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2.
Nat Commun ; 11(1): 5109, 2020 10 09.
Artigo em Inglês | MEDLINE | ID: mdl-33037209

RESUMO

Perceptual decisions entail the accumulation of sensory evidence for a particular choice towards an action plan. An influential framework holds that sensory cortical areas encode the instantaneous sensory evidence and downstream, action-related regions accumulate this evidence. The large-scale distribution of this computation across the cerebral cortex has remained largely elusive. Here, we develop a regionally-specific magnetoencephalography decoding approach to exhaustively map the dynamics of stimulus- and choice-specific signals across the human cortical surface during a visual decision. Comparison with the evidence accumulation dynamics inferred from behavior disentangles stimulus-dependent and endogenous components of choice-predictive activity across the visual cortical hierarchy. We find such an endogenous component in early visual cortex (including V1), which is expressed in a low (<20 Hz) frequency band and tracks, with delay, the build-up of choice-predictive activity in (pre-) motor regions. Our results are consistent with choice- and frequency-specific cortical feedback signaling during decision formation.


Assuntos
Córtex Cerebral/fisiologia , Tomada de Decisões , Magnetoencefalografia/métodos , Percepção Visual/fisiologia , Comportamento de Escolha , Feminino , Humanos , Masculino , Experimentação Humana não Terapêutica , Processamento de Sinais Assistido por Computador , Córtex Visual/fisiologia
3.
Nat Commun ; 11(1): 4518, 2020 09 09.
Artigo em Inglês | MEDLINE | ID: mdl-32908146

RESUMO

The human brain is specialized for face processing, yet we sometimes perceive illusory faces in objects. It is unknown whether these natural errors of face detection originate from a rapid process based on visual features or from a slower, cognitive re-interpretation. Here we use a multifaceted approach to understand both the spatial distribution and temporal dynamics of illusory face representation in the brain by combining functional magnetic resonance imaging and magnetoencephalography neuroimaging data with model-based analysis. We find that the representation of illusory faces is confined to occipital-temporal face-selective visual cortex. The temporal dynamics reveal a striking evolution in how illusory faces are represented relative to human faces and matched objects. Illusory faces are initially represented more similarly to real faces than matched objects are, but within ~250 ms, the representation transforms, and they become equivalent to ordinary objects. This is consistent with the initial recruitment of a broadly-tuned face detection mechanism which privileges sensitivity over selectivity.


Assuntos
Reconhecimento Facial/fisiologia , Ilusões/fisiologia , Modelos Neurológicos , Lobo Temporal/fisiologia , Córtex Visual/fisiologia , Adolescente , Adulto , Mapeamento Encefálico , Simulação por Computador , Feminino , Humanos , Imagem por Ressonância Magnética , Magnetoencefalografia , Masculino , Neuroimagem , Estimulação Luminosa , Tempo de Reação , Lobo Temporal/diagnóstico por imagem , Córtex Visual/diagnóstico por imagem , Adulto Jovem
4.
PLoS One ; 15(8): e0238246, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32866203

RESUMO

Young children exhibit poorer visual performance than adults due to immaturity of the fovea and of the fundamental processing of visual functions such as masking and crowding. Recent studies suggest that masking and crowding are closely related to the size of the fundamental processing unit-the perceptive field (PF). However, while it is known that the retina and basic visual functions develop throughout childhood, it is not clear whether and how changes in the size of the PF affect masking and crowding. Furthermore, no retinal and perceptual development data have been collected from the same cohort and time. Here we explored the developmental process of the PF and the basic visual functions. Psychophysical and imaging methods were used to test visual functions and foveal changes in participants ranging from 3-17 years old. Lateral masking, crowding and contrast sensitivity were tested using computerized tasks. Foveal measurements were obtained from spectral-domain optical coherence tomography (OCT). The children patterns below 6 years exhibited high crowding, while the expected facilitation was found only at a larger target-flanker distance than required for children above 6 years, who exhibited the typical adult. Foveal thickness and macular volume for the children below 6 years were significantly lower than for the older group. Significant correlation was found for contrast sensitivity, foveal thickness and macular volume with age and between contrast sensitivity and foveal thickness. Our data suggest that the developmental processes at the retina and visual cortex occur in the same age range. Thus, in parallel to maturation of the PF, which enables reduction in crowding, foveal development contributes to increasing contrast sensitivity.


