Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 17.016
Filtrar
1.
Phys Rev Lett ; 123(17): 178103, 2019 Oct 25.
Artigo em Inglês | MEDLINE | ID: mdl-31702278

RESUMO

We develop a phenomenological coarse-graining procedure for activity in a large network of neurons, and apply this to recordings from a population of 1000+ cells in the hippocampus. Distributions of coarse-grained variables seem to approach a fixed non-Gaussian form, and we see evidence of scaling in both static and dynamic quantities. These results suggest that the collective behavior of the network is described by a nontrivial fixed point.


Assuntos
Hipocampo/fisiologia , Modelos Neurológicos , Neurônios/fisiologia , Animais , Hipocampo/citologia , Humanos , Camundongos , Rede Nervosa/citologia , Rede Nervosa/fisiologia , Neurônios/citologia
2.
Nat Neurosci ; 22(10): 1669-1676, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31477898

RESUMO

Visual attention dramatically improves individuals' ability to see and modulates the responses of neurons in every known visual and oculomotor area, but whether such modulations can account for perceptual improvements is unclear. We measured the relationship between populations of visual neurons, oculomotor neurons and behavior during detection and discrimination tasks. We found that neither of the two prominent hypothesized neuronal mechanisms underlying attention (which concern changes in information coding and the way sensory information is read out) provide a satisfying account of the observed behavioral improvements. Instead, our results are more consistent with the hypothesis that attention reshapes the representation of attended stimuli to more effectively influence behavior. Our results suggest a path toward understanding the neural underpinnings of perception and cognition in health and disease by analyzing neuronal responses in ways that are constrained by behavior and interactions between brain areas.


Assuntos
Atenção/fisiologia , Neurônios/fisiologia , Animais , Tomada de Decisões/fisiologia , Discriminação (Psicologia)/fisiologia , Macaca mulatta , Masculino , Neurônios Motores/fisiologia , Rede Nervosa/fisiologia , Desempenho Psicomotor/fisiologia , Psicofísica
3.
Nat Neurosci ; 22(10): 1586-1597, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31551602

RESUMO

Emotional learning and memory are functionally and dysfunctionally regulated by the neuromodulatory state of the brain. While the role of excitatory and inhibitory neural circuits mediating emotional learning and its control have been the focus of much research, we are only now beginning to understand the more diffuse role of neuromodulation in these processes. Recent experimental studies of the acetylcholine, noradrenaline and dopamine systems in fear learning and extinction of fear responding provide surprising answers to key questions in neuromodulation. One area of research has revealed how modular organization, coupled with context-dependent coding modes, allows for flexible brain-wide or targeted neuromodulation. Other work has shown how these neuromodulators act in downstream targets to enhance signal-to-noise ratios and gain, as well as to bind distributed circuits through neuronal oscillations. These studies elucidate how different neuromodulatory systems regulate aversive emotional processing and reveal fundamental principles of neuromodulatory function.


Assuntos
Aprendizagem da Esquiva/fisiologia , Emoções/fisiologia , Rede Nervosa/fisiologia , Animais , Medo/fisiologia , Medo/psicologia , Humanos , Aprendizagem/fisiologia , Memória/fisiologia , Neurotransmissores/fisiologia
4.
Nat Biotechnol ; 37(9): 1013-1023, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31406326

RESUMO

Monitoring and modulating the diversity of signals used by neurons and glia in a closed-loop fashion is necessary to establish causative links between biochemical processes within the nervous system and observed behaviors. As developments in neural-interface hardware strive to keep pace with rapid progress in genetically encoded and synthetic reporters and modulators of neural activity, the integration of multiple functional features becomes a key requirement and a pressing challenge in the field of neural engineering. Electrical, optical and chemical approaches have been used to manipulate and record neuronal activity in vivo, with a recent focus on technologies that both integrate multiple modes of interaction with neurons into a single device and enable bidirectional communication with neural circuits with enhanced spatiotemporal precision. These technologies not only are facilitating a greater understanding of the brain, spinal cord and peripheral circuits in the context of health and disease, but also are informing the development of future closed-loop therapies for neurological, neuro-immune and neuroendocrine conditions.


Assuntos
Encéfalo/fisiologia , Técnicas de Diagnóstico Neurológico , Estimulação Elétrica , Rede Nervosa/fisiologia , Humanos , Neurônios/fisiologia
5.
Top Magn Reson Imaging ; 28(4): 189-196, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31385898

RESUMO

Functional MRI (fMRI) is currently used for pre-surgical planning, but is often limited to information on the motor and language systems. Resting state fMRI can provide more information on multiple other networks to the neurosurgeon and neuroradiologist; however, currently, these networks are not well known among clinicians. The purpose of this manuscript is to provide an introduction to these networks for the clinician and to discuss how they could be used in the future for precise and individualized surgical planning. We provide a short introduction to resting state fMRI and discuss multiple currently accepted resting state networks with a review of the literature. We review the characteristics and function of multiple somatosensory, association, and other networks. We discuss the concept of critical nodes in the brain and how the neurosurgeon can use this information to individually customize patient care. Although further research is necessary, future application of pre-surgical planning will require consideration of networks other than just motor and language in order to minimize post-surgical morbidity and customize patient care.


Assuntos
Mapeamento Encefálico/métodos , Encéfalo/diagnóstico por imagem , Encéfalo/fisiologia , Imagem por Ressonância Magnética/métodos , Rede Nervosa/diagnóstico por imagem , Rede Nervosa/fisiologia , Humanos , Linguagem , Atividade Motora , Descanso/fisiologia
6.
Nat Neurosci ; 22(9): 1512-1520, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31406365

RESUMO

Neural circuits construct distributed representations of key variables-external stimuli or internal constructs of quantities relevant for survival, such as an estimate of one's location in the world-as vectors of population activity. Although population activity vectors may have thousands of entries (dimensions), we consider that they trace out a low-dimensional manifold whose dimension and topology match the represented variable. This manifold perspective enables blind discovery and decoding of the represented variable using only neural population activity (without knowledge of the input, output, behavior or topography). We characterize and directly visualize manifold structure in the mammalian head direction circuit, revealing that the states form a topologically nontrivial one-dimensional ring. The ring exhibits isometry and is invariant across waking and rapid eye movement sleep. This result directly demonstrates that there are continuous attractor dynamics and enables powerful inference about mechanism. Finally, external rather than internal noise limits memory fidelity, and the manifold approach reveals new dynamical trajectories during sleep.


Assuntos
Encéfalo/fisiologia , Modelos Neurológicos , Rede Nervosa/fisiologia , Sono REM/fisiologia , Vigília/fisiologia , Animais , Feminino , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Redes Neurais (Computação)
7.
Nat Commun ; 10(1): 3075, 2019 07 12.
Artigo em Inglês | MEDLINE | ID: mdl-31300665

RESUMO

The brain has a remarkable capacity to adapt to changes in sensory inputs and to learn from experience. However, the neural circuits responsible for this flexible processing remain poorly understood. Using optogenetic silencing of ArchT-expressing neurons in adult ferrets, we show that within-trial activity in primary auditory cortex (A1) is required for training-dependent recovery in sound-localization accuracy following monaural deprivation. Because localization accuracy under normal-hearing conditions was unaffected, this highlights a specific role for cortical activity in learning. A1-dependent plasticity appears to leave a memory trace that can be retrieved, facilitating adaptation during a second period of monaural deprivation. However, in ferrets in which learning was initially disrupted by perturbing A1 activity, subsequent optogenetic suppression during training no longer affected localization accuracy when one ear was occluded. After the initial learning phase, the reweighting of spatial cues that primarily underpins this plasticity may therefore occur in A1 target neurons.


