Neuronal Response to Reward and Luminance in Macaque LIP During Saccadic Choice / 神经科学通报·英文版

Recent work in decision neuroscience suggests that visual saliency can interact with reward-based choice, and the lateral intraparietal cortex (LIP) is implicated in this process. In this study, we recorded from LIP neurons while monkeys performed a two alternative choice task in which the reward and luminance associated with each offer were varied independently. We discovered that the animal's choice was dictated by the reward amount while the luminance had a marginal effect. In the LIP, neuronal activity corresponded well with the animal's choice pattern, in that a majority of reward-modulated neurons encoded the reward amount in the neuron's preferred hemifield with a positive slope. In contrast, compared to their responses to low luminance, an approximately equal proportion of luminance-sensitive neurons responded to high luminance with increased or decreased activity, leading to a much weaker population-level response. Meanwhile, in the non-preferred hemifield, the strength of encoding for reward amount and luminance was positively correlated, suggesting the integration of these two factors in the LIP. Moreover, neurons encoding reward and luminance were homogeneously distributed along the anterior-posterior axis of the LIP. Overall, our study provides further evidence supporting the neural instantiation of a priority map in the LIP in reward-based decisions.

Cortical Mechanisms of Multisensory Linear Self-motion Perception / 神经科学通报·英文版

Accurate self-motion perception, which is critical for organisms to survive, is a process involving multiple sensory cues. The two most powerful cues are visual (optic flow) and vestibular (inertial motion). Psychophysical studies have indicated that humans and nonhuman primates integrate the two cues to improve the estimation of self-motion direction, often in a statistically Bayesian-optimal way. In the last decade, single-unit recordings in awake, behaving animals have provided valuable neurophysiological data with a high spatial and temporal resolution, giving insight into possible neural mechanisms underlying multisensory self-motion perception. Here, we review these findings, along with new evidence from the most recent studies focusing on the temporal dynamics of signals in different modalities. We show that, in light of new data, conventional thoughts about the cortical mechanisms underlying visuo-vestibular integration for linear self-motion are challenged. We propose that different temporal component signals may mediate different functions, a possibility that requires future studies.

Evaluation of Visual Acuity of Ametropia with Visual Event-Related Potential Nogo-P3 Component / 法医学杂志

OBJECTIVES@#To analyze the Nogo-P3 component of event-related potential (ERP) in the process of visual acuity processing, to provide electrophysiological evidence for objective evaluation of visual acuity.@*METHODS@#Twenty-six subjects with no other ocular diseases except for ametropia were recruited, and all subjects had uncorrected visual acuity both eyes 1/10 (evaluated using Monoyer chart). Block letter E with different visual angles and directions were used as graphic stimuli. The Go/Nogo paradigm was used for ERP studies. The visual angle of Go stimulation angle was 1°15', Nogo stimuli were 1°15', 55', 24' and 15'. The visual acuity test was performed on each of the two naked eyes separately in all subjects, and the characteristics of the Nogo-P3 component were analyzed.@*RESULTS@#The latency of Nogo-P3 showed no difference between the stimuli of 1°15' and 55', and between Nogo stimulation angle 24' and 15'. There was significant difference between Nogo stimulation angle 1°15' and 24', and between Nogo stimulation angle 1°15' and 15' (P<0.05). There was significant difference between Nogo stimulation angle 55' and 24', and between Nogo stimulation angle 55' and 15' (P<0.05). No significant differences were observed in the Nogo-P3 amplitude among Nogo stimulation.@*CONCLUSIONS@#In the Go/Nogo paradigm, Nogo-P3 can reflect the cognitive response of subjects to Nogo stimulation, which can be used for objective evaluation of visual acuity.

Pars plana vitrectomy and visual stimulation for treatment of vitreomacular traction secondary to toxoplasmosis retinochoroiditis in a 5-year-old child / Vitrectomia via pars plana e estimulação visual para tratamento da tração vitreomacular secundária à retinocoroidite por toxoplasmose em criança de 5 anos

ABSTRACT Objective: A unusual case of ocular toxoplasmosis with significant vitreomacular traction is reported. The patient improved significantly following pars plana vitrectomy combined with visual stimulation and occlusion therapy. Methods: The case of a 5-year-old girl with significant unilateral vision loss associated with vitreous condensation and macular traction is described. Results: Pars plana vitrectomy was carried out for vitreomacular traction release. This was followed by visual stimulation and occlusion therapy. Significant improvement was observed. Conclusion: Despite structural damage, the combination of properly indicated surgery and amblyopia management strategies allowed the achievement of maximum vision goals in this case, suggesting structural damage may be associated with functional amblyopia.

RESUMO Objetivo: Relata-se um caso de apresentação atípica de toxoplasmose ocular, com importante tração vitreomacular. A paciente apresentou melhora significativa após vitrectomia via pars plana, com estimulação visual e oclusão. Métodos: Descreve-se o caso de uma menina de 5 anos, com importante perda de visão unilateral associada à condensação vítrea e à tração macular. Resultados: Foi realizada vitrectomia via pars plana para alívio da tração vitreomacular, seguida de estimulação visual e oclusão. Foi observada melhora significativa. Conclusão: Apesar dos danos estruturais, a combinação de cirurgia bem indicada com estratégias de tratamento da ambliopia permitiu alcançar o máximo do potencial visual nesta paciente, sugerindo que os danos estruturais podem estar associados à ambliopia funcional.

Modulation of Spike Count Correlations Between Macaque Primary Visual Cortex Neurons by Difficulty of Attentional Task / 神经科学通报·英文版

Studies have shown that spatial attention remarkably affects the trial-to-trial response variability shared between neurons. Difficulty in the attentional task adjusts how much concentration we maintain on what is currently important and what is filtered as irrelevant sensory information. However, how task difficulty mediates the interactions between neurons with separated receptive fields (RFs) that are attended to or attended away is still not clear. We examined spike count correlations between single-unit activities recorded simultaneously in the primary visual cortex (V1) while monkeys performed a spatial attention task with two levels of difficulty. Moreover, the RFs of the two neurons recorded were non-overlapping to allow us to study fluctuations in the correlated responses between competing visual inputs when the focus of attention was allocated to the RF of one neuron. While increasing difficulty in the spatial attention task, spike count correlations were either decreased to become negative between neuronal pairs, implying competition among them, with one neuron (or none) exhibiting attentional enhancement of firing rate, or increased to become positive, suggesting inter-neuronal cooperation, with one of the pair showing attentional suppression of spiking responses. Besides, the modulation of spike count correlations by task difficulty was independent of the attended locations. These findings provide evidence that task difficulty affects the functional interactions between different neuronal pools in V1 when selective attention resolves the spatial competition.

A review of researches on decoding algorithms of steady-state visual evoked potentials / 生物医学工程学杂志

Brain-computer interface (BCI) systems based on steady-state visual evoked potential (SSVEP) have become one of the major paradigms in BCI research due to their high signal-to-noise ratio and short training time required by users. Fast and accurate decoding of SSVEP features is a crucial step in SSVEP-BCI research. However, the current researches lack a systematic overview of SSVEP decoding algorithms and analyses of the connections and differences between them, so it is difficult for researchers to choose the optimum algorithm under different situations. To address this problem, this paper focuses on the progress of SSVEP decoding algorithms in recent years and divides them into two categories-trained and non-trained-based on whether training data are needed. This paper also explains the fundamental theories and application scopes of decoding algorithms such as canonical correlation analysis (CCA), task-related component analysis (TRCA) and the extended algorithms, concludes the commonly used strategies for processing decoding algorithms, and discusses the challenges and opportunities in this field in the end.

Progresses and prospects on frequency recognition methods for steady-state visual evoked potential / 生物医学工程学杂志

Steady-state visual evoked potential (SSVEP) is one of the commonly used control signals in brain-computer interface (BCI) systems. The SSVEP-based BCI has the advantages of high information transmission rate and short training time, which has become an important branch of BCI research field. In this review paper, the main progress on frequency recognition algorithm for SSVEP in past five years are summarized from three aspects, i.e., unsupervised learning algorithms, supervised learning algorithms and deep learning algorithms. Finally, some frontier topics and potential directions are explored.

