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1.
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
2.
Nat Commun ; 12(1): 2143, 2021 04 09.
Artigo em Inglês | MEDLINE | ID: mdl-33837210

RESUMO

Spiking neural networks (SNNs) promise to bridge the gap between artificial neural networks (ANNs) and biological neural networks (BNNs) by exploiting biologically plausible neurons that offer faster inference, lower energy expenditure, and event-driven information processing capabilities. However, implementation of SNNs in future neuromorphic hardware requires hardware encoders analogous to the sensory neurons, which convert external/internal stimulus into spike trains based on specific neural algorithm along with inherent stochasticity. Unfortunately, conventional solid-state transducers are inadequate for this purpose necessitating the development of neural encoders to serve the growing need of neuromorphic computing. Here, we demonstrate a biomimetic device based on a dual gated MoS2 field effect transistor (FET) capable of encoding analog signals into stochastic spike trains following various neural encoding algorithms such as rate-based encoding, spike timing-based encoding, and spike count-based encoding. Two important aspects of neural encoding, namely, dynamic range and encoding precision are also captured in our demonstration. Furthermore, the encoding energy was found to be as frugal as ≈1-5 pJ/spike. Finally, we show fast (≈200 timesteps) encoding of the MNIST data set using our biomimetic device followed by more than 91% accurate inference using a trained SNN.


Assuntos
Materiais Biomiméticos , Redes Neurais de Computação , Transistores Eletrônicos , Potenciais de Ação/fisiologia , Algoritmos , Biomimética/instrumentação , Conjuntos de Dados como Assunto , Humanos , Rede Nervosa/citologia , Rede Nervosa/fisiologia , Células Receptoras Sensoriais/fisiologia , Córtex Visual/citologia , Córtex Visual/fisiologia
3.
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 , Imagem 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
4.
Neuron ; 109(7): 1074-1076, 2021 04 07.
Artigo em Inglês | MEDLINE | ID: mdl-33831362

RESUMO

Errors yield unfavorable outcomes but also elicit adaptive mechanisms optimizing future behavior. Norman et al. demonstrate a previously unknown direct projection from medial frontal performance-monitoring areas in mice that modulate visual cortex network activity and enable post-error attentional adaptation.


Assuntos
Desempenho Psicomotor , Córtex Visual , Adaptação Fisiológica , Animais , Atenção , Humanos , Camundongos , Lobo Parietal
5.
Nat Commun ; 12(1): 2003, 2021 03 31.
Artigo em Inglês | MEDLINE | ID: mdl-33790282

RESUMO

Understanding how activity of visual neurons represents distinct components of attention and their dynamics that account for improved visual performance remains elusive because single-unit experiments have not isolated the intensive aspect of attention from attentional selectivity. We isolated attentional intensity and its single trial dynamics as determined by spatially non-selective attentional performance in an orientation discrimination task while recording from neurons in monkey visual area V4. We found that attentional intensity is a distinct cognitive signal that can be distinguished from spatial selectivity, reward expectations and motor actions. V4 spiking on single trials encodes a combination of sensory and cognitive signals on different time scales. Attentional intensity and the detection of behaviorally relevant sensory signals are well represented, but immediate reward expectation and behavioral choices are poorly represented in V4 spiking. These results provide a detailed representation of perceptual and cognitive signals in V4 that are crucial for attentional performance.


Assuntos
Algoritmos , Atenção/fisiologia , Macaca mulatta/fisiologia , Neurônios/fisiologia , Córtex Visual/fisiologia , Percepção Visual/fisiologia , Animais , Fenômenos Eletrofisiológicos , Modelos Lineares , Masculino , Estimulação Luminosa/métodos , Pupila/fisiologia , Córtex Visual/citologia
6.
J Physiol ; 599(8): 2131, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33687076
7.
Nat Commun ; 12(1): 1795, 2021 03 19.
Artigo em Inglês | MEDLINE | ID: mdl-33741933

