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1.
J Neurosci ; 40(5): 944-954, 2020 Jan 29.
Artigo em Inglês | MEDLINE | ID: mdl-31996470

RESUMO

The brilliant and often prescient hypotheses of Ramon y Cajal have proven foundational for modern neuroscience, but his statement that "In adult centers the nerve paths are something fixed, ended, immutable … " is an exception that did not stand the test of empirical study. Mechanisms of cellular and circuit-level plasticity continue to shape and reshape many regions of the adult nervous system long after the neurodevelopmental period. Initially focused on neurons alone, the field has followed a meteoric trajectory in understanding of activity-regulated neurodevelopment and ongoing neuroplasticity with an arc toward appreciating neuron-glial interactions and the role that each neural cell type plays in shaping adaptable neural circuity. In this review, as part of a celebration of the 50th anniversary of Society for Neuroscience, we provide a historical perspective, following this arc of inquiry from neuronal to neuron-glial mechanisms by which activity and experience modulate circuit structure and function. The scope of this consideration is broad, and it will not be possible to cover the wealth of knowledge about all aspects of activity-dependent circuit development and plasticity in depth.


Assuntos
Encéfalo/metabolismo , Rede Nervosa/metabolismo , Plasticidade Neuronal/fisiologia , Neurônios/metabolismo , Animais , Encéfalo/citologia , Humanos , Rede Nervosa/citologia
2.
Adv Exp Med Biol ; 1131: 965-984, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31646541

RESUMO

Synaptic plasticity is a fundamental property of neurons referring to the activity-dependent changes in the strength and efficacy of synaptic transmission at preexisting synapses. Such changes can last from milliseconds to hours, days, or even longer and are involved in learning and memory as well as in development and response of the brain to injuries. Several types of synaptic plasticity have been described across neuronal types, brain regions, and species, but all of them share in one way or another capital importance of Ca2+-mediated processes. In this chapter, we will focus on the Ca2+-dependent events necessary for the induction and expression of multiple forms of synaptic plasticity.


Assuntos
Cálcio , Plasticidade Neuronal , Sinapses , Cálcio/metabolismo , Humanos , Potenciação de Longa Duração , Plasticidade Neuronal/fisiologia , Sinapses/fisiologia , Transmissão Sináptica
3.
Adv Exp Med Biol ; 1131: 985-1012, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31646542

RESUMO

Calcium (Ca2+) ions are highly versatile intracellular signaling molecules and are universal second messenger for regulating a variety of cellular and physiological functions including synaptic plasticity. Ca2+ homeostasis in the central nervous system endures subtle dysregulation with advancing age. Research has provided abundant evidence that brain aging is associated with altered neuronal Ca2+ regulation and synaptic plasticity mechanisms. Much of the work has focused on the hippocampus, a brain region critically involved in learning and memory, which is particularly susceptible to dysfunction during aging. The current chapter takes a specific perspective, assessing various Ca2+ sources and the influence of aging on Ca2+ sources and synaptic plasticity in the hippocampus. Integrating the knowledge of the complexity of age-related alterations in neuronal Ca2+ signaling and synaptic plasticity mechanisms will positively shape the development of highly effective therapeutics to treat brain disorders including cognitive impairment associated with aging and neurodegenerative disease.


Assuntos
Envelhecimento , Encéfalo , Sinalização do Cálcio , Doenças Neurodegenerativas , Plasticidade Neuronal , Encéfalo/fisiopatologia , Hipocampo/fisiopatologia , Humanos , Plasticidade Neuronal/fisiologia
4.
Nat Rev Neurol ; 15(12): 732-745, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31728042

RESUMO

Over the past decade, we have witnessed a flourishing of novel strategies to enhance neuroplasticity and promote axon regeneration following spinal cord injury, and results from preclinical studies suggest that some of these strategies have the potential for clinical translation. Spinal cord injury leads to the disruption of neural circuitry and connectivity, resulting in permanent neurological disability. Recovery of function relies on augmenting neuroplasticity to potentiate sprouting and regeneration of spared and injured axons, to increase the strength of residual connections and to promote the formation of new connections and circuits. Neuroplasticity can be fostered by exploiting four main biological properties: neuronal intrinsic signalling, the neuronal extrinsic environment, the capacity to reconnect the severed spinal cord via neural stem cell grafts, and modulation of neuronal activity. In this Review, we discuss experimental evidence from rodents, nonhuman primates and patients regarding interventions that target each of these four properties. We then highlight the strengths and challenges of individual and combinatorial approaches with respect to clinical translation. We conclude by considering future developments and providing views on how to bridge the gap between preclinical studies and clinical translation.


Assuntos
Regeneração Nervosa/fisiologia , Plasticidade Neuronal/fisiologia , Recuperação de Função Fisiológica/fisiologia , Traumatismos da Medula Espinal/metabolismo , Pesquisa Médica Translacional/métodos , Animais , Axônios/fisiologia , Humanos , Traumatismos da Medula Espinal/diagnóstico , Traumatismos da Medula Espinal/genética
5.
Nat Neurosci ; 22(11): 1782-1792, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31636451

RESUMO

Microglia are the brain's resident innate immune cells and also have a role in synaptic plasticity. Microglial processes continuously survey the brain parenchyma, interact with synaptic elements and maintain tissue homeostasis. However, the mechanisms that control surveillance and its role in synaptic plasticity are poorly understood. Microglial dynamics in vivo have been primarily studied in anesthetized animals. Here we report that microglial surveillance and injury response are reduced in awake mice as compared to anesthetized mice, suggesting that arousal state modulates microglial function. Pharmacologic stimulation of ß2-adrenergic receptors recapitulated these observations and disrupted experience-dependent plasticity, and these effects required the presence of ß2-adrenergic receptors in microglia. These results indicate that microglial roles in surveillance and synaptic plasticity in the mouse brain are modulated by noradrenergic tone fluctuations between arousal states and emphasize the need to understand the effect of disruptions of adrenergic signaling in neurodevelopment and neuropathology.


Assuntos
Microglia/fisiologia , Plasticidade Neuronal/fisiologia , Norepinefrina/fisiologia , Córtex Visual/fisiologia , Animais , Benzilaminas/farmacologia , Receptor 1 de Quimiocina CX3C/genética , Movimento Celular/efeitos dos fármacos , Movimento Celular/fisiologia , Ritmo Circadiano/fisiologia , Clembuterol/farmacologia , Dexmedetomidina/farmacologia , Dominância Ocular , Feminino , Fentanila/farmacologia , Locus Cerúleo/efeitos dos fármacos , Masculino , Camundongos , Camundongos Transgênicos , Microglia/citologia , Microglia/efeitos dos fármacos , Nadolol/farmacologia , Plasticidade Neuronal/efeitos dos fármacos , Neurônios/metabolismo , Neurônios/fisiologia , Norepinefrina/metabolismo , Propanolaminas/farmacologia , Restrição Física/fisiologia , Terbutalina/farmacologia , Vigília , Ferimentos e Lesões/fisiopatologia
6.
Nat Commun ; 10(1): 4799, 2019 10 22.
Artigo em Inglês | MEDLINE | ID: mdl-31641124

RESUMO

Metabolic diseases harm brain health and cognitive functions, but whether maternal metabolic unbalance may affect brain plasticity of next generations is still unclear. Here, we demonstrate that maternal high fat diet (HFD)-dependent insulin resistance multigenerationally impairs synaptic plasticity, learning and memory. HFD downregulates BDNF and insulin signaling in maternal tissues and epigenetically inhibits BDNF expression in both germline and hippocampus of progeny. Notably, exposure of the HFD offspring to novel enriched environment restores Bdnf epigenetic activation in the male germline and counteracts the transmission of cognitive impairment to the next generations. BDNF administration to HFD-fed mothers or preserved insulin sensitivity in HFD-fed p66Shc KO mice also prevents the intergenerational transmission of brain damage to the progeny. Collectively, our data suggest that maternal diet multigenerationally impacts on descendants' brain health via gametic mechanisms susceptible to lifestyle.


Assuntos
Dieta Hiperlipídica/efeitos adversos , Resistência à Insulina , Aprendizagem/fisiologia , Memória/fisiologia , Plasticidade Neuronal/fisiologia , Animais , Fator Neurotrófico Derivado do Encéfalo/genética , Fator Neurotrófico Derivado do Encéfalo/metabolismo , Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico/genética , Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico/metabolismo , Epigênese Genética , Feminino , Proteína Forkhead Box O3/metabolismo , Regulação da Expressão Gênica , Hipocampo/fisiopatologia , Histona Desacetilase 2/metabolismo , Masculino , Camundongos Endogâmicos C57BL , Camundongos Knockout , Ovário/metabolismo , Sirtuína 2/metabolismo , Proteína 1 de Transformação que Contém Domínio 2 de Homologia de Src/genética
7.
Medicina (B Aires) ; 79 Suppl 3: 29-32, 2019.
Artigo em Espanhol | MEDLINE | ID: mdl-31603840

RESUMO

Recent studies have demonstrated that while we are sleeping, our brain is very busy processing all information we have acquired along the day. Lack of sleep has shown to produce deficits in memory consolidation and plays an important role in brain development and brain plasticity in the several developmental stages of the human brain. At the cellular level, circadian cycles coordinate complex mechanism that "turn on and off" genes and cellular structures regulating individual cell functions to impact global organ and systems physiological activities. At the end a perfect and coordinated equilibrium in the mental, emotional and physiological is the goal of this complex process. Sleep impacts memory, learning, mood, behavior, immunological responses, metabolism, hormone levels, digestive process and many more physiological functions. We present a review of three basic aspects related with sleep: a. brain electrical activity during the sleep and neuroanatomic correlation with mechanism related with memory and learning; b. circadian cycles and impact in several physiological systems; c some examples of clinical disorders associated with sleep disorders and impact in learning and memory.


Assuntos
Ritmo Circadiano/fisiologia , Aprendizagem/fisiologia , Memória/fisiologia , Plasticidade Neuronal/fisiologia , Sono/fisiologia , Encéfalo/fisiologia , Emoções/fisiologia , Humanos , Transtornos do Sono-Vigília/fisiopatologia
8.
Nat Commun ; 10(1): 4441, 2019 09 30.
Artigo em Inglês | MEDLINE | ID: mdl-31570719

RESUMO

What is the physiological basis of long-term memory? The prevailing view in Neuroscience attributes changes in synaptic efficacy to memory acquisition, implying that stable memories correspond to stable connectivity patterns. However, an increasing body of experimental evidence points to significant, activity-independent fluctuations in synaptic strengths. How memories can survive these fluctuations and the accompanying stabilizing homeostatic mechanisms is a fundamental open question. Here we explore the possibility of memory storage within a global component of network connectivity, while individual connections fluctuate. We find that homeostatic stabilization of fluctuations differentially affects different aspects of network connectivity. Specifically, memories stored as time-varying attractors of neural dynamics are more resilient to erosion than fixed-points. Such dynamic attractors can be learned by biologically plausible learning-rules and support associative retrieval. Our results suggest a link between the properties of learning-rules and those of network-level memory representations, and point at experimentally measurable signatures.


