Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 10.487
Filtrar
1.
Proc Natl Acad Sci U S A ; 118(39)2021 09 28.
Artigo em Inglês | MEDLINE | ID: mdl-34556573

RESUMO

Many sensory systems utilize parallel ON and OFF pathways that signal stimulus increments and decrements, respectively. These pathways consist of ensembles or grids of ON and OFF detectors spanning sensory space. Yet, encoding by opponent pathways raises a question: How should grids of ON and OFF detectors be arranged to optimally encode natural stimuli? We investigated this question using a model of the retina guided by efficient coding theory. Specifically, we optimized spatial receptive fields and contrast response functions to encode natural images given noise and constrained firing rates. We find that the optimal arrangement of ON and OFF receptive fields exhibits a transition between aligned and antialigned grids. The preferred phase depends on detector noise and the statistical structure of the natural stimuli. These results reveal that noise and stimulus statistics produce qualitative shifts in neural coding strategies and provide theoretical predictions for the configuration of opponent pathways in the nervous system.


Assuntos
Modelos Neurológicos , Ruído , Retina/fisiologia , Campos Visuais/fisiologia , Vias Visuais/fisiologia , Animais , Humanos , Estimulação Luminosa , Retina/citologia , Razão Sinal-Ruído , Percepção Visual
2.
Nat Hum Behav ; 5(9): 1127-1144, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-34545237

RESUMO

Human visual perception carves a scene at its physical joints, decomposing the world into objects, which are selectively attended, tracked and predicted as we engage our surroundings. Object representations emancipate perception from the sensory input, enabling us to keep in mind that which is out of sight and to use perceptual content as a basis for action and symbolic cognition. Human behavioural studies have documented how object representations emerge through grouping, amodal completion, proto-objects and object files. By contrast, deep neural network models of visual object recognition remain largely tethered to sensory input, despite achieving human-level performance at labelling objects. Here, we review related work in both fields and examine how these fields can help each other. The cognitive literature provides a starting point for the development of new experimental tasks that reveal mechanisms of human object perception and serve as benchmarks driving the development of deep neural network models that will put the object into object recognition.


Assuntos
Reconhecimento Visual de Modelos/fisiologia , Reconhecimento Psicológico/fisiologia , Percepção Visual/fisiologia , Humanos , Redes Neurais de Computação , Vias Visuais/fisiologia
3.
Nat Commun ; 12(1): 4911, 2021 08 13.
Artigo em Inglês | MEDLINE | ID: mdl-34389710

RESUMO

The mammalian sensory neocortex consists of hierarchically organized areas reciprocally connected via feedforward (FF) and feedback (FB) circuits. Several theories of hierarchical computation ascribe the bulk of the computational work of the cortex to looped FF-FB circuits between pairs of cortical areas. However, whether such corticocortical loops exist remains unclear. In higher mammals, individual FF-projection neurons send afferents almost exclusively to a single higher-level area. However, it is unclear whether FB-projection neurons show similar area-specificity, and whether they influence FF-projection neurons directly or indirectly. Using viral-mediated monosynaptic circuit tracing in macaque primary visual cortex (V1), we show that V1 neurons sending FF projections to area V2 receive monosynaptic FB inputs from V2, but not other V1-projecting areas. We also find monosynaptic FB-to-FB neuron contacts as a second motif of FB connectivity. Our results support the existence of FF-FB loops in primate cortex, and suggest that FB can rapidly and selectively influence the activity of incoming FF signals.


Assuntos
Biorretroalimentação Psicológica/fisiologia , Macaca fascicularis/fisiologia , Neurônios/fisiologia , Córtex Visual/fisiologia , Vias Visuais/fisiologia , Animais , Feminino , Corpos Geniculados/citologia , Corpos Geniculados/fisiologia , Modelos Neurológicos , Reflexo Monosináptico/fisiologia , Córtex Visual/citologia
4.
Nat Rev Neurosci ; 22(9): 573-583, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-34345018

