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1.
Neural Netw ; 121: 339-355, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31593840

RESUMO

Previous research has shown that performance of a novice skill can be easily interfered with by subsequent training of another skill. We address the open questions whether extensively trained skills show the same vulnerability to interference as novice skills and which memory mechanism regulates interference between expert skills. We developed a recurrent neural network model of V1 able to learn from feedback experienced over the course of a long-term orientation discrimination experiment. After first exposing the model to one discrimination task for 3480 consecutive trials, we assessed how its performance was affected by subsequent training in a second, similar task. Training the second task strongly interfered with the first (highly trained) discrimination skill. The magnitude of interference depended on the relative amounts of training devoted to the different tasks. We used these and other model outcomes as predictions for a perceptual learning experiment in which human participants underwent the same training protocol as our model. Specifically, over the course of three months participants underwent baseline training in one orientation discrimination task for 15 sessions before being trained for 15 sessions on a similar task and finally undergoing another 15 sessions of training on the first task (to assess interference). Across all conditions, the pattern of interference observed empirically closely matched model predictions. According to our model, behavioral interference can be explained by antagonistic changes in neuronal tuning induced by the two tasks. Remarkably, this did not stem from erasing connections due to earlier learning but rather from a reweighting of lateral inhibition.


Assuntos
Memória/fisiologia , Orientação/fisiologia , Estimulação Luminosa/métodos , Córtex Visual/fisiologia , Percepção Visual/fisiologia , Adulto , Feminino , Humanos , Masculino , Neurônios/fisiologia , Adulto Jovem
2.
Brain Nerve ; 71(12): 1341-1347, 2019 Dec.
Artigo em Japonês | MEDLINE | ID: mdl-31787623

RESUMO

My study has been a chain of successes and failures, including those of cerebellar efferent system and laminar dependency of visual cortical circuitry and plasticity. It could have never been in existence but for Professor Masao Ito.


Assuntos
Cerebelo/fisiologia , Cérebro/fisiologia , Plasticidade Neuronal , Córtex Visual/fisiologia , Humanos
3.
Nat Commun ; 10(1): 5684, 2019 12 12.
Artigo em Inglês | MEDLINE | ID: mdl-31831751

RESUMO

We experience the world through multiple senses simultaneously. To better understand mechanisms of multisensory processing we ask whether inputs from two senses (auditory and visual) can interact and drive plasticity in neural-circuits of the primary visual cortex (V1). Using genetically-encoded voltage and calcium indicators, we find coincident audio-visual experience modifies both the supra and subthreshold response properties of neurons in L2/3 of mouse V1. Specifically, we find that after audio-visual pairing, a subset of multimodal neurons develops enhanced auditory responses to the paired auditory stimulus. This cross-modal plasticity persists over days and is reflected in the strengthening of small functional networks of L2/3 neurons. We find V1 processes coincident auditory and visual events by strengthening functional associations between feature specific assemblies of multimodal neurons during bouts of sensory driven co-activity, leaving a trace of multisensory experience in the cortical network.


Assuntos
Córtex Auditivo/fisiologia , Percepção Auditiva/fisiologia , Rede Nervosa/fisiologia , Córtex Visual/fisiologia , Percepção Visual/fisiologia , Estimulação Acústica , Animais , Camundongos , Modelos Animais , Modelos Biológicos , Plasticidade Neuronal , Neurônios/fisiologia , Estimulação Luminosa , Privação Sensorial/fisiologia
4.
PLoS Comput Biol ; 15(11): e1007418, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31682598

RESUMO

A recent hemodynamic model is extended and applied to simulate and explore the feasibility of detecting ocular dominance (OD) and orientation preference (OP) columns in primary visual cortex by means of functional magnetic resonance imaging (fMRI). The stimulation entails a short oriented bar stimulus being presented to one eye and mapped to cortical neurons with corresponding OD and OP selectivity. Activated neurons project via patchy connectivity to excite other neurons with similar OP in nearby visual fields located preferentially along the direction of stimulus orientation. The resulting blood oxygen level dependent (BOLD) response is estimated numerically via the model's spatiotemporal hemodynamic response function. The results are then used to explore the feasibility of detecting spatial OD-OP modulation, either directly measuring BOLD or by using Wiener deconvolution to filter the image and estimate the underlying neural activity. The effect of noise is also considered and it is estimated that direct detection can be robust for fMRI resolution of around 0.5 mm, whereas detection with Wiener deconvolution is possible at a broader range from 0.125 mm to 1 mm resolution. The detection of OD-OP features is strongly dependent on hemodynamic parameters, such as low velocity and high damping reduce response spreads and result in less blurring. The short-bar stimulus that gives the most detectable response is found to occur when neural projections are at 45 relative to the edge of local OD boundaries, which provides a constraint on the OD-OP architecture even when it is not fully resolved.


Assuntos
Dominância Ocular/fisiologia , Orientação Espacial/fisiologia , Córtex Visual/fisiologia , Encéfalo/fisiologia , Mapeamento Encefálico/métodos , Estudos de Viabilidade , Hemodinâmica/fisiologia , Humanos , Imagem por Ressonância Magnética/métodos , Modelos Teóricos , Neurônios/fisiologia , Estimulação Luminosa , Percepção Visual/fisiologia
5.
PLoS Comput Biol ; 15(11): e1007397, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31725723

RESUMO

Many everyday interactions with moving objects benefit from an accurate perception of their movement. Self-motion, however, complicates object motion perception because it generates a global pattern of motion on the observer's retina and radically influences an object's retinal motion. There is strong evidence that the brain compensates by suppressing the retinal motion due to self-motion, however, this requires estimates of depth relative to the object-otherwise the appropriate self-motion component to remove cannot be determined. The underlying neural mechanisms are unknown, but neurons in brain areas MT and MST may contribute given their sensitivity to motion parallax and depth through joint direction, speed, and disparity tuning. We developed a neural model to investigate whether cells in areas MT and MST with well-established neurophysiological properties can account for human object motion judgments during self-motion. We tested the model by comparing simulated object motion signals to human object motion judgments in environments with monocular, binocular, and ambiguous depth. Our simulations show how precise depth information, such as that from binocular disparity, may improve estimates of the retinal motion pattern due the self-motion through increased selectivity among units that respond to the global self-motion pattern. The enhanced self-motion estimates emerged from recurrent feedback connections in MST and allowed the model to better suppress the appropriate direction, speed, and disparity signals from the object's retinal motion, improving the accuracy of the object's movement direction represented by motion signals.


Assuntos
Percepção de Profundidade/fisiologia , Percepção de Movimento/fisiologia , Percepção Visual/fisiologia , Simulação por Computador , Sinais (Psicologia) , Humanos , Modelos Neurológicos , Modelos Teóricos , Movimento (Física) , Movimento/fisiologia , Neurônios/fisiologia , Retina , Disparidade Visual , Visão Binocular/fisiologia , Córtex Visual/fisiologia
6.
PLoS Comput Biol ; 15(11): e1007484, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31747389

RESUMO

Visual neurons respond to static images with specific dynamics: neuronal responses sum sub-additively over time, reduce in amplitude with repeated or sustained stimuli (neuronal adaptation), and are slower at low stimulus contrast. Here, we propose a simple model that predicts these seemingly disparate response patterns observed in a diverse set of measurements-intracranial electrodes in patients, fMRI, and macaque single unit spiking. The model takes a time-varying contrast time course of a stimulus as input, and produces predicted neuronal dynamics as output. Model computation consists of linear filtering, expansive exponentiation, and a divisive gain control. The gain control signal relates to but is slower than the linear signal, and this delay is critical in giving rise to predictions matched to the observed dynamics. Our model is simpler than previously proposed related models, and fitting the model to intracranial EEG data uncovers two regularities across human visual field maps: estimated linear filters (temporal receptive fields) systematically differ across and within visual field maps, and later areas exhibit more rapid and substantial gain control. The model is further generalizable to account for dynamics of contrast-dependent spike rates in macaque V1, and amplitudes of fMRI BOLD in human V1.