Assuntos
Memória/fisiologia , Modelos Neurológicos , Rede Nervosa/fisiologia , Sinapses/fisiologia , Algoritmos , Simulação por Computador , Homeostase , Aprendizagem , Memória de Longo Prazo/fisiologia , Plasticidade Neuronal/fisiologia , Neurônios/fisiologia , Dinâmica não Linear , Software
9.
J Altern Complement Med ; 25(12): 1172-1182, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31556688

RESUMO

Objective: Previous studies evaluating neurophysiological correlates of long-term meditation are constrained by some methodological limitations. The objective of this study was to measure changes in the regional cerebral glucose metabolism during meditation using a novel methodological approach. Design: The present study was a part of a larger, nonrandomized, single-center open-label study. Setting/location: The study was conducted at the Department of Physiology and Department of Nuclear Medicine and Positron Emission Tomography. A dedicated place was set up as a yoga room, away from the positron emission tomography (PET) scanning room in the Department of Nuclear Medicine and Positron Emission Tomography, where meditators performed meditation in a peaceful environment in a sitting posture with eyes closed. The electroencephalography (EEG) was recorded to affirm the meditation objectively. Subjects: Twenty-four sets of PET scans were obtained at 2 different occasions (baseline and postmeditation within 40 min of 18FDG [18fluorodeoxyglucose] injection) from 12 apparently healthy, male, right-handed long-term meditators practicing Preksha meditation (since >5 years, at least 5 days a week) who were recruited from a well-established meditation center in Delhi. Outcome measures: Changes in the regional cerebral glucose metabolism during meditation versus baseline. Results: Regional cluster analysis showed significantly activated well-defined areas of fronto-parieto-temporal regions of the right versus left hemisphere during meditation. Interestingly, right homolog of Broca's area and right lentiform nucleus were hyperactive during meditation in all the meditators. Conclusions: Long-term meditation might potentially enhance the explicit functions of specific parts of the right hemisphere, possibly due to neuroplastic changes in the brain. Importantly, results of the current study are encouraging and show a novel methodological approach to acquire 18FDG PET/CT (computed tomography) images. The study was registered at Clinical Trial Registry India (CTRI), CTRI/2009/091/000727.


Assuntos
Química Encefálica/fisiologia , Encéfalo , Fluordesoxiglucose F18/metabolismo , Meditação , Plasticidade Neuronal/fisiologia , Adulto , Encéfalo/diagnóstico por imagem , Encéfalo/metabolismo , Humanos , Masculino , Tomografia por Emissão de Pósitrons , Adulto Jovem
10.
Nat Commun ; 10(1): 4263, 2019 09 19.
Artigo em Inglês | MEDLINE | ID: mdl-31537790

RESUMO

Mesostriatal dopaminergic neurons possess extensively branched axonal arbours. Whether action potentials are converted to dopamine output in the striatum will be influenced dynamically and critically by axonal properties and mechanisms that are poorly understood. Here, we address the roles for mechanisms governing release probability and axonal activity in determining short-term plasticity of dopamine release, using fast-scan cyclic voltammetry in the ex vivo mouse striatum. We show that brief short-term facilitation and longer short term depression are only weakly dependent on the level of initial release, i.e. are release insensitive. Rather, short-term plasticity is strongly determined by mechanisms which govern axonal activation, including K+-gated excitability and the dopamine transporter, particularly in the dorsal striatum. We identify the dopamine transporter as a master regulator of dopamine short-term plasticity, governing the balance between release-dependent and independent mechanisms that also show region-specific gating.


Assuntos
Axônios/metabolismo , Corpo Estriado/metabolismo , Proteínas da Membrana Plasmática de Transporte de Dopamina/metabolismo , Dopamina/metabolismo , Neurônios Dopaminérgicos/metabolismo , Animais , Transporte Biológico , Inibidores da Captação de Dopamina/farmacologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Plasticidade Neuronal/fisiologia
11.
12.
Biochemistry (Mosc) ; 84(8): 896-904, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31522671

