Form Properties of Moving Targets Bias Smooth Pursuit Target Selection in Monkeys / 神经科学通报·英文版

During natural viewing, we often recognize multiple objects, detect their motion, and select one object as the target to track. It remains to be determined how such behavior is guided by the integration of visual form and motion perception. To address this, we studied how monkeys made a choice to track moving targets with different forms by smooth pursuit eye movements in a two-target task. We found that pursuit responses were biased toward the motion direction of a target with a hole. By computing the relative weighting, we found that the target with a hole exhibited a larger weight for vector computation. The global hole feature dominated other form properties. This dominance failed to account for changes in pursuit responses to a target with different forms moving singly. These findings suggest that the integration of visual form and motion perception can reshape the competition in sensorimotor networks to guide behavioral selection.

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.

Augmentation of Doppler Radar Data Using Generative Adversarial Network for Human Motion Analysis / 대한의료정보학회지

OBJECTIVES: Human motion analysis can be applied to the diagnosis of musculoskeletal diseases, rehabilitation therapies, fall detection, and estimation of energy expenditure. To analyze human motion with micro-Doppler signatures measured by radar, a deep learning algorithm is one of the most effective approaches. Because deep learning requires a large data set, the high cost involved in measuring large amounts of human data is an intrinsic problem. The objective of this study is to augment human motion micro-Doppler data employing generative adversarial networks (GANs) to improve the accuracy of human motion classification. METHODS: To test data augmentation provided by GANs, authentic data for 7 human activities were collected using micro-Doppler radar. Each motion yielded 144 data samples. Software including GPU driver, CUDA library, cuDNN library, and Anaconda were installed to train the GANs. Keras-GPU, SciPy, Pillow, OpenCV, Matplotlib, and Git were used to create an Anaconda environment. The data produced by GANs were saved every 300 epochs, and the training was stopped at 3,000 epochs. The images generated from each epoch were evaluated, and the best images were selected. RESULTS: Each data set of the micro-Doppler signatures, consisting of 144 data samples, was augmented to produce 1,472 synthesized spectrograms of 64 × 64. Using the augmented spectrograms, the deep neural network was trained, increasing the accuracy of human motion classification. CONCLUSIONS: Data augmentation to increase the amount of training data was successfully conducted through the use of GANs. Thus, augmented micro-Doppler data can contribute to improving the accuracy of human motion recognition.

Phase portrait analysis of eye movement waveforms in congenital nystagmus eyes / 中华实验眼科杂志

Background The characteristics of eye movement waveforms in congenital nystagmus eyes is so complicated that the time-series waveform can hardly demonstrate the oscillational kinetic property of the eye movement of nystagmus,which is not convenient for the clinical diagnosis and evaluation.The eye movement system is a nonlinear feedback control system,and phase portrait analysis is a useful method in describing the characteristics of movement in a nonlinear system.Objective This study was to establish the phase portrait analysis method of the eye movement waveforms in congenital nystagmus eyes and provide a new technique for the clinical diagnosis and evaluation of congenital nystagmus.Methods A prospective series-case observational study was performed.This study complied with the Declaration of Helsinki and was approved by Ethic Commission of Tianjin Eye Hospital.Written informed consent was obtained from each patient before examination.Twenty-five patients with congenital nystagmus were enrolled and received examination of video-oculography (VOG) in Tianjin Eye Hospital from April 2012 to February 2013,including 12 patients with congenital motor nystagmus (CMN) and 13 patients with latent nystagmus (LN).The VOG data were format-converted and processed by a Matlab routine.VOG-based phase portraits of eye movement cycles were drawn and related parameters were measured from the phase portraits for further analysis and comparison.Main measurement indexes were cycle position shift (CPS),slow phase peak velocity (SPV),standardized slow-phase peak (SSPV),fast phase peak velocity (FPV) and standardized fast-phase peak velocity (SFPV).Two principal types of waveforms,increasing-velocity type and decreasing-velocity type were compared.Results The phase portraits of the waveforms of congenital nystagmus were cycles of reciprocating trajectories.The slow phases were in dense ribbon region,and the fast phases were in sparse annular region,and all the trajectories travelled in clockwise.The CPS,SPV and FPV of increasing-velocity type were (4.646 ± 1.565),(223.821 ± 114.049),(767.481 ±263.560) ° per second,respectively.The CPS,SPV and FPV of decreasing-velocity type were (9.373 ±4.189),(357.531 ± 154.300) and (1 148.706 ±541.362) ° per second,respectively.The SPVs and FPVs of both increasing-velocity type and decreasing-velocity type showed strong correlation with CPS,respectively (the increasing-velocity type:rSPV-CPS =0.685,P=0.000;rFPV-CPS =0.680,P=0.000;the decreasing-velocity type rSPV-CPS =0.783,P =0.000;rFPV-CPS =0.803,P =0.000).FPVs were significantly larger than SPVs in both types of waveforms (t =6.558,P =0.000;t =5.068,P =0.000).The SSPV of increasing-velocity type was (48.062 ± 15.365) ° per second,which was slightly larger than (41.099± 17.027) ° per second of decreasing-velocity type,with no significant difference between them (t=1.070,P=0.296).The SFPV of increasing-velocity type was (171.186±47.825)° per second,which was larger than (125.317-±38.266)° per second of decreasing-velocity type,showing a significant difference between them (t =2.658,P =0.014).Conclusions Phase portraits can visualize the cyclically dynamic features of congenital nystagmus in a direct way.It facilitates the measurement of eye movement amplitude,speed and other parameters.The phase portrait analysis method provides a novel useful tool in the clinical diagnosis and treatment efficacy evaluation of congenital nystagmus.

Implied movement in static images reveals biological timing processing / Movimento implícito em imagens estáticas revelou um processamento biológico do tempo / Movimiento Implícito en Imágenes Estáticas Revelo un Procesamiento Biológico de lo Tiempo

Visual perception is adapted toward a better understanding of our own movements than those of non-conspecifics. The present study determined whether time perception is affected by pictures of different species by considering the evolutionary scale. Static (“S”) and implied movement (“M”) images of a dog, cheetah, chimpanzee, and man were presented to undergraduate students. S and M images of the same species were presented in random order or one after the other (S-M or M-S) for two groups of participants. Movement, Velocity, and Arousal semantic scales were used to characterize some properties of the images. Implied movement affected time perception, in which M images were overestimated. The results are discussed in terms of visual motion perception related to biological timing processing that could be established early in terms of the adaptation of humankind to the environment.

A percepção visual é adaptada para compreender melhor os movimentos da própria espécie do que aqueles de outras espécies. O objetivo deste estudo foi verificar se a percepção temporal seria afetada por fotografias de diferentes espécies de animais levando em consideração a escala evolutiva. Imagens sem (“S”) e com movimento implícito (“M”) de um cachorro, guepardo, chimpanzé e homem foram expostas a estudantes universitários. As imagens S e M de cada espécie foram apresentadas em ordem aleatória ou uma após a outra (S-M ou M-S) para dois grupos de participantes. Escalas Semânticas para Movimento, Velocidade e Arousal foram utilizadas para a caracterização de algumas propriedades das imagens. O movimento implícito afetou a percepção do tempo: as imagens M foram superestimadas. Os resultados foram discutidos em termos da percepção visual de movimento relacionada a um processamento de tempo biológico que pode ter sido estabelecido cedo em termos de adaptação do homem ao meio ambiente.

La percepción visual es adaptada para comprender mejor los movimientos de la misma especie que aquellos de otras especies. Este estudio examinó si la percepción del tiempo se vería afectada por fotografías de diferentes especies de animales, teniendo en cuenta la escala evolutiva. Imágenes sin (“S”) y con movimiento implícito (“M”) de un perro, guepardo, chimpancé y hombre fueron expuestas a estudiantes universitarios. Las imágenes S y M de cada especie se presentaron en orden aleatorio, o una después de la otra (MS o MS), para 2 grupos de participantes. Escalas semánticas para Movimiento, Velocidad y Arousal fueron utilizadas para la caracterización de las imágenes. Movimiento implícito afectó la percepción del tiempo: M imágenes fueron sobreestimadas. Los resultados se discutieron en términos de la percepción visual del movimiento relacionada con lo procesamiento biológico del tiempo que pueda haberse fijado al principio de la adaptación del hombre con el medio ambiente.

Explorando a trajetória espácio-temporal da representação dinâmica de projéteis / Exploring the spatiotemporal trajectory of the dynamic representation of projectiles

Quando é mostrado a observadores humanos um objeto em movimento horizontal que desaparece subitamente, e se instruídos a indicar o local de desaparecimento, emerge sistematicamente um erro para diante na direção do movimento (Desfasamento M) e para baixo na direção da gravidade (Desfasamento O). Ainda que diversos determinantes do fenómeno estejam bem documentados, pouco é ainda sabido acerca do seu curso temporal. O presente estudo procura preencher esta lacuna. Objetos descrevendo movimentos horizontais foram mostrados a participantes instruídos a indicarem o seu local de desaparecimento, usando ou um mouse ou um ponteiro (num ecrã táctil), após um intervalo de retenção variado. Os resultados revelaram uma trajetória ordenada para os erros de localização em função do tempo, passível de ser descrita em duas fases - numa primeira, até cerca de 300ms, os erros progrediram para diante sem qualquer desfasamento vertical; após os 300ms o erro tende a aumentar na direção descendente sem qualquer incremento horizontal. Paralelos deste padrão com tarefas de física intuitiva (Física de Road Runner) e antecedentes na História Pré-Galilaica da Física são referidos e os resultados discutidos no âmbito de uma representação implícita de invariantes físicos na perceção de eventos dinâmicos...

When human observers are shown a horizontally moving target which suddenly disappears and they are further instructed to locate its vanishing position, both forward in the direction of motion (M Displacement) and downward in the direction of gravity (O Displacement), errors of localization typically occur. Though several determinants of those errors have been ascertained, little is known regarding their time course. The present study attempts to fill this gap. Horizontally moving targets were presented and participants instructed to locate their vanishing position, either via a mouse or a pointer (on a touch screen) after a variable time delay. Outcomes revealed an orderly time-dependent trajectory of errors being describable in two stages - during the first 300ms, the errors increased in the direction of motion with a constant vertical error; after 300ms the downward error increased with no further horizontal displacement. Similarities between this pattern and reported results from the Intuitive Physics (Road Runner Physics) and the History of Ancient Physics are noticed and discussed under the notion of an implicit representation of physical invariants in the perception of dynamic events...

Aprendizagem motora baseada em demonstrações de movimento biológico / Motor learning based on biological motion demonstrations

O objetivo deste estudo foi avaliar o processo de aprendizagem motora de uma habilidade complexa da Ginástica Artística a partir da observação de demonstrações de modelos de pontos de luz e vídeo. Dezesseis participantes divididas em grupos dos respectivos modelos executaram um pré-teste, seguido de 100 tentativas de uma parada de mãos, igualmente distribuídas em blocos de 10 tentativas em dois dias, alternando períodos de demonstração e prática, com um teste de retenção após um dia. Cinemática de braço, tronco e perna das participantes possibilitaram análise da semelhança entre a coordenação de cada participante e do modelo e do tempo de movimento; a performance das participantes também foi avaliada por duas especialistas em Ginástica Artística. Ambas as análises indicaram que os grupos não diferiram. Os resultados são discutidos em termos da hipótese de suficiência de informação nos modelos de movimento biológico particularmente aplicada ao processo de aprendizagem de habilidades motoras complexas.

The aim of this study was to evaluate the motor learning process of a complex Artistic Gymnastics skill following demonstrations of point-light and video models. Sixteen participants divided into the respective model groups performed a pre-test and 100 trials of a handstand, equally distributed in blocks of 10 trials in two days, alternating periods of demonstration and practice, with retention test a day later. Participants' kinematics of arm, trunk, and leg was used to analyze the coordination similarities between each participant and the model and movement time; participants' performance was also evaluated by two Artistic Gymnastics experts. Both analyses revealed that the groups did not differ. Results are discussed in terms of the hypothesis of information sufficiency in biological motion models particularly applied to the learning process of complex motor skills.