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1.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 1899-1902, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33018372

RESUMO

The in-vivo optical imaging of the cortical surface provides the ability to record different types of biophysiological signals, e.g., structural information, intrinsic signals, like blood oxygenation coupled reflection changes as well as extrinsic properties of voltage sensitive probes, like fluorescent voltage-sensitive dyes. The recorded data sets have very high temporal and spatial resolutions on a meso- to macroscopic scale, which surpass conventional multi-electrode recordings. Both, intrinsic and functional data sets, each provide unique information about temporal and spatial dynamics of cortical functioning, yet have individual drawbacks. To optimize the informational value it would thus be opportune to combine different types of optical imaging in a near simultaneous recording.Due to the low signal-to-noise ratio of voltage-sensitive dyes it is necessary to reduce stray light pollution below the level of the camera's dark noise. It is thus impossible to record full-spectrum optical data sets. We address this problem by a time-multiplexed illumination, bespoke to the utilized voltage sensitive dye, to record an alternating series of intrinsic and extrinsic frames by a high-frequency CMOS sensor. These near simultaneous data series can be used to compare the mutual influence of intrinsic and extrinsic dynamics (with regards to extracorporeal functional imaging) as well as for motion compensation and thus for minimizing frame averaging, which in turn results in increased spatial precision of functional data and in a reduction of necessary experimental data sets (3R principle).


Assuntos
Iluminação , Imagem Óptica , Corantes Fluorescentes , Estimulação Luminosa , Razão Sinal-Ruído
2.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 2873-2876, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33018606

RESUMO

Recently, rhythmic visual stimulation (RVS) has been demonstrated to affect the brain function by entraining neural oscillations. However, less is known about how RVS influences the functional connectivity across the whole brain. Here, we applied a graph theoretical approach to analyze the electroencephalography (EEG) connections of 60 nodes when subjects deployed their attention on visual task with different background stimulation, i.e. no background flicker, jittered flicker, and RVS of 6, 10, 15 and 40 Hz, respectively. Thirty-three subjects participated in this study. As a result, the 40-Hz rhythm led to the significantly fastest reaction among all conditions. Furthermore, significantly higher clustering coefficient (C) and small worldness (σ) of θ-band brain network were observed for higher-frequency RVS, which were significantly negatively correlated with reaction time (RT) (C-RT: r =-0.917, p =0.010; σ-RT: r =-0.894, p =0.016). In addition, we found an increase in the connections between dorsolateral prefrontal and visual cortices under RVS compared to no flicker. Our results indicate that RVS can improve the efficiency of brain cortical functional network to facilitate attention.


Assuntos
Atenção , Encéfalo , Eletroencefalografia , Estimulação Luminosa , Tempo de Reação
3.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 2877-2880, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33018607

RESUMO

Error-related potentials (ErrPs) can reflect the brain's response to errors. Recently, it has been used in the studies on neural mechanisms of human cognition, such as error detection and conflict monitoring. Moreover, ErrPs have provided technical support for the development of brain-computer interface (BCI). However, the different effects of visual stimulation modes (dynamic or static) on ErrPs have not been revealed. This may seriously affect the recognition accuracy of the ErrPs in practical applications. Therefore, the aim of this study was to investigate how people respond to different types of visual stimulations. Nineteen participants were recruited in the ErrPs-based tasks with two visual stimulation modes (dynamic and static). The ErrPs were analyzed and the feature values (N1, P2, P3, N6 and P8, named by the occurrence time) were statistically compared. The results showed that the difference between correctness and error was reflected in P3, N6, P8 in dynamic stimulation; and N1, P3, N6 and P8 in static stimulation. In the event-related potential based on error, the differences between dynamic and static tasks were reflected in N1 and P2. In conclusion, this study found that the features with later occurrence were significantly affected by correctness and error in both cases, while the error-related change in N1 only existed under the static stimulation. We also found that the recognition of stimulation modes came earlier within about 300 ms after the start of visual stimulation.


Assuntos
Interfaces Cérebro-Computador , Eletroencefalografia , Encéfalo , Potenciais Evocados , Humanos , Estimulação Luminosa
4.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 2946-2949, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33018624

RESUMO

The steady-state visual evoked potential (SSVEP) is a robust brain activity that has been used in brain-computer interface (BCI) applications. However, previous studies of SSVEP-based BCIs give contradictory results on which stimulation medium provides the best performance. This paper describes a comparison of electroencephalography (EEG) decoding accuracy between using an LCD screen, clear LEDs, and frosted LEDs to deliver flashing light stimulation. The LCD screen and frosted LEDs achieved similar mean accuracies, and both of them were significantly better than clear LEDs. Background contrast with the LEDs did not significantly influence SSVEP decoding accuracy. A strong correlation was found between SSVEP accuracy and frequency domain magnitudes of EEG measurements.


Assuntos
Interfaces Cérebro-Computador , Potenciais Evocados Visuais , Eletroencefalografia , Exame Neurológico , Estimulação Luminosa
5.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 3031-3034, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33018644

RESUMO

The mapping of visual space onto human striate cortex allows the location of stimuli to affect the scalp distributions of electroencephalogram (EEG). To clarify the relationship between the characteristics of elicited high-frequency steady-state visual evoked potentials (SSVEPs) and the polar angle of stimulus, this study divided the annulus into eight symmetrical annular sectors (i.e., octants) as separate visual stimuli. For both 30 Hz and 60 Hz, the response intensity and classification accuracy indicated that the annular sectors in the lower visual field evoked stronger responses than those in the upper visual field. This paper also evaluated the phase differences between SSVEPs at specific polar angles and found clear individual differences across subjects. These findings may lead to inspirations for the design of new space coding methods for the SSVEP-based brain-computer interfaces (BCIs).


Assuntos
Interfaces Cérebro-Computador , Córtex Visual , Eletroencefalografia , Potenciais Evocados Visuais , Humanos , Estimulação Luminosa
6.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 3054-3057, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33018649

RESUMO

In order to explore the effect of low frequency stimulation on pupil size and electroencephalogram (EEG), we presented subjects with 1-6Hz black-and-white-alternating flickering stimulus, and compared the differences of signal-to-noise ratio (SNR) and classification performance between pupil size and visual evoked potentials (VEPs). The results showed that the SNR of the pupillary response reached the highest at 1Hz (17.19± 0.10dB) and 100% accuracy was obtained at 1s data length, while the performance was poor at the stimulation frequency above 3Hz. In contrast, the SNR of VEPs reached the highest at 6Hz (18.57± 0.37dB), and the accuracy of all stimulus frequencies could reach 100%, with the minimum data length of 1.5s. This study lays a theoretical foundation for further implementation of a hybrid brain-computer interface (BCI) that integrates pupillometry and EEG.


Assuntos
Interfaces Cérebro-Computador , Potenciais Evocados Visuais , Eletroencefalografia , Estimulação Luminosa , Pupila
7.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 4310-4313, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33018949

RESUMO

A subretinal stimulator chip has been designed and tested, which combines high pixel number with highest simulation voltages, lowest power consumption, spatial peaking and illumination adaptation. A supporting ASIC completes the implantable device electronics. Blind mouse retina has successfully been stimulated in vitro.


Assuntos
Iluminação , Próteses e Implantes , Animais , Eletrodos , Camundongos , Estimulação Luminosa
8.
PLoS Biol ; 18(9): e3000854, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32898172

RESUMO

Working memory is imprecise, and these imprecisions can be explained by the combined influences of random diffusive error and systematic drift toward a set of stable states ("attractors"). However, the neural correlates of diffusion and drift remain unknown. Here, we investigated how delay-period activity in frontal and parietal cortex, which is known to correlate with the decline in behavioral memory precision observed with increasing memory load, might relate to diffusion and drift. We analyzed data from an existing experiment in which subjects performed delayed recall for line orientation, at different loads, during functional magnetic resonance imaging (fMRI) scanning. To quantify the influence of drift and diffusion, we modeled subjects' behavior using a discrete attractor model and calculated within-subject correlation between frontal and parietal delay-period activity and whole-trial estimates of drift and diffusion. We found that although increases in frontal and parietal activity were associated with increases in both diffusion and drift, diffusion explained the most variance in frontal and parietal delay-period activity. In comparison, a subsequent whole-brain regression analysis showed that drift, rather than diffusion, explained the most variance in delay-period activity in lateral occipital cortex. These results are consistent with a model of the differential recruitment of general frontoparietal mechanisms in response to diffusive noise and of stimulus-specific biases in occipital cortex.


Assuntos
Lobo Frontal/fisiologia , Memória de Curto Prazo/fisiologia , Lobo Occipital/fisiologia , Lobo Parietal/fisiologia , Percepção Visual/fisiologia , Adolescente , Adulto , Viés , Mapeamento Encefálico/métodos , Feminino , Lobo Frontal/anatomia & histologia , Lobo Frontal/diagnóstico por imagem , Humanos , Imagem por Ressonância Magnética , Masculino , Rememoração Mental/fisiologia , Lobo Occipital/anatomia & histologia , Lobo Occipital/diagnóstico por imagem , Lobo Parietal/anatomia & histologia , Lobo Parietal/diagnóstico por imagem , Estimulação Luminosa , Razão Sinal-Ruído , Fatores de Tempo , Vias Visuais/anatomia & histologia , Vias Visuais/diagnóstico por imagem , Vias Visuais/fisiologia , Adulto Jovem
9.
Nat Commun ; 11(1): 4518, 2020 09 09.
Artigo em Inglês | MEDLINE | ID: mdl-32908146

RESUMO

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


Assuntos
Reconhecimento Facial/fisiologia , Ilusões/fisiologia , Modelos Neurológicos , Lobo Temporal/fisiologia , Córtex Visual/fisiologia , Adolescente , Adulto , Mapeamento Encefálico , Simulação por Computador , Feminino , Humanos , Imagem por Ressonância Magnética , Magnetoencefalografia , Masculino , Neuroimagem , Estimulação Luminosa , Tempo de Reação , Lobo Temporal/diagnóstico por imagem , Córtex Visual/diagnóstico por imagem , Adulto Jovem
10.
Nat Commun ; 11(1): 4605, 2020 09 14.
Artigo em Inglês | MEDLINE | ID: mdl-32929073

RESUMO

From starlight to sunlight, adaptation alters retinal output, changing both the signal and noise among populations of retinal ganglion cells (RGCs). Here we determine how these light level-dependent changes impact decoding of retinal output, testing the importance of accounting for RGC noise correlations to optimally read out retinal activity. We find that at moonlight conditions, correlated noise is greater and assuming independent noise severely diminishes decoding performance. In fact, assuming independence among a local population of RGCs produces worse decoding than using a single RGC, demonstrating a failure of population codes when correlated noise is substantial and ignored. We generalize these results with a simple model to determine what conditions dictate this failure of population processing. This work elucidates the circumstances in which accounting for noise correlations is necessary to take advantage of population-level codes and shows that sensory adaptation can strongly impact decoding requirements on downstream brain areas.


Assuntos
Retina/fisiologia , Adaptação Ocular/efeitos da radiação , Animais , Teorema de Bayes , Luz , Modelos Lineares , Visão Noturna/fisiologia , Estimulação Luminosa , Ratos Long-Evans , Retina/efeitos da radiação , Células Ganglionares da Retina/fisiologia , Células Ganglionares da Retina/efeitos da radiação
11.
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
12.
PLoS One ; 15(8): e0237854, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32853262

RESUMO

Drug-induced long QT syndrome (diLQTS), characterized by a prolongation of the QT-interval on the electrocardiogram (ECG), is a serious adverse drug reaction that can cause the life-threatening arrhythmia Torsade de Points (TdP). Self-monitoring for diLQTS could therefore save lives, but detecting it on the ECG is difficult, particularly at high and low heart rates. In this paper, we evaluate whether using a pseudo-colouring visualisation technique and changing the coordinate system (Cartesian vs. Polar) can support lay people in identifying QT-prolongation at varying heart rates. Four visualisation techniques were evaluated using a counterbalanced repeated measures design including Cartesian no-colouring, Cartesian pseudo-colouring, Polar no-colouring and Polar pseudo-colouring. We used a multi-reader, multi-case (MRMC) receiver operating characteristic (ROC) study design within a psychophysical paradigm, along with eye-tracking technology. Forty-three lay participants read forty ECGs (TdP risk n = 20, no risk n = 20), classifying each QT-interval as normal/abnormal, and rating their confidence on a 6-point scale. The results show that introducing pseudo-colouring to the ECG significantly increased accurate detection of QT-interval prolongation regardless of heart rate, T-wave morphology and coordinate system. Pseudo-colour also helped to reduce reaction times and increased satisfaction when reading the ECGs. Eye movement analysis indicated that pseudo-colour helped to focus visual attention on the areas of the ECG crucial to detecting QT-prolongation. The study indicates that pseudo-colouring enables lay people to visually identify drug-induced QT-prolongation regardless of heart rate, with implications for the more rapid identification and management of diLQTS.