RESUMO

RNA editing by adenosine deaminases of the ADAR family attracts a growing interest of researchers, both zoologists studying ecological and evolutionary plasticity of invertebrates and medical biochemists focusing on the mechanisms of cancer and other human diseases. These enzymes deaminate adenosine residues in the double-stranded (ds) regions of RNA with the formation of inosine. As a result, some RNAs change their three-dimensional structure and functions. Adenosine-to-inosine editing in the mRNA coding sequences may cause amino acid substitutions in the encoded proteins. Here, we reviewed current concepts on the functions of two active ADAR isoforms identified in mammals (including humans). The ADAR1 protein, which acts non-specifically on extended dsRNA regions, is capable of immunosuppression via inactivation of the dsRNA interactions with specific sensors inducing the cell immunity. Expression of a specific ADAR1 splicing variant is regulated by the type I interferons by the negative feedback mechanism. It was shown that immunosuppressing effects of ADAR1 facilitate progression of some types of cancer. On the other hand, changes in the amino acid sequences resulting from the mRNA editing by the ADAR enzymes can result in the formation of neoantigens that can activate the antitumor immunity. The ADAR2 isoform acts on RNA more selectively; its function is associated with the editing of mRNA coding regions and can lead to the amino acid substitutions, in particular, those essential for the proper functioning of some neurotransmitter receptors in the central nervous system.


Assuntos
Adenosina Desaminase/metabolismo , Carcinogênese/metabolismo , Plasticidade Neuronal/fisiologia , Edição de RNA/fisiologia , Proteínas de Ligação a RNA/metabolismo , Adenosina Desaminase/imunologia , Sequência de Aminoácidos , Animais , Senescência Celular/fisiologia , Humanos , Inosina/metabolismo , Interferon Tipo I/metabolismo , Proteoma/metabolismo , RNA de Cadeia Dupla/metabolismo , Proteínas de Ligação a RNA/imunologia
13.
Neural Netw ; 119: 332-340, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31499357

RESUMO

In recent years, spiking neural networks (SNNs) have demonstrated great success in completing various machine learning tasks. We introduce a method for learning image features with locally connected layers in SNNs using a spike-timing-dependent plasticity (STDP) rule. In our approach, sub-networks compete via inhibitory interactions to learn features from different locations of the input space. These locally-connected SNNs (LC-SNNs) manifest key topological features of the spatial interaction of biological neurons. We explore a biologically inspired n-gram classification approach allowing parallel processing over various patches of the image space. We report the classification accuracy of simple two-layer LC-SNNs on two image datasets, which respectively match state-of-art performance and are the first results to date. LC-SNNs have the advantage of fast convergence to a dataset representation, and they require fewer learnable parameters than other SNN approaches with unsupervised learning. Robustness tests demonstrate that LC-SNNs exhibit graceful degradation of performance despite the random deletion of large numbers of synapses and neurons. Our results have been obtained using the BindsNET library, which allows efficient machine learning implementations of spiking neural networks.


Assuntos
Aprendizado de Máquina , Plasticidade Neuronal/fisiologia , Neurônios/fisiologia , Modelos Neurológicos
14.
Nat Neurosci ; 22(10): 1718-1730, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31501571

RESUMO

Activity-driven transcription plays an important role in many brain processes, including those underlying memory and epilepsy. Here we combine genetic tagging of nuclei and ribosomes with RNA sequencing, chromatin immunoprecipitation with sequencing, assay for transposase-accessible chromatin using sequencing and Hi-C to investigate transcriptional and chromatin changes occurring in mouse hippocampal excitatory neurons at different time points after synchronous activation during seizure and sparse activation by novel context exploration. The transcriptional burst is associated with an increase in chromatin accessibility of activity-regulated genes and enhancers, de novo binding of activity-regulated transcription factors, augmented promoter-enhancer interactions and the formation of gene loops that bring together the transcription start site and transcription termination site of induced genes and may sustain the fast reloading of RNA polymerase complexes. Some chromatin occupancy changes and interactions, particularly those driven by AP1, remain long after neuronal activation and could underlie the changes in neuronal responsiveness and circuit connectivity observed in these neuroplasticity paradigms, perhaps thereby contributing to metaplasticity in the adult brain.


