound autophagy alternations. The results suggest that Al2O3-NPs has dose-dependent and time-dependent progressive damage on learning and memory performance in adult zebrafish when treated in embryos. This is the first study of the effects of Al2O3-NPs on learning and memory during the development of zebrafish from embryo to adult.


Assuntos
Óxido de Alumínio/toxicidade , Aprendizagem/efeitos dos fármacos , Memória/efeitos dos fármacos , Nanopartículas/toxicidade , Alumínio/farmacologia , Óxido de Alumínio/química , Animais , Embrião não Mamífero , Nanopartículas Metálicas , Estresse Oxidativo/efeitos dos fármacos , Tamanho da Partícula , Peixe-Zebra/embriologia
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA