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Nat Commun ; 12(1): 4714, 2021 08 05.
Artigo em Inglês | MEDLINE | ID: mdl-34354071


Although the contents of working memory can be decoded from visual cortex activity, these representations may play a limited role if they are not robust to distraction. We used model-based fMRI to estimate the impact of distracting visual tasks on working memory representations in several visual field maps in visual and frontoparietal association cortex. Here, we show distraction causes the fidelity of working memory representations to briefly dip when both the memorandum and distractor are jointly encoded by the population activities. Distraction induces small biases in memory errors which can be predicted by biases in neural decoding in early visual cortex, but not other regions. Although distraction briefly disrupts working memory representations, the widespread redundancy with which working memory information is encoded may protect against catastrophic loss. In early visual cortex, the neural representation of information in working memory and behavioral performance are intertwined, solidifying its importance in visual memory.

Memória de Curto Prazo/fisiologia , Córtex Visual/fisiologia , Adulto , Atenção/fisiologia , Mapeamento Encefálico , Feminino , Neuroimagem Funcional , Humanos , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Modelos Neurológicos , Modelos Psicológicos , Estimulação Luminosa , Análise e Desempenho de Tarefas
J Neurosci ; 40(49): 9487-9495, 2020 12 02.
Artigo em Inglês | MEDLINE | ID: mdl-33115927


Theoretically, working memory (WM) representations are encoded by population activity of neurons with distributed tuning across the stored feature. Here, we leverage computational neuroimaging approaches to map the topographic organization of human superior colliculus (SC) and model how population activity in SC encodes WM representations. We first modeled receptive field properties of voxels in SC, deriving a detailed topographic organization resembling that of the primate SC. Neural activity within human (5 male and 1 female) SC persisted throughout a retention interval of several types of modified memory-guided saccade tasks. Assuming an underlying neural architecture of the SC based on its retinotopic organization, we used an encoding model to show that the pattern of activity in human SC represents locations stored in WM. Our tasks and models allowed us to dissociate the locations of visual targets and the motor metrics of memory-guided saccades from the spatial locations stored in WM, thus confirming that human SC represents true WM information. These data have several important implications. They add the SC to a growing number of cortical and subcortical brain areas that form distributed networks supporting WM functions. Moreover, they specify a clear neural mechanism by which topographically organized SC encodes WM representations.SIGNIFICANCE STATEMENT Using computational neuroimaging approaches, we mapped the topographic organization of human superior colliculus (SC) and modeled how population activity in SC encodes working memory (WM) representations, rather than simpler visual or motor properties that have been traditionally associated with the laminar maps in the primate SC. Together, these data both position the human SC into a distributed network of brain areas supporting WM and elucidate the neural mechanisms by which the SC supports WM.

Memória de Curto Prazo/fisiologia , Memória Espacial/fisiologia , Colículos Superiores/fisiologia , Adulto , Mapeamento Encefálico , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Desempenho Psicomotor/fisiologia , Tempo de Reação/fisiologia , Retina/fisiologia , Movimentos Sacádicos/fisiologia , Colículos Superiores/diagnóstico por imagem , Campos Visuais/fisiologia , Percepção Visual/fisiologia
J Cogn Neurosci ; 30(2): 219-233, 2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-28984524


Although the content of working memory (WM) can be decoded from the spatial patterns of brain activity in early visual cortex, how populations encode WM representations remains unclear. Here, we address this limitation by using a model-based approach that reconstructs the feature encoded by population activity measured with fMRI. Using this approach, we could successfully reconstruct the locations of memory-guided saccade goals based on the pattern of activity in visual cortex during a memory delay. We could reconstruct the saccade goal even when we dissociated the visual stimulus from the saccade goal using a memory-guided antisaccade procedure. By comparing the spatiotemporal population dynamics, we find that the representations in visual cortex are stable but can also evolve from a representation of a remembered visual stimulus to a prospective goal. Moreover, because the representation of the antisaccade goal cannot be the result of bottom-up visual stimulation, it must be evoked by top-down signals presumably originating from frontal and/or parietal cortex. Indeed, we find that trial-by-trial fluctuations in delay period activity in frontal and parietal cortex correlate with the precision with which our model reconstructed the maintained saccade goal based on the pattern of activity in visual cortex. Therefore, the population dynamics in visual cortex encode WM representations, and these representations can be sculpted by top-down signals from frontal and parietal cortex.

Memória de Curto Prazo/fisiologia , Córtex Visual/fisiologia , Percepção Visual/fisiologia , Adulto , Mapeamento Encefálico , Feminino , Lobo Frontal/diagnóstico por imagem , Lobo Frontal/fisiologia , Humanos , Imageamento por Ressonância Magnética , Masculino , Modelos Neurológicos , Lobo Parietal/diagnóstico por imagem , Lobo Parietal/fisiologia , Retina/fisiologia , Movimentos Sacádicos/fisiologia , Córtex Visual/diagnóstico por imagem , Vias Visuais/diagnóstico por imagem , Vias Visuais/fisiologia
Vision Res ; 105: 70-6, 2014 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-25240420


Visual working memory is a system used to hold information actively in mind for a limited time. The number of items and the precision with which we can store information has limits that define its capacity. How much control do we have over the precision with which we store information when faced with these severe capacity limitations? Here, we tested the hypothesis that rank-ordered attentional priority determines the precision of multiple working memory representations. We conducted two psychophysical experiments that manipulated the priority of multiple items in a two-alternative forced choice task (2AFC) with distance discrimination. In Experiment 1, we varied the probabilities with which memorized items were likely to be tested. To generalize the effects of priority beyond simple cueing, in Experiment 2, we manipulated priority by varying monetary incentives contingent upon successful memory for items tested. Moreover, we illustrate our hypothesis using a simple model that distributed attentional resources across items with rank-ordered priorities. Indeed, we found evidence in both experiments that priority affects the precision of working memory in a monotonic fashion. Our results demonstrate that representations of priority may provide a mechanism by which resources can be allocated to increase the precision with which we encode and briefly store information.

Atenção/fisiologia , Memória de Curto Prazo/fisiologia , Percepção Visual/fisiologia , Adulto , Sinais (Psicologia) , Discriminação Psicológica , Feminino , Humanos , Masculino , Modelos Teóricos , Estimulação Luminosa/métodos , Psicofísica , Adulto Jovem
Multisens Res ; 26(1-2): 159-76, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23713204


Causal inference in sensory cue combination is the process of determining whether multiple sensory cues have the same cause or different causes. Psychophysical evidence indicates that humans closely follow the predictions of a Bayesian causal inference model. Here, we explore how Bayesian causal inference could be implemented using probabilistic population coding and plausible neural operations, but conclude that the resulting architecture is unrealistic.

Percepção Auditiva/fisiologia , Sinais (Psicologia) , Modelos Neurológicos , Redes Neurais de Computação , Percepção Visual/fisiologia , Teorema de Bayes , Comportamento/fisiologia , Humanos , Psicofísica/métodos