Assuntos
Córtex Auditivo/fisiologia , Aprendizagem/fisiologia , Localização de Som/fisiologia , Estimulação Acústica , Animais , Córtex Auditivo/citologia , Feminino , Furões , Modelos Animais , Rede Nervosa/fisiologia , Plasticidade Neuronal/fisiologia , Neurônios/fisiologia , Optogenética
8.
Philos Trans A Math Phys Eng Sci ; 377(2153): 20180128, 2019 Sep 09.
Artigo em Inglês | MEDLINE | ID: mdl-31329071

RESUMO

We study the spatio-temporal dynamics of a multiplex network of delay-coupled FitzHugh-Nagumo oscillators with non-local and fractal connectivities. Apart from chimera states, a new regime of coexistence of slow and fast oscillations is found. An analytical explanation for the emergence of such coexisting partial synchronization patterns is given. Furthermore, we propose a control scheme for the number of fast and slow neurons in each layer. This article is part of the theme issue 'Nonlinear dynamics of delay systems'.


Assuntos
Modelos Neurológicos , Rede Nervosa/fisiologia , Neurônios/fisiologia , Simulação por Computador , Humanos
9.
Nat Commun ; 10(1): 2620, 2019 06 13.
Artigo em Inglês | MEDLINE | ID: mdl-31197165

RESUMO

Conventional drug screens and treatments often ignore the underlying complexity of brain network dysfunctions, resulting in suboptimal outcomes. Here we ask whether we can correct abnormal functional connectivity of the entire brain by identifying and combining multiple neuromodulators that perturb connectivity in complementary ways. Our approach avoids the combinatorial complexity of screening all drug combinations. We develop a high-speed platform capable of imaging more than 15000 neurons in 50ms to map the entire brain functional connectivity in large numbers of vertebrates under many conditions. Screening a panel of drugs in a zebrafish model of human Dravet syndrome, we show that even drugs with related mechanisms of action can modulate functional connectivity in significantly different ways. By clustering connectivity fingerprints, we algorithmically select small subsets of complementary drugs and rapidly identify combinations that are significantly more effective at correcting abnormal networks and reducing spontaneous seizures than monotherapies, while minimizing behavioral side effects. Even at low concentrations, our polytherapy performs superior to individual drugs even at highest tolerated concentrations.


Assuntos
Epilepsias Mioclônicas/tratamento farmacológico , Modelos Biológicos , Rede Nervosa/efeitos dos fármacos , Fenômenos Fisiológicos do Sistema Nervoso/efeitos dos fármacos , Neurotransmissores/farmacologia , Algoritmos , Animais , Animais Geneticamente Modificados , Comportamento Animal/efeitos dos fármacos , Encéfalo/citologia , Encéfalo/diagnóstico por imagem , Encéfalo/efeitos dos fármacos , Encéfalo/fisiologia , Mapeamento Encefálico/métodos , Modelos Animais de Doenças , Avaliação Pré-Clínica de Medicamentos/métodos , Sinergismo Farmacológico , Quimioterapia Combinada/métodos , Epilepsias Mioclônicas/genética , Epilepsias Mioclônicas/patologia , Ensaios de Triagem em Larga Escala/métodos , Humanos , Microscopia Confocal/métodos , Rede Nervosa/diagnóstico por imagem , Rede Nervosa/fisiologia , Neurônios/efeitos dos fármacos , Neurônios/fisiologia , Neurotransmissores/uso terapêutico , Peixe-Zebra
10.
Nat Commun ; 10(1): 2654, 2019 06 14.
Artigo em Inglês | MEDLINE | ID: mdl-31201326

RESUMO

Animal locomotion requires spatiotemporally coordinated contraction of muscles throughout the body. Here, we investigate how contractions of antagonistic groups of muscles are intersegmentally coordinated during bidirectional crawling of Drosophila larvae. We identify two pairs of higher-order premotor excitatory interneurons present in each abdominal neuromere that intersegmentally provide feedback to the adjacent neuromere during motor propagation. The two feedback neuron pairs are differentially active during either forward or backward locomotion but commonly target a group of premotor interneurons that together provide excitatory inputs to transverse muscles and inhibitory inputs to the antagonistic longitudinal muscles. Inhibition of either feedback neuron pair compromises contraction of transverse muscles in a direction-specific manner. Our results suggest that the intersegmental feedback neurons coordinate contraction of synergistic muscles by acting as delay circuits representing the phase lag between segments. The identified circuit architecture also shows how bidirectional motor networks could be economically embedded in the nervous system.