RESUMO

Neural computations are often fast and anatomically localized. Yet, investigating such computations in humans is challenging because non-invasive methods have either high temporal or spatial resolution, but not both. Of particular relevance, fast neural replay is known to occur throughout the brain in a coordinated fashion about which little is known. We develop a multivariate analysis method for functional magnetic resonance imaging that makes it possible to study sequentially activated neural patterns separated by less than 100 ms with precise spatial resolution. Human participants viewed five images individually and sequentially with speeds up to 32 ms between items. Probabilistic pattern classifiers were trained on activation patterns in visual and ventrotemporal cortex during individual image trials. Applied to sequence trials, probabilistic classifier time courses allow the detection of neural representations and their order. Order detection remains possible at speeds up to 32 ms between items (plus 100 ms per item). The frequency spectrum of the sequentiality metric distinguishes between sub- versus supra-second sequences. Importantly, applied to resting-state data our method reveals fast replay of task-related stimuli in visual cortex. This indicates that non-hippocampal replay occurs even after tasks without memory requirements and shows that our method can be used to detect such spontaneously occurring replay.


Assuntos
Encéfalo/diagnóstico por imagem , Encéfalo/fisiologia , Imagem por Ressonância Magnética/métodos , Memória/fisiologia , Córtex Visual/diagnóstico por imagem , Córtex Visual/fisiologia , Adulto , Algoritmos , Mapeamento Encefálico/métodos , Feminino , Humanos , Masculino , Modelos Neurológicos , Análise Multivariada , Tempo de Reação/fisiologia , Adulto Jovem
8.
Nat Commun ; 12(1): 1757, 2021 03 19.
Artigo em Inglês | MEDLINE | ID: mdl-33741947

RESUMO

Voluntary allocation of visual attention is controlled by top-down signals generated within the Frontal Eye Fields (FEFs) that can change the excitability of lower-level visual areas. However, the mechanism through which this control is achieved remains elusive. Here, we emulated the generation of an attentional signal using single-pulse transcranial magnetic stimulation to activate the FEFs and tracked its consequences over the visual cortex. First, we documented changes to brain oscillations using electroencephalography and found evidence for a phase reset over occipital sites at beta frequency. We then probed for perceptual consequences of this top-down triggered phase reset and assessed its anatomical specificity. We show that FEF activation leads to cyclic modulation of visual perception and extrastriate but not primary visual cortex excitability, again at beta frequency. We conclude that top-down signals originating in FEF causally shape visual cortex activity and perception through mechanisms of oscillatory realignment.


Assuntos
Lobo Frontal/fisiologia , Estimulação Magnética Transcraniana/métodos , Córtex Visual/fisiologia , Campos Visuais/fisiologia , Percepção Visual/fisiologia , Adulto , Algoritmos , Eletroencefalografia/métodos , Feminino , Humanos , Masculino , Modelos Neurológicos , Lobo Occipital/fisiologia , Estimulação Luminosa
9.
Nat Commun ; 12(1): 1872, 2021 03 25.
Artigo em Inglês | MEDLINE | ID: mdl-33767141

RESUMO

Deep neural networks have revolutionized computer vision, and their object representations across layers match coarsely with visual cortical areas in the brain. However, whether these representations exhibit qualitative patterns seen in human perception or brain representations remains unresolved. Here, we recast well-known perceptual and neural phenomena in terms of distance comparisons, and ask whether they are present in feedforward deep neural networks trained for object recognition. Some phenomena were present in randomly initialized networks, such as the global advantage effect, sparseness, and relative size. Many others were present after object recognition training, such as the Thatcher effect, mirror confusion, Weber's law, relative size, multiple object normalization and correlated sparseness. Yet other phenomena were absent in trained networks, such as 3D shape processing, surface invariance, occlusion, natural parts and the global advantage. These findings indicate sufficient conditions for the emergence of these phenomena in brains and deep networks, and offer clues to the properties that could be incorporated to improve deep networks.


Assuntos
Modelos Neurológicos , Redes Neurais de Computação , Reconhecimento Visual de Modelos/fisiologia , Córtex Visual/fisiologia , Humanos , Percepção Visual/fisiologia
10.
Neuron ; 109(8): 1381-1395.e7, 2021 04 21.
Artigo em Inglês | MEDLINE | ID: mdl-33667342

RESUMO

Perception improves by repeated practice with visual stimuli, a phenomenon known as visual perceptual learning (VPL). The interplay of attentional and neuromodulatory reward signals is hypothesized to cause these behavioral and associated neuronal changes, although VPL can occur without attention (i.e., task-irrelevant VPL). In addition, task-relevant VPL can be category-selective for simple attended oriented stimuli. Yet, it is unclear whether category-selective task-irrelevant VPL occurs and which brain centers mediate underlying forms of adult cortical plasticity. Here, we show that pairing subliminal complex visual stimuli (faces and bodies) with electrical microstimulation of the ventral tegmental area (VTA-EM) causes category-selective task-irrelevant VPL. These perceptual improvements are accompanied by fMRI signal changes in early and late visual and frontal areas, as well as the cerebellum, hippocampus, claustrum, and putamen. In conclusion, Pavlovian pairing of unattended complex stimuli with VTA-EM causes category-selective learning accompanied by changes of cortical and subcortical neural representations in macaques.


Assuntos
Atenção/fisiologia , Aprendizagem/fisiologia , Área Tegmentar Ventral/fisiologia , Córtex Visual/fisiologia , Percepção Visual/fisiologia , Animais , Estimulação Elétrica , Macaca , Imagem por Ressonância Magnética , Plasticidade Neuronal/fisiologia , Estimulação Luminosa , Área Tegmentar Ventral/diagnóstico por imagem , Córtex Visual/diagnóstico por imagem
11.
Neurosci Lett ; 750: 135805, 2021 04 17.
Artigo em Inglês | MEDLINE | ID: mdl-33705926

RESUMO

Research has confirmed that the visual working memory representation of objects' roughness is robust against illumination changes in the human ventral visual cortex and intraparietal sulcus, but not yet against visual distractors during memory maintenance. Thus, this study investigated the effects of visual distractors on roughness-related brain regions during the maintenance phase using multi-voxel pattern analysis (MVPA). We conducted an fMRI experiment in which participants were asked to memorize a sphere's roughness against visual distractors, presented during the delay period in random trials. Region of interest-based MVPA showed no contribution of the ventral visual cortex and intraparietal sulcus to the roughness memory, regardless of behavioral performance. Post hoc searchlight MVPA revealed an above-chance decoding performance level in the brain regions presumably related to haptic processing when no visual distractors were shown. In contrast, when visual distractors appeared in the delay period, decoding performance exceeded the chance level in the ventral visual cortex. These results suggest that when visual distractors are presented during the memory phase, both visual and haptic processing are related to visual working memory for roughness, and the weighting of modality changes depending on the presence of visual distractors.


Assuntos
Memória de Curto Prazo , Percepção do Tato , Córtex Visual/fisiologia , Percepção Visual , Atenção , Conectoma , Feminino , Humanos , Imagem por Ressonância Magnética , Masculino , Lobo Parietal/fisiologia , Adulto Jovem
12.
Neurol Sci ; 42(5): 1733-1749, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33675004

RESUMO

OBJECTIVE: To systematically review the literature on the use of the transcranial static magnetic stimulation (tSMS) technique in humans and animals, its effects on different areas of the central nervous system (CNS), its influence on neural excitability and on the subject's behavior, and its biological effects and future possibilities. All static magnetic field applications that can be considered to have a physiologically similar effect have been reviewed. METHODS: We searched studies using key terms in NCBI PubMed, Scopus, PEDro, SciELO, Cochrane, and links to publications (inception to September 2019). Three reviewers independently selected the studies, extracted data, and assessed the methodological quality of the studies using the recommendations described in the Cochrane Handbook for Systematic Reviews of Interventions, PRISMA guidelines. RESULTS: We analyzed 27 studies. The reviewed literature suggests that the use of these magnetic fields has an inhibitory effect on different areas of the CNS, such as motor, somatosensory, and visual cortex, cerebellum, and spinal cord. Regarding subject's behavior, the different effects of tSMS appear to be transient and dependent on the stimulated area, such as loss of visual discrimination or improvement of somatosensory perception. In addition, the technique has some therapeutic utility, specifically in pathologies with cortical hyperexcitability. CONCLUSIONS: These results suggest that tSMS may be a promising tool to modulate cerebral excitability in a safe and non-invasive way. Further investigations could give a better explanation of its precise mechanisms of action and applications.


Assuntos
Estimulação Magnética Transcraniana , Córtex Visual , Humanos , Fenômenos Magnéticos
13.
Neuron ; 109(7): 1227-1241.e5, 2021 04 07.
Artigo em Inglês | MEDLINE | ID: mdl-33592180

RESUMO

Normative theories and statistical inference provide complementary approaches for the study of biological systems. A normative theory postulates that organisms have adapted to efficiently solve essential tasks and proceeds to mathematically work out testable consequences of such optimality; parameters that maximize the hypothesized organismal function can be derived ab initio, without reference to experimental data. In contrast, statistical inference focuses on the efficient utilization of data to learn model parameters, without reference to any a priori notion of biological function. Traditionally, these two approaches were developed independently and applied separately. Here, we unify them in a coherent Bayesian framework that embeds a normative theory into a family of maximum-entropy "optimization priors." This family defines a smooth interpolation between a data-rich inference regime and a data-limited prediction regime. Using three neuroscience datasets, we demonstrate that our framework allows one to address fundamental challenges relating to inference in high-dimensional, biological problems.


Assuntos
Interpretação Estatística de Dados , Neurologia/estatística & dados numéricos , Algoritmos , Animais , Teorema de Bayes , Caenorhabditis elegans/fisiologia , Simulação por Computador , Bases de Dados Factuais , Entropia , Humanos , Modelos Neurológicos , Neurônios/fisiologia , Retina/fisiologia , Córtex Visual/fisiologia , Campos Visuais/fisiologia
14.
Neuron ; 109(7): 1202-1213.e5, 2021 04 07.
Artigo em Inglês | MEDLINE | ID: mdl-33609483

RESUMO

The frontal cortex, especially the anterior cingulate cortex area (ACA), is essential for exerting cognitive control after errors, but the mechanisms that enable modulation of attention to improve performance after errors are poorly understood. Here we demonstrate that during a mouse visual attention task, ACA neurons projecting to the visual cortex (VIS; ACAVIS neurons) are recruited selectively by recent errors. Optogenetic manipulations of this pathway collectively support the model that rhythmic modulation of ACAVIS neurons in anticipation of visual stimuli is crucial for adjusting performance following errors. 30-Hz optogenetic stimulation of ACAVIS neurons in anesthetized mice recapitulates the increased gamma and reduced theta VIS oscillatory changes that are associated with endogenous post-error performance during behavior and subsequently increased visually evoked spiking, a hallmark feature of visual attention. This frontal sensory neural circuit links error monitoring with implementing adjustments of attention to guide behavioral adaptation, pointing to a circuit-based mechanism for promoting cognitive control.


Assuntos
Atenção/fisiologia , Lobo Frontal/fisiologia , Recrutamento Neurofisiológico/fisiologia , Animais , Comportamento Animal , Eletroencefalografia , Fenômenos Eletrofisiológicos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Atividade Motora/fisiologia , Vias Neurais/fisiologia , Neurônios/fisiologia , Optogenética , Estimulação Luminosa , Desempenho Psicomotor/fisiologia , Tempo de Reação/fisiologia , Córtex Somatossensorial/fisiologia , Córtex Visual/fisiologia
15.
Arch Biochem Biophys ; 701: 108815, 2021 04 15.
Artigo em Inglês | MEDLINE | ID: mdl-33609537

RESUMO

Glaucoma is a neurodegenerative disease that affects eye structures and brain areas related to the visual system. Oxidative stress plays a key role in the development and progression of the disease. The aims of the present study were to evaluate the mitochondrial function and its participation in the brain redox metabolism in an experimental glaucoma model. 3-month-old female Wistar rats were subjected to cauterization of two episcleral veins of the left eye to elevate the intraocular pressure. Seven days after surgery, animals were sacrificed, the brain was carefully removed and the primary visual cortex was dissected. Mitochondrial bioenergetics and ROS production, and the antioxidant enzyme defenses from both mitochondrial and cytosolic fractions were evaluated. When compared to control, glaucoma decreased mitochondrial ATP production (23%, p < 0.05), with an increase in superoxide and hydrogen peroxide production (30%, p < 0.01 and 28%, p < 0.05, respectively), whereas no changes were observed in membrane potential and oxygen consumption rate. In addition, the glaucoma group displayed a decrease in complex II activity (34%, p < 0.01). Moreover, NOX4 expression was increased in glaucoma compared to the control group (27%, p < 0.05). Regarding the activity of enzymes associated with the regulation of the redox status, glaucoma showed an increase in mitochondrial SOD activity (34%, p < 0.05), mostly due to an increase in Mn-SOD (50%, p < 0.05). A decrease in mitochondrial GST activity was observed (11%, p < 0.05). GR and TrxR activity were decreased in both mitochondrial (16%, p < 0.05 and 20%, p < 0.05 respectively) and cytosolic (21%, p < 0.01 and 50%, p < 0.01 respectively) fractions in the glaucoma group. Additionally, glaucoma showed an increase in cytoplasmatic GPx (50%, p < 0.01). In this scenario, redox imbalance took place resulting in damage to mitochondrial lipids (39%, p < 0.01) and proteins (70%, p < 0.05). These results suggest that glaucoma leads to mitochondrial function impairment in brain visual targets, that is accompanied by an alteration in both mitochondrial and cytoplasmatic enzymatic defenses. As a consequence of redox imbalance, oxidative damage to macromolecules takes place and can further affect vital cellular functions. Understanding the role of the mitochondria in the development and progression of the disease could bring up new neuroprotective therapies.


Assuntos
Glaucoma/metabolismo , Mitocôndrias/metabolismo , Córtex Visual/metabolismo , Trifosfato de Adenosina/metabolismo , Animais , Modelos Animais de Doenças , Feminino , Glaucoma/patologia , Mitocôndrias/patologia , Proteínas Mitocondriais/metabolismo , NADPH Oxidase 4/metabolismo , Ratos , Ratos Wistar , Superóxido Dismutase/metabolismo , Córtex Visual/patologia
16.
Nat Commun ; 12(1): 1029, 2021 02 15.
Artigo em Inglês | MEDLINE | ID: mdl-33589635

RESUMO

A primary challenge in single-cell RNA sequencing (scRNA-seq) studies comes from the massive amount of data and the excess noise level. To address this challenge, we introduce an analysis framework, named single-cell Decomposition using Hierarchical Autoencoder (scDHA), that reliably extracts representative information of each cell. The scDHA pipeline consists of two core modules. The first module is a non-negative kernel autoencoder able to remove genes or components that have insignificant contributions to the part-based representation of the data. The second module is a stacked Bayesian autoencoder that projects the data onto a low-dimensional space (compressed). To diminish the tendency to overfit of neural networks, we repeatedly perturb the compressed space to learn a more generalized representation of the data. In an extensive analysis, we demonstrate that scDHA outperforms state-of-the-art techniques in many research sub-fields of scRNA-seq analysis, including cell segregation through unsupervised learning, visualization of transcriptome landscape, cell classification, and pseudo-time inference.


Assuntos
Redes Neurais de Computação , Análise de Sequência de RNA/estatística & dados numéricos , Análise de Célula Única/estatística & dados numéricos , Aprendizado de Máquina não Supervisionado/estatística & dados numéricos , Animais , Teorema de Bayes , Benchmarking , Separação Celular/métodos , Cerebelo/química , Cerebelo/citologia , Embrião de Mamíferos , Humanos , Fígado/química , Fígado/citologia , Pulmão/química , Pulmão/citologia , Camundongos , Células-Tronco Embrionárias Murinas/química , Células-Tronco Embrionárias Murinas/citologia , Pâncreas/química , Pâncreas/citologia , Retina/química , Retina/citologia , Análise de Célula Única/métodos , Córtex Visual/química , Córtex Visual/citologia , Zigoto/química , Zigoto/citologia
17.
Nat Commun ; 12(1): 1200, 2021 02 22.
Artigo em Inglês | MEDLINE | ID: mdl-33619256

RESUMO

Learning-activated engram neurons play a critical role in memory recall. An untested hypothesis is that these same neurons play an instructive role in offline memory consolidation. Here we show that a visually-cued fear memory is consolidated during post-conditioning sleep in mice. We then use TRAP (targeted recombination in active populations) to genetically label or optogenetically manipulate primary visual cortex (V1) neurons responsive to the visual cue. Following fear conditioning, mice respond to activation of this visual engram population in a manner similar to visual presentation of fear cues. Cue-responsive neurons are selectively reactivated in V1 during post-conditioning sleep. Mimicking visual engram reactivation optogenetically leads to increased representation of the visual cue in V1. Optogenetic inhibition of the engram population during post-conditioning sleep disrupts consolidation of fear memory. We conclude that selective sleep-associated reactivation of learning-activated sensory populations serves as a necessary instructive mechanism for memory consolidation.


