Assessment and comparison of image quality between two real-time sequences for dynamic MRI of distal joints at 3.0 Tesla

BACKGROUND

Real-time sequences allow functional evaluation of various joint structures during a continuous motion and help understand the pathomechanics of underlying musculoskeletal diseases.

PURPOSE

To assess and compare the image quality of the two most frequently used real-time sequences for joint dynamic magnetic resonance imaging (MRI), acquired during finger and ankle joint motion.

MATERIAL AND METHODS

A real-time dynamic acquisition protocol, including radiofrequency (RF)-spoiled and balanced steady-state free precession (bSSFP) sequences, optimized for temporal resolution with similar spatial resolution, was performed using a 3.0-T MRI scanner on 10 fingers and 12 ankles from healthy individuals during active motion. Image quality criteria were evaluated on each time frame and compared between these two sequences. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were determined and compared from regions of interest placed on cortical bone, tendon, fat, and muscle. Visualization of anatomical structures and overall image quality appreciation were rated by two radiologists using a 0-10 grading scale.

RESULTS

Mean CNR was significantly higher with bSSFP sequence compared to RF-spoiled sequence. The grading score was in the range of 5-9.3 and was significantly higher with RF-spoiled sequence for bone and joint evaluation and overall image appreciation on the two joints. The standard deviation for SNR, CNR, and grading score during motion was smaller with RF-spoiled sequence for both the joints. The inter-reader reliability was excellent (>0.75) for evaluating anatomical structures in both sequences.

CONCLUSION

A RF-spoiled real-time sequence is recommended for the in vivo clinical evaluation of distal joints on a 3.0-T MRI scanner.

The turn of the dice: Patrick Hughes' Hollow Dice and Reverspectives

Patrick Hughes' Reverspectives demonstrate the importance of perspective as a source of information about the structure and layout of the three-dimensional (3D) world. More recently, he has created a new work of art-Hollow Dice-in which the actual concave structure of the dice is seen as convex. In this article, we examine the similarities and differences between these two perceptual phenomena as well as attempting to explain how and why they arise. Popular interest in both effects is based on the fact that "what we perceive" does not correspond to "what the reality is." As a consequence, Reverspectives and Hollow Dice are often categorized and labeled as "illusions." However, if we consider the information that is available in patterns of light reaching our eyes-rather than the "actual" 3D structure of the Reverspectives and the Hollow Dice-we are in a better position to explain how the size, the viewing distance, the perspective features, the convexity bias, and observer movements determine what we see when viewing these novel and fascinating visual effects.

Pilot Tone-Triggered MRI for Quantitative Assessment of Cardiac Function, Motion, and Structure

OBJECTIVE

The aim of this study was to test the hypothesis that there are good agreements between cardiac functional and structural indices derived from magnetic resonance imaging (MRI) sequences triggered with pilot tone (PT) and electrocardiogram (ECG).

MATERIALS AND METHODS

Sixteen healthy volunteers (11 male, age 21-76 years) underwent a cardiac MRI scan. Cine MRI, T1, and T2 mapping were acquired by using PT and ECG triggering. Quantitative measurements, including left and right ventricular end-diastolic volume, end-systolic volume, stroke volume, ejection fraction, longitudinal strain, left ventricular T1 and T2 values, left and right atrial longitudinal strain, and maximal/minimal volumes, were measured. The interclass correlation coefficient, coefficient of variation, and Bland-Altman plots were used to evaluate the agreements between measurements derived by MRI sequences triggered with 2 methods.

RESULTS

There were no significant differences among end-diastolic volume, end-systolic volume, stroke volume, ejection fraction, left ventricle mass, T1 and T2 values, or longitudinal strains acquired using PT and ECG. There were good agreements and low variations between the levels of these indices acquired with PT and ECG. Interclass correlation coefficients mainly ranged from 0.73 to 0.98. The coefficients of variation ranged from 1.4% to 22.6%.

CONCLUSIONS

Pilot tone-triggered MRI provides comparable measurements of cardiac function, motion, and structure as ECG-triggered MRI. Pilot tone has the potential to become a backup of ECG gating in cardiovascular imaging.