Representations of object animacy and real-world size in the ventral visual pathway / 生理学报

How the brain perceives objects and classifies perceived objects is one of the important goals of visual cognitive neuroscience. Previous research has shown that when we see objects, the brain's ventral visual pathway recognizes and classifies them, leading to different ways of interacting with them. In this paper, we summarize the latest research progress of the ventral visual pathway related to the visual classification of objects. From the perspective of the neural representation of objects and its underlying mechanisms in the visual cortex, we summarize the current research status of the two important organizational dimensions of object animacy and real-world size, provide new insights, and point out the direction of further research.

Human detection and motion recovery based on monocular vision / Detecção humana e recuperação de movimento com base na visão monocular / Detección humana y recuperación de movimiento basada en visión monocular

ABSTRACT Objective: Provides interactive games and human animation real motion data and technical options. Therefore, how to complete the position, attitude detection, and motion recovery under monocular vision has become an important research direction. Methods: This paper improves the part-based human detection algorithm and uses the AdaBoost multi-instance learning algorithm to train the part detector. Results: The results show that obtaining blood pressure waveform based on monocular vision pulse wave is feasible and has generalization. Conclusions: The results show the feasibility and accuracy of the gait motion detection, motion recovery and analysis system for human lower limbs based on monocular vision. Level of evidence II; Therapeutic studies - investigation of treatment results.

RESUMO Objetivo: Fornece jogos interativos e dados de movimento real de animação humana e opções técnicas. Portanto, como completar a posição, detecção de atitude e recuperação de movimento sob visão monocular tornou-se uma importante direção de pesquisa. Métodos: este artigo aprimora o algoritmo de detecção humana baseado em partes e usa o algoritmo de aprendizado de múltiplas instâncias AdaBoost para treinar o detector de partes. Resultados: Os resultados mostram que o método de obtenção da forma de onda da pressão arterial com base na onda de pulso de visão monocular é viável e se pode generalizar. Conclusões: Os resultados mostram a viabilidade e precisão do sistema de detecção, recuperação e análise do movimento da marcha para membros inferiores humanos com base na visão monocular. Nível de evidência II; Estudos terapêuticos- investigação dos resultados do tratamento.

RESUMEN Objetivo: Proporciona juegos interactivos y animación humana, datos de movimiento real y opciones técnicas. Por lo tanto, cómo completar la posición, la detección de actitud y la recuperación de movimiento bajo visión monocular se ha convertido en una importante dirección de investigación. Métodos: este documento mejora el algoritmo de detección humana basado en piezas y utiliza el algoritmo de aprendizaje de instancias múltiples AdaBoost para entrenar el detector de piezas. Resultados: Los resultados muestran que el método de obtención de la forma de onda de la presión arterial basado en la onda de pulso de visión monocular es factible y se puede generalizar. Conclusiones: Los resultados muestran la viabilidad y precisión del sistema de detección, recuperación y análisis del movimiento de la marcha para miembros inferiores humanos basado en visión monocular. Nivel de evidencia II; Estudios terapéuticos- investigación de los resultados del tratamiento.

Influência do estímulo visual e posição dos membros superiores no controle postural ortostático de crianças e adolescentes / Influence of visual stimulus and upper limbs' position in the orthostatic postural control of children and adolescents

O objetivo do estudo foi verificar a influência do estímulo visual e posicionamento dos membros superiores no controle postural ortostático e avaliar o efeito do sexo e idade nas respostas posturais de crianças e adolescentes. Estudo transversal, com amostra de 84 participantes com idade entre 11 e 14 anos, ambos os sexos (55 meninas), de escola pública de Goiânia (GO). Além do exame físico, o controle postural foi avaliado na posição ortostática pela baropodometria computadorizada em três condições: olhos abertos, olhos fechados e olhos abertos com ombros a 90° de abdução. A ausência do estímulo visual gerou maior instabilidade postural em comparação à condição de olhos abertos. Em relação as diferenças existentes entre os sexos, foi observado que as meninas tiveram menores valores de deslocamento anteroposterior e área da elipse que os meninos. Comparando-se os olhos abertos e fechados, as meninas apresentaram maiores valores na área da elipse e os meninos nos deslocamentos anteroposterior e látero-lateral. Ao analisar o efeito da idade foi observado que o grupo com 13 e 14 anos apresentou maiores valores em todas as variáveis analisadas. A ausência do estímulo visual aumentou os valores da área da elipse no grupo com 11 e 12 e dos deslocamentos no grupo com 13 e 14 anos. Não foi verificado efeito interativo entre sexo e idade. Na condição de abdução dos membros superiores não houve diferença no controle postural. Conclui-se que a ausência do estímulo visual foi mais impactante na manutenção do controle postural ortostático em crianças e adolescentes em relação as outras condições avaliadas, existindo diferença entre os sexos e a idade, em que os meninos e o grupo com 13 e 14 anos realizaram mais ajustes para manter o controle postural. (AU)