Assuntos
Retina/fisiologia , Acuidade Visual/fisiologia , Córtex Visual/fisiologia , Adolescente , Criança , Pré-Escolar , Sensibilidades de Contraste/fisiologia , Aglomeração , Feminino , Fóvea Central/fisiologia , Humanos , Edema Macular/fisiopatologia , Masculino , Tomografia de Coerência Óptica/métodos
5.
Nat Commun ; 11(1): 4819, 2020 09 23.
Artigo em Inglês | MEDLINE | ID: mdl-32968048

RESUMO

In many parts of the nervous system, experience-dependent refinement of neuronal circuits predominantly involves synapse elimination. The role of sleep in this process remains unknown. We investigated the role of sleep in experience-dependent dendritic spine elimination of layer 5 pyramidal neurons in the visual (V1) and frontal association cortex (FrA) of 1-month-old mice. We found that monocular deprivation (MD) or auditory-cued fear conditioning (FC) caused rapid spine elimination in V1 or FrA, respectively. MD- or FC-induced spine elimination was significantly reduced after total sleep or REM sleep deprivation. Total sleep or REM sleep deprivation also prevented MD- and FC-induced reduction of neuronal activity in response to visual or conditioned auditory stimuli. Furthermore, dendritic calcium spikes increased substantially during REM sleep, and the blockade of these calcium spikes prevented MD- and FC-induced spine elimination. These findings reveal an important role of REM sleep in experience-dependent synapse elimination and neuronal activity reduction.


Assuntos
Córtex Cerebral/fisiologia , Espinhas Dendríticas/fisiologia , Sono REM/fisiologia , Animais , Condicionamento Clássico , Medo/fisiologia , Camundongos , Camundongos Transgênicos , Modelos Animais , Plasticidade Neuronal/fisiologia , Neurônios/fisiologia , Células Piramidais/fisiologia , Privação Sensorial/fisiologia , Privação do Sono , Sinapses , Córtex Visual/fisiologia
6.
PLoS Comput Biol ; 16(9): e1008164, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32877405

RESUMO

The majority of neurons in primary visual cortex respond selectively to bars of light that have a specific orientation and move in a specific direction. The spatial and temporal responses of such neurons are non-separable. How neurons accomplish that computational feat without resort to explicit time delays is unknown. We propose a novel neural mechanism whereby visual cortex computes non-separable responses by generating endogenous traveling waves of neural activity that resonate with the space-time signature of the visual stimulus. The spatiotemporal characteristics of the response are defined by the local topology of excitatory and inhibitory lateral connections in the cortex. We simulated the interaction between endogenous traveling waves and the visual stimulus using spatially distributed populations of excitatory and inhibitory neurons with Wilson-Cowan dynamics and inhibitory-surround coupling. Our model reliably detected visual gratings that moved with a given speed and direction provided that we incorporated neural competition to suppress false motion signals in the opposite direction. The findings suggest that endogenous traveling waves in visual cortex can impart direction-selectivity on neural responses without resort to explicit time delays. They also suggest a functional role for motion opponency in eliminating false motion signals.