Assuntos
Retroalimentação Fisiológica , Locomoção/fisiologia , Rede Nervosa/fisiologia , Animais , Animais Geneticamente Modificados , Proteínas de Drosophila/genética , Drosophila melanogaster/fisiologia , Interneurônios/fisiologia , Larva/fisiologia , Microscopia Eletrônica , Modelos Animais , Contração Muscular/fisiologia , Músculos/inervação , Músculos/fisiologia , Optogenética
11.
Neuron ; 103(2): 242-249.e4, 2019 07 17.
Artigo em Inglês | MEDLINE | ID: mdl-31153646

RESUMO

For thirsty animals, fluid intake provides both satiation and pleasure of drinking. How the brain processes these factors is currently unknown. Here, we identified neural circuits underlying thirst satiation and examined their contribution to reward signals. We show that thirst-driving neurons receive temporally distinct satiation signals by liquid-gulping-induced oropharyngeal stimuli and gut osmolality sensing. We demonstrate that individual thirst satiation signals are mediated by anatomically distinct inhibitory neural circuits in the lamina terminalis. Moreover, we used an ultrafast dopamine (DA) sensor to examine whether thirst satiation itself stimulates the reward-related circuits. Interestingly, spontaneous drinking behavior but not thirst drive reduction triggered DA release. Importantly, chemogenetic stimulation of thirst satiation neurons did not activate DA neurons under water-restricted conditions. Together, this study dissected the thirst satiation circuit, the activity of which is functionally separable from reward-related brain activity.


Assuntos
Neurônios GABAérgicos/fisiologia , Rede Nervosa/fisiologia , Vias Neurais/fisiologia , Saciação/fisiologia , Estômago/inervação , Órgão Subfornical/citologia , Animais , Cálcio/metabolismo , Dopamina/metabolismo , Ingestão de Líquidos/fisiologia , Feminino , Peptídeo 1 Semelhante ao Glucagon/metabolismo , Proteínas Luminescentes/genética , Proteínas Luminescentes/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Óxido Nítrico Sintase Tipo I/genética , Óxido Nítrico Sintase Tipo I/metabolismo , Optogenética , Concentração Osmolar , Fragmentos de Peptídeos/metabolismo , Estimulação Física
12.
Neuron ; 103(4): 702-718.e5, 2019 08 21.
Artigo em Inglês | MEDLINE | ID: mdl-31227310

RESUMO

The locus coeruleus (LC) supplies norepinephrine (NE) to the entire forebrain and regulates many fundamental brain functions. Studies in humans have suggested that strong LC activation might shift network connectivity to favor salience processing. To causally test this hypothesis, we use a mouse model to study the effect of LC stimulation on large-scale functional connectivity by combining chemogenetic activation of the LC with resting-state fMRI, an approach we term "chemo-connectomics." We show that LC activation rapidly interrupts ongoing behavior and strongly increases brain-wide connectivity, with the most profound effects in the salience and amygdala networks. Functional connectivity changes strongly correlate with transcript levels of alpha-1 and beta-1 adrenergic receptors across the brain, and functional network connectivity correlates with NE turnover within select brain regions. We propose that these changes in large-scale network connectivity are critical for optimizing neural processing in the context of increased vigilance and threat detection.