Assuntos
Epigenômica , Hipocampo/fisiologia , Neurônios/fisiologia , Animais , Cromatina/genética , Elementos Facilitadores Genéticos/genética , Genes Precoces/genética , Hipocampo/citologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Plasticidade Neuronal/genética , Plasticidade Neuronal/fisiologia , Regiões Promotoras Genéticas/genética , Convulsões/genética , Convulsões/fisiopatologia , Estado Epiléptico/genética , Estado Epiléptico/fisiopatologia , Fator de Transcrição AP-1/genética , Transcrição Genética/genética , Transcrição Genética/fisiologia
15.
Int J Mol Sci ; 20(17)2019 Sep 03.
Artigo em Inglês | MEDLINE | ID: mdl-31484392

RESUMO

Brain-derived neurotrophic factor (BDNF) has previously been shown to play an important role in glutamatergic synaptic plasticity in the amygdala, correlating with cued fear learning. While glutamatergic neurotransmission is facilitated by BDNF signaling in the amygdala, its mechanism of action at inhibitory synapses in this nucleus is far less understood. We therefore analyzed the impact of chronic BDNF depletion on GABAA-mediated synaptic transmission in BDNF heterozygous knockout mice (BDNF+/-). Analysis of miniature and evoked inhibitory postsynaptic currents (IPSCs) in the lateral amygdala (LA) revealed neither pre- nor postsynaptic differences in BDNF+/- mice compared to wild-type littermates. In addition, long-term potentiation (LTP) of IPSCs was similar in both genotypes. In contrast, facilitation of spontaneous IPSCs (sIPSCs) by norepinephrine (NE) was significantly reduced in BDNF+/- mice. These results argue against a generally impaired efficacy and plasticity at GABAergic synapses due to a chronic BDNF deficit. Importantly, the increase in GABAergic tone mediated by NE is reduced in BDNF+/- mice. As release of NE is elevated during aversive behavioral states in the amygdala, effects of a chronic BDNF deficit on GABAergic inhibition may become evident in response to states of high arousal, leading to amygdala hyper-excitability and impaired amygdala function.


Assuntos
Tonsila do Cerebelo/metabolismo , Fator Neurotrófico Derivado do Encéfalo/metabolismo , Potenciação de Longa Duração/fisiologia , Animais , Fator Neurotrófico Derivado do Encéfalo/genética , Feminino , Potenciação de Longa Duração/genética , Camundongos , Camundongos Knockout , Plasticidade Neuronal/genética , Plasticidade Neuronal/fisiologia , Técnicas de Patch-Clamp , Transmissão Sináptica/genética , Transmissão Sináptica/fisiologia , Ácido gama-Aminobutírico/metabolismo
16.
J Clin Neurosci ; 69: 250-256, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31477463

RESUMO

Electroacupuncture (EA) is an adjuvant therapy for peripheral nerve injury (PNI). Both peripheral and central alterations contribute to the rehabilitation process. We employed diffusion tensor imaging (DTI) to investigate the diffusion plasticity of afferent and efferent pathways caused by EA in model of peripheral nerve injury and reparation. Twenty-four rats were divided into three groups: normal group, model group and intervention group. Rats of the model group and the intervention group underwent sciatic nerve transection and anastomosis. EA intervention was performed on the intervention group at ST-36 and GB-30 for three months. Gait assessment and DTI were conducted at days post-operative (DPO) 30, 60 and 90. We selected corticospinal tract, spinothalamic tract and internal capsule as regions of interest and analyzed diffusion metrics including fractional anisotropy (FA), axial diffusivity (AD) and radial diffusivity (RD). FA values and RD values displayed significant differences or obvious tendency while AD values maintained a stable level. RD values displayed better indicative performance than FA in internal capsule. The intervention group presented significant correlation between RD values and Regularity Index (RI) during the intervention period. The effect of EA on peripheral nerve injury repairing rats appeared to be accelerated recovery process of sensory and motor neural pathway. We proposed that RD was a potential in vivo indicator for structural plasticity caused by EA and PNI.