RESUMO

How does the brain encode information about the environment? Decades of research have led to the pervasive notion that the object-processing pathway in primate cortex consists of multiple areas that are each specialized to process different object categories (such as faces, bodies, hands, non-face objects and scenes). The anatomical consistency and modularity of these regions have been interpreted as evidence that these regions are innately specialized. Here, we propose that ventral-stream modules do not represent clusters of circuits that each evolved to process some specific object category particularly important for survival, but instead reflect the effects of experience on a domain-general architecture that evolved to be able to adapt, within a lifetime, to its particular environment. Furthermore, we propose that the mechanisms underlying the development of domains are both evolutionarily old and universal across cortex. Topographic maps are fundamental, governing the development of specializations across systems, providing a framework for brain organization.


Assuntos
Lobo Temporal/fisiologia , Vias Visuais/fisiologia , Animais , Mapeamento Encefálico , Humanos , Macaca mulatta , Neurônios/fisiologia , Estimulação Luminosa , Percepção Visual/fisiologia
5.
Neuron ; 109(18): 2928-2942.e8, 2021 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-34390651

RESUMO

The ability to encode the direction of image motion is fundamental to our sense of vision. Direction selectivity along the four cardinal directions is thought to originate in direction-selective ganglion cells (DSGCs) because of directionally tuned GABAergic suppression by starburst cells. Here, by utilizing two-photon glutamate imaging to measure synaptic release, we reveal that direction selectivity along all four directions arises earlier than expected at bipolar cell outputs. Individual bipolar cells contained four distinct populations of axon terminal boutons with different preferred directions. We further show that this bouton-specific tuning relies on cholinergic excitation from starburst cells and GABAergic inhibition from wide-field amacrine cells. DSGCs received both tuned directionally aligned inputs and untuned inputs from among heterogeneously tuned glutamatergic bouton populations. Thus, directional tuning in the excitatory visual pathway is incrementally refined at the bipolar cell axon terminals and their recipient DSGC dendrites by two different neurotransmitters co-released from starburst cells.


Assuntos
Axônios/fisiologia , Conectoma/métodos , Estimulação Luminosa/métodos , Terminações Pré-Sinápticas/fisiologia , Células Bipolares da Retina/fisiologia , Vias Visuais/fisiologia , Animais , Axônios/química , Feminino , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Microscopia de Fluorescência por Excitação Multifotônica/métodos , Terminações Pré-Sinápticas/química , Células Bipolares da Retina/química , Vias Visuais/química
6.
Nat Neurosci ; 24(9): 1280-1291, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-34341586

RESUMO

Predictive motion encoding is an important aspect of visually guided behavior that allows animals to estimate the trajectory of moving objects. Motion prediction is understood primarily in the context of translational motion, but the environment contains other types of behaviorally salient motion correlation such as those produced by approaching or receding objects. However, the neural mechanisms that detect and predictively encode these correlations remain unclear. We report here that four of the parallel output pathways in the primate retina encode predictive motion information, and this encoding occurs for several classes of spatiotemporal correlation that are found in natural vision. Such predictive coding can be explained by known nonlinear circuit mechanisms that produce a nearly optimal encoding, with transmitted information approaching the theoretical limit imposed by the stimulus itself. Thus, these neural circuit mechanisms efficiently separate predictive information from nonpredictive information during the encoding process.


Assuntos
Percepção de Movimento/fisiologia , Células Ganglionares da Retina/fisiologia , Vias Visuais/fisiologia , Animais , Macaca , Estimulação Luminosa
7.
Nat Commun ; 12(1): 4448, 2021 07 21.
Artigo em Inglês | MEDLINE | ID: mdl-34290247

RESUMO

Cortical representations of brief, static stimuli become more invariant to identity-preserving transformations along the ventral stream. Likewise, increased invariance along the visual hierarchy should imply greater temporal persistence of temporally structured dynamic stimuli, possibly complemented by temporal broadening of neuronal receptive fields. However, such stimuli could engage adaptive and predictive processes, whose impact on neural coding dynamics is unknown. By probing the rat analog of the ventral stream with movies, we uncovered a hierarchy of temporal scales, with deeper areas encoding visual information more persistently. Furthermore, the impact of intrinsic dynamics on the stability of stimulus representations grew gradually along the hierarchy. A database of recordings from mouse showed similar trends, additionally revealing dependencies on the behavioral state. Overall, these findings show that visual representations become progressively more stable along rodent visual processing hierarchies, with an important contribution provided by intrinsic processing.


Assuntos
Tempo de Reação/fisiologia , Córtex Visual/fisiologia , Percepção Visual/fisiologia , Animais , Locomoção/fisiologia , Camundongos , Modelos Neurológicos , Neurônios/fisiologia , Estimulação Luminosa , Ratos , Vias Visuais/fisiologia , Vigília/fisiologia
8.
Nat Commun ; 12(1): 3635, 2021 06 15.
Artigo em Inglês | MEDLINE | ID: mdl-34131142

RESUMO

Neuronal activity in sensory cortex fluctuates over time and across repetitions of the same input. This variability is often considered detrimental to neural coding. The theory of neural sampling proposes instead that variability encodes the uncertainty of perceptual inferences. In primary visual cortex (V1), modulation of variability by sensory and non-sensory factors supports this view. However, it is unknown whether V1 variability reflects the statistical structure of visual inputs, as would be required for inferences correctly tuned to the statistics of the natural environment. Here we combine analysis of image statistics and recordings in macaque V1 to show that probabilistic inference tuned to natural image statistics explains the widely observed dependence between spike count variance and mean, and the modulation of V1 activity and variability by spatial context in images. Our results show that the properties of a basic aspect of cortical responses-their variability-can be explained by a probabilistic representation tuned to naturalistic inputs.


Assuntos
Neurônios/fisiologia , Córtex Visual/diagnóstico por imagem , Córtex Visual/fisiologia , Animais , Macaca , Macaca fascicularis , Masculino , Modelos Neurológicos , Estimulação Luminosa , Vias Visuais/fisiologia , Percepção Visual/fisiologia
9.
Neuron ; 109(15): 2457-2468.e12, 2021 08 04.
Artigo em Inglês | MEDLINE | ID: mdl-34146468

RESUMO

Segregation of retinal ganglion cell (RGC) axons by type and eye of origin is considered a hallmark of dorsal lateral geniculate nucleus (dLGN) structure. However, recent anatomical studies have shown that neurons in mouse dLGN receive input from multiple RGC types of both retinae. Whether convergent input leads to relevant functional interactions is unclear. We studied functional eye-specific retinogeniculate convergence using dual-color optogenetics in vitro. dLGN neurons were strongly dominated by input from one eye. Most neurons received detectable input from the non-dominant eye, but this input was weak, with a prominently reduced AMPAR:NMDAR ratio. Consistent with this, only a small fraction of thalamocortical neurons was binocular in vivo across visual stimuli and cortical projection layers. Anatomical overlap between RGC axons and dLGN neuron dendrites alone did not explain the strong bias toward monocularity. We conclude that functional eye-specific input selection and refinement limit convergent interactions in dLGN, favoring monocularity.


Assuntos
Lateralidade Funcional/fisiologia , Corpos Geniculados/citologia , Células Ganglionares da Retina/citologia , Visão Binocular/fisiologia , Vias Visuais/citologia , Animais , Corpos Geniculados/fisiologia , Camundongos , Células Ganglionares da Retina/fisiologia , Vias Visuais/fisiologia
10.
PLoS Biol ; 19(6): e3001275, 2021 06.
Artigo em Inglês | MEDLINE | ID: mdl-34077415

RESUMO

Episodic memory depends on interactions between the hippocampus and interconnected neocortical regions. Here, using data-driven analyses of resting-state functional magnetic resonance imaging (fMRI) data, we identified the networks that interact with the hippocampus-the default mode network (DMN) and a "medial temporal network" (MTN) that included regions in the medial temporal lobe (MTL) and precuneus. We observed that the MTN plays a critical role in connecting the visual network to the DMN and hippocampus. The DMN could be further divided into 3 subnetworks: a "posterior medial" (PM) subnetwork comprised of posterior cingulate and lateral parietal cortices; an "anterior temporal" (AT) subnetwork comprised of regions in the temporopolar and dorsomedial prefrontal cortex; and a "medial prefrontal" (MP) subnetwork comprised of regions primarily in the medial prefrontal cortex (mPFC). These networks vary in their functional connectivity (FC) along the hippocampal long axis and represent different kinds of information during memory-guided decision-making. Finally, a Neurosynth meta-analysis of fMRI studies suggests new hypotheses regarding the functions of the MTN and DMN subnetworks, providing a framework to guide future research on the neural architecture of episodic memory.


Assuntos
Hipocampo/fisiologia , Rede Nervosa/fisiologia , Humanos , Memória/fisiologia , Descanso/fisiologia , Análise e Desempenho de Tarefas , Lobo Temporal/fisiologia , Vias Visuais/fisiologia
11.
Neuron ; 109(12): 1996-2008.e6, 2021 06 16.
Artigo em Inglês | MEDLINE | ID: mdl-33979633

RESUMO

Sensory processing involves information flow between neocortical areas, assumed to rely on direct intracortical projections. However, cortical areas may also communicate indirectly via higher-order nuclei in the thalamus, such as the pulvinar or lateral posterior nucleus (LP) in the visual system of rodents. The fine-scale organization and function of these cortico-thalamo-cortical pathways remains unclear. We find that responses of mouse LP neurons projecting to higher visual areas likely derive from feedforward input from primary visual cortex (V1) combined with information from many cortical and subcortical areas, including superior colliculus. Signals from LP projections to different higher visual areas are tuned to specific features of visual stimuli and their locomotor context, distinct from the signals carried by direct intracortical projections from V1. Thus, visual transthalamic pathways are functionally specific to their cortical target, different from feedforward cortical pathways, and combine information from multiple brain regions, linking sensory signals with behavioral context.


Assuntos
Núcleos Laterais do Tálamo/fisiologia , Neurônios/fisiologia , Pulvinar/fisiologia , Tálamo/fisiologia , Córtex Visual/fisiologia , Vias Visuais/fisiologia , Animais , Córtex Cerebral/fisiologia , Locomoção/fisiologia , Camundongos , Estimulação Luminosa , Colículos Superiores/fisiologia
12.
Invest Ophthalmol Vis Sci ; 62(6): 17, 2021 05 03.
Artigo em Inglês | MEDLINE | ID: mdl-33988692

RESUMO

Purpose: The purpose of this study was to characterize summation of temporal L- and M-cone contrasts in the parvo- (P-) and magnocellular (M-) pathways in glaucoma and the relationship between the respective temporal contrast sensitivities (tCS) and clinical parameters. Methods: Perifoveal tCS to isolated or combined L- and M-cone contrasts (with different contrast ratios, and therefore different luminance and chromatic components) were measured at different temporal frequencies (at 1 or 2 Hz and at 20 Hz) using triple silent substitution in 73 subjects (13 healthy, 25 with glaucoma, and 35 with perimetric glaucoma). A vector summation model was used to analyze whether perception was driven by the P-pathway, the M-pathway, or both. Using this model, L- and M-cone input strengths (AL, AM) and phase differences between L- and M-cone inputs were estimated. Results: Perception was always mediated by the P-pathway at low frequencies, as indicated by a median phase angle of 179.84 degrees (cone opponency) and a median AL/AM ratio of 1.04 (balanced L- and M-cone input strengths). In contrast, perception was exclusively mediated by the M-pathway at higher frequencies (input strength not balanced: AL/AM = 2.94, median phase angles = 130.17 degrees). Differences in phase were not significant between diagnosis groups (Kruskal-Wallis = 0.092 for P- and 0.35 for M-pathway). We found differences between groups only for the M-pathway (L-cone tCS deviations at 20 Hz were significantly lower in the patients with glaucoma P = 0.014, with a strong tendency in M-cones P = 0.049). L-cone driven tCS deviations at 20 Hz were linearly correlated with perimetric mean defect (MD) and quadratically correlated with retinal nerve fiber layer (RNFL) thickness. Conclusions: Unaltered phase angles between L- and M-cone inputs in glaucoma indicated intact temporal processing. Only in the M-pathway, contrast sensitivity deviations were closely related to diagnosis group, MD, and RNFL thickness, indicating M-pathway involvement.


Assuntos
Opsinas dos Cones/fisiologia , Sensibilidades de Contraste/fisiologia , Corpos Geniculados/fisiologia , Glaucoma de Ângulo Aberto/fisiopatologia , Células Fotorreceptoras Retinianas Cones/fisiologia , Células Ganglionares da Retina/fisiologia , Adulto , Idoso , Feminino , Humanos , Pressão Intraocular/fisiologia , Masculino , Pessoa de Meia-Idade , Tomografia de Coerência Óptica , Testes de Campo Visual , Campos Visuais/fisiologia , Vias Visuais/fisiologia
13.
Nat Commun ; 12(1): 2315, 2021 04 19.
Artigo em Inglês | MEDLINE | ID: mdl-33875667

RESUMO

The clustering of neurons with similar response properties is a conspicuous feature of neocortex. In primary visual cortex (V1), maps of several properties like orientation preference are well described, but the functional architecture of color, central to visual perception in trichromatic primates, is not. Here we used two-photon calcium imaging in macaques to examine the fine structure of chromatic representation and found that neurons responsive to spatially uniform, chromatic stimuli form unambiguous clusters that coincide with blobs. Further, these responsive groups have marked substructure, segregating into smaller ensembles or micromaps with distinct chromatic signatures that appear columnar in upper layer 2/3. Spatially structured chromatic stimuli revealed maps built on the same micromap framework but with larger subdomains that go well beyond blobs. We conclude that V1 has an architecture for color representation that switches between blobs and a combined blob/interblob system based on the spatial content of the visual scene.


Assuntos
Percepção de Cores/fisiologia , Macaca mulatta/fisiologia , Neurônios/fisiologia , Córtex Visual/fisiologia , Vias Visuais/fisiologia , Animais , Cor , Feminino , Masculino , Microscopia de Fluorescência por Excitação Multifotônica/métodos , Estimulação Luminosa/métodos , Córtex Visual/citologia
14.
Int J Mol Sci ; 22(9)2021 Apr 27.
Artigo em Inglês | MEDLINE | ID: mdl-33925390

RESUMO

Decussation of axonal tracts is an important hallmark of vertebrate neuroanatomy resulting in one brain hemisphere controlling the contralateral side of the body and also computing the sensory information originating from that respective side. Here, we show that BMP interferes with optic chiasm formation and RGC pathfinding in zebrafish. Experimental induction of BMP4 at 15 hpf results in a complete ipsilateral projection of RGC axons and failure of commissural connections of the forebrain, in part as the result of an interaction with shh signaling, transcriptional regulation of midline guidance cues and an affected optic stalk morphogenesis. Experimental induction of BMP4 at 24 hpf, resulting in only a mild repression of forebrain shh ligand expression but in a broad expression of pax2a in the diencephalon, does not per se prevent RGC axons from crossing the midline. It nevertheless shows severe pathologies of RGC projections e.g., the fasciculation of RGC axons with the ipsilateral optic tract resulting in the innervation of one tectum by two eyes or the projection of RGC axons in the direction of the contralateral eye.


Assuntos
Proteínas Morfogenéticas Ósseas/metabolismo , Quiasma Óptico/embriologia , Células Ganglionares da Retina/metabolismo , Animais , Axônios/metabolismo , Proteínas Morfogenéticas Ósseas/fisiologia , Quiasma Óptico/metabolismo , Quiasma Óptico/fisiologia , Nervo Óptico/fisiologia , Retina/metabolismo , Células Ganglionares da Retina/fisiologia , Vias Visuais/fisiologia , Peixe-Zebra/metabolismo , Proteínas de Peixe-Zebra/metabolismo
15.
Nat Commun ; 12(1): 2278, 2021 04 15.
Artigo em Inglês | MEDLINE | ID: mdl-33859195

RESUMO

Face-processing occurs across ventral and lateral visual streams, which are involved in static and dynamic face perception, respectively. However, the nature of spatial computations across streams is unknown. Using functional MRI and population receptive field (pRF) mapping, we measured pRFs in face-selective regions. Results reveal that spatial computations by pRFs in ventral face-selective regions are concentrated around the center of gaze (fovea), but spatial computations in lateral face-selective regions extend peripherally. Diffusion MRI reveals that these differences are mirrored by a preponderance of white matter connections between ventral face-selective regions and foveal early visual cortex (EVC), while connections with lateral regions are distributed more uniformly across EVC eccentricities. These findings suggest a rethinking of spatial computations in face-selective regions, showing that they vary across ventral and lateral streams, and further propose that spatial computations in high-level regions are scaffolded by the fine-grain pattern of white matter connections from EVC.


Assuntos
Reconhecimento Facial/fisiologia , Lobo Temporal/fisiologia , Córtex Visual/fisiologia , Vias Visuais/fisiologia , Substância Branca/fisiologia , Adulto , Mapeamento Encefálico , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Lobo Temporal/diagnóstico por imagem , Córtex Visual/diagnóstico por imagem , Substância Branca/diagnóstico por imagem , Adulto Jovem
16.
Elife ; 102021 03 22.
Artigo em Inglês | MEDLINE | ID: mdl-33749595

RESUMO

A central feature of cortical function is hierarchical processing of information. Little is currently known about how cortical processing cascades develop. Here, we investigate the joint development of two nodes of the ferret's visual motion pathway, primary visual cortex (V1), and higher-level area PSS. In adult animals, motion processing transitions from local to global computations between these areas. We now show that PSS global motion signals emerge a week after the development of V1 and PSS direction selectivity. Crucially, V1 responses to more complex motion stimuli change in parallel, in a manner consistent with supporting increased PSS motion integration. At the same time, these V1 responses depend on feedback from PSS. Our findings suggest that development does not just proceed in parallel in different visual areas, it is coordinated across network nodes. This has important implications for understanding how visual experience and developmental disorders can influence the developing visual system.


Assuntos
Furões/fisiologia , Percepção de Movimento/fisiologia , Córtex Visual/fisiologia , Vias Visuais/fisiologia , Animais , Feminino , Masculino , Modelos Neurológicos , Estimulação Luminosa
17.
Elife ; 102021 03 24.
Artigo em Inglês | MEDLINE | ID: mdl-33759760

RESUMO

Human and nonhuman primates are good at identifying an object based on its motion, a task that is believed to be carried out by the ventral visual pathway. However, the neural mechanisms underlying such ability remains unclear. We trained macaque monkeys to do orientation discrimination for motion boundaries (MBs) and recorded neuronal response in area V2 with microelectrode arrays. We found 10.9% of V2 neurons exhibited robust orientation selectivity to MBs, and their responses correlated with monkeys' orientation-discrimination performances. Furthermore, the responses of V2 direction-selective neurons recorded at the same time showed correlated activity with MB neurons for particular MB stimuli, suggesting that these motion-sensitive neurons made specific functional contributions to MB discrimination tasks. Our findings support the view that V2 plays a critical role in MB analysis and may achieve this through a neural circuit within area V2.


Assuntos
Macaca mulatta/fisiologia , Percepção de Movimento/fisiologia , Neurônios/fisiologia , Córtex Visual/fisiologia , Vias Visuais/fisiologia , Animais , Masculino , Estimulação Luminosa
18.
PLoS Comput Biol ; 17(3): e1008775, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33760819

RESUMO

While vision evokes a dense network of feedforward and feedback neural processes in the brain, visual processes are primarily modeled with feedforward hierarchical neural networks, leaving the computational role of feedback processes poorly understood. Here, we developed a generative autoencoder neural network model and adversarially trained it on a categorically diverse data set of images. We hypothesized that the feedback processes in the ventral visual pathway can be represented by reconstruction of the visual information performed by the generative model. We compared representational similarity of the activity patterns in the proposed model with temporal (magnetoencephalography) and spatial (functional magnetic resonance imaging) visual brain responses. The proposed generative model identified two segregated neural dynamics in the visual brain. A temporal hierarchy of processes transforming low level visual information into high level semantics in the feedforward sweep, and a temporally later dynamics of inverse processes reconstructing low level visual information from a high level latent representation in the feedback sweep. Our results append to previous studies on neural feedback processes by presenting a new insight into the algorithmic function and the information carried by the feedback processes in the ventral visual pathway.