Assuntos
Biologia Computacional/métodos , Percepção Visual/fisiologia , Potenciais de Ação/fisiologia , Adaptação Fisiológica/fisiologia , Adulto , Animais , Encéfalo/fisiologia , Feminino , Previsões/métodos , Humanos , Imagem por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Modelos Neurológicos , Modelos Teóricos , Percepção de Movimento/fisiologia , Neurônios/fisiologia , Estimulação Luminosa/métodos , Córtex Visual/fisiologia , Vias Visuais/fisiologia
7.
Nat Neurosci ; 22(12): 2060-2065, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31686023

RESUMO

Finding sensory stimuli that drive neurons optimally is central to understanding information processing in the brain. However, optimizing sensory input is difficult due to the predominantly nonlinear nature of sensory processing and high dimensionality of the input. We developed 'inception loops', a closed-loop experimental paradigm combining in vivo recordings from thousands of neurons with in silico nonlinear response modeling. Our end-to-end trained, deep-learning-based model predicted thousands of neuronal responses to arbitrary, new natural input with high accuracy and was used to synthesize optimal stimuli-most exciting inputs (MEIs). For mouse primary visual cortex (V1), MEIs exhibited complex spatial features that occurred frequently in natural scenes but deviated strikingly from the common notion that Gabor-like stimuli are optimal for V1. When presented back to the same neurons in vivo, MEIs drove responses significantly better than control stimuli. Inception loops represent a widely applicable technique for dissecting the neural mechanisms of sensation.


Assuntos
Modelos Neurológicos , Neurônios/fisiologia , Córtex Visual/fisiologia , Animais , Simulação por Computador , Movimentos Oculares/fisiologia , Feminino , Masculino , Camundongos , Camundongos Transgênicos , Dinâmica não Linear , Estimulação Luminosa/métodos , Percepção Visual/fisiologia
8.
Nat Neurosci ; 22(11): 1782-1792, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31636451

RESUMO

Microglia are the brain's resident innate immune cells and also have a role in synaptic plasticity. Microglial processes continuously survey the brain parenchyma, interact with synaptic elements and maintain tissue homeostasis. However, the mechanisms that control surveillance and its role in synaptic plasticity are poorly understood. Microglial dynamics in vivo have been primarily studied in anesthetized animals. Here we report that microglial surveillance and injury response are reduced in awake mice as compared to anesthetized mice, suggesting that arousal state modulates microglial function. Pharmacologic stimulation of ß2-adrenergic receptors recapitulated these observations and disrupted experience-dependent plasticity, and these effects required the presence of ß2-adrenergic receptors in microglia. These results indicate that microglial roles in surveillance and synaptic plasticity in the mouse brain are modulated by noradrenergic tone fluctuations between arousal states and emphasize the need to understand the effect of disruptions of adrenergic signaling in neurodevelopment and neuropathology.


Assuntos
Microglia/fisiologia , Plasticidade Neuronal/fisiologia , Norepinefrina/fisiologia , Córtex Visual/fisiologia , Animais , Benzilaminas/farmacologia , Receptor 1 de Quimiocina CX3C/genética , Movimento Celular/efeitos dos fármacos , Movimento Celular/fisiologia , Ritmo Circadiano/fisiologia , Clembuterol/farmacologia , Dexmedetomidina/farmacologia , Dominância Ocular , Feminino , Fentanila/farmacologia , Locus Cerúleo/efeitos dos fármacos , Masculino , Camundongos , Camundongos Transgênicos , Microglia/citologia , Microglia/efeitos dos fármacos , Nadolol/farmacologia , Plasticidade Neuronal/efeitos dos fármacos , Neurônios/metabolismo , Neurônios/fisiologia , Norepinefrina/metabolismo , Propanolaminas/farmacologia , Restrição Física/fisiologia , Terbutalina/farmacologia , Vigília , Ferimentos e Lesões/fisiopatologia
9.
Nat Commun ; 10(1): 4915, 2019 10 29.
Artigo em Inglês | MEDLINE | ID: mdl-31664052