The aim of this study was to verify the influence of visual stimulus and positioning of the upper limbs in the orthostatic postural control, and to assess the effects of gender and age in the postural responses of children and adolescents. This was a transversal study involving 84 participants (of which 55 were girls) from public schools in Goiania (GO - Brazil) with age between 11 and 14 years. Besides physical examination, the participants' postural control was assessed in the orthostatic position by computerized baropodometry in three different conditions: eyes-open, eyes-closed, and eyes-open with shoulders at 90º abduction. The absence of visual stimulus generated more postural instability in relation to the eyes-open condition. Regarding gender differences, the girls had lower anteroposterior and ellipse area displacement than boys. Comparing the eyes-open and eyes-closed conditions, the girls presented higher values in the ellipse area and the boys presented higher values in the anteroposterior and laterolateral displacements. Analyzing the effect of age, the participants between 13 and 14 years old presented higher values in all variables. The absence of visual stimulus increased the values of the ellipse area in the participants between 11 and 12 years of age and the values of displacements in the participants between 13 and 14 years of age. Interactive effect between genders and age has not been verified. There were no postural control differences in the upper limbs abduction condition. Conclusion: The absence of visual stimulus was more impacting in the support of orthostatic postural control in children and adolescents than the other conditions assessed; the boys and the participants between 13 and 14 years of age made more adjustments in order to maintain postural control. (AU)

A relevância da localização para a recuperação de informações visuais / La relevancia de la localización para la recuperación de información visual / The Relevance of Location for Retrieving Visual Information

O papel da localização na integração das características visuais na memória é controverso. Algumas evidências sugerem que a localização perde importância logo depois da consolidação da informação, outras, que a localização permanece associada à representação do objeto por mais tempo. Nós investigamos o papel da localização para a memória de objetos definidos por cor e forma. Os participantes (36) realizaram uma tarefa de detecção de mudança com 3 e 6 estímulos, com dois intervalos de retenção (500 e 1.500 milis-segundos). O desempenho é melhor quando a carga é menor, quando os estímulos são apresentados nos mesmos lugares em que foram memorizados, e depen-de da interação entre estes fatores. O intervalo de retenção não interfere no efeito da localização, mas modula o efeito da carga. Estes resultados sugerem que a localização é codificada de forma incidental com os estímulos visuais e que esta associação permanece inalterada dentro dos limites de tempo investigados.

El papel de la localización en la integración de las características visuales en la memoria es controverti-do. Algunas evidencias sugieren que la localización pierde importancia poco después de la consolida-ción de la información, otras, que la localización per-manece asociada a la representación del objeto durante más tiempo. Investigamos el papel de la localización para la memoria de los objetos definidos por el color y la forma. Los 36 participantes realizaron una tarea de detección de cambios con 3 y 6 estímulos, con dos intervalos de retención (500 y 1.500 milisegundos). El rendimiento es mejor cuando la carga es menor, cuando los estímulos se presentan en los mismos lugares donde fueron memorizados, y depende de la interacción entre estos factores. El intervalo de retención no interfiere con el efecto de ubicación, pero modula el efecto de carga. Estos resultados sugieren que la ubicación se codifica incidentalmente con estímulos visuales y que esta asociación permanece sin cambios dentro de los límites de tiempo investigados

The role of localization in the integration of visual char-acteristics into memory is controversial. Some evidence suggests that location loses importance soon after the consolidation of information; others, that the location remains associated with the representation of the object for longer. We investigated the role of location for the memory of objects defined by color and shape. Partici-pants (36) performed a change detection task with 3 and 6 stimuli, with two retention intervals (500 and 1. 500 milliseconds). Performance is better when the load is lower, stimuli are presented in the same places where they were memorized, and it depends on the interaction between these factors. The retention interval does not interfere with the location effect but modulates that of the load. These results suggest that localization is incidental-ly encoded with visual stimuli and that this association remains unchanged within the time limits investigated.