Assuntos
Conectoma , Locus Cerúleo/fisiologia , Receptores Adrenérgicos alfa 1/fisiologia , Receptores Adrenérgicos beta 1/fisiologia , Animais , Ansiedade/fisiopatologia , Clozapina/farmacologia , Corpo Estriado/metabolismo , Drogas Desenhadas/farmacologia , Dopamina/metabolismo , Comportamento Exploratório/fisiologia , Neuroimagem Funcional , Genes fos , Locus Cerúleo/efeitos dos fármacos , Imagem por Ressonância Magnética , Masculino , Camundongos , Camundongos Transgênicos , Rede Nervosa/fisiologia , Proteínas do Tecido Nervoso/biossíntese , Proteínas do Tecido Nervoso/genética , Norepinefrina/metabolismo , Proteínas Proto-Oncogênicas c-fos/biossíntese , Proteínas Proto-Oncogênicas c-fos/genética , Receptores Adrenérgicos alfa 1/biossíntese , Receptores Adrenérgicos alfa 1/genética , Receptores Adrenérgicos beta 1/biossíntese , Receptores Adrenérgicos beta 1/genética , Receptores de Droga/fisiologia , Teste de Desempenho do Rota-Rod , Regulação para Cima/efeitos dos fármacos
13.
Neuron ; 103(4): 719-733.e7, 2019 08 21.
Artigo em Inglês | MEDLINE | ID: mdl-31253469

RESUMO

A central goal in learning and memory research is to reveal the neural substrates underlying episodic memory formation. The hallmark of sequential spatial trajectory learning, a model of episodic memory, has remained equivocal, with proposals ranging from de novo creation of compressed sequential replay from blank slate networks to selection of pre-existing compressed preplay sequences. Here, we show that increased millisecond-timescale activation of cell assemblies expressed during de novo sequential experience and increased neuronal firing rate correlations can explain the difference between post-experience trajectory replay and robust preplay. This increased activation results from an improved neuronal tuning to specific cell assemblies, higher recruitment of experience-tuned neurons into pre-existing cell assemblies, and increased recruitment of cell assemblies in replay. In contrast, changes in overall neuronal and cell assembly temporal order within extended sequences do not account for sequential trajectory learning. We propose the coordinated strengthening of cell assemblies played sequentially on robust pre-existing temporal frameworks could support rapid formation of episodic-like memory.


Assuntos
Região CA1 Hipocampal/fisiologia , Memória Episódica , Modelos Neurológicos , Rede Nervosa/fisiologia , Plasticidade Neuronal/fisiologia , Memória Espacial , Animais , Região CA1 Hipocampal/citologia , Simulação por Computador , Locomoção/fisiologia , Masculino , Ratos , Ratos Long-Evans , Sono/fisiologia , Distribuições Estatísticas , Transmissão Sináptica/fisiologia , Fatores de Tempo
14.
Neuron ; 103(3): 520-532.e5, 2019 08 07.
Artigo em Inglês | MEDLINE | ID: mdl-31230761

RESUMO

In economic decisions, we make a good-based choice first, then we transform the outcome into an action to obtain the good. To elucidate the network mechanisms for such transformation, we constructed a neural circuit model consisting of modules representing choice, integration of choice with target locations, and the final action plan. We examined three scenarios regarding how the final action plan could emerge in the neural circuit and compared their implications with experimental data. Our model with heterogeneous connectivity predicts the coexistence of three types of neurons with distinct functions, confirmed by analyzing the neural activity in the lateral prefrontal cortex (LPFC) of behaving monkeys. We obtained a much more distinct classification of functional neuron types in the ventral than the dorsal region of LPFC, suggesting that the action plan is initially generated in ventral LPFC. Our model offers a biologically plausible neural circuit architecture that implements good-to-action transformation during economic choice.


Assuntos
Comportamento de Escolha/fisiologia , Tomada de Decisões/fisiologia , Modelos Neurológicos , Rede Nervosa/fisiologia , Córtex Pré-Frontal/fisiologia , Animais , Feminino , Fixação Ocular/fisiologia , Macaca mulatta , Masculino , Memória de Curto Prazo/fisiologia , Movimentos Sacádicos/fisiologia
15.
Neuron ; 103(3): 506-519.e4, 2019 08 07.
Artigo em Inglês | MEDLINE | ID: mdl-31201123