Assuntos
Processamento de Imagem Assistida por Computador/métodos , Redes Neurais de Computação , Córtex Visual , Vias Visuais , Adulto , Algoritmos , Encéfalo/diagnóstico por imagem , Encéfalo/fisiologia , Biologia Computacional , Retroalimentação Fisiológica/fisiologia , Feminino , Humanos , Imageamento por Ressonância Magnética , Magnetoencefalografia , Córtex Visual/diagnóstico por imagem , Córtex Visual/fisiologia , Vias Visuais/diagnóstico por imagem , Vias Visuais/fisiologia , Adulto Jovem
19.
Commun Biol ; 4(1): 348, 2021 03 17.
Artigo em Inglês | MEDLINE | ID: mdl-33731846

RESUMO

Newly learned information undergoes a process of awake reactivation shortly after the learning offset and we recently demonstrated that this effect can be observed as early as area V1. However, reactivating all experiences can be wasteful and unnecessary, especially for familiar stimuli. Therefore, here we tested whether awake reactivation occurs differentially for new and familiar stimuli. Subjects completed a brief visual task on a stimulus that was either novel or highly familiar due to extensive prior training on it. Replicating our previous results, we found that awake reactivation occurred in V1 for the novel stimulus. On the other hand, brief exposure to the familiar stimulus led to 'awake suppression' such that neural activity patterns immediately after exposure to the familiar stimulus diverged from the patterns associated with that stimulus. Further, awake reactivation was observed selectively in V1, whereas awake suppression had similar strength across areas V1-V3. These results are consistent with the presence of a competition between local awake reactivation and top-down awake suppression, with suppression becoming dominant for familiar stimuli.


Assuntos
Ondas Encefálicas , Plasticidade Neuronal , Estimulação Luminosa , Reconhecimento Psicológico , Córtex Visual/fisiologia , Percepção Visual , Vigília , Adulto , Mapeamento Encefálico , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino , Córtex Visual/diagnóstico por imagem , Vias Visuais/diagnóstico por imagem , Vias Visuais/fisiologia , Adulto Jovem
20.
Nat Commun ; 12(1): 1900, 2021 03 26.
Artigo em Inglês | MEDLINE | ID: mdl-33772000

RESUMO

The computations performed by a neural circuit depend on how it integrates its input signals into an output of its own. In the retina, ganglion cells integrate visual information over time, space, and chromatic channels. Unlike the former two, chromatic integration is largely unexplored. Analogous to classical studies of spatial integration, we here study chromatic integration in mouse retina by identifying chromatic stimuli for which activation from the green or UV color channel is maximally balanced by deactivation through the other color channel. This reveals nonlinear chromatic integration in subsets of On, Off, and On-Off ganglion cells. Unlike the latter two, nonlinear On cells display response suppression rather than activation under balanced chromatic stimulation. Furthermore, nonlinear chromatic integration occurs independently of nonlinear spatial integration, depends on contributions from the rod pathway and on surround inhibition, and may provide information about chromatic boundaries, such as the skyline in natural scenes.


Assuntos
Potenciais de Ação/fisiologia , Retina/fisiologia , Células Ganglionares da Retina/fisiologia , Campos Visuais/fisiologia , Vias Visuais/fisiologia , Potenciais de Ação/efeitos dos fármacos , Algoritmos , Animais , Cor , Feminino , HEPES/farmacologia , Masculino , Camundongos Endogâmicos C57BL , Dinâmica não Linear , Estimulação Luminosa/métodos , Piridazinas/farmacologia , Retina/citologia , Estricnina/farmacologia
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...