Neural Suppression Elicited During Motor Imagery Following the Observation of Biological Motion From Point-Light Walker Stimuli

Introduction: Advantageous effects of biological motion (BM) detection, a low-perceptual mechanism that allows the rapid recognition and understanding of spatiotemporal characteristics of movement via salient kinematics information, can be amplified when combined with motor imagery (MI), i.e., the mental simulation of motor acts. According to Jeannerod’s neurostimulation theory, asynchronous firing and reduction of mu and beta rhythm oscillations, referred to as suppression over the sensorimotor area, are sensitive to both MI and action observation (AO) of BM. Yet, not many studies investigated the use of BM stimuli using combined AO-MI tasks. In this study, we assessed the neural response in the form of event-related synchronization and desynchronization (ERD/S) patterns following the observation of point-light-walkers and concordant MI, as compared to MI alone.Methods: Twenty right-handed healthy participants accomplished the experimental task by observing BM stimuli and subsequently performing the same movement using kinesthetic MI (walking, cycling, and jumping conditions). We recorded an electroencephalogram (EEG) with 32 channels and performed time-frequency analysis on alpha (8–13 Hz) and beta (18–24 Hz) frequency bands during the MI task. A two-way repeated-measures ANOVA was performed to test statistical significance among conditions and electrodes of interest.Results: The results revealed significant ERD/S patterns in the alpha frequency band between conditions and electrode positions. Post hoc comparisons showed significant differences between condition 1 (walking) and condition 3 (jumping) over the left primary motor cortex. For the beta band, a significantly less difference in ERD patterns (p < 0.01) was detected only between condition 3 (jumping) and condition 4 (reference).Discussion: Our results confirmed that the observation of BM combined with MI elicits a neural suppression, although just in the case of jumping. This is in line with previous findings of AO and MI (AOMI) eliciting a neural suppression for simulated whole-body movements. In the last years, increasing evidence started to support the integration of AOMI training as an adjuvant neurorehabilitation tool in Parkinson’s disease (PD).Conclusion: We concluded that using BM stimuli in AOMI training could be promising, as it promotes attention to kinematic features and imitative motor learning.

П’ЄЗОДАТЧИК ЯК ЕЛЕМЕНТ УПРАВЛІННЯ СВІТЛОМ ДЛЯ СТВОРЕННЯ ДИЗАЙНУ ДИТЯЧОГО ПРИМІЩЕННЯ

Purpose. Substantiation and creation of automatic lighting control in interactive rooms using piezoelectric converters. The introduction of this technology will significantly reduce energy consumption during the operation of such premises. The addition of further technological solutions based on the use of phosphor coatings and ultraviolet lighting will create a full range of innovative methods of child interaction in the social space.Methodology. The combination of piezo sensors with design elements such as "live" tiles as a trigger mechanism will create the necessary connection between the physical activity of the child and the regulation of light. The modern level of development and complete safety of materials such as phosphors in combination with specially designed point light sources will make it possible to create additional lighting and a field for the imagination of the child. Since the main attention when lighting children's rooms should be directed to the safe stay of the child, the use of light sources under a translucent floor will solve safety issues with a low level of energy consumption.Findings. An experimental study of the methods has proven the feasibility of using the proposed elements for any interactive children's room. The low cost of both equipment and the energy efficiency of all the technologies used is a significant advantage of this project over other developments with a large use of digital gadgets. The ability of create light of different spectral composition and color temperature is analyzed by using color filters and special light sources.Originality. The technologies and techniques presented in this work will be used for the first time to create interactive activities for a child. Separately, each technological solution was applied individually. This project combines separate developments to create a single interactive and light space. A low level of electricity consumption is achieved by using specially designed piezoelectric elements. Replacing standard ceiling lighting with lower (floor) lighting allows you to achieve the desired illumination using luminaires of lower power.Practical value. Recently, it has been proven that digitalization has a negative impact on the emotional state of the child and the only solution to replace it is to switch the child's attention to other more physically active actions. The proposed solutions in the work will allow their to be involved in group trainings. At the same time, the power consumption for obtaining such rooms will be much lower than the rest of the existing ones. The simplicity of the equipment and the possibility of variation during the operation of the premises make it available for creation in any institution of education, medicine, sports, etc.