RESUMO

Cortical populations produce complex spatiotemporal activity spontaneously without sensory inputs. However, the fundamental computational roles of such spontaneous activity remain unclear. Here, we propose a new neural computation mechanism for understanding how spontaneous activity is actively involved in cortical processing: Computing by Modulating Spontaneous Activity (CMSA). Using biophysically plausible circuit models, we demonstrate that spontaneous activity patterns with dynamical properties, as found in empirical observations, are modulated or redistributed by external stimuli to give rise to neural responses. We find that this CMSA mechanism of generating neural responses provides profound computational advantages, such as actively speeding up cortical processing. We further reveal that the CMSA mechanism provides a unifying explanation for many experimental findings at both the single-neuron and circuit levels, and that CMSA in response to natural stimuli such as face images is the underlying neurophysiological mechanism of perceptual "bubbles" as found in psychophysical studies.


Assuntos
Modelos Neurológicos , Neurônios/química , Animais , Humanos , Camundongos , Plasticidade Neuronal , Neurônios/citologia , Córtex Visual/química , Córtex Visual/citologia , Córtex Visual/fisiologia , Percepção Visual
10.
Nat Commun ; 10(1): 4879, 2019 10 25.
Artigo em Inglês | MEDLINE | ID: mdl-31653855

RESUMO

The normalization model provides an elegant account of contextual modulation in individual neurons of primary visual cortex. Understanding the implications of normalization at the population level is hindered by the heterogeneity of cortical neurons, which differ in the composition of their normalization pools and semi-saturation constants. Here we introduce a geometric approach to investigate contextual modulation in neural populations and study how the representation of stimulus orientation is transformed by the presence of a mask. We find that population responses can be embedded in a low-dimensional space and that an affine transform can account for the effects of masking. The geometric analysis further reveals a link between changes in discriminability and bias induced by the mask. We propose the geometric approach can yield new insights into the image processing computations taking place in early visual cortex at the population level while coping with the heterogeneity of single cell behavior.


Assuntos
Neurônios/fisiologia , Mascaramento Perceptivo/fisiologia , Córtex Visual/fisiologia , Animais , Camundongos , Imagem Óptica , Estimulação Luminosa/métodos , Córtex Visual/citologia , Córtex Visual/diagnóstico por imagem
11.
PLoS Biol ; 17(10): e3000487, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31581198

RESUMO

Predictive coding is a key mechanism to understand the computational processes underlying brain functioning: in a hierarchical network, higher levels predict the activity of lower levels, and the unexplained residuals (i.e., prediction errors) are passed back to higher layers. Because of its recursive nature, we wondered whether predictive coding could be related to brain oscillatory dynamics. First, we show that a simple 2-level predictive coding model of visual cortex, with physiological communication delays between levels, naturally gives rise to alpha-band rhythms, similar to experimental observations. Then, we demonstrate that a multilevel version of the same model can explain the occurrence of oscillatory traveling waves across levels, both forward (during visual stimulation) and backward (during rest). Remarkably, the predictions of our model are matched by the analysis of 2 independent electroencephalography (EEG) datasets, in which we observed oscillatory traveling waves in both directions.


Assuntos
Ritmo alfa/fisiologia , Modelos Neurológicos , Rede Nervosa/fisiologia , Córtex Visual/fisiologia , Adulto , Conjuntos de Dados como Assunto , Eletroencefalografia , Feminino , Humanos , Masculino , Estimulação Luminosa , Descanso/fisiologia
12.
PLoS Comput Biol ; 15(10): e1007370, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31581240

RESUMO

When probed with complex stimuli that extend beyond their classical receptive field, neurons in primary visual cortex display complex and non-linear response characteristics. Sparse coding models reproduce some of the observed contextual effects, but still fail to provide a satisfactory explanation in terms of realistic neural structures and cortical mechanisms, since the connection scheme they propose consists only of interactions among neurons with overlapping input fields. Here we propose an extended generative model for visual scenes that includes spatial dependencies among different features. We derive a neurophysiologically realistic inference scheme under the constraint that neurons have direct access only to local image information. The scheme can be interpreted as a network in primary visual cortex where two neural populations are organized in different layers within orientation hypercolumns that are connected by local, short-range and long-range recurrent interactions. When trained with natural images, the model predicts a connectivity structure linking neurons with similar orientation preferences matching the typical patterns found for long-ranging horizontal axons and feedback projections in visual cortex. Subjected to contextual stimuli typically used in empirical studies, our model replicates several hallmark effects of contextual processing and predicts characteristic differences for surround modulation between the two model populations. In summary, our model provides a novel framework for contextual processing in the visual system proposing a well-defined functional role for horizontal axons and feedback projections.


Assuntos
Modelos Neurológicos , Rede Nervosa/fisiologia , Percepção Visual/fisiologia , Potenciais de Ação/fisiologia , Animais , Axônios/fisiologia , Simulação por Computador , Humanos , Modelos Biológicos , Neurônios/fisiologia , Orientação/fisiologia , Estimulação Luminosa/métodos , Córtex Visual/fisiologia , Campos Visuais , Vias Visuais/fisiologia
13.
Acta Neurobiol Exp (Wars) ; 79(3): 225-231, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31587014

RESUMO

The present study used optical imaging to investigate the development of the optical signal within orientational columns in primary visual cortex of cats reared under conditions of rhythmic light stimulation. Results showed that, although inter-columnar spacing was unchanged, a 3-5-fold decrement in optical signal from orientation columns and a drastic decline in contrast sensitivity was observed in both areas 18 and 17. These data suggest the modification of cortical columnar functioning under artificially correlated synchronization of retinal input.


Assuntos
Orientação/fisiologia , Estimulação Luminosa , Córtex Visual/fisiologia , Percepção Visual/fisiologia , Animais , Mapeamento Encefálico , Gatos , Processamento de Imagem Assistida por Computador/métodos , Estimulação Luminosa/métodos
14.
Invest Ophthalmol Vis Sci ; 60(13): 4109-4119, 2019 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-31574139

RESUMO

Purpose: We measure neural responses associated with form and motion processing in children with anisometropia before and after treatment with spectacles and occlusion. Methods: In this prospective, case-control treatment study, 10 children with anisometropia and amblyopia and 16 age-matched visually normal children participated. Steady-state visual evoked potentials (VEP) were recorded from electrodes over the occipital cortex. The visual stimulus comprised a horizontal bar grating into which Vernier offsets were introduced and withdrawn periodically at 3.75 Hz. The VEP amplitude at 3.75 Hz (first harmonic [1F]) and 7.5 Hz (second harmonic [2F]) were recorded to index the sensitivity of form/position-sensitive versus motion/transient-sensitive neural populations, respectively. Response amplitude at 1F and 2F were recorded over a series of 10 logarithmically spaced offset sizes before and after treatment. Main outcome measures are VEP amplitude versus displacement functions, interocular response amplitude differences. Results: After relaxing into spectacles (minimally-treated state), form/position-sensitive responses in the dominant/less ametropic eye of the children with anisometropia were larger and responses in the more ametropic eye were smaller than those of controls. Motion-transient responses were equal to those of controls in the less ametropic eye, but were smaller than controls in the more ametropic eye. After treatment, responses did not differ from those of controls. Conclusions: Form and motion responses are differentially susceptible to neural deprivation via optical blur. Form responses are more plastic than motion responses in minimally-treated children with anisometropic amblyopia. Most treatment effects occurred above threshold range, suggesting some treatment effects are not detected clinically.


Assuntos
Ambliopia/fisiopatologia , Anisometropia/fisiopatologia , Óculos , Percepção de Forma/fisiologia , Percepção de Movimento/fisiologia , Ambliopia/reabilitação , Anisometropia/reabilitação , Estudos de Casos e Controles , Criança , Pré-Escolar , Potenciais Evocados Visuais , Feminino , Humanos , Masculino , Estudos Prospectivos , Acuidade Visual , Córtex Visual/fisiologia
15.
PLoS Biol ; 17(10): e3000511, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31603894

RESUMO

Cognitive processes are almost exclusively investigated under highly controlled settings during which voluntary body movements are suppressed. However, recent animal work suggests differences in sensory processing between movement states by showing drastically changed neural responses in early visual areas between locomotion and stillness. Does locomotion also modulate visual cortical activity in humans, and what are the perceptual consequences? Our study shows that walking increased the contrast-dependent influence of peripheral visual input on central visual input. This increase is prevalent in stimulus-locked electroencephalogram (EEG) responses (steady-state visual evoked potential [SSVEP]) alongside perceptual performance. Ongoing alpha oscillations (approximately 10 Hz) further positively correlated with the walking-induced changes of SSVEP amplitude, indicating the involvement of an altered inhibitory process during walking. The results predicted that walking leads to an increased processing of peripheral visual input. A second study indeed showed an increased contrast sensitivity for peripheral compared to central stimuli when subjects were walking. Our work shows complementary neurophysiological and behavioural evidence corroborating animal findings that walking leads to a change in early visual neuronal activity in humans. That neuronal modulation due to walking is indeed linked to specific perceptual changes extends the existing animal work.


Assuntos
Potenciais Evocados Visuais/fisiologia , Reconhecimento Visual de Modelos/fisiologia , Desempenho Psicomotor/fisiologia , Visão Ocular/fisiologia , Caminhada/fisiologia , Adulto , Ritmo alfa/fisiologia , Feminino , Humanos , Locomoção/fisiologia , Masculino , Estimulação Luminosa , Córtex Visual/fisiologia
16.
Nat Neurosci ; 22(11): 1857-1870, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31548723

RESUMO

Recent anatomical evidence suggests a functionally significant back-projection pathway from the subiculum to the CA1. Here we show that the afferent circuitry of CA1-projecting subicular neurons is biased by inputs from CA1 inhibitory neurons and the visual cortex, but lacks input from the entorhinal cortex. Efferents of the CA1-projecting subiculum neurons also target the perirhinal cortex, an area strongly implicated in object-place learning. We identify a critical role for CA1-projecting subicular neurons in object-location learning and memory, and show that this projection modulates place-specific activity of CA1 neurons and their responses to displaced objects. Together, these experiments reveal a novel pathway by which cortical inputs, particularly those from the visual cortex, reach the hippocampal output region CA1. Our findings also implicate this circuitry in the formation of complex spatial representations and learning of object-place associations.


Assuntos
Região CA1 Hipocampal/fisiologia , Córtex Entorrinal/fisiologia , Hipocampo/fisiologia , Aprendizagem/fisiologia , Córtex Perirrinal/fisiologia , Córtex Visual/fisiologia , Animais , Feminino , Masculino , Camundongos , Camundongos Transgênicos , Vias Neurais/fisiologia , Neurônios/fisiologia , Percepção Espacial/fisiologia
17.
Elife ; 82019 09 10.
Artigo em Inglês | MEDLINE | ID: mdl-31502537

RESUMO

An important computational goal of the visual system is 'representational untangling' (RU): representing increasingly complex features of visual scenes in an easily decodable format. RU is typically assumed to be achieved in high-level visual cortices via several stages of cortical processing. Here we show, using a canonical population coding model, that RU of low-level orientation information is already performed at the first cortical stage of visual processing, but not before that, by a fundamental cellular-level property: the thresholded firing rate nonlinearity of simple cells in the primary visual cortex (V1). We identified specific, experimentally measurable parameters that determined the optimal firing threshold for RU and found that the thresholds of V1 simple cells extracted from in vivo recordings in awake behaving mice were near optimal. These results suggest that information re-formatting, rather than maximisation, may already be a relevant computational goal for the early visual system.


Assuntos
Potenciais de Ação , Neurônios/fisiologia , Orientação Espacial , Córtex Visual/citologia , Córtex Visual/fisiologia , Percepção Visual , Animais , Camundongos , Modelos Neurológicos
18.
Nat Commun ; 10(1): 4106, 2019 09 11.
Artigo em Inglês | MEDLINE | ID: mdl-31511514

RESUMO

Conscious perception is crucial for adaptive behaviour yet access to consciousness varies for different types of objects. The visual system comprises regions with widely distributed category information and exemplar-level representations that cluster according to category. Does this categorical organisation in the brain provide insight into object-specific access to consciousness? We address this question using the Attentional Blink approach with visual objects as targets. We find large differences across categories in the attentional blink. We then employ activation patterns extracted from a deep convolutional neural network to reveal that these differences depend on mid- to high-level, rather than low-level, visual features. We further show that these visual features can be used to explain variance in performance across trials. Taken together, our results suggest that the specific organisation of the higher-tier visual system underlies important functions relevant for conscious perception of differing natural images.


Assuntos
Estado de Consciência/fisiologia , Imagem Tridimensional , Córtex Visual/fisiologia , Percepção Visual/fisiologia , Atenção/fisiologia , Piscadela , Feminino , Humanos , Masculino , Adulto Jovem
19.
PLoS Biol ; 17(9): e3000280, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31513563

RESUMO

The human lateral occipital complex (LOC) is more strongly activated by images of objects compared to scrambled controls, but detailed information at the neuronal level is currently lacking. We recorded with microelectrode arrays in the LOC of 2 patients and obtained highly selective single-unit, multi-unit, and high-gamma responses to images of objects. Contrary to predictions derived from functional imaging studies, all neuronal properties indicated that the posterior subsector of LOC we recorded from occupies an unexpectedly high position in the hierarchy of visual areas. Notably, the response latencies of LOC neurons were long, the shape selectivity was spatially clustered, LOC receptive fields (RFs) were large and bilateral, and a number of LOC neurons exhibited three-dimensional (3D)-structure selectivity (a preference for convex or concave stimuli), which are all properties typical of end-stage ventral stream areas. Thus, our results challenge prevailing ideas about the position of the more posterior subsector of LOC in the hierarchy of visual areas.


Assuntos
Córtex Visual/fisiologia , Percepção Visual/fisiologia , Mapeamento Encefálico , Humanos , Imagem por Ressonância Magnética
20.
Nat Commun ; 10(1): 3910, 2019 09 02.
Artigo em Inglês | MEDLINE | ID: mdl-31477706

RESUMO

Vision relies on both specific knowledge of visual attributes, such as object categories, and general brain states, such as those reflecting arousal. We hypothesized that these phenomena independently influence recognition of forthcoming stimuli through distinct processes reflected in spontaneous neural activity. Here, we recorded magnetoencephalographic (MEG) activity in participants (N = 24) who viewed images of objects presented at recognition threshold. Using multivariate analysis applied to sensor-level activity patterns recorded before stimulus presentation, we identified two neural processes influencing subsequent subjective recognition: a general process, which disregards stimulus category and correlates with pupil size, and a specific process, which facilitates category-specific recognition. The two processes are doubly-dissociable: the general process correlates with changes in criterion but not in sensitivity, whereas the specific process correlates with changes in sensitivity but not in criterion. Our findings reveal distinct mechanisms of how spontaneous neural activity influences perception and provide a framework to integrate previous findings.


Assuntos
Reconhecimento Visual de Modelos/fisiologia , Visão Ocular/fisiologia , Córtex Visual/fisiologia , Percepção Visual/fisiologia , Adulto , Algoritmos , Feminino , Humanos , Magnetoencefalografia , Masculino , Modelos Neurológicos , Estimulação Luminosa/métodos , Adulto Jovem
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