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1.
Neuroimage ; 228: 117688, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33385563

RESUMO

There is growing research interest in the neural mechanisms underlying the recognition of material categories and properties. This research field, however, is relatively more recent and limited compared to investigations of the neural mechanisms underlying object and scene category recognition. Motion is particularly important for the perception of non-rigid materials, but the neural basis of non-rigid material motion remains unexplored. Using fMRI, we investigated which brain regions respond preferentially to material motion versus other types of motion. We introduce a new database of stimuli - dynamic dot materials - that are animations of moving dots that induce vivid percepts of various materials in motion, e.g. flapping cloth, liquid waves, wobbling jelly. Control stimuli were scrambled versions of these same animations and rigid three-dimensional rotating dots. Results showed that isolating material motion properties with dynamic dots (in contrast with other kinds of motion) activates a network of cortical regions in both ventral and dorsal visual pathways, including areas normally associated with the processing of surface properties and shape, and extending to somatosensory and premotor cortices. We suggest that such a widespread preference for material motion is due to strong associations between stimulus properties. For example viewing dots moving in a specific pattern not only elicits percepts of material motion; one perceives a flexible, non-rigid shape, identifies the object as a cloth flapping in the wind, infers the object's weight under gravity, and anticipates how it would feel to reach out and touch the material. These results are a first important step in mapping out the cortical architecture and dynamics in material-related motion processing.


Assuntos
Encéfalo/fisiologia , Percepção de Movimento/fisiologia , Adulto , Mapeamento Encefálico/métodos , Feminino , Percepção de Forma/fisiologia , Humanos , Imagem por Ressonância Magnética/métodos , Masculino , Estimulação Luminosa , Adulto Jovem
2.
Nat Commun ; 12(1): 360, 2021 01 15.
Artigo em Inglês | MEDLINE | ID: mdl-33452252

RESUMO

Endogenous attention is the cognitive function that selects the relevant pieces of sensory information to achieve goals and it is known to be controlled by dorsal fronto-parietal brain areas. Here we expand this notion by identifying a control attention area located in the temporal lobe. By combining a demanding behavioral paradigm with functional neuroimaging and diffusion tractography, we show that like fronto-parietal attentional areas, the human posterior inferotemporal cortex exhibits significant attentional modulatory activity. This area is functionally distinct from surrounding cortical areas, and is directly connected to parietal and frontal attentional regions. These results show that attentional control spans three cortical lobes and overarches large distances through fiber pathways that run orthogonally to the dominant anterior-posterior axes of sensory processing, thus suggesting a different organizing principle for cognitive control.


Assuntos
Atenção/fisiologia , Lobo Frontal/fisiologia , Lobo Parietal/fisiologia , Lobo Temporal/fisiologia , Adulto , Mapeamento Encefálico , Imagem de Tensor de Difusão , Feminino , Lobo Frontal/diagnóstico por imagem , Voluntários Saudáveis , Humanos , Masculino , Percepção de Movimento/fisiologia , Vias Neurais/diagnóstico por imagem , Vias Neurais/fisiologia , Lobo Parietal/diagnóstico por imagem , Estimulação Luminosa/métodos , Lobo Temporal/diagnóstico por imagem , Adulto Jovem
3.
Phys Rev Lett ; 126(1): 018101, 2021 Jan 08.
Artigo em Inglês | MEDLINE | ID: mdl-33480762

RESUMO

Many organisms use visual signals to estimate motion, and these estimates typically are biased. Here, we ask whether these biases may reflect physical rather than biological limitations. Using a camera-gyroscope system, we sample the joint distribution of images and rotational motions in a natural environment, and from this distribution we construct the optimal estimator of velocity based on local image intensities. Over most of the natural dynamic range, this estimator exhibits the biases observed in neural and behavioral responses. Thus, imputed errors in sensory processing may represent an optimal response to the physical signals sampled from the environment.