Numerical Simulation of Friction Stir Spot Welding of Aluminium-6061 and Magnesium AZ-31B

Friction stir spot welding process is a solid state joining process which has attracted great attention due to its ability to join low melting point light weight alloys such as aluminium and magnesium with high efficiency. In order to understand the complex thermo-mechanical joining process involved with friction stir spot welding, a numerical simulation study was done using ABAQUS finite element software. The simulation primarily aims to interpret the effect of a set of process parameters and tool geometry on the workpiece plates. Johnson-Cook damage criteria model was used to obtain the stress and strain distribution on the workpiece consisting of aluminium 6061 and magnesium AZ-31B placed in a lap configuration. Temperature distribution of the workpiece was obtained by simulating a penalty based frictional contact between the tool and the plate. The thermal results showed that the maximum temperatures attained were significantly lower than the melting points of the base materials indicating that the material mixing and joining occurred as a result of superplastic deformation process instead of melting. Change in material flow behaviour was also observed by the model as pin and shoulder geometries changed.

Perceiving fingerspelling via point-light displays: The stimulus and the perceiver both matter

Signed language users communicate in a wide array of sub-optimal environments, such as in dim lighting or from a distance. While fingerspelling is a common and essential part of signed languages, the perception of fingerspelling in varying visual environments is not well understood. Signed languages such as American Sign Language (ASL) rely on visuospatial information that combines hand and bodily movements, facial expressions, and fingerspelling. Linguistic information in ASL is conveyed with movement and spatial patterning, which lends itself well to using dynamic Point Light Display (PLD) stimuli to represent sign language movements. We created PLD videos of fingerspelled location names. The location names were either Real (e.g., KUWAIT) or Pseudo-names (e.g., CLARTAND), and the PLDs showed either a High or a Low number of markers. In an online study, Deaf and Hearing ASL users (total N = 283) watched 27 PLD stimulus videos that varied by Realness and Number of Markers. We calculated accuracy and confidence scores in response to each video. We predicted that when signers see ASL fingerspelled letter strings in a suboptimal visual environment, language experience in ASL will be positively correlated with accuracy and self-rated confidence scores. We also predicted that Real location names would be understood better than Pseudo names. Our findings show that participants were more accurate and confident in response to Real place names than Pseudo names and for stimuli with High rather than Low markers. We also discovered a significant interaction between Age and Realness, which shows that as people age, they can better use outside world knowledge to inform their fingerspelling success. Finally, we examined the accuracy and confidence in fingerspelling perception in sub-groups of people who had learned ASL before the age of four. Studying the relationship between language experience with PLD fingerspelling perception allows us to explore how hearing status, ASL fluency levels, and age of language acquisition affect the core abilities of understanding fingerspelling.

COLOUR PERCEPTION OF LED POINT LIGHT SOURCES IN SCOTOPIC VISION

When stimuli are made sufficiently small, colour-normal individuals report a loss in hue perception, similar to tritanopia. This effect is referred to as small-field tritanopia. The interaction between small-field tritanopia and the rods working in scotopic vision has not been clarified. In this study, the problem is investigated by freely adjusting the hue, lightness, and saturation of the test stimulus to match the colour of the reference stimulus by observers. Three colours on the blackbody radiation trajectory with colour temperatures of 3500K, 5400K, and 11600K were used as reference colours. Each stimulus subtended a diameter of 6' and 10.8'. The 5400K and 11600K stimuli were distributed diagonally from the lower left to the upper right of each reference stimulus in the CIE 1976 u’v’ uniform chromaticity scale diagram. The distribution was similar to those of tritanopia. For the 3500K stimulus, the result did not show the influence of small-field tritanopia.

A time-division correction method for adaptive optics system

An adaptive optics system can measure and compensate the wavefront distortion caused by dynamic disturbance in real time. It is usually used for astronomical observation and other occasions. According to the current technology, it is only suitable for small field of view optical system or point target, but not for ground extended target detection. In order to solve this problem, a correction method is proposed: firstly, the sub aperture image of wavefront sensor is divided into several sub regions, each sub region corresponds to a certain light direction or field angle range; secondly, calculate the offset of the image feature points in each sub region, and an image with good correction effect in a field of view in this direction is obtained; the last step is to measure each sub region one by one and combine these images into a full frame image. Through comparison, it is found that the method proposed in this paper is essentially to divide the extended target into multiple point light sources for correction.