4D Atlas: Statistical Analysis of the Spatiotemporal Variability in Longitudinal 3D Shape Data

We propose a novel framework to learn the spatiotemporal variability in longitudinal 3D shape data sets, which contain observations of objects that evolve and deform over time. This problem is challenging since surfaces come with arbitrary parameterizations and thus, they need to be spatially registered. Also, different deforming objects, hereinafter referred to as 4D surfaces, evolve at different speeds and thus they need to be temporally aligned. We solve this spatiotemporal registration problem using a Riemannian approach. We treat a 3D surface as a point in a shape space equipped with an elastic Riemannian metric that measures the amount of bending and stretching that the surfaces undergo. A 4D surface can then be seen as a trajectory in this space. With this formulation, the statistical analysis of 4D surfaces can be cast as the problem of analyzing trajectories embedded in a nonlinear Riemannian manifold. However, performing the spatiotemporal registration, and subsequently computing statistics, on such nonlinear spaces is not straightforward as they rely on complex nonlinear optimizations. Our core contribution is the mapping of the surfaces to the space of Square-Root Normal Fields (SRNF) where the [Formula: see text] metric is equivalent to the partial elastic metric in the space of surfaces. Thus, by solving the spatial registration in the SRNF space, the problem of analyzing 4D surfaces becomes the problem of analyzing trajectories embedded in the SRNF space, which has a euclidean structure. In this paper, we develop the building blocks that enable such analysis. These include: (1) the spatiotemporal registration of arbitrarily parameterized 4D surfaces even in the presence of large elastic deformations and large variations in their execution rates; (2) the computation of geodesics between 4D surfaces; (3) the computation of statistical summaries, such as means and modes of variation, of collections of 4D surfaces; and (4) the synthesis of random 4D surfaces. We demonstrate the performance of the proposed framework using 4D facial surfaces and 4D human body shapes.

Wrist motion assessment using Microsoft Azure Kinect DK: A reliability study in healthy individuals

BACKGROUND

Motion analysis systems have been widely used in orthopedics and rehabilitation for diagnostics, patient monitoring and outcome evaluation purposes. Since Microsoft Azure Kinect Developer Kit (DK) had been released, only a few studies were published concerning its usage. However, it has not been used for wrist motion assessments, even though the use of standardized examinations with known reliability, validity and responsiveness remains a constant challenge.

OBJECTIVES

This study aimed to examine the reliability of hand and forearm range of motion (ROM) measurements recorded using new software utilizing the Microsoft Azure Kinect DK.

MATERIAL AND METHODS

Twenty-eight healthy males and 28 healthy females participated in measurements of active ROM for wrist extension, wrist flexion, radial deviation, ulnar deviation, and forearm supination and pronation on 3 separate occasions. Sessions 1 and 2 were carried out on the same day with a 90-minute rest period between each session, while the 3rd session was conducted a week later. Data were recorded simultaneously in both limbs using a custom-made software developed by a software development company (Oleksy Medical & Sports Sciences, Łańcut, Poland) for the purposes of the present study using Microsoft Azure Kinect DK. The assessment of intra-day and inter-day reliability was based on intraclass correlation coefficient (ICC) calculations and interpreted based on commonly used guidelines.

RESULTS

In the group of males, the lowest ICC was 0.846 for intra-day comparisons and 0.816 for inter-day analyses. In the female group, the lowest ICC for intra-day comparisons was 0.826 and exceeded 0.833 for inter-day comparisons.

CONCLUSIONS

The developed software using Microsoft Azure Kinect DK demonstrated high reliability in measuring wrist and forearm active ROM. These promising results support the use of Microsoft Azure Kinect DK in a clinical capacity as a potential hand assessment and rehabilitation tool.

Do you hear what I see? How do early blind individuals experience object motion?

One of the most important tasks for 3D vision is tracking the movement of objects in space. The ability of early blind individuals to understand motion in the environment from noisy and unreliable auditory information is an impressive example of cortical adaptation that is only just beginning to be understood. Here, we compare visual and auditory motion processing, and discuss the effect of early blindness on the perception of auditory motion. Blindness leads to cross-modal recruitment of the visual motion area hMT+ for auditory motion processing. Meanwhile, the planum temporale, associated with auditory motion in sighted individuals, shows reduced selectivity for auditory motion. We discuss how this dramatic shift in the cortical basis of motion processing might influence the perceptual experience of motion in early blind individuals. This article is part of a discussion meeting issue 'New approaches to 3D vision'.

How the brain stays in sync with the real world

The brain can predict the location of a moving object to compensate for the delays caused by the processing of neural signals.

