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1.
Nat Commun ; 12(1): 4081, 2021 07 02.
Artigo em Inglês | MEDLINE | ID: mdl-34215754

RESUMO

A central regularity of visual perception is the co-occurrence of objects in the natural environment. Here we use machine learning and fMRI to test the hypothesis that object co-occurrence statistics are encoded in the human visual system and elicited by the perception of individual objects. We identified low-dimensional representations that capture the latent statistical structure of object co-occurrence in real-world scenes, and we mapped these statistical representations onto voxel-wise fMRI responses during object viewing. We found that cortical responses to single objects were predicted by the statistical ensembles in which they typically occur, and that this link between objects and their visual contexts was made most strongly in parahippocampal cortex, overlapping with the anterior portion of scene-selective parahippocampal place area. In contrast, a language-based statistical model of the co-occurrence of object names in written text predicted responses in neighboring regions of object-selective visual cortex. Together, these findings show that the sensory coding of objects in the human brain reflects the latent statistics of object context in visual and linguistic experience.


Assuntos
Encéfalo/fisiologia , Idioma , Percepção Visual/fisiologia , Adulto , Mapeamento Encefálico , Feminino , Humanos , Imageamento por Ressonância Magnética , Reconhecimento Visual de Modelos , Percepção , Córtex Visual/fisiologia
2.
Sci Rep ; 11(1): 14448, 2021 07 14.
Artigo em Inglês | MEDLINE | ID: mdl-34262075

RESUMO

Faces hold a substantial value for effective social interactions and sharing. Covering faces with masks, due to COVID-19 regulations, may lead to difficulties in using social signals, in particular, in individuals with neurodevelopmental conditions. Daily-life social participation of individuals who were born preterm is of immense importance for their quality of life. Here we examined face tuning in individuals (aged 12.79 ± 1.89 years) who were born preterm and exhibited signs of periventricular leukomalacia (PVL), a dominant form of brain injury in preterm birth survivors. For assessing the face sensitivity in this population, we implemented a recently developed experimental tool, a set of Face-n-Food images bordering on the style of Giuseppe Arcimboldo. The key benefit of these images is that single components do not trigger face processing. Although a coarse face schema is thought to be hardwired in the brain, former preterms exhibit substantial shortages in the face tuning not only compared with typically developing controls but also with individuals with autistic spectrum disorders. The lack of correlations between the face sensitivity and other cognitive abilities indicates that these deficits are domain-specific. This underscores impact of preterm birth sequelae for social functioning at large. Comparison of the findings with data in individuals with other neurodevelopmental and neuropsychiatric conditions provides novel insights into the origins of deficient face processing.


Assuntos
Encéfalo/fisiologia , Reconhecimento Facial , Reconhecimento Visual de Modelos , Nascimento Prematuro , Cognição Social , Adolescente , Transtorno do Espectro Autista , COVID-19 , Criança , Cognição , Neurociência Cognitiva , Expressão Facial , Feminino , Humanos , Leucomalácia Periventricular , Gravidez , Qualidade de Vida , Reconhecimento Psicológico/fisiologia , Fatores Sexuais , Comportamento Social , Percepção Visual/fisiologia
3.
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
4.
Nat Commun ; 12(1): 4005, 2021 06 28.
Artigo em Inglês | MEDLINE | ID: mdl-34183661

RESUMO

Synaptic inputs on cortical dendrites are organized with remarkable subcellular precision at the micron level. This organization emerges during early postnatal development through patterned spontaneous activity and manifests both locally where nearby synapses are significantly correlated, and globally with distance to the soma. We propose a biophysically motivated synaptic plasticity model to dissect the mechanistic origins of this organization during development and elucidate synaptic clustering of different stimulus features in the adult. Our model captures local clustering of orientation in ferret and receptive field overlap in mouse visual cortex based on the receptive field diameter and the cortical magnification of visual space. Including action potential back-propagation explains branch clustering heterogeneity in the ferret and produces a global retinotopy gradient from soma to dendrite in the mouse. Therefore, by combining activity-dependent synaptic competition and species-specific receptive fields, our framework explains different aspects of synaptic organization regarding stimulus features and spatial scales.


Assuntos
Visão Ocular/fisiologia , Córtex Visual/fisiologia , Percepção Visual/fisiologia , Potenciais de Ação/fisiologia , Animais , Fator Neurotrófico Derivado do Encéfalo/metabolismo , Dendritos/fisiologia , Furões , Camundongos , Modelos Neurológicos , Fatores de Crescimento Neural/metabolismo , Plasticidade Neuronal/fisiologia , Sinapses/fisiologia , Córtex Visual/anatomia & histologia
5.
Nat Commun ; 12(1): 4004, 2021 06 28.
Artigo em Inglês | MEDLINE | ID: mdl-34183678

RESUMO

The superior colliculus (SC) receives diverse and robust cortical inputs to drive a range of cognitive and sensorimotor behaviors. However, it remains unclear how descending cortical input arising from higher-order associative areas coordinate with SC sensorimotor networks to influence its outputs. Here, we construct a comprehensive map of all cortico-tectal projections and identify four collicular zones with differential cortical inputs: medial (SC.m), centromedial (SC.cm), centrolateral (SC.cl) and lateral (SC.l). Further, we delineate the distinctive brain-wide input/output organization of each collicular zone, assemble multiple parallel cortico-tecto-thalamic subnetworks, and identify the somatotopic map in the SC that displays distinguishable spatial properties from the somatotopic maps in the neocortex and basal ganglia. Finally, we characterize interactions between those cortico-tecto-thalamic and cortico-basal ganglia-thalamic subnetworks. This study provides a structural basis for understanding how SC is involved in integrating different sensory modalities, translating sensory information to motor command, and coordinating different actions in goal-directed behaviors.


Assuntos
Colículos Superiores/anatomia & histologia , Colículos Superiores/fisiologia , Visão Ocular/fisiologia , Percepção Visual/fisiologia , Animais , Gânglios da Base/fisiologia , Cognição/fisiologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Vias Visuais
6.
Nat Commun ; 12(1): 4029, 2021 06 29.
Artigo em Inglês | MEDLINE | ID: mdl-34188047

RESUMO

The representation of space in mouse visual cortex was thought to be relatively uniform. Here we reveal, using population receptive-field (pRF) mapping techniques, that mouse visual cortex contains a region in which pRFs are considerably smaller. This region, the "focea," represents a location in space in front of, and slightly above, the mouse. Using two-photon imaging we show that the smaller pRFs are due to lower scatter of receptive-fields at the focea and an over-representation of binocular regions of space. We show that receptive-fields of single-neurons in areas LM and AL are smaller at the focea and that mice have improved visual resolution in this region of space. Furthermore, freely moving mice make compensatory eye-movements to hold this region in front of them. Our results indicate that mice have spatial biases in their visual processing, a finding that has important implications for the use of the mouse model of vision.


Assuntos
Movimentos Oculares/fisiologia , Córtex Visual/fisiologia , Campos Visuais/fisiologia , Percepção Visual/fisiologia , Animais , Feminino , Movimentos da Cabeça/fisiologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Estimulação Luminosa
7.
Psychol Aging ; 36(4): 520-530, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-34124922

RESUMO

Multisensory input can improve perception of ambiguous unisensory information. For example, speech heard in noise can be more accurately identified when listeners see a speaker's articulating face. Importantly, these multisensory effects can be superadditive to listeners' ability to process unisensory speech, such that audiovisual speech identification is better than the sum of auditory-only and visual-only speech identification. Age-related declines in auditory and visual speech perception have been hypothesized to be concomitant with stronger cross-sensory influences on audiovisual speech identification, but little evidence exists to support this. Currently, studies do not account for the multisensory superadditive benefit of auditory-visual input in their metrics of the auditory or visual influence on audiovisual speech perception. Here we treat multisensory superadditivity as independent from unisensory auditory and visual processing. In the current investigation, older and younger adults identified auditory, visual, and audiovisual speech in noisy listening conditions. Performance across these conditions was used to compute conventional metrics of the auditory and visual influence on audiovisual speech identification and a metric of auditory-visual superadditivity. Consistent with past work, auditory and visual speech identification declined with age, audiovisual speech identification was preserved, and no age-related differences in the auditory or visual influence on audiovisual speech identification were observed. However, we found that auditory-visual superadditivity improved with age. The novel findings suggest that multisensory superadditivity is independent of unisensory processing. As auditory and visual speech identification decline with age, compensatory changes in multisensory superadditivity may preserve audiovisual speech identification in older adults. (PsycInfo Database Record (c) 2021 APA, all rights reserved).


Assuntos
Percepção Auditiva/fisiologia , Inteligibilidade da Fala/fisiologia , Percepção Visual/fisiologia , Adulto , Idoso , Envelhecimento , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Percepção da Fala , Adulto Jovem
8.
Nat Commun ; 12(1): 3374, 2021 06 07.
Artigo em Inglês | MEDLINE | ID: mdl-34099735

RESUMO

Numerosity, the set size of a group of items, helps guide behaviour and decisions. Non-symbolic numerosities are represented by the approximate number system. However, distinct behavioural performance suggests that small numerosities, i.e. subitizing range, are implemented differently in the brain than larger numerosities. Prior work has shown that neural populations selectively responding (i.e. hemodynamic responses) to small numerosities are organized into a network of topographical maps. Here, we investigate how neural populations respond to large numerosities, well into the ANS. Using 7 T fMRI and biologically-inspired analyses, we found a network of neural populations tuned to both small and large numerosities organized within the same topographic maps. These results demonstrate a continuum of numerosity preferences that progressively cover both the subitizing range and beyond within the same numerosity map, suggesting a single neural mechanism. We hypothesize that differences in map properties, such as cortical magnification and tuning width, underlie known differences in behaviour.


Assuntos
Mapeamento Encefálico/métodos , Encéfalo/fisiologia , Rede Nervosa/fisiologia , Percepção Visual/fisiologia , Adulto , Encéfalo/diagnóstico por imagem , Feminino , Humanos , Imageamento por Ressonância Magnética/métodos , Masculino , Pessoa de Meia-Idade , Rede Nervosa/diagnóstico por imagem , Estimulação Luminosa/métodos , Reprodutibilidade dos Testes
9.
Neuron ; 109(13): 2150-2164.e5, 2021 07 07.
Artigo em Inglês | MEDLINE | ID: mdl-34038743

RESUMO

Processing of sensory information in neural circuits is modulated by an animal's behavioral state, but the underlying cellular mechanisms are not well understood. Focusing on the mouse visual cortex, here we analyze the role of GABAergic interneurons that are located in layer 1 and express Ndnf (L1 NDNF INs) in the state-dependent control over sensory processing. We find that the ongoing and sensory-evoked activity of L1 NDNF INs is strongly enhanced when an animal is aroused and that L1 NDNF INs gain-modulate local excitatory neurons selectively during high-arousal states by inhibiting their apical dendrites while disinhibiting their somata via Parvalbumin-expressing interneurons. Because active NDNF INs are evenly spread in L1 and can affect excitatory neurons across all cortical layers, this indicates that the state-dependent activation of L1 NDNF INs and the subsequent shift of inhibition in excitatory neurons toward their apical dendrites gain-modulate sensory processing in whole cortical columns.


Assuntos
Comportamento Animal , Neurônios GABAérgicos/fisiologia , Interneurônios/fisiologia , Fatores de Crescimento Neural/fisiologia , Córtex Visual/fisiologia , Percepção Visual/fisiologia , Animais , Feminino , Neurônios GABAérgicos/metabolismo , Interneurônios/metabolismo , Masculino , Camundongos Endogâmicos C57BL , Fatores de Crescimento Neural/metabolismo , Estimulação Luminosa , Córtex Visual/metabolismo
10.
Nat Commun ; 12(1): 2632, 2021 05 11.
Artigo em Inglês | MEDLINE | ID: mdl-33976141

RESUMO

The neural systems supporting scene-perception and spatial-memory systems of the human brain are well-described. But how do these neural systems interact? Here, using fine-grained individual-subject fMRI, we report three cortical areas of the human brain, each lying immediately anterior to a region of the scene perception network in posterior cerebral cortex, that selectively activate when recalling familiar real-world locations. Despite their close proximity to the scene-perception areas, network analyses show that these regions constitute a distinct functional network that interfaces with spatial memory systems during naturalistic scene understanding. These "place-memory areas" offer a new framework for understanding how the brain implements memory-guided visual behaviors, including navigation.


Assuntos
Córtex Cerebral/fisiologia , Rememoração Mental/fisiologia , Memória Espacial/fisiologia , Navegação Espacial/fisiologia , Percepção Visual/fisiologia , Adulto , Córtex Cerebral/diagnóstico por imagem , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino , Rede Nervosa/diagnóstico por imagem , Rede Nervosa/fisiologia , Adulto Jovem
11.
Medicine (Baltimore) ; 100(21): e25823, 2021 May 28.
Artigo em Inglês | MEDLINE | ID: mdl-34032696

RESUMO

ABSTRACT: Sexual dysfunction is a common problem after cerebral infarction; however, little is known about sexual arousal in poststroke patients. Thus, this study aimed to investigate brain activation in response to visual sexual stimuli in patients with right middle cerebral artery (MCA) territory infarction using functional magnetic resonance imaging (fMRI). Using fMRI in 20 participants (11 right MCA infarction patients and 9 age-matched healthy controls), we assessed brain activation elicited by visual sexual stimuli (erotic images) and visual nonsexual stimuli (landscape images). In right MCA infarction patients, the left dorsolateral prefrontal cortex and the left frontal subgyral area were more strongly activated by visual sexual stimuli than by nonvisual sexual stimuli. Brain areas that were more activated by visual sexual stimuli in right MCA infarction patients than in controls included the right parahippocampal gyrus and the bilateral frontal subgyral area. These fMRI results suggest that brain activation patterns in response to visual sexual stimuli might be influenced by right MCA infarction. Further research is needed to explore the association between sexual dysfunction and brain activation in poststroke patients.


Assuntos
Encéfalo/fisiopatologia , Infarto da Artéria Cerebral Média/complicações , Comportamento Sexual/fisiologia , Disfunções Sexuais Fisiológicas/fisiopatologia , Percepção Visual/fisiologia , Adulto , Idoso , Encéfalo/irrigação sanguínea , Encéfalo/diagnóstico por imagem , Mapeamento Encefálico , Estudos de Casos e Controles , Literatura Erótica , Humanos , Infarto da Artéria Cerebral Média/fisiopatologia , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Estimulação Luminosa/métodos , Disfunções Sexuais Fisiológicas/etiologia
12.
Optom Vis Sci ; 98(4): 310-325, 2021 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-33828038

RESUMO

SIGNIFICANCE: This article summarizes the evidence for a higher prevalence of binocular vision dysfunctions in individuals with vision impairment. Assessment for and identification of binocular vision dysfunctions can detect individuals experiencing difficulties in activities including reading, object placement tasks, and mobility.Comprehensive vision assessment in low vision populations is necessary to identify the extent of remaining vision and to enable directed rehabilitation efforts. In patients with vision impairment, little attention is typically paid to assessments of binocular vision, including ocular vergence, stereopsis, and binocular summation characteristics. In addition, binocular measurements of threshold automated visual fields are not routinely performed in clinical practice, leading to an incomplete understanding of individuals' binocular visual field and may affect rehabilitation outcomes.First, this review summarizes the prevalence of dysfunctions in ocular vergence, stereopsis, and binocular summation characteristics across a variety of ocular pathologies causing vision impairment. Second, this review examines the links between clinical measurements of binocular visual functions and outcome measures including quality of life and performance in functional tasks. There is an increased prevalence of dysfunctions in ocular alignment, stereopsis, and binocular summation across low vision cohorts compared with those with normal vision. The identification of binocular vision dysfunctions during routine low vision assessments is especially important in patients experiencing difficulties in activities of daily living, including but not limited to reading, object placement tasks, and mobility. However, further research is required to determine whether addressing the identified deficits in binocular vision in low vision rehabilitative efforts directly impacts patient outcomes.


Assuntos
Visão Binocular/fisiologia , Baixa Visão/fisiopatologia , Atividades Cotidianas/psicologia , Percepção de Profundidade/fisiologia , Humanos , Qualidade de Vida/psicologia , Leitura , Baixa Visão/psicologia , Campos Visuais/fisiologia , Percepção Visual/fisiologia , Pessoas com Deficiência Visual
13.
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
14.
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
15.
PLoS Comput Biol ; 17(3): e1008714, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33651793

RESUMO

In the last two decades rodents have been on the rise as a dominant model for visual neuroscience. This is particularly true for earlier levels of information processing, but a number of studies have suggested that also higher levels of processing such as invariant object recognition occur in rodents. Here we provide a quantitative and comprehensive assessment of this claim by comparing a wide range of rodent behavioral and neural data with convolutional deep neural networks. These networks have been shown to capture hallmark properties of information processing in primates through a succession of convolutional and fully connected layers. We find that performance on rodent object vision tasks can be captured using low to mid-level convolutional layers only, without any convincing evidence for the need of higher layers known to simulate complex object recognition in primates. Our approach also reveals surprising insights on assumptions made before, for example, that the best performing animals would be the ones using the most abstract representations-which we show to likely be incorrect. Our findings suggest a road ahead for further studies aiming at quantifying and establishing the richness of representations underlying information processing in animal models at large.


Assuntos
Aprendizado Profundo , Modelos Neurológicos , Percepção Visual/fisiologia , Animais , Biologia Computacional , Estimulação Luminosa , Ratos
16.
J Clin Exp Neuropsychol ; 43(1): 15-32, 2021 02.
Artigo em Inglês | MEDLINE | ID: mdl-33641640

RESUMO

Introduction: We hypothesized that diabetic patients without mild cognitive impairment would present deficiencies in visuospatial incidental/intentional memory processing and alterations in the underlying EEG alpha, theta and gamma patterns.Methods: Non-diabetic, diabetic-controlled, and diabetic-uncontrolled patients underwent a visuospatial incidental-intentional memory test under simultaneous recording of temporal, parietal, and frontal EEG. The test required patients to solve a maze, with eight objects irrelevant to the task, embedded in it, after an interference instruction, participants were asked to recall the positions of the objects (incidental test). Finally, the participants were explicitly told to study the object positions, and then were asked to recall the objects again (intentional test). Power from baseline, incidental learning, incidental memory, and intentional learning conditions was obtained in alpha, theta, and low-gamma bands. Comparisons were made across groups and conditions for each band, with age, sex, and years from the diagnosis as covariates (ANCOVA with blocking).Results: Diabetic patients showed spared incidental but deficient intentional visuospatial learning. Uncontrolled patients showed a more profound intentional learning deficit as they scored similar numbers of correct positions under incidental and intentional conditions; whereas, non-diabetic and diabetic-controlled patients increased their number after the intentional study. Non-diabetic participants showed increased power during intentional learning compared with the baseline condition in frontal theta, frontoparietal gamma (Fp2 and P4) and frontal alpha (F4) bands; whereas in diabetic patients the power increased in the theta band, in T5 (uncontrolled) and T5 and F7 (controlled).Conclusions: Diabetic patients without mild cognitive impairment show deficient intentional visuospatial learning which was worse in uncontrolled patients. Theta and gamma power increased in healthy participants during intentional learning principally in frontal areas. These EEG power changes were absent in diabetic patients. The reduced accuracy of diabetic patients in intentional visuospatial learning was associated with different EEG learning-related patterns.


Assuntos
Ondas Encefálicas/fisiologia , Córtex Cerebral/fisiopatologia , Disfunção Cognitiva/fisiopatologia , Complicações do Diabetes/fisiopatologia , Aprendizagem/fisiologia , Memória Espacial/fisiologia , Percepção Visual/fisiologia , Adulto , Disfunção Cognitiva/etiologia , Complicações do Diabetes/complicações , Feminino , Humanos , Masculino , Rememoração Mental/fisiologia , Pessoa de Meia-Idade
17.
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
18.
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 , Imageamento por Ressonância Magnética , Plasticidade Neuronal/fisiologia , Estimulação Luminosa , Área Tegmentar Ventral/diagnóstico por imagem , Córtex Visual/diagnóstico por imagem
19.
Neurology ; 96(17): e2160-e2171, 2021 04 27.
Artigo em Inglês | MEDLINE | ID: mdl-33722996

RESUMO

OBJECTIVE: To test the hypothesis that lateropulsion is an entity expressing an impaired body orientation with respect to gravity in relation to a biased graviception and spatial neglect. METHODS: Data from the DOBRAS cohort (ClinicalTrials.gov: NCT03203109) were collected 30 days after a first hemisphere stroke. Lateral body tilt, pushing, and resistance were assessed with the Scale for Contraversive Pushing. RESULTS: Among 220 individuals, 72% were upright and 28% showed lateropulsion (tilters [14%] less severe than pushers [14%]). The 3 signs had very high factor loadings (>0.90) on a same dimension, demonstrating that lateropulsion was effectively an entity comprising body tilt (cardinal sign), pushing, and resistance. The factorial analyses also showed that lateropulsion was inseparable from the visual vertical (VV), a criterion referring to vertical orientation (graviception). Contralesional VV biases were frequent (44%), with a magnitude related to lateropulsion severity: upright -0.6° (-2.9; 2.4), tilters -2.9° (-7; 0.8), and pushers -12.3° (-15.4; -8.5). Ipsilesional VV biases were less frequent and milder (p < 0.001). They did not deal with graviception, 84% being found in upright individuals. Multivariate, factorial, contingency, and prediction analyses congruently showed strong similarities between lateropulsion and spatial neglect, the latter encompassing the former. CONCLUSIONS: Lateropulsion (pusher syndrome) is a trinity constituted by body tilt, pushing, and resistance. It is a way to adjust the body orientation in the roll plane to a wrong reference of verticality. Referring to straight above, lateropulsion might correspond to a form of spatial neglect (referring to straight ahead), which would advocate for 3D maps in the human brain involving the internal model of verticality.


Assuntos
Encéfalo/fisiopatologia , Orientação/fisiologia , Acidente Vascular Cerebral/terapia , Percepção Visual/fisiologia , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Transtornos da Percepção/reabilitação , Transtornos da Percepção/terapia , Equilíbrio Postural/fisiologia , Postura/fisiologia
20.
JAMA Netw Open ; 4(3): e213687, 2021 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-33783515

RESUMO

Importance: Preterm birth is associated with an increased risk for long-lasting attention deficits. Early-life markers of attention abnormalities have not been established to date but could provide insights into the pathogenesis of attention abnormalities and could help identify susceptible individuals. Objective: To examine whether preterm birth is associated with visual attention impairments in early life, and if so, in which attention functions and at which developmental period during the first 2 years of life. Data Sources: PubMed and PsycINFO were searched on November 17, 2019, to identify studies involving visual attention outcomes in infants born preterm vs full term. Study Selection: Peer-reviewed studies from the past 50 years met the eligibility criteria if they directly assessed visual attention outcomes until the age of 2 years in generally healthy infants born preterm or full term. The selection process was conducted by 2 independent reviewers. Data Extraction and Synthesis: The Meta-analysis of Observational Studies in Epidemiology (MOOSE) reporting guideline was followed. Random-effects models were used to determine standardized mean differences. The risk of bias was assessed both within and between studies. Main Outcomes and Measures: Five nascent indices of visual attention were analyzed, including very basic functions-namely, the abilities to follow and fixate on visual targets-and more complex functions, such as visual processing (ie, habituation), recognition memory (ie, novelty preference), and the ability to effortfully focus attention for learning. Results: A total of 53 studies were included, with 69 effect sizes and assessing a total of 3998 infants (2047 born preterm and 1951 born full term; of the 3376 for whom sex was reported, 1693 [50.1%] were girls). Preterm birth was associated with impairments in various attention indices, including visual-following in infancy (Cohen d, -0.77; 95% CI, -1.23 to -0.31), latency to fixate (Cohen d, -0.18; 95% CI, -0.33 to -0.02), novelty preference (Cohen d, -0.20; 95% CI, -0.32 to -0.08), and focused attention (Cohen d, -0.28; 95% CI, -0.45 to -0.11). In the neonatal period, preterm birth was associated with superior visual-following (Cohen d, 0.22; 95% CI, 0.03 to 0.40), possibly owing to the additional extrauterine exposure to sensory stimulation. However, this early association waned rapidly in infancy (Cohen d, -0.77; 95% CI, -1.23 to -0.31). Conclusions and Relevance: The findings suggest that preterm birth is associated with impingements to visual attention development in early life, as manifested in basic and then complex forms of attention. Advancements in neonatal care may underlie improvements found in the current era and accentuate several early protective factors.


Assuntos
Atenção/fisiologia , Cognição/fisiologia , Recém-Nascido Prematuro/fisiologia , Nascimento Prematuro/fisiopatologia , Percepção Visual/fisiologia , Pré-Escolar , Feminino , Idade Gestacional , Humanos , Lactente , Recém-Nascido , Masculino , Gravidez
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