Assuntos
Modelos Neurológicos , Percepção de Movimento/fisiologia , Córtex Visual , Animais , Gatos , Biologia Computacional , Simulação por Computador , Haplorrinos , Orientação Espacial/fisiologia , Córtex Visual/citologia , Córtex Visual/fisiologia
7.
PLoS One ; 15(9): e0239535, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32946533

RESUMO

To solve the problem that the details of fusion images are not retained well and the information of feature targets is incomplete, we proposed a new fusion method of infrared (IR) and visible (VI) image-IR and VI image fusion method of dual non-subsampled contourlet transform (NSCT) and pulse-coupled neural network (PCNN). The method makes full use of the flexible multi-resolution and multi-directional of NSCT, and the global coupling and pulse synchronization excitation characteristics of PCNN, effectively combining the features of IR image with the texture details of VI image. Experimental results show that the algorithm can combine IR and VI image features well. At the same time, the obtained fusion image can better display the texture information of image. The fusion performance in contrast, detail information and other aspects is better than the classical fusion algorithm, which has better visual effect and evaluation index.


Assuntos
Algoritmos , Inteligência Artificial , Processamento de Imagem Assistida por Computador , Redes Neurais de Computação , Animais , Gatos , Humanos , Raios Infravermelhos , Rede Nervosa/fisiologia , Córtex Visual/fisiologia
8.
Nat Commun ; 11(1): 3925, 2020 08 06.
Artigo em Inglês | MEDLINE | ID: mdl-32764538

RESUMO

Adaptation is a ubiquitous property of sensory systems. It is typically considered that neurons adapt to dominant energy in the ambient environment to function optimally. However, perceptual representation of the stimulus, often modulated by feedback signals, sometimes do not correspond to the input state of the stimulus, which tends to be more linked with feedforward signals. Here we investigated the relative contributions to cortical adaptation from feedforward and feedback signals, taking advantage of a visual illusion, the Flash-Grab Effect, to disassociate the feedforward and feedback representation of an adaptor. Results reveal that orientation adaptation is exclusively dependent on the perceived rather than the retinal orientation of the adaptor. Combined fMRI and EEG measurements demonstrate that the perceived orientation of the Flash-Grab Effect is indeed supported by feedback signals in the cortex. These findings highlight the important contribution of feedback signals for cortical neurons to recalibrate their sensitivity.


Assuntos
Adaptação Fisiológica , Ilusões/fisiologia , Orientação Espacial/fisiologia , Adulto , Eletroencefalografia , Potenciais Evocados Visuais , Retroalimentação Fisiológica , Feminino , Neuroimagem Funcional , Humanos , Imagem por Ressonância Magnética , Masculino , Ilusões Ópticas/fisiologia , Estimulação Luminosa , Psicofísica , Retina/fisiologia , Córtex Visual/fisiologia , Percepção Visual/fisiologia , Adulto Jovem
9.
Nat Commun ; 11(1): 4014, 2020 08 11.
Artigo em Inglês | MEDLINE | ID: mdl-32782303

RESUMO

Perception reflects not only sensory inputs, but also the endogenous state when these inputs enter the brain. Prior studies show that endogenous neural states influence stimulus processing through non-specific, global mechanisms, such as spontaneous fluctuations of arousal. It is unclear if endogenous activity influences circuit and stimulus-specific processing and behavior as well. Here we use intracranial recordings from 30 pre-surgical epilepsy patients to show that patterns of endogenous activity are related to the strength of trial-by-trial neural tuning in different visual category-selective neural circuits. The same aspects of the endogenous activity that relate to tuning in a particular neural circuit also correlate to behavioral reaction times only for stimuli from the category that circuit is selective for. These results suggest that endogenous activity can modulate neural tuning and influence behavior in a circuit- and stimulus-specific manner, reflecting a potential mechanism by which endogenous neural states facilitate and bias perception.


Assuntos
Rede Nervosa/fisiologia , Córtex Visual/fisiologia , Percepção Visual/fisiologia , Adulto , Eletrocorticografia , Epilepsia/fisiopatologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Modelos Neurológicos , Reconhecimento Visual de Modelos/fisiologia , Estimulação Luminosa , Tempo de Reação/fisiologia
10.
Proc Natl Acad Sci U S A ; 117(36): 22494-22505, 2020 09 08.
Artigo em Inglês | MEDLINE | ID: mdl-32843341