Position representations of moving objects align with real-time position in the early visual response

When interacting with the dynamic world, the brain receives outdated sensory information, due to the time required for neural transmission and processing. In motion perception, the brain may overcome these fundamental delays through predictively encoding the position of moving objects using information from their past trajectories. In the present study, we evaluated this proposition using multivariate analysis of high temporal resolution electroencephalographic data. We tracked neural position representations of moving objects at different stages of visual processing, relative to the real-time position of the object. During early stimulus-evoked activity, position representations of moving objects were activated substantially earlier than the equivalent activity evoked by unpredictable flashes, aligning the earliest representations of moving stimuli with their real-time positions. These findings indicate that the predictability of straight trajectories enables full compensation for the neural delays accumulated early in stimulus processing, but that delays still accumulate across later stages of cortical processing.

The accuracy of object motion perception during locomotion

Human observers are capable of perceiving the motion of moving objects relative to the stationary world, even while undergoing self-motion. Perceiving world-relative object motion is complicated because the local optical motion of objects is influenced by both observer and object motion, and reflects object motion in observer coordinates. It has been proposed that observers recover world-relative object motion using global optic flow to factor out the influence of self-motion. However, object-motion judgments during simulated self-motion are biased, as if the visual system cannot completely compensate for the influence of self-motion. Recently, Xie et al. demonstrated that humans are capable of accurately judging world-relative object motion when self-motion is real, actively generated by walking, and accompanied by optic flow. However, the conditions used in that study differ from those found in the real world in that the moving object was a small dot with negligible optical expansion that moved at a fixed speed in retinal (rather than world) coordinates and was only visible for 500 ms. The present study investigated the accuracy of object motion perception under more ecologically valid conditions. Subjects judged the trajectory of an object that moved through a virtual environment viewed through a head-mounted display. Judgments exhibited bias in the case of simulated self-motion but were accurate when self-motion was real, actively generated, and accompanied by optic flow. The findings are largely consistent with the conclusions of Xie et al. and demonstrate that observers are capable of accurately perceiving world-relative object motion under ecologically valid conditions.

Differences in Brain Activity and Body Movements Between Virtual Reality and Offline Exercise: Randomized Crossover Trial

BACKGROUND

Virtual reality (VR) has been suggested to be effective at enhancing physical exercises because of its immersive characteristics. However, few studies have quantitatively assessed the range of motion and brain activity during VR exercises.

OBJECTIVE

We hypothesized that 3D immersive VR could stimulate body movement and brain activity more effectively than standard exercises and that the increased range of motions during 3D immersive VR exercises would be associated with orbitofrontal activation.

METHODS

A randomized crossover trial was conducted to compare exercises with and without VR. A total of 24 healthy males performed the same motions when exercising with and without 3D immersive VR, and the recorded videos were used for motion analysis. Hemodynamic changes in the prefrontal cortex were assessed using functional near-infrared spectroscopy.

RESULTS

There were significant differences in the total angle (z=-2.31; P=.02), length (z=-2.78; P=.005), calorie consumption (z=-3.04; P=.002), and change in accumulated oxygenated hemoglobin within the right orbitofrontal cortex (F^1,94=9.36; P=.003) between the VR and offline trials. Hemodynamic changes in the right orbitofrontal cortex were positively correlated with the total angle (r=0.45; P=.001) and length (r=0.38; P=.007) in the VR exercise; however, there was no significant correlation in the offline trial.

CONCLUSIONS

The results of this study suggest that 3D immersive VR exercise effectively increases the range of motion in healthy individuals in relation to orbitofrontal activation.

TRIAL REGISTRATION

Clinical Research Information Service KCT0008021; https://cris.nih.go.kr/cris/search/detailSearch.do/23671.

Simulation-based prediction of bone healing and treatment recommendations for lower leg fractures: Effects of motion, weight-bearing and fibular mechanics

Despite recent experimental and clinical progress in the treatment of tibial and fibular fractures, in clinical practice rates of delayed bone healing and non-union remain high. The aim of this study was to simulate and compare different mechanical conditions after lower leg fractures to assess the effects of postoperative motion, weight-bearing restrictions and fibular mechanics on the strain distribution and the clinical course. Based on the computed tomography (CT) data set of a real clinical case with a distal diaphyseal tibial fracture, a proximal and a distal fibular fracture, finite element simulations were run. Early postoperative motion data, recorded via an inertial measuring unit system and pressure insoles were recorded and processed to study strain. The simulations were used to compute interfragmentary strain and the von Mises stress distribution of the intramedullary nail for different treatments of the fibula, as well as several walking velocities (1.0 km/h; 1.5 km/h; 2.0 km/h) and levels of weight-bearing restriction. The simulation of the real treatment was compared to the clinical course. The results show that a high postoperative walking speed was associated with higher loads in the fracture zone. In addition, a larger number of areas in the fracture gap with forces that exceeded beneficial mechanical properties longer was observed. Moreover, the simulations showed that surgical treatment of the distal fibular fracture had an impact on the healing course, whereas the proximal fibular fracture barely mattered. Weight-bearing restrictions were beneficial in reducing excessive mechanical conditions, while it is known that it is difficult for patients to adhere to partial weight-bearing recommendations. In conclusion, it is likely that motion, weight bearing and fibular mechanics influence the biomechanical milieu in the fracture gap. Simulations may improve decisions on the choice and location of surgical implants, as well as give recommendations for loading in the postoperative course of the individual patient.

Motion-robust, multi-slice, real-time MR thermometry for MR-guided thermal therapy in abdominal organs

PURPOSE

To develop an effective and practical reconstruction pipeline to achieve motion-robust, multi-slice, real-time MR thermometry for monitoring thermal therapy in abdominal organs.

METHODS

The application includes a fast spiral magnetic resonance imaging (MRI) pulse sequence and a real-time reconstruction pipeline based on multi-baseline proton resonance frequency shift (PRFS) method with visualization of temperature imaging. The pipeline supports multi-slice acquisition with minimal reconstruction lag. Simulations with a virtual motion phantom were performed to investigate the influence of the number of baselines and respiratory rate on the accuracy of temperature measurement. Phantom experiments with ultrasound heating were performed using a custom-made motion phantom to evaluate the performance of the pipeline. Lastly, experiments in healthy volunteers (N = 2) without heating were performed to evaluate the accuracy and stability of MR thermometry in abdominal organs (liver and kidney).

RESULTS

The multi-baseline approach with greater than 25 baselines resulted in minimal temperature errors in the simulation. Phantom experiments demonstrated a 713 ms update time for 3-slice acquisitions. Temperature maps with 30 baselines showed clear temperature distributions caused by ultrasound heating in the respiratory phantom. Finally, the pipeline was evaluated with physiologic motions in healthy volunteers without heating, which demonstrated the accuracy (root mean square error [RMSE]) of 1.23  ±   0.18 °C (liver) and 1.21  ±   0.17 °C (kidney) and precision of 1.13  ±   0.11 °C (liver) and 1.16  ±   0.15 °C (kidney) using 32 baselines.

CONCLUSIONS

The proposed real-time acquisition and reconstruction pipeline allows motion-robust, multi-slice, real-time temperature monitoring within the abdomen during free breathing.

Seeing Things: A Community Science Investigation into Motion Illusion Susceptibility in Domestic Cats (Felis silvestris catus) and Dogs (Canis lupus familiaris)

Illusions-visual fields that distort perception-can inform the understanding of visual perception and its evolution. An example of one such illusion, the Rotating Snakes illusion, causes the perception of motion in a series of static concentric circles. The current study investigated pet dogs' and cats' perception of the Rotating Snakes illusion in a community science paradigm. The results reveal that neither species spent significantly more time at the illusion than at either of the controls, failing to indicate susceptibility to the illusion. Specific behavioral data at each stimulus reveal that the most common behaviors of both species were Inactive and Stationary, while Locomotion and Pawing were the least common, supporting the finding that susceptibility may not be present. This study is the first to examine susceptibility to the Rotating Snakes illusion in dogs, as well as to directly compare the phenomenon between dogs and cats. We suggest future studies might consider exploring alternative methods in testing susceptibility to motion illusions in non-human animals.

Pattern Motion Direction Is Encoded in the Population Activity of Macaque Area MT