Assuntos
Eletroacupuntura , Cápsula Interna/fisiopatologia , Vias Neurais/fisiopatologia , Plasticidade Neuronal/fisiologia , Traumatismos dos Nervos Periféricos/fisiopatologia , Animais , Imagem de Tensor de Difusão/métodos , Modelos Animais de Doenças , Masculino , Ratos , Ratos Sprague-Dawley , Nervo Isquiático/lesões
17.
Nat Neurosci ; 22(10): 1565-1575, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31477897

RESUMO

The dentate gyrus-CA3 circuit of the hippocampus is continuously modified by the integration of adult-born dentate granule cells (abDGCs). All abDGCs undergo a prolonged period of maturation, during which they exhibit heightened synaptic plasticity and refinement of electrophysiological properties and connectivity. Consistent with theoretical models and the known functions of the dentate gyrus-CA3 circuit, acute or chronic manipulations of abDGCs support a role for abDGCs in the regulation of memory interference. In this Review, we integrate insights from studies that examine the maturation of abDGCs and their integration into the circuit with network mechanisms that support memory discrimination, consolidation and clearance. We propose that adult hippocampal neurogenesis enables the generation of a library of experiences, each registered in mature abDGC physiology and connectivity. Mature abDGCs recruit inhibitory microcircuits to support pattern separation and memory indexing.


Assuntos
Hipocampo/crescimento & desenvolvimento , Hipocampo/fisiologia , Memória/fisiologia , Neurogênese/fisiologia , Neurônios/fisiologia , Animais , Região CA3 Hipocampal/crescimento & desenvolvimento , Região CA3 Hipocampal/fisiologia , Giro Denteado/crescimento & desenvolvimento , Giro Denteado/fisiologia , Humanos , Plasticidade Neuronal/fisiologia
18.
Nat Neurosci ; 22(10): 1536-1543, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31477899

RESUMO

Activity-dependent synaptic plasticity has since long been proposed to represent the subcellular substrate of learning and memory, one of the most important behavioral processes through which we adapt to our environment. Despite the undisputed importance of synaptic plasticity for brain function, its exact contribution to learning processes in the context of cellular and connectivity modifications remains obscure. Causally bridging synaptic and behavioral modifications indeed remains limited by the available tools to measure and control synaptic strength and plasticity in vivo under behaviorally relevant conditions. After a brief summary of the current state of knowledge of the links between synaptic plasticity and learning, we will review and discuss the available and desired tools to progress in this endeavor.


Assuntos
Aprendizagem/fisiologia , Plasticidade Neuronal/fisiologia , Animais , Encéfalo/citologia , Encéfalo/fisiologia , Humanos , Vias Neurais/citologia , Vias Neurais/fisiologia
19.
Rehabilitación (Madr., Ed. impr.) ; 53(3): 181-188, jul.-sept. 2019. tab, graf
Artigo em Espanhol | IBECS | ID: ibc-185555