RESUMO

The normalization model has been applied to explain neural activity in diverse neural systems including primary visual cortex (V1). The model's defining characteristic is that the response of each neuron is divided by a factor that includes a weighted sum of activity of a pool of neurons. Despite the success of the normalization model, there are three unresolved issues. 1) Experimental evidence supports the hypothesis that normalization in V1 operates via recurrent amplification, i.e., amplifying weak inputs more than strong inputs. It is unknown how normalization arises from recurrent amplification. 2) Experiments have demonstrated that normalization is weighted such that each weight specifies how one neuron contributes to another's normalization pool. It is unknown how weighted normalization arises from a recurrent circuit. 3) Neural activity in V1 exhibits complex dynamics, including gamma oscillations, linked to normalization. It is unknown how these dynamics emerge from normalization. Here, a family of recurrent circuit models is reported, each of which comprises coupled neural integrators to implement normalization via recurrent amplification with arbitrary normalization weights, some of which can recapitulate key experimental observations of the dynamics of neural activity in V1.


Assuntos
Modelos Neurológicos , Redes Neurais de Computação , Neurônios/fisiologia , Córtex Visual/fisiologia , Animais , Biologia Computacional , Neurônios/citologia , Córtex Visual/citologia
11.
Proc Natl Acad Sci U S A ; 117(31): 18799-18809, 2020 08 04.
Artigo em Inglês | MEDLINE | ID: mdl-32680968

RESUMO

We try to deploy the retinal fovea to optimally scrutinize an object of interest by directing our eyes to it. The horizontal and vertical components of eye positions acquired by goal-directed saccades are determined by the object's location. However, the eccentric eye positions also involve a torsional component, which according to Donder's law is fully determined by the two-dimensional (2D) eye position acquired. According to von Helmholtz, knowledge of the amount of torsion provided by Listing's law, an extension of Donder's law, alleviates the perceptual interpretation of the image tilt that changes with 2D eye position, a view supported by psychophysical experiments he pioneered. We address the question of where and how Listing's law is implemented in the visual system and we show that neurons in monkey area V1 use knowledge of eye torsion to compensate the image tilt associated with specific eye positions as set by Listing's law.


Assuntos
Movimentos Oculares/fisiologia , Neurônios/fisiologia , Córtex Visual , Animais , Macaca mulatta , Masculino , Estimulação Luminosa , Córtex Visual/citologia , Córtex Visual/fisiologia
12.
Nat Commun ; 11(1): 3565, 2020 07 16.
Artigo em Inglês | MEDLINE | ID: mdl-32678087

RESUMO

Perception of visual motion is important for a range of ethological behaviors in mammals. In primates, specific visual cortical regions are specialized for processing of coherent visual motion. However, whether mouse visual cortex has a similar organization remains unclear, despite powerful genetic tools available for measuring population neural activity. Here, we use widefield and 2-photon calcium imaging of transgenic mice to measure mesoscale and cellular responses to coherent motion. Imaging of primary visual cortex (V1) and higher visual areas (HVAs) during presentation of natural movies and random dot kinematograms (RDKs) reveals varied responsiveness to coherent motion, with stronger responses in dorsal stream areas compared to ventral stream areas. Moreover, there is considerable anisotropy within visual areas, such that neurons representing the lower visual field are more responsive to coherent motion. These results indicate that processing of visual motion in mouse cortex is distributed heterogeneously both across and within visual areas.


Assuntos
Percepção de Movimento/fisiologia , Córtex Visual/fisiologia , Animais , Mapeamento Encefálico , Feminino , Masculino , Camundongos , Camundongos Transgênicos , Neurônios/citologia , Neurônios/fisiologia , Estimulação Luminosa , Córtex Visual/citologia , Campos Visuais/fisiologia
13.
PLoS Comput Biol ; 16(7): e1008022, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32706770