RESUMO

In motor neocortex, preparatory activity predictive of specific movements is maintained by a positive feedback loop with the thalamus. Motor thalamus receives excitatory input from the cerebellum, which learns to generate predictive signals for motor control. The contribution of this pathway to neocortical preparatory signals remains poorly understood. Here, we show that, in a virtual reality conditioning task, cerebellar output neurons in the dentate nucleus exhibit preparatory activity similar to that in anterolateral motor cortex prior to reward acquisition. Silencing activity in dentate nucleus by photoactivating inhibitory Purkinje cells in the cerebellar cortex caused robust, short-latency suppression of preparatory activity in anterolateral motor cortex. Our results suggest that preparatory activity is controlled by a learned decrease of Purkinje cell firing in advance of reward under supervision of climbing fiber inputs signaling reward delivery. Thus, cerebellar computations exert a powerful influence on preparatory activity in motor neocortex.


Assuntos
Córtex Cerebelar/fisiologia , Núcleos Cerebelares/fisiologia , Córtex Motor/fisiologia , Movimento/fisiologia , Rede Nervosa/fisiologia , Animais , Condicionamento Operante/fisiologia , Sinais (Psicologia) , Retroalimentação Fisiológica , Feminino , Masculino , Aprendizagem em Labirinto/fisiologia , Camundongos Endogâmicos C57BL , Células de Purkinje/fisiologia , Tempo de Reação/fisiologia , Recompensa , Tálamo/fisiologia , Fatores de Tempo , Realidade Virtual
16.
Neuron ; 103(3): 459-472.e4, 2019 08 07.
Artigo em Inglês | MEDLINE | ID: mdl-31204083

RESUMO

Vocalizations are fundamental to mammalian communication, but the underlying neural circuits await detailed characterization. Here, we used an intersectional genetic method to label and manipulate neurons in the midbrain periaqueductal gray (PAG) that are transiently active in male mice when they produce ultrasonic courtship vocalizations (USVs). Genetic silencing of PAG-USV neurons rendered males unable to produce USVs and impaired their ability to attract females. Conversely, activating PAG-USV neurons selectively triggered USV production, even in the absence of any female cues. Optogenetic stimulation combined with axonal tracing indicates that PAG-USV neurons gate downstream vocal-patterning circuits. Indeed, activating PAG neurons that innervate the nucleus retroambiguus, but not those innervating the parabrachial nucleus, elicited USVs in both male and female mice. These experiments establish that a dedicated population of PAG neurons gives rise to a descending circuit necessary and sufficient for USV production while also demonstrating the communicative salience of male USVs. VIDEO ABSTRACT.


Assuntos
Corte , Rede Nervosa/fisiologia , Substância Cinzenta Periaquedutal/fisiologia , Vocalização Animal/fisiologia , Animais , Sinais (Psicologia) , Vias Eferentes/fisiologia , Feminino , Genes Reporter , Vetores Genéticos/genética , Lentivirus/genética , Masculino , Camundongos , Neurônios/fisiologia , Neurotransmissores/metabolismo , Optogenética , Centro Respiratório/fisiologia
17.
Nat Commun ; 10(1): 2715, 2019 06 20.
Artigo em Inglês | MEDLINE | ID: mdl-31222009

RESUMO

Most adaptive behaviors require precise tracking of targets in space. In pursuit behavior with a moving target, mice use distance to target to guide their own movement continuously. Here, we show that in the sensorimotor striatum, parvalbumin-positive fast-spiking interneurons (FSIs) can represent the distance between self and target during pursuit behavior, while striatal projection neurons (SPNs), which receive FSI projections, can represent self-velocity. FSIs are shown to regulate velocity-related SPN activity during pursuit, so that movement velocity is continuously modulated by distance to target. Moreover, bidirectional manipulation of FSI activity can selectively disrupt performance by increasing or decreasing the self-target distance. Our results reveal a key role of the FSI-SPN interneuron circuit in pursuit behavior and elucidate how this circuit implements distance to velocity transformation required for the critical underlying computation.