Assuntos
Eletrocardiografia , Frequência Cardíaca , Síndrome do QT Longo/diagnóstico por imagem , Síndrome do QT Longo/fisiopatologia , Adulto , Cor , Movimentos Oculares/fisiologia , Feminino , Fixação Ocular/fisiologia , Humanos , Masculino , Pessoa de Meia-Idade , Satisfação Pessoal , Estimulação Luminosa , Psicofísica , Curva ROC , Tempo de Reação , Fatores de Risco , Sensibilidade e Especificidade , Adulto Jovem
13.
PLoS One ; 15(8): e0237717, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32810159

RESUMO

The effect of spatial contexts on attention is important for evaluating the risk of human errors and the accessibility of information in different situations. In traditional studies, this effect has been investigated using display-based and non-laboratory procedures. However, these two procedures are inadequate for measuring attention directed toward 360-degree environments and controlling exogeneous stimuli. In order to resolve these limitations, we used a virtual-reality-based procedure and investigated how spatial contexts of 360-degree environments influence attention. In the experiment, 20 students were asked to search for and report a target that was presented at any location in 360-degree virtual spaces as accurately and quickly as possible. Spatial contexts comprised a basic context (a grey and objectless space) and three specific contexts (a square grid floor, a cubic room, and an infinite floor). We found that response times for the task and eye movements were influenced by the spatial context of 360-degree surrounding spaces. In particular, although total viewing times for the contexts did not match the saliency maps, the differences in total viewing times between the basic and specific contexts did resemble the maps. These results suggest that attention comprises basic and context-dependent characteristics, and the latter are influenced by the saliency of 360-degree contexts even when the contexts are irrelevant to a task.


Assuntos
Atenção/fisiologia , Processamento Espacial/fisiologia , Adulto , Movimentos Oculares/fisiologia , Feminino , Humanos , Masculino , Estimulação Luminosa/métodos , Tempo de Reação/fisiologia , Realidade Virtual , Adulto Jovem
14.
PLoS One ; 15(8): e0238022, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32845918

RESUMO

Working memory (WM) is the key process linking perception to action. Several lines of research have, accordingly, highlighted WM's engagement in sensori-motor associations between retrospective stimuli and future behavior. Using human fMRI we investigated whether prior information about the effector used to respond in a WM task would have an impact on the way the same sensory stimulus is maintained in memory despite a behavioral response could not be readily planned. We focused on WM-related activity in posterior parietal cortex during the maintenance of spatial items for a subsequent match-to-sample comparison, which was reported either with a verbal or with a manual response. We expected WM activity to be higher for manual response trials, because of posterior parietal cortex's engagement in both spatial WM and hand movement preparation. Increased fMRI activity for manual response trials in bilateral anterior intraparietal sulcus confirmed our expectations. These results imply that the maintenance of sensory material in WM is optimized for motor context, i.e. for the effector that will be relevant in the upcoming behavioral responses.


Assuntos
Memória de Curto Prazo , Lobo Parietal/fisiologia , Adulto , Mapeamento Encefálico , Feminino , Humanos , Imagem por Ressonância Magnética , Masculino , Lobo Parietal/diagnóstico por imagem , Estimulação Luminosa , Estudos Retrospectivos , Análise e Desempenho de Tarefas , Adulto Jovem
15.
PLoS One ; 15(8): e0236999, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32813734

RESUMO

Snakes have been important ambush predators of both primates and human hunter-gatherers throughout their co-evolutionary history. Viperid snakes in particular are responsible for most fatal venomous snakebites worldwide and thus represent a strong selective pressure. They elicit intense fear in humans and are easily recognizable thanks to their distinctive morphotype. In this study, we measured skin resistance (SR) and heart rate (HR) in human subjects exposed to snake pictures eliciting either high fear (10 venomous viperid species) or disgust (10 nonvenomous fossorial species). Venomous snakes subjectively evaluated as frightening trigger a stronger physiological response (higher SR amplitude) than repulsive non-venomous snakes. However, stimuli presented in a block (more intense stimulation) do not trigger a stronger emotional response compared to sequentially presented stimuli (less intense stimulation). There are significant interindividual differences as subjects with high fear of snakes confronted with images of viperid snakes show stronger, longer-lasting, and more frequent changes in SR and higher HR compared to low-fear subjects. Thus, we show that humans demonstrate a remarkable ability to discriminate between dangerous viperids and harmless fossorial snakes, which is also reflected in distinct autonomous body responses.


Assuntos
Medo/fisiologia , Medo/psicologia , Mordeduras de Serpentes/psicologia , Serpentes , Adolescente , Adulto , Animais , Sistema Nervoso Autônomo/fisiologia , Evolução Biológica , Asco , Feminino , Resposta Galvânica da Pele/fisiologia , Frequência Cardíaca/fisiologia , Humanos , Masculino , Modelos Psicológicos , Estimulação Luminosa , Psicometria , Psicofisiologia , Venenos de Serpentes/envenenamento , Adulto Jovem
16.
PLoS One ; 15(8): e0224471, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32797090