RESUMO

Feed-forward deep convolutional neural networks (DCNNs) are, under specific conditions, matching and even surpassing human performance in object recognition in natural scenes. This performance suggests that the analysis of a loose collection of image features could support the recognition of natural object categories, without dedicated systems to solve specific visual subtasks. Research in humans however suggests that while feedforward activity may suffice for sparse scenes with isolated objects, additional visual operations ('routines') that aid the recognition process (e.g. segmentation or grouping) are needed for more complex scenes. Linking human visual processing to performance of DCNNs with increasing depth, we here explored if, how, and when object information is differentiated from the backgrounds they appear on. To this end, we controlled the information in both objects and backgrounds, as well as the relationship between them by adding noise, manipulating background congruence and systematically occluding parts of the image. Results indicate that with an increase in network depth, there is an increase in the distinction between object- and background information. For more shallow networks, results indicated a benefit of training on segmented objects. Overall, these results indicate that, de facto, scene segmentation can be performed by a network of sufficient depth. We conclude that the human brain could perform scene segmentation in the context of object identification without an explicit mechanism, by selecting or "binding" features that belong to the object and ignoring other features, in a manner similar to a very deep convolutional neural network.


Assuntos
Redes Neurais de Computação , Reconhecimento Visual de Modelos , Processamento de Sinais Assistido por Computador , Córtex Visual/fisiologia , Percepção Visual , Adolescente , Adulto , Encéfalo , Feminino , Humanos , Masculino , Reconhecimento Psicológico , Reprodutibilidade dos Testes , Adulto Jovem
14.
PLoS One ; 15(7): e0235309, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32614860

RESUMO

Recent researches revealed that the EEG component caused by the flickering visual stimulus, which is called steady-state visually evoked potential (SSVEP), might be a potential index for object recognition. This study examined whether SSVEP reflects different states during object recognition. In one trial, a binary image (BI), which is difficult to recognize, was followed by a grayscale image (GI) of the same object as the answer. Both BI and GI were presented in a flickering manner at a frequency of 7.5 Hz. Participants were first asked to answer whether they could recognize BI. Then, after GI was shown, participants were requested to answer whether they recognized it. We analyzed the evoked and induced component of SSVEPs from the two recognition conditions. As a result, the SSVEPs to BI were significantly larger than that to GI. In addition, induced component to GI after the BI was unrecognized was smaller than after the BI was recognized. The present data provide evidence that SSVEPs reflect a transition of cognitive state to ambiguous figures is reflected.


Assuntos
Eletroencefalografia/métodos , Potenciais Evocados Visuais , Reconhecimento Visual de Modelos/fisiologia , Estimulação Luminosa/métodos , Córtex Visual/fisiologia , Adulto , Feminino , Humanos , Masculino , Adulto Jovem
15.
PLoS One ; 15(6): e0235128, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32589671

RESUMO

Segmentation of a natural scene into objects and background is a fundamental but challenging task for recognizing objects. Investigating intermediate-level visual cortical areas with a focus on local information is a crucial step towards understanding the formation of the cortical representations of figure and ground. We examined the activity of a population of macaque V4 neurons during the presentation of natural image patches and their respective variations. The natural image patches were optimized to exclude the influence of global context but included various characteristics of local stimulus. Around one fourth of the patch-responsive V4 neurons exhibited significant modulation of firing activity that was dependent on the positional relation between the figural region of the stimulus and the classical receptive field of the neuron. However, the individual neurons showed low consistency in figure-ground modulation across a variety of image patches (55-62%), indicating that individual neurons were capable of correctly signaling figure and ground only for a limited number of stimuli. We examined whether integration of the activity of multiple neurons enabled higher consistency across a variety of natural patches by training a support vector machine to classify figure and ground of the stimuli from the population firing activity. The integration of the activity of a few tens of neurons yielded discrimination accuracy much greater than that of single neurons (up to 85%), suggesting a crucial role of population coding for figure-ground discrimination in natural images.