Assuntos
Medo/fisiologia , Consolidação da Memória/fisiologia , Memória/fisiologia , Sono/fisiologia , Animais , Condicionamento Psicológico/fisiologia , Sinais (Psicologia) , Eletrodos , Tecnologia de Fibra Óptica , Camundongos Transgênicos , Plasticidade Neuronal/fisiologia , Neurônios/fisiologia , Optogenética , Privação do Sono/fisiopatologia , Córtex Visual/fisiopatologia
18.
Neuron ; 109(3): 398-400, 2021 02 03.
Artigo em Inglês | MEDLINE | ID: mdl-33539774

RESUMO

Wang et al. show that normal development of mouse binocular vision involves the selective apoptosis of chandelier interneurons in binocular visual cortex. This process is driven by retinal and transcallosal activity before eye-opening and may promote subsequent selective wiring of binocular connections.


Assuntos
Córtex Visual , Animais , Apoptose , Interneurônios , Camundongos , Neurônios , Visão Binocular
19.
Nat Commun ; 12(1): 862, 2021 02 08.
Artigo em Inglês | MEDLINE | ID: mdl-33558487

RESUMO

The adult brain lacks sensitivity to changes in the sensory environment found in the juvenile brain. The transplantation of embryonic interneurons has been shown to restore juvenile plasticity to the adult host visual cortex. It is unclear whether transplanted interneurons directly mediate the renewed cortical plasticity or whether these cells act indirectly by modifying the host interneuron circuitry. Here we find that the transplant-induced reorganization of mouse host circuits is specifically mediated by Neuregulin (NRG1)/ErbB4 signaling in host parvalbumin (PV) interneurons. Brief visual deprivation reduces the visual activity of host PV interneurons but has negligible effects on the responses of transplanted PV interneurons. Exogenous NRG1 both prevents the deprivation-induced reduction in the visual responses of host PV interneurons and blocks the transplant-induced reorganization of the host circuit. While deletion of ErbB4 receptors from host PV interneurons blocks cortical plasticity in the transplant recipients, deletion of the receptors from the donor PV interneurons does not. Altogether, our results indicate that transplanted embryonic interneurons reactivate cortical plasticity by rejuvenating the function of host PV interneurons.


Assuntos
Transplante de Células , Interneurônios/fisiologia , Interneurônios/transplante , Plasticidade Neuronal/fisiologia , Córtex Visual/embriologia , Animais , Diferenciação Celular , Dominância Ocular , Feminino , Masculino , Camundongos Endogâmicos C57BL , Neuregulina-1/metabolismo , Parvalbuminas/metabolismo , Receptor ErbB-4/metabolismo , Privação Sensorial , Transdução de Sinais , Sinapses/fisiologia
20.
Nat Commun ; 12(1): 228, 2021 01 11.
Artigo em Inglês | MEDLINE | ID: mdl-33431862

RESUMO

The sensory neocortex consists of hierarchically-organized areas reciprocally connected via feedforward and feedback circuits. Feedforward connections shape the receptive field properties of neurons in higher areas within parallel streams specialized in processing specific stimulus attributes. Feedback connections have been implicated in top-down modulations, such as attention, prediction and sensory context. However, their computational role remains unknown, partly because we lack knowledge about rules of feedback connectivity to constrain models of feedback function. For example, it is unknown whether feedback connections maintain stream-specific segregation, or integrate information across parallel streams. Using viral-mediated labeling of feedback connections arising from specific cytochrome-oxidase stripes of macaque visual area V2, here we show that feedback to the primary visual cortex (V1) is organized into parallel streams resembling the reciprocal feedforward pathways. This suggests that functionally-specialized V2 feedback channels modulate V1 responses to specific stimulus attributes, an organizational principle potentially extending to feedback pathways in other sensory systems.


Assuntos
Retroalimentação Sensorial/fisiologia , Córtex Visual/fisiologia , Animais , Axônios/metabolismo , Feminino , Proteínas de Fluorescência Verde/metabolismo , Macaca fascicularis , Masculino , Modelos Biológicos
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