RESUMO

We present normative data for an expanded set of stimuli designed to investigate past experience effects on object detection. The stimuli are vertically-elongated "bipartite" displays comprising two equal-area regions meeting at an articulated central border. When the central border is assigned to one side, a shaped figure (i.e., an object) is detected on that side. Participants viewing brief masked exposures typically detect figures more often on the critical side of Intact displays where a common ("familiar") object is depicted than on a matched critical side of Part-Rearranged (PR) displays comprising the same parts arranged in novel configurations. This pattern of results showed that past experience in the form of familiar configuration rather than familiar parts is a prior for figure assignment. Spurred by research implicating a network involving the perirhinal cortex of the medial temporal lobe in these familiar configuration effects, we enlarged the stimulus set from 24 to 48 base stimuli to increase its usefulness for behavioral, neuropsychological, and neuroimaging experiments. We measured the percentage of participants who agreed on a single interpretation for each side of Intact, Upright PR, and Inverted PR displays (144 displays; 288 sides) under long exposure conditions. High inter-subject agreement is taken to operationally define a familiar configuration. This new stimulus set is well-suited to investigate questions concerning how parts and wholes are integrated and how high- and low-level brain areas interact in object detection. This set also allows tests of predictions regarding cross-border competition in figure assignment and assessments of individual differences. The displays, their image statistics, and normative data are available online (https://osf.io/j9kz2/).


Assuntos
Percepção de Forma/fisiologia , Reconhecimento Visual de Modelos/fisiologia , Percepção Visual/fisiologia , Adulto , Encéfalo , Feminino , Humanos , Masculino , Testes Neuropsicológicos , Estimulação Luminosa/métodos , Reconhecimento Psicológico , Lobo Temporal
17.
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
18.
PLoS One ; 15(8): e0236809, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32785237

RESUMO

While we are performing a demanding cognitive task, not only do we have a sense of cognitive effort, we are also subjectively aware that we are initiating, executing and controlling our thoughts and actions (i.e., sense of agency). Previous studies have shown that cognitive effort can be both detrimental and facilitative for the experienced sense of agency. We hypothesized that the reason for these contradictory findings might lie in the use of differential time windows in which cognitive effort operates. The current study therefore examined the effect of cognitive effort exerted on the current trial, on the previous trial or across a block of trials on sense of agency, using implicit (Experiment 1) and explicit (Experiment 2) measures of sense of agency. We showed that the exertion of more cognitive control on current trials led to a higher explicit sense of agency. This surprising result was contrasted to previous studies to establish potential reasons for this surprising finding and to formulate recommendations for future studies.


Assuntos
Cognição/fisiologia , Desempenho Psicomotor/fisiologia , Adolescente , Adulto , Feminino , Humanos , Masculino , Estimulação Luminosa , Tempo de Reação , Adulto Jovem
19.
Nat Commun ; 11(1): 3886, 2020 08 04.
Artigo em Inglês | MEDLINE | ID: mdl-32753603

RESUMO

The ability to recognize written letter strings is foundational to human reading, but the underlying neuronal mechanisms remain largely unknown. Recent behavioral research in baboons suggests that non-human primates may provide an opportunity to investigate this question. We recorded the activity of hundreds of neurons in V4 and the inferior temporal cortex (IT) while naïve macaque monkeys passively viewed images of letters, English words and non-word strings, and tested the capacity of those neuronal representations to support a battery of orthographic processing tasks. We found that simple linear read-outs of IT (but not V4) population responses achieved high performance on all tested tasks, even matching the performance and error patterns of baboons on word classification. These results show that the IT cortex of untrained primates can serve as a precursor of orthographic processing, suggesting that the acquisition of reading in humans relies on the recycling of a brain network evolved for other visual functions.


Assuntos
Evolução Biológica , Macaca mulatta/fisiologia , Reconhecimento Visual de Modelos/fisiologia , Lobo Temporal/fisiologia , Animais , Mapeamento Encefálico , Tomada de Decisões , Imagem por Ressonância Magnética , Masculino , Estimulação Luminosa/métodos , Leitura , Lobo Temporal/diagnóstico por imagem
20.
Nat Commun ; 11(1): 3925, 2020 08 06.
Artigo em Inglês | MEDLINE | ID: mdl-32764538

RESUMO

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


Assuntos
Adaptação Fisiológica , Ilusões/fisiologia , Orientação Espacial/fisiologia , Adulto , Eletroencefalografia , Potenciais Evocados Visuais , Retroalimentação Fisiológica , Feminino , Neuroimagem Funcional , Humanos , Imagem por Ressonância Magnética , Masculino , Ilusões Ópticas/fisiologia , Estimulação Luminosa , Psicofísica , Retina/fisiologia , Córtex Visual/fisiologia , Percepção Visual/fisiologia , Adulto Jovem
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