Assuntos
Neurônios/fisiologia , Reconhecimento Visual de Modelos/fisiologia , Córtex Visual/fisiologia , Percepção Visual/fisiologia , Animais , Feminino , Macaca fuscata , Estimulação Luminosa/métodos
16.
Nature ; 582(7813): 545-549, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32499655

RESUMO

Animals sense the environment through pathways that link sensory organs to the brain. In the visual system, these feedforward pathways define the classical feedforward receptive field (ffRF), the area in space in which visual stimuli excite a neuron1. The visual system also uses visual context-the visual scene surrounding a stimulus-to predict the content of the stimulus2, and accordingly, neurons have been identified that are excited by stimuli outside their ffRF3-8. However, the mechanisms that generate excitation to stimuli outside the ffRF are unclear. Here we show that feedback projections onto excitatory neurons in the mouse primary visual cortex generate a second receptive field that is driven by stimuli outside the ffRF. The stimulation of this feedback receptive field (fbRF) elicits responses that are slower and are delayed in comparison with those resulting from the stimulation of the ffRF. These responses are preferentially reduced by anaesthesia and by silencing higher visual areas. Feedback inputs from higher visual areas have scattered receptive fields relative to their putative targets in the primary visual cortex, which enables the generation of the fbRF. Neurons with fbRFs are located in cortical layers that receive strong feedback projections and are absent in the main input layer, which is consistent with a laminar processing hierarchy. The observation that large, uniform stimuli-which cover both the fbRF and the ffRF-suppress these responses indicates that the fbRF and the ffRF are mutually antagonistic. Whereas somatostatin-expressing inhibitory neurons are driven by these large stimuli, inhibitory neurons that express parvalbumin and vasoactive intestinal peptide have mutually antagonistic fbRF and ffRF, similar to excitatory neurons. Feedback projections may therefore enable neurons to use context to estimate information that is missing from the ffRF and to report differences in stimulus features across visual space, regardless of whether excitation occurs inside or outside the ffRF. By complementing the ffRF, the fbRF that we identify here could contribute to predictive processing.


Assuntos
Retroalimentação Fisiológica , Neurônios/fisiologia , Estimulação Luminosa , Córtex Visual/citologia , Córtex Visual/fisiologia , Vias Visuais , Animais , Feminino , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Modelos Neurológicos , Fatores de Tempo
17.
Nat Commun ; 11(1): 2784, 2020 06 03.
Artigo em Inglês | MEDLINE | ID: mdl-32493971

RESUMO

The orbitofrontal cortex (OFC) encodes expected outcomes and plays a critical role in flexible, outcome-guided behavior. The OFC projects to primary visual cortex (V1), yet the function of this top-down projection is unclear. We find that optogenetic activation of OFC projection to V1 reduces the amplitude of V1 visual responses via the recruitment of local somatostatin-expressing (SST) interneurons. Using mice performing a Go/No-Go visual task, we show that the OFC projection to V1 mediates the outcome-expectancy modulation of V1 responses to the reward-irrelevant No-Go stimulus. Furthermore, V1-projecting OFC neurons reduce firing during expectation of reward. In addition, chronic optogenetic inactivation of OFC projection to V1 impairs, whereas chronic activation of SST interneurons in V1 improves the learning of Go/No-Go visual task, without affecting the immediate performance. Thus, OFC top-down projection to V1 is crucial to drive visual associative learning by modulating the response gain of V1 neurons to non-relevant stimulus.


Assuntos
Aprendizagem/fisiologia , Córtex Pré-Frontal/fisiologia , Córtex Visual/fisiologia , Animais , Axônios/fisiologia , Axônios/efeitos da radiação , Comportamento Animal , Potenciais Pós-Sinápticos Excitadores/efeitos da radiação , Potenciais Pós-Sinápticos Inibidores/efeitos da radiação , Lasers , Luz , Camundongos Endogâmicos C57BL , Estimulação Luminosa , Córtex Pré-Frontal/efeitos da radiação , Recompensa , Análise e Desempenho de Tarefas , Córtex Visual/efeitos da radiação
18.
Proc Natl Acad Sci U S A ; 117(25): 14453-14463, 2020 06 23.
Artigo em Inglês | MEDLINE | ID: mdl-32513717