Robotic arm control system based on augmented reality brain-computer interface and computer vision / 生物医学工程学杂志

Brain-computer interface (BCI) has great potential to replace lost upper limb function. Thus, there has been great interest in the development of BCI-controlled robotic arm. However, few studies have attempted to use noninvasive electroencephalography (EEG)-based BCI to achieve high-level control of a robotic arm. In this paper, a high-level control architecture combining augmented reality (AR) BCI and computer vision was designed to control a robotic arm for performing a pick and place task. A steady-state visual evoked potential (SSVEP)-based BCI paradigm was adopted to realize the BCI system. Microsoft's HoloLens was used to build an AR environment and served as the visual stimulator for eliciting SSVEPs. The proposed AR-BCI was used to select the objects that need to be operated by the robotic arm. The computer vision was responsible for providing the location, color and shape information of the objects. According to the outputs of the AR-BCI and computer vision, the robotic arm could autonomously pick the object and place it to specific location. Online results of 11 healthy subjects showed that the average classification accuracy of the proposed system was 91.41%. These results verified the feasibility of combing AR, BCI and computer vision to control a robotic arm, and are expected to provide new ideas for innovative robotic arm control approaches.

Topography of Visual Features in the Human Ventral Visual Pathway / 神经科学通报·英文版

Visual object recognition in humans and nonhuman primates is achieved by the ventral visual pathway (ventral occipital-temporal cortex, VOTC), which shows a well-documented object domain structure. An on-going question is what type of information is processed in the higher-order VOTC that underlies such observations, with recent evidence suggesting effects of certain visual features. Combining computational vision models, fMRI experiment using a parametric-modulation approach, and natural image statistics of common objects, we depicted the neural distribution of a comprehensive set of visual features in the VOTC, identifying voxel sensitivities with specific feature sets across geometry/shape, Fourier power, and color. The visual feature combination pattern in the VOTC is significantly explained by their relationships to different types of response-action computation (fight-or-flight, navigation, and manipulation), as derived from behavioral ratings and natural image statistics. These results offer a comprehensive visual feature map in the VOTC and a plausible theoretical explanation as a mapping onto different types of downstream response-action systems.

Interaction Between Conscious and Unconscious Information-Processing of Faces and Words / 神经科学通报·英文版

It is widely acknowledged that holistic processing is a key characteristic of face perception. Although holistic processing implies the automatic integration of face parts, it is unclear whether such processing requires the awareness of face parts. Here, we investigated the interactions between visible face parts and face parts rendered invisible using continuous flash suppression (CFS). In the first experiment with the upper half-face visible and the lower half-face invisible, the results showed that perceived face identity was influenced by the invisible lower half-face, suggesting that integration occurs between the visible and invisible face parts, a variant of the "composite face effect". In the second experiment, we investigated the influence of visible face parts on the processing of invisible face parts, as measured by the time it took for the invisible parts to break out from CFS. The results showed a visible-to-invisible facilitation effect, that the aligned invisible face parts broke through CFS faster than when the visible and invisible face parts were misaligned. Visible eyes had a stronger influence on the invisible nose/mouth than the other way around. Such facilitation of processing from visible to invisible parts was also found when Chinese characters were used as stimuli. These results show that information integration occurs across the consciousness boundary.