Assuntos
Modelos Biológicos , Percepção de Movimento/fisiologia , Animais , Meio Ambiente , Fotografação
4.
Neural Netw ; 135: 13-28, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33338802

RESUMO

The biological visual system includes multiple types of motion sensitive neurons which preferentially respond to specific perceptual regions. However, it still keeps open how to borrow such neurons to construct bio-inspired computational models for multiple-regional collision detection. To fill this gap, this work proposes a visual joint perception neural network with two subnetworks - presynaptic and postsynaptic neural networks, inspired by the preferentialperception characteristics of three horizontal and vertical motion sensitive neurons. Related to the neural network and three hazard detection mechanisms, an artificial fly visual synthesized collision detection model for multiple-regional collision detection is originally developed to monitor possible danger occurrence in the case where one or more moving objects appear in the whole field of view. The experiments can clearly draw two conclusions: (i) the acquired neural network can effectively display the characteristics of visual movement, and (ii) the collision detection model, which outperforms the compared models, can effectively perform multiple-regional collision detection at a high success rate, and only takes about 0.24s to complete the process of collision detection for each virtual or actual image frame with resolution 110×60.


Assuntos
Inteligência Artificial , Percepção de Movimento/fisiologia , Movimento/fisiologia , Redes Neurais de Computação , Estimulação Luminosa/métodos , Vias Visuais/fisiologia , Animais , Inteligência Artificial/tendências , Dípteros , Humanos , Neurônios/fisiologia , Percepção Visual/fisiologia
5.
Rev. int. med. cienc. act. fis. deporte ; 19(80): 577-594, dic. 2020. tab
Artigo em Espanhol | IBECS | ID: ibc-198574

RESUMO

El objetivo del presente estudio fue analizar las diferencias en el número y tipo de acciones técnico-tácticas de los porteros en competición en función de la división y de si juegan como local o visitante. Para ello, se han analizado 80 partidos con un total de 160 porteros de 1ª, 2ª, 2ªB y 3ª división española. Los resultados mostraron que no existen diferencias significativas entre el número de acciones medias realizadas por partido en cada división, pero sí se encontraron diferencias significativas en 9 de los 48 gestos técnico-tácticos específicos estudiados. Además, se encontraron pequeñas diferencias en cuanto al número de acciones en función de si los porteros juegan como local o visitante. Por tanto, la principal conclusión de este estudio es la importancia de analizar los tipos de acciones técnico-tácticas de los porteros ya que nos pueden ofrecer información relevante para el entrenamiento y la competición


The present study tries to respond about three different objectives: a) to quantify the number of technical-tactical actions carried out by goalkeepers during matches and to analyze if there are differences between divisions, b) to examine the possible differences in the number and type of technical-tactical actions between divisions under investigation, and c) to analyze the differences between this number and the type of technical-tactical actions when goalkeepers play at home team or away teams . To this end, a viewing was made of the 80 matches of the four most important divisions of Spanish football and a total of 160 goalkeepers were analyzed using the observational methodology. After the application of the tests the H-test of Krustal-Wallis and U of Mann-Whitney, showed no significant differences between the number of average actions performed per game in each division. Only significant differences were found in 9 of the 48 specific technical-tactical gestures studied. So, the first conclusion in this study is the importance of analyzing the types of technical-tactical actions of goalkeepers, due to they can offer relevant information for training and competition


Assuntos
Humanos , Masculino , Adulto , Futebol/fisiologia , Futebol/psicologia , Percepção de Movimento/fisiologia , Desempenho Psicomotor/fisiologia , Tempo de Reação/fisiologia , Percepção Visual , Esportes/psicologia
6.
PLoS One ; 15(12): e0244110, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33332442

RESUMO

Recently, Flavell et al. (2019) demonstrated that an object's motion fluency (how smoothly and predictably it moves) influences liking of the object itself. Though the authors demonstrated learning of object-motion associations, participants only preferred fluently associated objects over disfluently associated objects when ratings followed a moving presentation but not a stationary presentation. In the presented experiment, we tested the possibility that this apparent failure of associative learning / evaluative conditioning was due to stimulus choice. To do so we replicate part of the original work but change the 'naturally stationary' household object stimuli with winged insects which move in a similar way to the original motions. Though these more ecologically valid stimuli should have facilitated object to motion associations, we again found that preference effects were only apparent following moving presentations. These results confirm the potential of motion fluency for 'in the moment' preference change, and they demonstrate a critical boundary condition that should be considered when attempting to generalise fluency effects across contexts such as in advertising or behavioural interventions.


Assuntos
Atenção/fisiologia , Comportamento de Escolha/fisiologia , Aprendizagem/fisiologia , Percepção de Movimento/fisiologia , Feminino , Humanos , Masculino
7.
PLoS One ; 15(12): e0243430, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33315877

RESUMO

A large number of psychophysical and neurophysiological studies have demonstrated that smooth pursuit eye movements are tightly related to visual motion perception. This could be due to the fact that visual motion sensitive cortical areas such as meddle temporal (MT), medial superior temporal (MST) areas are involved in motion perception as well as pursuit initiation. Although the directional-discrimination and perceived target velocity tasks are used to evaluate visual motion perception, it is still uncertain whether the speed of visual motion perception, which is determined by visuomotor reaction time (RT) to a small target, is related to pursuit initiation. Therefore, we attempted to determine the relationship between pursuit latency/acceleration and the visual motion RT which was measured to the visual motion stimuli that moved leftward or rightward. The participants were instructed to fixate on a stationary target and press one of the buttons corresponding to the direction of target motion as soon as possible once the target starts to move. We applied five different visual motion stimuli including first- and second-order motion for smooth pursuit and visual motion RT tasks. It is well known that second-order motion induces lower retinal image motion, which elicits weaker responses in MT and MST compared to first-order motion stimuli. Our results showed that pursuit initiation including latency and initial eye acceleration were suppressed by second-order motion. In addition, second-order motion caused a delay in visual motion RT. The better performances in both pursuit initiation and visual motion RT were observed for first-order motion, whereas second-order (theta motion) induced remarkable deficits in both variables. Furthermore, significant Pearson's correlation and within-subjects correlation coefficients were obtained between visual motion RT and pursuit latency/acceleration. Our findings support the suggestion that there is a common neuronal pathway involved in both pursuit initiation and the speed of visual motion perception.


Assuntos
Movimentos Oculares/fisiologia , Neurônios/fisiologia , Acompanhamento Ocular Uniforme/fisiologia , Córtex Visual/fisiologia , Adulto , Animais , Feminino , Humanos , Macaca mulatta/fisiologia , Masculino , Percepção de Movimento/fisiologia , Estimulação Luminosa , Desempenho Psicomotor/fisiologia , Tempo de Reação/fisiologia , Lobo Temporal/fisiologia , Percepção Visual/fisiologia , Adulto Jovem
8.
PLoS One ; 15(12): e0227462, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33382701

RESUMO

An age-old hypothesis proposes that object motion across the receptor surface organizes sensory maps (Lotze, 19th century). Skin patches learn their relative positions from the order in which they are stimulated during motion events. We propose that reversing the local motion within a global motion sequence ('motion scrambling') provides a good test for this idea, and present results of the first experiment implementing the paradigm. We used 6-point apparent motion along the forearm. In the Scrambled sequence, two middle locations were touched in reversed order (1-2-4-3-5-6, followed by 6-5-3-4-2-1, in a continuous loop). This created a double U-turn within an otherwise constant-velocity motion, as if skin patches 3 and 4 physically swapped locations. The control condition, Orderly, proceeded at constant velocity at inter-stimulus onset interval of 120 ms. The 26.4-minute conditioning (delivered in twenty-four 66-s bouts) was interspersed with testing of perceived motion direction between the two middle tactors presented on their own (sequence 3-4 or 4-3). Our twenty participants reported motion direction. Direction discrimination was degraded following exposure to Scrambled pattern and was 0.31 d' weaker than following Orderly conditioning (p = .007). Consistent with the proposed role of motion, this could be the beginning of re-learning of relative positions. An alternative explanation is that greater speed adaptation occurred in the Scrambled pattern, raising direction threshold. In future studies, longer conditioning should tease apart the two explanations: our re-mapping hypothesis predicts an overall reversal in perceived motion direction between critical locations (for either motion direction), whereas the speed adaptation alternative predicts chance-level performance at worst, without reversing.


Assuntos
Adaptação Fisiológica , Condicionamento Psicológico , Percepção de Movimento/fisiologia , Percepção do Tato/fisiologia , Tato/fisiologia , Adolescente , Adulto , Fenômenos Biomecânicos/fisiologia , Feminino , Antebraço/inervação , Antebraço/fisiologia , Humanos , Masculino , Movimento (Física) , Psicofísica/métodos , Pele/inervação , Fenômenos Fisiológicos da Pele
9.
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
10.
PLoS One ; 15(8): e0238125, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32822439

RESUMO

The majority of psychoacoustic research investigating sound localization has utilized stationary sources, yet most naturally occurring sounds are in motion, either because the sound source itself moves, or the listener does. In normal hearing (NH) listeners, previous research showed the extent to which sound duration and velocity impact the ability of listeners to detect sound movement. By contrast, little is known about how listeners with hearing impairments perceive moving sounds; the only study to date comparing the performance of NH and bilateral cochlear implant (BiCI) listeners has demonstrated significantly poorer performance on motion detection tasks in BiCI listeners. Cochlear implants, auditory protheses offered to profoundly deaf individuals for access to spoken language, retain the signal envelope (ENV), while discarding temporal fine structure (TFS) of the original acoustic input. As a result, BiCI users do not have access to low-frequency TFS cues, which have previously been shown to be crucial for sound localization in NH listeners. Instead, BiCI listeners seem to rely on ENV cues for sound localization, especially level cues. Given that NH and BiCI listeners differentially utilize ENV and TFS information, the present study aimed to investigate the usefulness of these cues for auditory motion perception. We created acoustic chimaera stimuli, which allowed us to test the relative contributions of ENV and TFS to auditory motion perception. Stimuli were either moving or stationary, presented to NH listeners in free field. The task was to track the perceived sound location. We found that removing low-frequency TFS reduces sensitivity to sound motion, and fluctuating speech envelopes strongly biased the judgment of sounds to be stationary. Our findings yield a possible explanation as to why BiCI users struggle to identify sound motion, and provide a first account of cues important to the functional aspect of auditory motion perception.


Assuntos
Percepção Auditiva/fisiologia , Percepção de Movimento/fisiologia , Localização de Som/fisiologia , Estimulação Acústica/métodos , Adulto , Limiar Auditivo/fisiologia , Implante Coclear/reabilitação , Implantes Cocleares , Sinais (Psicologia) , Feminino , Audição , Perda Auditiva/fisiopatologia , Testes Auditivos , Humanos , Masculino , Movimento (Física) , Pessoas com Deficiência Auditiva/reabilitação , Psicoacústica , Som , Percepção da Fala/fisiologia
11.
PLoS One ; 15(8): e0236800, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32776962

RESUMO

Deafness leads to brain modifications that are generally associated with a cross-modal activity of the auditory cortex, particularly for visual stimulations. In the present study, we explore the cortical processing of biological motion that conveyed either non-communicative (pantomimes) or communicative (emblems) information, in early-deaf and hearing individuals, using fMRI analyses. Behaviorally, deaf individuals showed an advantage in detecting communicative gestures relative to hearing individuals. Deaf individuals also showed significantly greater activation in the superior temporal cortex (including the planum temporale and primary auditory cortex) than hearing individuals. The activation levels in this region were correlated with deaf individuals' response times. This study provides neural and behavioral evidence that cross-modal plasticity leads to functional advantages in the processing of biological motion following lifelong auditory deprivation.


Assuntos
Comportamento , Surdez/fisiopatologia , Percepção de Movimento/fisiologia , Adulto , Córtex Auditivo/diagnóstico por imagem , Mapeamento Encefálico , Feminino , Gestos , Humanos , Imagem por Ressonância Magnética , Masculino , Estimulação Luminosa , Lobo Temporal/diagnóstico por imagem , Adulto Jovem
12.
Nat Commun ; 11(1): 3857, 2020 07 31.
Artigo em Inglês | MEDLINE | ID: mdl-32737317

RESUMO

It is becoming widely appreciated that human perceptual decision making is suboptimal but the nature and origins of this suboptimality remain poorly understood. Most past research has employed tasks with two stimulus categories, but such designs cannot fully capture the limitations inherent in naturalistic perceptual decisions where choices are rarely between only two alternatives. We conduct four experiments with tasks involving multiple alternatives and use computational modeling to determine the decision-level representation on which the perceptual decisions are based. The results from all four experiments point to the existence of robust suboptimality such that most of the information in the sensory representation is lost during the transformation to a decision-level representation. These results reveal severe limits in the quality of decision-level representations for multiple alternatives and have strong implications about perceptual decision making in naturalistic settings.


Assuntos
Comportamento de Escolha/fisiologia , Tomada de Decisões/fisiologia , Modelos Psicológicos , Adolescente , Adulto , Percepção de Cores/fisiologia , Feminino , Humanos , Masculino , Percepção de Movimento/fisiologia , Reconhecimento Visual de Modelos/fisiologia , Estimulação Luminosa
13.
Proc Natl Acad Sci U S A ; 117(37): 23044-23053, 2020 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-32839324

RESUMO

Visual motion detection is one of the most important computations performed by visual circuits. Yet, we perceive vivid illusory motion in stationary, periodic luminance gradients that contain no true motion. This illusion is shared by diverse vertebrate species, but theories proposed to explain this illusion have remained difficult to test. Here, we demonstrate that in the fruit fly Drosophila, the illusory motion percept is generated by unbalanced contributions of direction-selective neurons' responses to stationary edges. First, we found that flies, like humans, perceive sustained motion in the stationary gradients. The percept was abolished when the elementary motion detector neurons T4 and T5 were silenced. In vivo calcium imaging revealed that T4 and T5 neurons encode the location and polarity of stationary edges. Furthermore, our proposed mechanistic model allowed us to predictably manipulate both the magnitude and direction of the fly's illusory percept by selectively silencing either T4 or T5 neurons. Interestingly, human brains possess the same mechanistic ingredients that drive our model in flies. When we adapted human observers to moving light edges or dark edges, we could manipulate the magnitude and direction of their percepts as well, suggesting that mechanisms similar to the fly's may also underlie this illusion in humans. By taking a comparative approach that exploits Drosophila neurogenetics, our results provide a causal, mechanistic account for a long-known visual illusion. These results argue that this illusion arises from architectures for motion detection that are shared across phyla.


Assuntos
Drosophila/fisiologia , Ilusões/fisiologia , Percepção de Movimento/fisiologia , Animais , Humanos , Movimento (Física) , Neurônios/fisiologia , Visão Ocular/fisiologia , Vias Visuais/fisiologia
14.
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
15.
J Neurosci ; 40(28): 5431-5442, 2020 07 08.
Artigo em Inglês | MEDLINE | ID: mdl-32532886

RESUMO

Altered sensory experience in early life often leads to altered response properties of the sensory neurons. This process is mostly thought to happen in the brain, not in the sensory organs. We show that in the mouse retina of both sexes, exposed to a motion-dominated visual environment from eye-opening, the ON-OFF direction selective ganglion cells (ooDSGCs) develop significantly stronger direction encoding ability for motion in all directions. This improvement occurs independent of the motion direction used for training. We demonstrated that this enhanced ability to encode motion direction is mainly attributed to increased response reliability of ooDSGCs. Closer examination revealed that the excitatory inputs from the ON bipolar pathway showed enhanced response reliability after the motion experience training, while other synaptic inputs remain relatively unchanged. Our results demonstrate that retina adapts to the visual environment during neonatal development.SIGNIFICANCE STATEMENT We found that retina, as the first stage of visual sensation, can also be affected by experience dependent plasticity during development. Exposure to a motion enriched visual environment immediately after eye-opening greatly improves motion direction encoding by direction selective retinal ganglion cells (RGCs). These results motivate future studies aimed at understanding how visual experience shapes the retinal circuits and the response properties of retinal neurons.


Assuntos
Potenciais de Ação/fisiologia , Percepção de Movimento/fisiologia , Retina/fisiologia , Células Ganglionares da Retina/fisiologia , Visão Ocular/fisiologia , Animais , Feminino , Masculino , Camundongos , Estimulação Luminosa , Vias Visuais/fisiologia
16.
J Vis ; 20(6): 6, 2020 06 03.
Artigo em Inglês | MEDLINE | ID: mdl-32516356

RESUMO

Visually inferring the elasticity of a bouncing object poses a challenge to the visual system: The observable behavior of the object depends on its elasticity but also on extrinsic factors, such as its initial position and velocity. Estimating elasticity requires disentangling these different contributions to the observed motion. We created 2-second simulations of a cube bouncing in a room and varied the cube's elasticity in 10 steps. The cube's initial position, orientation, and velocity were varied randomly to gain three random samples for each level of elasticity. We systematically limited the visual information by creating three versions of each stimulus: (a) a full rendering of the scene, (b) the cube in a completely black environment, and (c) a rigid version of the cube following the same trajectories but without rotating or deforming (also in a completely black environment). Thirteen observers rated the apparent elasticity of the cubes and the typicality of their motion. Generally, stimuli were judged as less typical if they showed rigid motion without rotations, highly elastic cubes, or unlikely events. Overall, elasticity judgments correlated strongly with the true elasticity but did not show perfect constancy. Yet, importantly, we found similar results for all three stimulus conditions, despite significant differences in their apparent typicality. This suggests that the trajectory alone contains the information required to make elasticity judgments.


Assuntos
Elasticidade/fisiologia , Percepção de Movimento/fisiologia , Adulto , Simulação por Computador , Feminino , Humanos , Julgamento , Masculino , Movimento (Física) , Orientação , Adulto Jovem
17.
Nat Neurosci ; 23(8): 1004-1015, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32541964

RESUMO

Neurons represent spatial information in diverse reference frames, but it remains unclear whether neural reference frames change with task demands and whether these changes can account for behavior. In this study, we examined how neurons represent the direction of a moving object during self-motion, while monkeys switched, from trial to trial, between reporting object direction in head- and world-centered reference frames. Self-motion information is needed to compute object motion in world coordinates but should be ignored when judging object motion in head coordinates. Neural responses in the ventral intraparietal area are modulated by the task reference frame, such that population activity represents object direction in either reference frame. In contrast, responses in the lateral portion of the medial superior temporal area primarily represent object motion in head coordinates. Our findings demonstrate a neural representation of object motion that changes with task requirements.


Assuntos
Potenciais de Ação/fisiologia , Percepção de Movimento/fisiologia , Neurônios/fisiologia , Lobo Parietal/fisiologia , Animais , Macaca mulatta , Masculino , Estimulação Luminosa , Percepção Espacial/fisiologia
18.
J Neurosci ; 40(28): 5471-5479, 2020 07 08.
Artigo em Inglês | MEDLINE | ID: mdl-32513825

RESUMO

Apparent motion (AM) is induced when two stationary visual stimuli are presented in alternating sequence. Intriguingly, AM leads to an impaired detectability of stimuli along the AM path (i.e., AM-induced masking). It has been hypothesized that AM triggers an internal representation of a moving object in early visual cortex, which competes with stimulus-evoked representations of visual stimuli on the motion path in early visual cortex of 25 human adults (16 female). We tested this hypothesis by measuring BOLD responses in early visual cortex during the process of AM-induced masking, using fMRI and population receptive field methods. Surprisingly, and counter to our hypothesis, we showed that AM suppressed, rather than increased, BOLD responses along early visual (V1 and V2) representations of the AM path, including regions that were not directly activated by the AM inducer stimuli. This activity suppression of the visual response predicted the subsequent reduction in detectability of the target that appeared in the middle of the AM path. Our data thereby provide direct empirical evidence for suppressive neural mechanisms underlying AM and suggest that illusory motion can render us blind to objects on the motion path by suppressing neural activity at the earliest cortical stages of visual perception.SIGNIFICANCE STATEMENT When two spatially distinct visual objects are presented in alternating sequence, apparent motion (AM) occurs and impairs detectability of stimuli along its path. The underlying mechanism is thought to be that increased activation in human early visual cortex evoked by AM interferes with the representation of the stimulus. Strikingly, however, we show that AM suppresses neural activity along the motion path, and the strength of activity suppression predicts the subsequent behavioral performance decrement in terms of detecting a stimulus along the AM path. Our findings provide empirical evidence for a suppressive, rather than faciliatory, mechanism underlying AM.


Assuntos
Percepção de Movimento/fisiologia , Córtex Visual/fisiologia , Adulto , Feminino , Neuroimagem Funcional , Humanos , Imagem por Ressonância Magnética , Masculino , Movimento (Física) , Estimulação Luminosa , Córtex Visual/diagnóstico por imagem , Adulto Jovem
19.
PLoS One ; 15(6): e0234026, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32525897

RESUMO

Social cognition is dependent on the ability to extract information from human stimuli. Of those, patterns of biological motion (BM) and in particular walking patterns of other humans, are prime examples. Although most often tested in isolation, BM outside the laboratory is often associated with multisensory cues (i.e. we often hear and see someone walking) and there is evidence that vision-based judgments of BM stimuli are systematically influenced by motor signals. Furthermore, cross-modal visuo-tactile mechanisms have been shown to influence perception of bodily stimuli. Based on these observations, we here investigated if somatosensory inputs would affect visual BM perception. In two experiments, we asked healthy participants to perform a speed discrimination task on two point light walkers (PLW) presented one after the other. In the first experiment, we quantified somatosensory-visual interactions by presenting PLW together with tactile stimuli either on the participants' forearms or feet soles. In the second experiment, we assessed the specificity of these interactions by presenting tactile stimuli either synchronously or asynchronously with upright or inverted PLW. Our results confirm that somatosensory input in the form of tactile foot stimulation influences visual BM perception. When presented with a seen walker's footsteps, additional tactile cues enhanced sensitivity on a speed discrimination task, but only if the tactile stimuli were presented on the relevant body-part (under the feet) and when the tactile stimuli were presented synchronously with the seen footsteps of the PLW, whether upright or inverted. Based on these findings we discuss potential mechanisms of somatosensory-visual interactions in BM perception.


Assuntos
Percepção de Movimento/fisiologia , Estimulação Luminosa/métodos , Estimulação Física/métodos , Percepção do Tato/fisiologia , Percepção Visual/fisiologia , Adulto , Feminino , Humanos , Julgamento/fisiologia , Masculino , Adulto Jovem
20.
Nat Commun ; 11(1): 2675, 2020 05 29.
Artigo em Inglês | MEDLINE | ID: mdl-32472088

RESUMO

Abnormal sensory processing has been observed in autism, including superior visual motion discrimination, but the neural basis for these sensory changes remains unknown. Leveraging well-characterized suppressive neural circuits in the visual system, we used behavioral and fMRI tasks to demonstrate a significant reduction in neural suppression in young adults with autism spectrum disorder (ASD) compared to neurotypical controls. MR spectroscopy measurements revealed no group differences in neurotransmitter signals. We show how a computational model that incorporates divisive normalization, as well as narrower top-down gain (that could result, for example, from a narrower window of attention), can explain our observations and divergent previous findings. Thus, weaker neural suppression is reflected in visual task performance and fMRI measures in ASD, and may be attributable to differences in top-down processing.


Assuntos
Transtorno Autístico/patologia , Percepção de Movimento/fisiologia , Acuidade Visual/fisiologia , Adolescente , Adulto , Atenção/fisiologia , Mapeamento Encefálico , Cognição/fisiologia , Simulação por Computador , Discriminação Psicológica/fisiologia , Feminino , Humanos , Imagem por Ressonância Magnética , Masculino , Células Receptoras Sensoriais/fisiologia , Adulto Jovem
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