RESUMO

Introducción: las intervenciones terapéuticas formales basadas en la música han sido usadas en rehabilitación para estimular funciones cerebrales implicadas en el movimiento. Objetivo: el objetivo del estudio es realizar una revisión sistemática y conducir un meta-análisis siguiendo las recomendaciones PRISMA sobre la eficacia de la terapia musical en la funcionalidad del miembro superior en pacientes con hemiparesia secundaria a un ictus. Métodos: se realizó una búsqueda en las bases de datos de Pubmed, clinicaltrials.gov y Cochrane en septiembre de 2018. Los artículos incluidos en esta revisión debían cumplir los siguientes criterios: ensayos controlados aleatorizados con intervenciones terapéuticas musicales que evaluasen la mejora en la destreza manual, medido con el test de cajas y bloques (Box and Block Test) en sujetos mayores de 18 años con un déficit residual secundario a un ictus isquémico o hemorrágico en los meses previos. Resultados: seis estudios de 371 trabajos analizados fueron incluidos en el estudio y posterior meta-análisis con un total de 149 pacientes. Las intervenciones musicales mejoraban la funcionalidad de la extremidad parética en pacientes con ictus frente a los controles con tratamiento convencional siendo el efecto significativamente estadístico en el meta-análisis, con una diferencia de la media estandarizada en el Box and Block Test de 0.40 (95% CI 0.09 - 0.72). Conclusiones: las intervenciones musicales podrían ser beneficiosas para la recuperación funcional de la extremidad superior. Estos resultados son motivadores pero se requiere de un mayor número de ensayos clínicos para confirmar estos hallazgos para su posterior implantación en la práctica clínica


Introduction: formal therapeutic interventions based on music have been used in rehabilitation to stimulate the brain functions involved in movement. Objective: the objective of this study was to conduct a systematic review and meta-analysis following the PRISMA recommendations on the effectiveness of music therapy in improving the functionality of the upper limb in patients with hemiparesis secondary to stroke. Methods: a search of the Pubmed, clinicaltrials.gov and Cochrane databases was performed in September 2018. The articles included in this review had to meet the following criteria: randomised controlled trials with therapeutic interventions that evaluated improvement in manual dexterity, measured with the box and block test in patients older than 18 years with a residual deficit secondary to an ischaemic or haemorrhagic stroke in the previous months. Results: of 371 studies analysed, six were included in the study and subsequent meta-analysis with a total of 149 patients. The musical interventions improved the functionality of the parietal limb in patients with stroke compared with that in controls who received conventional treatment. This effect was statistically significant in the meta-analysis, with a difference in the standardised mean in the box and block test of 0.40 (95% CI 0.09 - 0.72). Conclusions: musical interventions could be beneficial for the functional recovery of the upper extremity. These results are encouraging but a greater number of clinical trials are required to confirm these findings before their subsequent implementation in clinical practice


Assuntos
Humanos , Acidente Vascular Cerebral/complicações , Reabilitação do Acidente Vascular Cerebral/métodos , Musicoterapia/métodos , Plasticidade Neuronal/fisiologia , Resultado do Tratamento
20.
PLoS Comput Biol ; 15(8): e1006604, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31430280

RESUMO

We provide a novel computational framework on how biological and artificial agents can learn to flexibly couple and decouple neural task modules for cognitive processing. In this way, they can address the stability-plasticity dilemma. For this purpose, we combine two prominent computational neuroscience principles, namely Binding by Synchrony and Reinforcement Learning. The model learns to synchronize task-relevant modules, while also learning to desynchronize currently task-irrelevant modules. As a result, old (but currently task-irrelevant) information is protected from overwriting (stability) while new information can be learned quickly in currently task-relevant modules (plasticity). We combine learning to synchronize with task modules that learn via one of several classical learning algorithms (Rescorla-Wagner, backpropagation, Boltzmann machines). The resulting combined model is tested on a reversal learning paradigm where it must learn to switch between three different task rules. We demonstrate that our combined model has significant computational advantages over the original network without synchrony, in terms of both stability and plasticity. Importantly, the resulting models' processing dynamics are also consistent with empirical data and provide empirically testable hypotheses for future MEG/EEG studies.


Assuntos
Modelos Neurológicos , Modelos Psicológicos , Algoritmos , Animais , Encéfalo/fisiologia , Biologia Computacional , Simulação por Computador , Humanos , Rede Nervosa/fisiologia , Plasticidade Neuronal/fisiologia , Neurônios/fisiologia , Análise de Sistemas , Análise e Desempenho de Tarefas
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