A quantitative analysis of postural control in elderly patients with vestibular disorders using visual stimulation by virtual reality / Análise quantitativa do controle postural em pacientes idosos com disfunção vestibular utilizando a estimulação visual por realidade virtual

Abstract Introduction: Postural instability is one the most common disabling features in vestibular disorders. Objective: This study aimed to analyze the limit of stability and the influence of manipulation of visual, somatosensorial and visual-vestibular information on postural control in older adults with vestibular disorder, with and without a history of falls. Methods: Cross-sectional study. Participants - 76 elderly patients with vestibular disorder (G1, without falls; G2, with falls) and 41 healthy elderly subjects (control group; CG). Using posturography, analyzed were limit of stability area, body center of pressure, and velocity of oscillation in the standing position in 10 conditions, including open/closed eyes, unstable surface with eyes closed, saccadic and optokinetic stimuli, and visual-vestibular interaction. Results: Limit of stability area in CG was better compared with G1-2, and center of pressure values were worse in G1 than in CG. Center of pressure area in all conditions and velocity of oscillation in the following conditions: open/closed eyes, optokinetic stimulation, and visual-vestibular interaction showed worse values in G2 than in CG. Center of pressure area in the following conditions: open/closed eyes, saccadic and optokinetic stimuli, visual-vestibular interaction, and unstable surface with eyes closed showed worse values in G2 than in G1. Conclusion: Older adults with vestibular disorder presented reduced limit of stability and increased postural sway in the following conditions: conflict between visual and somatosensory information and visual-vestibular interaction. Deterioration in postural control was significantly associated with history of falls.

Resumo Introdução: Instabilidade postural é uma das características incapacitantes mais comuns nos distúrbios vestibulares. Objetivo: Analisar o limite de estabilidade e a influência da manipulação de informações visuais, somatossensoriais e visuais-vestibulares no controle postural em idosos com disfunção vestibular, com e sem histórico de quedas. Método: Estudo transversal. Participantes: 76 idosos com distúrbios vestibulares (G1, sem quedas; G2, com quedas) e 41 idosos saudáveis (grupo controle; GC). Com o uso da posturografia, foram analisadas a área do limite de estabilidade, centro de pressão e velocidade de oscilação na posição ereta em 10 condições, incluindo olhos abertos/fechados, superfície instável com olhos fechados, estímulos sacádicos e optocinéticos e interação visual-vestibular. Resultados: A área de limite de estabilidade no GC foi melhor comparada com o G1-2 e os valores do centro de pressão foram piores no G1 do que no GC. A área do centro de pressão em todas as condições e a velocidade de oscilação nas seguintes condições: olhos abertos/fechados, estímulo optocinético e interação visual-vestibular mostraram valores piores no G2 do que no GC. A área do centro de pressão nas seguintes condições: olhos abertos/fechados, estímulos sacádicos e optocinéticos, interação visual-vestibular e superfície instável com olhos fechados apresentou valores piores no G2 do que no G1. Conclusão: Idosos com disfunção vestibular apresentaram redução de limite de estabilidade e aumento da oscilação postural nas seguintes condições: conflito entre informação visual e somatossensorial e interação visual-vestibular. A deterioração no controle postural foi significantemente associada ao histórico de quedas.

Preterm infants with peri/intraventricular hemorrhage have poorer habituation responses to external stimuli / Neonatos prematuros com hemorragia peri-intraventricular apresentam respostas de habituação piores a estímulos externos

ABSTRACT Objective: To evaluate the association between intra-ventricular hemorrhage and habituation responses to external stimuli in preterm infants at 36-38 weeks post-conceptual age. Methods: Cross-sectional study of infants with gestational age <32 weeks. Intra-ventricular hemorrhage was identified by cranial ultrasonography and classified according to Papile et al. (1978). The luminous (flashlight), sound (rattle, bell), and tactile stimuli were presented, and the responses were scored according to Lester and Tronik (2004). Habituation response scores were compared between groups by Student's t-test. The association between IVH and habituation scores was evaluated by linear regression adjusted for GA, clinical severity score, post-conceptual age at habituation assessment, sepsis, and bronchopulmonary dysplasia. Results: Sixty-five infants were studied, 20 with intra-ventricular hemorrhage (16 grades I/II; four grades III/IV) and 45 without intra-ventricular hemorrhage. Infants with intra-ventricular hemorrhage had lower gestational age (28.2 ± 2.2 vs. 29.7 ± 1.7 weeks) and birth weight (990 ± 305 vs. 1275 ± 360 g). Infants with intra-ventricular hemorrhage at 36-38 weeks post-conceptual age had lower habituation scores to light (4.21 ± 2.23 vs. 6.09 ± 2.44), rattle (3.84 ± 2.12 vs. 6.18 ± 2.27), and bell (3.58 ± 1.74 vs. 5.20 ± 2.47) after controlling for confounders. No differences were found for tactile stimulus. Conclusion: Infants with gestational age <32 weeks and intra-ventricular hemorrhage had poorer habituation responses to external stimuli than those without intra-ventricular hemorrhage at 36-38 weeks post-conceptual age.

RESUMO Objetivo: Avaliar a associação entre hemorragia intraventricular e as respostas de habituação a estímulos externos em neonatos prematuros com idade pós-conceptual de 36-38 semanas. Métodos: Estudo transversal com neonatos com idade gestacional < 32 semanas. A hemorragia intraventricular foi identificada por ultrassonografia craniana e classificada de acordo com Papile et al. (1978). Os estímulos luminosos (lanterna), sonoros (chocalho, sino) e táteis foram apresentados e as respostas foram pontuadas de acordo com Lester & Tronik (2004). Os escores das respostas de habituação foram comparadas entre os grupos pelo teste t de Student. A associação entre a hemorragia intraventricular e os escores de habituação foi avaliada por regressão linear ajustada para a idade gestacional, escore de gravidade clínica, idade pós-conceptual na avaliação da habituação, sepse e displasia broncopulmonar. Resultados: 65 neonatos foram estudados, 20 com hemorragia intraventricular (16 graus I/II;4 graus III/IV) e 45 sem hemorragia intraventricular. Os neonatos com hemorragia intraventricular apresentaram menor idade gestacional (28,2 ± 2,2 vs. 29,7 ± 1,7 semanas) e peso ao nascer (990 ± 305 vs. 1275 ± 360 g). Os neonatos com hemorragia intraventricular na idade pós-conceptual de 36-38 semanas apresentaram escores de habituação menores a luz (4,21 ± 2,23 vs. 6,09 ± 2,44), chocalho (3,84 ± 2,12 vs. 6,18 ± 2,27) e campainha (3,58 ± 1,74 vs. 5,20 ± 2,47) após controle para variáveis de confusão. Nenhuma diferença foi encontrada para os estímulos táteis. Conclusão: Neonatos com idade gestacional < 32 semanas e hemorragia intraventricular apresentaram respostas de habituação piores a estímulos externos que os sem hemorragia intraventricular, na idade pós-conceptual de 36-38 semanas.

Objective Verification of Physiologic Changes during Accommodation under Binocular, Monocular, and Pinhole Conditions

BACKGROUND: To objectively investigate accommodative response to various refractive stimuli in subjects with normal accommodation. METHODS: This prospective, non-randomized clinical trial included 64 eyes of 32 subjects with a mean spherical equivalent −1.4 diopters (D). We evaluated changes in accommodative power, pupil diameter, astigmatic value, and axis when visual stimuli were applied to binocular, monocular (dominant eye, non-dominant eye, ipsilateral, and contralateral), and pinhole conditions. Visual stimuli were given at 0.25 D (4 m), 2 D (50 cm), 3 D (33 cm), and 4 D (25 cm) and accommodative response was evaluated using open view binocular autorefractor/keratometer. RESULTS: The accommodative response to binocular stimulus was 90.9% of the actual refractive stimulus, while that of the monocular stimulus was 84.6%. The binocular stimulus induced a smaller pupil diameter than did the monocular stimulus. There was no difference in accommodative response between the dominant eye and non-dominant eye or between ipsilateral and contralateral stimuli. As the refractive stimuli became stronger, the absolute astigmatic value increased and the direction of the astigmatism axis became more horizontal. Pinhole glasses required 10%–15% less accommodative power compared with the monocular condition. CONCLUSION: Binocular stimuli enable more precise and effective accommodation than do monocular stimuli. Accommodative response is composed of 90% true accommodation and 10% pseudo-accommodation, and the refractive stimulus in one eye affects the contralateral eye to the same extent. This should be taken into account when developing guidelines for wearing smart glasses while driving, as visual stimulation is applied to only one eye, but far distance attention is constantly needed. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT03557346