Assuntos
Corpo Estriado/fisiologia , Interneurônios/fisiologia , Locomoção/fisiologia , Animais , Técnicas de Observação do Comportamento/métodos , Corpo Estriado/citologia , Corpo Estriado/diagnóstico por imagem , Feminino , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Rede Nervosa/fisiologia , Imagem Óptica , Comportamento Predatório/fisiologia , Comportamento Sexual Animal/fisiologia
18.
Chaos ; 29(5): 053121, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-31154794

RESUMO

Spatiotemporal chaos collapses to either a rest state or a propagating pulse in a ring network of diffusively coupled, excitable Morris-Lecar neurons. Adding global varying synaptic coupling to the ring network reveals complex transient behavior. Spatiotemporal chaos collapses into a transient pulse that reinitiates spatiotemporal chaos to allow sequential pattern switching until a collapse to the rest state. A domain of irregular neuron activity coexists with a domain of inactive neurons forming a transient chimeralike state. Transient spatial localization of the chimeralike state is observed for stronger synapses.


Assuntos
Neurônios/fisiologia , Dinâmica não Linear , Análise Espaço-Temporal , Modelos Neurológicos , Rede Nervosa/fisiologia , Sinapses/fisiologia
19.
PLoS Comput Biol ; 15(5): e1007074, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-31150376

RESUMO

Several recent studies have shown that neural activity in vivo tends to be constrained to a low-dimensional manifold. Such activity does not arise in simulated neural networks with homogeneous connectivity and it has been suggested that it is indicative of some other connectivity pattern in neuronal networks. In particular, this connectivity pattern appears to be constraining learning so that only neural activity patterns falling within the intrinsic manifold can be learned and elicited. Here, we use three different models of spiking neural networks (echo-state networks, the Neural Engineering Framework and Efficient Coding) to demonstrate how the intrinsic manifold can be made a direct consequence of the circuit connectivity. Using this relationship between the circuit connectivity and the intrinsic manifold, we show that learning of patterns outside the intrinsic manifold corresponds to much larger changes in synaptic weights than learning of patterns within the intrinsic manifold. Assuming larger changes to synaptic weights requires extensive learning, this observation provides an explanation of why learning is easier when it does not require the neural activity to leave its intrinsic manifold.


Assuntos
Modelos Neurológicos , Rede Nervosa/fisiologia , Potenciais de Ação/fisiologia , Algoritmos , Animais , Biologia Computacional , Simulação por Computador , Haplorrinos/fisiologia , Haplorrinos/psicologia , Aprendizagem/fisiologia , Aprendizado de Máquina , Redes Neurais (Computação) , Neurônios/fisiologia , Sinapses/fisiologia
20.
Phys Rev E ; 99(5-1): 052418, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-31212571

RESUMO

In large neuronal networks, it is believed that functions emerge through the collective behavior of many interconnected neurons. Recently, the development of experimental techniques that allow simultaneous recording of calcium concentration from a large fraction of all neurons in Caenorhabditis elegans-a nematode with 302 neurons-creates the opportunity to ask whether such emergence is universal, reaching down to even the smallest brains. Here, we measure the activity of 50+ neurons in C. elegans, and analyze the data by building the maximum entropy model that matches the mean activity and pairwise correlations among these neurons. To capture the graded nature of the cells' responses, we assign each cell multiple states. These models, which are equivalent to a family of Potts glasses, successfully predict higher statistical structure in the network. In addition, these models exhibit signatures of collective behavior: the state of single cells can be predicted from the state of the rest of the network; the network, despite being sparse in a way similar to the structural connectome, distributes its response globally when locally perturbed; the distribution over network states has multiple local maxima, as in models of memory; and the parameters that describe the real network are close to a critical surface in this family of models.


Assuntos
Encéfalo/anatomia & histologia , Encéfalo/fisiologia , Caenorhabditis elegans/anatomia & histologia , Caenorhabditis elegans/fisiologia , Modelos Neurológicos , Potenciais de Ação , Animais , Encéfalo/citologia , Caenorhabditis elegans/citologia , Entropia , Rede Nervosa/citologia , Rede Nervosa/fisiologia , Neurônios/citologia , Tamanho do Órgão
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA