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1.
Elife ; 102021 08 10.
Artigo em Inglês | MEDLINE | ID: mdl-34374647

RESUMO

Objects can be recognized based on their intrinsic features, including shape, color, and texture. In daily life, however, such features are often not clearly visible, for example when objects appear in the periphery, in clutter, or at a distance. Interestingly, object recognition can still be highly accurate under these conditions when objects are seen within their typical scene context. What are the neural mechanisms of context-based object recognition? According to parallel processing accounts, context-based object recognition is supported by the parallel processing of object and scene information in separate pathways. Output of these pathways is then combined in downstream regions, leading to contextual benefits in object recognition. Alternatively, according to feedback accounts, context-based object recognition is supported by (direct or indirect) feedback from scene-selective to object-selective regions. Here, in three pre-registered transcranial magnetic stimulation (TMS) experiments, we tested a key prediction of the feedback hypothesis: that scene-selective cortex causally and selectively supports context-based object recognition before object-selective cortex does. Early visual cortex (EVC), object-selective lateral occipital cortex (LOC), and scene-selective occipital place area (OPA) were stimulated at three time points relative to stimulus onset while participants categorized degraded objects in scenes and intact objects in isolation, in different trials. Results confirmed our predictions: relative to isolated object recognition, context-based object recognition was selectively and causally supported by OPA at 160-200 ms after onset, followed by LOC at 260-300 ms after onset. These results indicate that context-based expectations facilitate object recognition by disambiguating object representations in the visual cortex.


Assuntos
Mapeamento Encefálico/métodos , Reconhecimento Visual de Modelos/fisiologia , Percepção Visual , Adolescente , Adulto , Feminino , Humanos , Lobo Occipital/fisiologia , Estimulação Luminosa/métodos , Estimulação Magnética Transcraniana/métodos , Adulto Jovem
2.
iScience ; 24(5): 102392, 2021 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-33997677

RESUMO

Cognitive processes-from basic sensory analysis to language understanding-are typically contextualized. While the importance of considering context for understanding cognition has long been recognized in psychology and philosophy, it has not yet had much impact on cognitive neuroscience research, where cognition is often studied in decontextualized paradigms. Here, we present examples of recent studies showing that context changes the neural basis of diverse cognitive processes, including perception, attention, memory, and language. Within the domains of perception and language, we review neuroimaging results showing that context interacts with stimulus processing, changes activity in classical perception and language regions, and recruits additional brain regions that contribute crucially to naturalistic perception and language. We discuss how contextualized cognitive neuroscience will allow for discovering new principles of the mind and brain.

3.
Sci Rep ; 11(1): 640, 2021 01 12.
Artigo em Inglês | MEDLINE | ID: mdl-33436692

RESUMO

How the brain makes correct inferences about its environment based on noisy and ambiguous observations is one of the fundamental questions in Neuroscience. Prior knowledge about the probability with which certain events occur in the environment plays an important role in this process. Humans are able to incorporate such prior knowledge in an efficient, Bayes optimal, way in many situations, but it remains an open question how the brain acquires and represents this prior knowledge. The long time spans over which prior knowledge is acquired make it a challenging question to investigate experimentally. In order to guide future experiments with clear empirical predictions, we used a neural network model to learn two commonly used tasks in the experimental literature (i.e. orientation classification and orientation estimation) where the prior probability of observing a certain stimulus is manipulated. We show that a population of neurons learns to correctly represent and incorporate prior knowledge, by only receiving feedback about the accuracy of their inference from trial-to-trial and without any probabilistic feedback. We identify different factors that can influence the neural responses to unexpected or expected stimuli, and find a novel mechanism that changes the activation threshold of neurons, depending on the prior probability of the encoded stimulus. In a task where estimating the exact stimulus value is important, more likely stimuli also led to denser tuning curve distributions and narrower tuning curves, allocating computational resources such that information processing is enhanced for more likely stimuli. These results can explain several different experimental findings, clarify why some contradicting observations concerning the neural responses to expected versus unexpected stimuli have been reported and pose some clear and testable predictions about the neural representation of prior knowledge that can guide future experiments.


Assuntos
Algoritmos , Teorema de Bayes , Encéfalo/fisiologia , Meio Ambiente , Modelos Neurológicos , Rede Nervosa/fisiologia , Neurônios/fisiologia , Humanos , Aprendizagem , Neurônios/classificação , Orientação
4.
Nat Hum Behav ; 5(5): 612-624, 2021 05.
Artigo em Inglês | MEDLINE | ID: mdl-33398144

RESUMO

The scope of unconscious processing is highly debated, with recent studies showing that even high-level functions such as perceptual integration and category-based attention occur unconsciously. For example, upright faces that are suppressed from awareness through interocular suppression break into awareness more quickly than inverted faces. Similarly, verbal object cues boost otherwise invisible objects into awareness. Here, we replicate these findings, but find that they reflect a general difference in detectability not specific to interocular suppression. To dissociate conscious and unconscious influences on visual detection effects, we use an additional discrimination task to rule out conscious processes as a cause for these differences. Results from this detection-discrimination dissociation paradigm reveal that, while face orientation is processed unconsciously, category-based attention requires awareness. These findings provide insights into the function of conscious perception and offer an experimental approach for mapping out the scope and limits of unconscious processing.


Assuntos
Atenção/fisiologia , Conscientização/fisiologia , Percepção Visual/fisiologia , Adolescente , Adulto , Feminino , Humanos , Masculino , Estimulação Luminosa , Adulto Jovem
5.
J Neurosci ; 41(4): 751-756, 2021 01 27.
Artigo em Inglês | MEDLINE | ID: mdl-33262244

RESUMO

Natural scenes are characterized by individual objects as well as by global scene properties such as spatial layout. Functional neuroimaging research has shown that this distinction between object and scene processing is one of the main organizing principles of human high-level visual cortex. For example, object-selective regions, including the lateral occipital complex (LOC), were shown to represent object content (but not scene layout), while scene-selective regions, including the occipital place area (OPA), were shown to represent scene layout (but not object content). Causal evidence for a double dissociation between LOC and OPA in representing objects and scenes is currently limited, however. One TMS experiment, conducted in a relatively small sample (N = 13), reported an interaction between LOC and OPA stimulation and object and scene recognition performance (Dilks et al., 2013). Here, we present a high-powered preregistered replication of this study (N = 72, including male and female human participants), using group-average fMRI coordinates to target LOC and OPA. Results revealed unambiguous evidence for a double dissociation between LOC and OPA: relative to vertex stimulation, TMS over LOC selectively impaired the recognition of objects, while TMS over OPA selectively impaired the recognition of scenes. Furthermore, we found that these effects were stable over time and consistent across individual objects and scenes. These results show that LOC and OPA can be reliably and selectively targeted with TMS, even when defined based on group-average fMRI coordinates. More generally, they support the distinction between object and scene processing as an organizing principle of human high-level visual cortex.SIGNIFICANCE STATEMENT Our daily-life environments are characterized both by individual objects and by global scene properties. The distinction between object and scene processing features prominently in visual cognitive neuroscience, with fMRI studies showing that this distinction is one of the main organizing principles of human high-level visual cortex. However, causal evidence for the selective involvement of object- and scene-selective regions in processing their preferred category is less conclusive. Here, testing a large sample (N = 72) using an established paradigm and a preregistered protocol, we found that TMS over object-selective cortex (lateral occipital complex) selectively impaired object recognition, while TMS over scene-selective cortex (occipital place area) selectively impaired scene recognition. These results provide strong causal evidence for the distinction between object and scene processing in human visual cortex.


Assuntos
Estimulação Magnética Transcraniana , Córtex Visual/fisiologia , Adolescente , Adulto , Mapeamento Encefálico , Feminino , Humanos , Individualidade , Imageamento por Ressonância Magnética , Masculino , Lobo Occipital/fisiologia , Desempenho Psicomotor/fisiologia , Tempo de Reação/fisiologia , Reconhecimento Psicológico/fisiologia , Reprodutibilidade dos Testes , Adulto Jovem
7.
Cereb Cortex ; 30(12): 6391-6404, 2020 11 03.
Artigo em Inglês | MEDLINE | ID: mdl-32754744

RESUMO

Much of what we know about object recognition arises from the study of isolated objects. In the real world, however, we commonly encounter groups of contextually associated objects (e.g., teacup and saucer), often in stereotypical spatial configurations (e.g., teacup above saucer). Here we used electroencephalography to test whether identity-based associations between objects (e.g., teacup-saucer vs. teacup-stapler) are encoded jointly with their typical relative positioning (e.g., teacup above saucer vs. below saucer). Observers viewed a 2.5-Hz image stream of contextually associated object pairs intermixed with nonassociated pairs as every fourth image. The differential response to nonassociated pairs (measurable at 0.625 Hz in 28/37 participants) served as an index of contextual integration, reflecting the association of object identities in each pair. Over right occipitotemporal sites, this signal was larger for typically positioned object streams, indicating that spatial configuration facilitated the extraction of the objects' contextual association. This high-level influence of spatial configuration on object identity integration arose ~ 320 ms post-stimulus onset, with lower-level perceptual grouping (shared with inverted displays) present at ~ 130 ms. These results demonstrate that contextual and spatial associations between objects interactively influence object processing. We interpret these findings as reflecting the high-level perceptual grouping of objects that frequently co-occur in highly stereotyped relative positions.

8.
Cereb Cortex ; 30(2): 597-606, 2020 03 21.
Artigo em Inglês | MEDLINE | ID: mdl-31216008

RESUMO

Sounds (e.g., barking) help us to visually identify objects (e.g., a dog) that are distant or ambiguous. While neuroimaging studies have revealed neuroanatomical sites of audiovisual interactions, little is known about the time course by which sounds facilitate visual object processing. Here we used magnetoencephalography to reveal the time course of the facilitatory influence of natural sounds (e.g., barking) on visual object processing and compared this to the facilitatory influence of spoken words (e.g., "dog"). Participants viewed images of blurred objects preceded by a task-irrelevant natural sound, a spoken word, or uninformative noise. A classifier was trained to discriminate multivariate sensor patterns evoked by animate and inanimate intact objects with no sounds, presented in a separate experiment, and tested on sensor patterns evoked by the blurred objects in the 3 auditory conditions. Results revealed that both sounds and words, relative to uninformative noise, significantly facilitated visual object category decoding between 300-500 ms after visual onset. We found no evidence for earlier facilitation by sounds than by words. These findings provide evidence for a semantic route of facilitation by both natural sounds and spoken words, whereby the auditory input first activates semantic object representations, which then modulate the visual processing of objects.


Assuntos
Percepção Auditiva/fisiologia , Sinais (Psicologia) , Reconhecimento Visual de Modelos/fisiologia , Semântica , Percepção da Fala/fisiologia , Estimulação Acústica , Adulto , Feminino , Humanos , Magnetoencefalografia , Masculino , Estimulação Luminosa , Adulto Jovem
9.
Cortex ; 122: 225-234, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-30563703

RESUMO

In daily life, attention is often directed to high-level object attributes, such as when we look out for cars before crossing a road. Previous work used MEG decoding to investigate the influence of such category-based attention on the time course of object category representations. Attended object categories were more strongly represented than unattended categories from 180 msec after scene onset. In the present study, we used a similar approach to determine when attention is spatially focused on the target. Participants completed two tasks. In the first, they detected cars and people at varying locations in photographs of real-world scenes. In the second, they detected a cross that appeared at salient locations in an array of lines. Multivariate classifiers were trained on data of the artificial salience experiment and tested on data of the naturalistic visual search experiment. Results showed that the location of both target and distracter objects could be accurately decoded shortly after scene onset (50 msec). However, the emergence of spatial attentional selection - reflected in better decoding of target location than distracter location - emerged only later in time (240 msec). Target presence itself (irrespective of location and category) could be decoded from 180 msec after stimulus onset. Combined with earlier work, these results suggest that naturalistic category search operates through an initial spatially-global modulation of category processing that then guides attention to the location of the target.


Assuntos
Reconhecimento Visual de Modelos , Humanos , Estimulação Luminosa
10.
Elife ; 82019 09 09.
Artigo em Inglês | MEDLINE | ID: mdl-31496518

RESUMO

The principles underlying the animacy organization of the ventral temporal cortex (VTC) remain hotly debated, with recent evidence pointing to an animacy continuum rather than a dichotomy. What drives this continuum? According to the visual categorization hypothesis, the continuum reflects the degree to which animals contain animal-diagnostic features. By contrast, the agency hypothesis posits that the continuum reflects the degree to which animals are perceived as (social) agents. Here, we tested both hypotheses with a stimulus set in which visual categorizability and agency were dissociated based on representations in convolutional neural networks and behavioral experiments. Using fMRI, we found that visual categorizability and agency explained independent components of the animacy continuum in VTC. Modeled together, they fully explained the animacy continuum. Finally, clusters explained by visual categorizability were localized posterior to clusters explained by agency. These results show that multiple organizing principles, including agency, underlie the animacy continuum in VTC.


Assuntos
Cognição , Reconhecimento Visual de Modelos , Lobo Temporal/fisiologia , Vias Visuais/fisiologia , Adulto , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Modelos Neurológicos , Estimulação Luminosa , Adulto Jovem
11.
Psychol Sci ; 30(10): 1497-1509, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31525114

RESUMO

When searching for relevant objects in our environment (say, an apple), we create a memory template (a red sphere), which causes our visual system to favor template-matching visual input (applelike objects) at the expense of template-mismatching visual input (e.g., leaves). Although this principle seems straightforward in a lab setting, it poses a problem in naturalistic viewing: Two objects that have the same size on the retina will differ in real-world size if one is nearby and the other is far away. Using the Ponzo illusion to manipulate perceived size while keeping retinal size constant, we demonstrated across 71 participants that visual objects attract attention when their perceived size matches a memory template, compared with mismatching objects that have the same size on the retina. This shows that memory templates affect visual selection after object representations are modulated by scene context, thus providing a working mechanism for template-based search in naturalistic vision.


Assuntos
Atenção , Memória de Curto Prazo , Reconhecimento Visual de Modelos , Percepção Visual , Adulto , Sinais (Psicologia) , Feminino , Humanos , Masculino , Estimulação Luminosa , Tempo de Reação , Adulto Jovem
12.
Trends Cogn Sci ; 23(8): 672-685, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31147151

RESUMO

In natural vision, objects appear at typical locations, both with respect to visual space (e.g., an airplane in the upper part of a scene) and other objects (e.g., a lamp above a table). Recent studies have shown that object vision is strongly adapted to such positional regularities. In this review we synthesize these developments, highlighting that adaptations to positional regularities facilitate object detection and recognition, and sharpen the representations of objects in visual cortex. These effects are pervasive across various types of high-level content. We posit that adaptations to real-world structure collectively support optimal usage of limited cortical processing resources. Taking positional regularities into account will thus be essential for understanding efficient object vision in the real world.


Assuntos
Encéfalo/fisiologia , Percepção Visual/fisiologia , Humanos
13.
Neuroimage ; 193: 167-177, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-30885785

RESUMO

Human high-level visual cortex shows a distinction between animate and inanimate objects, as revealed by fMRI. Recent studies have shown that object animacy can similarly be decoded from MEG sensor patterns. Which object properties drive this decoding? Here, we disentangled the influence of perceptual and categorical object properties by presenting perceptually matched objects (e.g., snake and rope) that were nonetheless easily recognizable as being animate or inanimate. In a series of behavioral experiments, three aspects of perceptual dissimilarity of these objects were quantified: overall dissimilarity, outline dissimilarity, and texture dissimilarity. Neural dissimilarity of MEG sensor patterns was modeled using regression analysis, in which perceptual dissimilarity (from the behavioral experiments) and categorical dissimilarity served as predictors of neural dissimilarity. We found that perceptual dissimilarity was strongly reflected in MEG sensor patterns from 80 ms after stimulus onset, with separable contributions of outline and texture dissimilarity. Surprisingly, when controlling for perceptual dissimilarity, MEG patterns did not carry information about object category (animate vs inanimate) at any time point. Nearly identical results were found in a second MEG experiment that required basic-level object recognition. This is in contrast to results observed in fMRI using the same stimuli, task, and analysis approach: fMRI voxel patterns in object-selective cortex showed a highly reliable categorical distinction even when controlling for perceptual dissimilarity. These results suggest that MEG sensor patterns do not capture object animacy independently of perceptual differences between animate and inanimate objects.


Assuntos
Magnetoencefalografia/métodos , Reconhecimento Visual de Modelos/fisiologia , Adulto , Feminino , Humanos , Imageamento por Ressonância Magnética/métodos , Masculino , Neuroimagem/métodos , Estimulação Luminosa , Córtex Visual/fisiologia , Adulto Jovem
14.
Emotion ; 19(5): 928-932, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-30762381

RESUMO

Using breaking continuous flash suppression (b-CFS; a perceptual suppression technique), Gomes, Soares, Silva, and Silva (2018) showed that human observers have an advantage in detecting images of snakes (constituting an evolutionarily old threat) over birds. In their study, images of snakes and birds were filtered to contain either coarse-scale or fine-grained information. The preferential detection of snakes relied on coarse-scale (rather than fine-grained) information, which was taken as support for the existence of an evolutionarily old subcortical pathway dedicated to snake detection. Here, we raise the concern that images of snakes and birds inherently differ in their visual characteristics, which can strongly affect detection times in b-CFS. Images of snakes, for instance, have a larger perimeter-to-surface ratio than images of birds. Importantly, these visual characteristics are not snake specific, as they are shared with many nonthreatening object categories. To illustrate this point, we compared detection times between images of bicycles and cars-nonthreatening image categories that differ in visual characteristics but for which detection is unlikely to capitalize on an evolutionarily old dedicated subcortical pathway. Observers exhibited an advantage for detecting bicycles over cars. Mirroring the snake-bird differences reported in Gomes et al., this advantage was driven by the coarse-scale (rather than fine-grained) information in the images. Hence, differences in visual characteristics between two nonthreatening, semantically matched stimulus categories suffice to produce the exact same pattern of findings as observed with snakes versus birds. We conclude that spatial frequency-specific detection differences in b-CFS cannot be unequivocally attributed to differences in processing pathways. (PsycINFO Database Record (c) 2019 APA, all rights reserved).


Assuntos
Aves , Medo , Animais , Humanos
15.
Sci Rep ; 9(1): 2112, 2019 02 14.
Artigo em Inglês | MEDLINE | ID: mdl-30765753

RESUMO

Scene context is known to facilitate object recognition in both machines and humans, suggesting that the underlying representations may be similar. Alternatively, they may be qualitatively different since the training experience of machines and humans are strikingly different. Machines are typically trained on images containing objects and their context, whereas humans frequently experience scenes without objects (such as highways without cars). If these context representations are indeed different, machine vision algorithms will be improved on augmenting them with human context representations, provided these expectations can be measured and are systematic. Here, we developed a paradigm to measure human contextual expectations. We asked human subjects to indicate the scale, location and likelihood at which cars or people might occur in scenes without these objects. This yielded highly systematic expectations that we could then accurately predict using scene features. This allowed us to predict human expectations on novel scenes without requiring explicit measurements. Next we augmented decisions made by deep neural networks with these predicted human expectations and obtained substantial gains in accuracy for detecting cars and people (1-3%) as well as on detecting associated objects (3-20%). In contrast, augmenting deep network decisions with other conventional computer vision features yielded far smaller gains. Taken together, our results show that augmenting deep neural networks with human-derived contextual expectations improves their performance, suggesting that contextual representations are qualitatively different in humans and deep neural networks.


Assuntos
Algoritmos , Encéfalo/fisiologia , Motivação/fisiologia , Reconhecimento Visual de Modelos/fisiologia , Estimulação Luminosa , Visão Ocular/fisiologia , Percepção Visual/fisiologia , Adulto , Feminino , Humanos , Processamento de Imagem Assistida por Computador/métodos , Masculino , Adulto Jovem
16.
J Cogn Neurosci ; 31(3): 390-400, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-29561241

RESUMO

We internally represent the structure of our surroundings even when there is little layout information available in the visual image, such as when walking through fog or darkness. One way in which we disambiguate such scenes is through object cues; for example, seeing a boat supports the inference that the foggy scene is a lake. Recent studies have investigated the neural mechanisms by which object and scene processing interact to support object perception. The current study examines the reverse interaction by which objects facilitate the neural representation of scene layout. Photographs of indoor (closed) and outdoor (open) real-world scenes were blurred such that they were difficult to categorize on their own but easily disambiguated by the inclusion of an object. fMRI decoding was used to measure scene representations in scene-selective parahippocampal place area (PPA) and occipital place area (OPA). Classifiers were trained to distinguish response patterns to fully visible indoor and outdoor scenes, presented in an independent experiment. Testing these classifiers on blurred scenes revealed a strong improvement in classification in left PPA and OPA when objects were present, despite the reduced low-level visual feature overlap with the training set in this condition. These findings were specific to left PPA/OPA, with no evidence for object-driven facilitation in right PPA/OPA, object-selective areas, and early visual cortex. These findings demonstrate separate roles for left and right scene-selective cortex in scene representation, whereby left PPA/OPA represents inferred scene layout, influenced by contextual object cues, and right PPA/OPA represents a scene's visual features.


Assuntos
Córtex Cerebral/diagnóstico por imagem , Lateralidade Funcional/fisiologia , Adulto , Mapeamento Encefálico , Córtex Cerebral/fisiologia , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino , Córtex Visual/diagnóstico por imagem , Córtex Visual/fisiologia , Adulto Jovem
17.
J Exp Psychol Gen ; 147(11): e1-e13, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30372110

RESUMO

Visual stimuli with social-emotional relevance have been claimed to gain preferential access to awareness. For example, recent studies used the breaking continuous flash suppression paradigm (b-CFS) to show that faces that are perceived as less dominant and more trustworthy are prioritized for awareness. Here we asked whether these effects truly reflect differences in social-emotional meaning or whether they can be equally explained by differences in low-level stimulus properties. In Experiment 1, we successfully replicated dominance- and untrustworthiness-related slowing for upright faces. However, these effects were equally strong for inverted faces, even though it was more difficult to perceive social characteristics in inverted faces. The previously reported correlation between dominance- and untrustworthiness-related slowing in b-CFS and self-reported propensity to trust did not replicate. Experiment 2 showed that dominance-related slowing in b-CFS can also be observed when only presenting the eye region of faces, and even when the eye region was presented inverted and/or with reversed contrast polarity, in which case personality traits were no longer discernible. These results were replicated in Experiment 3 following a preregistration protocol. Altogether, our findings link dominance-related slowing in b-CFS to physical differences in the eye region that are-when presented in isolation-unrelated to the perception of dominance. We conclude that low-level physical stimulus differences provide a parsimonious explanation for the effect of social facial characteristics on access to awareness. (PsycINFO Database Record (c) 2018 APA, all rights reserved).


Assuntos
Conscientização , Expressão Facial , Processos Mentais , Confiança/psicologia , Inconsciente Psicológico , Adulto , Emoções , Feminino , Humanos , Masculino , Adulto Jovem
18.
Neuroimage ; 181: 446-452, 2018 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-30033392

RESUMO

Understanding other people's actions and mental states includes the interpretation of body postures and movements. In particular, hand postures are an important channel to signal both action and communicative intentions. Recognizing hand postures is computationally challenging because hand postures often differ only in the subtle configuration of relative finger positions and because visual characteristics of hand postures change across viewpoints. To allow for accurate interpretation, the brain needs to represent hand postures in a view-invariant but posture-specific manner. Here we test for such representations in hand-, body-, and object-selective regions of the lateral occipitotemporal cortex (LOTC). We used multivariate pattern analysis of fMRI data to test for view-specific and view-invariant representations of individual hand postures, separately for two domains: action-related postures (e.g., a precision grasp) and communicative postures (e.g., thumbs up). Results showed that hand-selective LOTC, but not nearby body- and object-selective LOTC, represented hand postures in a view-invariant manner, with relatively similar activity patterns to the same hand posture seen from different viewpoints. View invariance was equally strong for action and communicative postures. By contrast, object-selective cortex represented hand postures in a view-specific manner. These results indicate a role for hand-selective LOTC in solving the view-invariance problem for individual hand postures. View-invariant representations of hand postures in this region may then be accessed and further interpreted by multiple downstream systems to inform high-level judgments related to action understanding, emotion recognition, and non-verbal communication.


Assuntos
Mapeamento Encefálico/métodos , Gestos , Mãos/fisiologia , Imageamento por Ressonância Magnética/métodos , Atividade Motora/fisiologia , Lobo Occipital/fisiologia , Reconhecimento Visual de Modelos/fisiologia , Postura/fisiologia , Lobo Temporal/fisiologia , Adulto , Feminino , Humanos , Masculino , Lobo Occipital/diagnóstico por imagem , Lobo Temporal/diagnóstico por imagem , Adulto Jovem
19.
Neuroimage ; 169: 334-341, 2018 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-29277645

RESUMO

To optimize processing, the human visual system utilizes regularities present in naturalistic visual input. One of these regularities is the relative position of objects in a scene (e.g., a sofa in front of a television), with behavioral research showing that regularly positioned objects are easier to perceive and to remember. Here we use fMRI to test how positional regularities are encoded in the visual system. Participants viewed pairs of objects that formed minimalistic two-object scenes (e.g., a "living room" consisting of a sofa and television) presented in their regularly experienced spatial arrangement or in an irregular arrangement (with interchanged positions). Additionally, single objects were presented centrally and in isolation. Multi-voxel activity patterns evoked by the object pairs were modeled as the average of the response patterns evoked by the two single objects forming the pair. In two experiments, this approximation in object-selective cortex was significantly less accurate for the regularly than the irregularly positioned pairs, indicating integration of individual object representations. More detailed analysis revealed a transition from independent to integrative coding along the posterior-anterior axis of the visual cortex, with the independent component (but not the integrative component) being almost perfectly predicted by object selectivity across the visual hierarchy. These results reveal a transitional stage between individual object and multi-object coding in visual cortex, providing a possible neural correlate of efficient processing of regularly positioned objects in natural scenes.


Assuntos
Mapeamento Encefálico/métodos , Reconhecimento Visual de Modelos/fisiologia , Percepção Espacial/fisiologia , Córtex Visual/fisiologia , Adulto , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino , Córtex Visual/diagnóstico por imagem , Adulto Jovem
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