Research on the separability of steady-state visual evoked potential features modulated by different visual attentional states / 生物医学工程学杂志

Attention can concentrate our mental resources on processing certain interesting objects, which is an important mental behavior and cognitive process. Recognizing attentional states have great significance in improving human's performance and reducing errors. However, it still lacks a direct and standardized way to monitor a person's attentional states. Based on the fact that visual attention can modulate the steady-state visual evoked potential (SSVEP), we designed a go/no-go experimental paradigm with 10 Hz steady state visual stimulation in background to investigate the separability of SSVEP features modulated by different visual attentional states. The experiment recorded the EEG signals of 15 postgraduate volunteers under high and low visual attentional states. High and low visual attentional states are determined by behavioral responses. We analyzed the differences of SSVEP signals between the high and low attentional levels, and applied classification algorithms to recognize such differences. Results showed that the discriminant canonical pattern matching (DCPM) algorithm performed better compared with the linear discrimination analysis (LDA) algorithm and the canonical correlation analysis (CCA) algorithm, which achieved up to 76% in accuracy. Our results show that the SSVEP features modulated by different visual attentional states are separable, which provides a new way to monitor visual attentional states.

Spatiotemporal Analysis of Event-related Current Density Reveals Dissociable Effects of Arousal and Valence on Emotional Picture Processing

BACKGROUND: The processing of emotional visual stimulation involves the processing of emotional and visuoperceptual information. It is not completely revealed how the valence and arousal affect these two aspects. The objective was to investigate the effects of valence and arousal on spatiotemporal characteristics of cortical information processing using distributed source imaging of event-related current density (ERCD). METHODS: Electroencephalograms (64 channels) were recorded from 19 healthy men while presenting affective pictures. Distributed source localization analysis was adopted to obtain the spatiotemporal pattern of ERCD on cortical surface in response to emotional visual stimulation. A nonparametric cluster-based permutation test was used to find meaningful time and space without prior knowledge. RESULTS: Significant changes of ERCD in 400–800 ms among positive, negative, and neutral emotional conditions were found in left posterior cingulate cortex (PCC) and right inferior temporal cortex (ITC). In the PCC, the stimuli with higher arousal levels showed more negative ERCD than neutral stimuli. In the ITC, the ERCD for negative stimuli was significantly more negative than those of positive and neutral ones. CONCLUSION: Arousal and valence had strong influence on memory encoding and visual analysis at late period. The location and time showing significant change in neural activity according to arousal and valence would provide valuable information for understanding the changes of cortical function by neuropsychiatric disorders.

Electroencephalographic Abnormalities in the Screening for Pilot Applicants in Korea

BACKGROUND AND PURPOSE: Electroencephalography (EEG) is often used as a screening tool for selecting pilots despite controversy regarding its contribution to aviation safety. We investigated EEG abnormalities in Korean commercial pilot applicants in order to identify the usefulness of EEG screening in this population. METHODS: We retrospectively analyzed the EEG results of 740 unselected pilot applicants who underwent waking EEG at Inha University Hospital from January 2013 to May 2017. EEG recording was performed for 30 minutes, which included 3 minutes of hyperventilation and intermittent photic stimulation. RESULTS: The pilot applicants were predominantly male (95.3%) and had a mean age of 27.8 years (range: 16–40 years). Nine of them (1.2%) exhibited EEG abnormalities; the most common abnormality (six applicants) was a small amount of generalized irregular slow activities, while the other three applicants (0.4%) exhibited epileptiform discharges, with two showing generalized spike-and-wave complexes and one showing a few spike-and-wave complexes in the left frontotemporal area. The two applicants with generalized spike-and-wave complexes were found to have experienced clinical seizures by a neurologist during detailed history-taking. CONCLUSIONS: This study found that 2 of 740 pilot applicants (0.3%) were diagnosed with epilepsy by routine EEG screening in an unselected population. Considering the low predictive value of EEG without the relevant clinical history in an unselected healthy young population, our findings raise questions regarding the cost-effectiveness of the current EEG screening protocol applied to pilot applicants. We suggest that a more-targeted and standardized EEG screening approach be applied to pilot applicants with epilepsy risk factors or a seizure history as determined by thorough medical history-taking.