RESUMO

Deep regions of the brain are not easily accessible to investigation at the mesoscale level in awake animals or humans. We have recently developed a functional ultrasound (fUS) technique that enables imaging hemodynamic responses to visual tasks. Using fUS imaging on two awake nonhuman primates performing a passive fixation task, we constructed retinotopic maps at depth in the visual cortex (V1, V2, and V3) in the calcarine and lunate sulci. The maps could be acquired in a single-hour session with relatively few presentations of the stimuli. The spatial resolution of the technology is illustrated by mapping patterns similar to ocular dominance (OD) columns within superficial and deep layers of the primary visual cortex. These acquisitions using fUS suggested that OD selectivity is mostly present in layer IV but with extensions into layers II/III and V. This imaging technology provides a new mesoscale approach to the mapping of brain activity at high spatiotemporal resolution in awake subjects within the whole depth of the cortex.


Assuntos
Mapeamento Encefálico/métodos , Córtex Visual/fisiologia , Vigília/fisiologia , Animais , Dominância Ocular/fisiologia , Feminino , Macaca mulatta , Masculino , Estimulação Luminosa , Reprodutibilidade dos Testes , Análise Espaço-Temporal , Ultrassonografia/métodos , Córtex Visual/diagnóstico por imagem
19.
PLoS Biol ; 18(6): e3000729, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32511238

RESUMO

The potential ability of the human brain to represent an artificial limb as a body part (embodiment) has been inspiring engineers, clinicians, and scientists as a means to optimise human-machine interfaces. Using functional MRI (fMRI), we studied whether neural embodiment actually occurs in prosthesis users' occipitotemporal cortex (OTC). Compared with controls, different prostheses types were visually represented more similarly to each other, relative to hands and tools, indicating the emergence of a dissociated prosthesis categorisation. Greater daily life prosthesis usage correlated positively with greater prosthesis categorisation. Moreover, when comparing prosthesis users' representation of their own prosthesis to controls' representation of a similar looking prosthesis, prosthesis users represented their own prosthesis more dissimilarly to hands, challenging current views of visual prosthesis embodiment. Our results reveal a use-dependent neural correlate for wearable technology adoption, demonstrating adaptive use-related plasticity within the OTC. Because these neural correlates were independent of the prostheses' appearance and control, our findings offer new opportunities for prosthesis design by lifting restrictions imposed by the embodiment theory for artificial limbs.


Assuntos
Membros Artificiais , Encéfalo/fisiologia , Mãos/fisiologia , Adulto , Análise por Conglomerados , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estimulação Luminosa , Córtex Visual/fisiologia , Adulto Jovem
20.
Proc Natl Acad Sci U S A ; 117(27): 16055-16064, 2020 07 07.
Artigo em Inglês | MEDLINE | ID: mdl-32571942

RESUMO

Visual awareness is thought to result from integration of low- and high-level processing; instances of integration failure provide a crucial window into the cognitive and neural bases of awareness. We present neurophysiological evidence of complex cognitive processing in the absence of awareness, raising questions about the conditions necessary for visual awareness. We describe an individual with a neurodegenerative disease who exhibits impaired visual awareness for the digits 2 to 9, and stimuli presented in close proximity to these digits, due to perceptual distortion. We identified robust event-related potential responses indicating 1) face detection with the N170 component and 2) task-dependent target-word detection with the P3b component, despite no awareness of the presence of faces or target words. These data force us to reconsider the relationship between neural processing and visual awareness; even stimuli processed by a workspace-like cognitive system can remain inaccessible to awareness. We discuss how this finding challenges and constrains theories of visual awareness.


Assuntos
Cognição/fisiologia , Potenciais Evocados/fisiologia , Transtornos da Visão/metabolismo , Percepção Visual/fisiologia , Conscientização/fisiologia , Encéfalo/fisiologia , Eletroencefalografia , Potenciais Evocados Visuais/fisiologia , Face , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Doenças Neurodegenerativas , Estimulação Luminosa , Córtex Visual/fisiologia
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