Direction selective neurons in macaque primary visual cortex are narrowly tuned for orientation, and are thus afflicted by the aperture problem. At the next stage of motion processing, in the middle temporal (MT) area, some cells appear to solve this problem, responding to the pattern motion direction of plaids. Models have been proposed to account for this computation, but they do not replicate the diversity of responses observed in MT. We recorded from 386 cells in area MT of two male macaques, while presenting a wide range of random-line stimuli and their compositions into noise plaids. As we broadened the range of stimuli used to probe the cells, yielding ever more challenging conditions for extracting pattern motion, the diversity of the responses observed increased, and the fraction of cells that faithfully encoded pattern motion direction shrank. However, we show here that a pattern motion signal is present at the population level. We identified four mechanisms, one never proposed before, that together might account for the observed diversity in single-cell responses. Pattern motion is thus extracted in area MT, but it is encoded across the population, and not in a small subset of pattern neurons.SIGNIFICANCE STATEMENT Some neurons in the middle temporal area of macaques solve the aperture problem, signaling the direction of motion of complex patterns. As the number of pattern types used to probe this mechanism is increased, fewer and fewer cells retain this capability. We show here that different cells fail in different ways, and that simply summing their responses averages away their failures, yielding a clear pattern motion signal. Similar encodings, which unequivocally violate the "neuron as a feature detector" hypothesis that has dominated sensory processing theories for the past 50 years, might apply throughout the brain.

Motion opponency at the middle temporal cortex: Preserved motion information and the effect of perceptual learning

Motion opponency, first observed within the primate middle temporal cortex (MT), refers to the suppressing effect of opposite motion directions on neuronal activity. Namely, when opposing motion directional signals stimulate an MT neuron's receptive field, this neuron's response is comparable with that induced by flicker noise. Under such suppression, it is unknown whether any directional information is still represented at MT. In this study, we applied support vector machine (SVM) learning to human functional magnetic resonance imaging data to investigate if any motion defined orientation information was still available from suppressed MT. We found that, at least at the level of ±45° discrimination, such orientation information was still available. Interestingly, after behavioural perceptual learning that improved human discrimination of fine orientation discrimination (e.g. 42° vs. 48°) using the MT-suppressive motion stimuli, the SVM discrimination of ±45° worsened when functional magnetic resonance imaging (fMRI) signals at post-learning MT were used. This result is consistent with findings in Thompson et al. (2013) that, post-perceptual learning, MT suppression was not released, suggesting that motion opponency was perhaps functionally too important for perceptual learning to overcome.

Moderate reliability of the lateral step down test amongst experienced and novice physical therapists

BACKGROUND/INTRODUCTION

The lateral step-down test is used to appraise movement quality in patients with patellofemoral pain (PFP), however, it is unclear if reliability of the test is affected by physical therapist experience.

OBJECTIVE

Determine if there is a difference in reliability between 'experienced' and 'novice' physical therapists appraising movement quality of patients with PFP during the lateral step-down test.

METHODS

Three 'experienced' and 3 'novice' physical therapists analyzed movement quality of 22 participants [mean age (SD) 28.25 (6.5) years] with PFP. Physical therapists viewed two-dimensional videos of participants performing the lateral step-down test and appraised the quality with a score (0-1 = 'good'; 2-3 = 'fair', and 4-5 = 'poor') at baseline and 1 week. Inter- and intra-rater reliability were calculated with kappa and percent agreement. Differences between the groups were assessed with the chi-square test with an a priori alpha level of < 0.05.

RESULTS

Inter- and intra-rater reliability ranged from fair to moderate (ĸ = 0.40-0.65). There was no difference in reliability between 'experienced' and 'novice' physical therapists at baseline (p = .13) or 1 week post testing (p = .94).

CONCLUSIONS

There was no difference in reliability between 'experienced' and 'novice' physical therapists using categories to appraise movement quality during the lateral step-down test for patients with chronic PFP.

Motility Assessment of Ram Spermatozoa

For successful fertilisation to occur, spermatozoa need to successfully migrate through the female reproductive tract and penetrate the oocyte. Predictably, poor sperm motility has been associated with low rates of fertilisation in many mammalian species, including the ram. As such, motility is one of the most important parameters used for in vitro evaluation of ram sperm quality and function. This review aims to outline the mechanical and energetic processes which underpin sperm motility, describe changes in motility which occur as a result of differences in sperm structure and the surrounding microenvironment, and assess the effectiveness of the various methods used to assess sperm motility in rams. Methods of subjective motility estimation are convenient, inexpensive methods widely used in the livestock industries, however, the subjective nature of these methods can make them unreliable. Computer-assisted sperm analysis (CASA) technology accurately and objectively measures sperm motility via two-dimensional tracing of sperm head motion, making it a popular method for sperm quality assurance in domesticated animal production laboratories. Newly developed methods of motility assessment including flagellar tracing, three-dimensional sperm tracing, in vivo motility assessment, and molecular assays which quantify motility-associated biomarkers, enable analysis of a new range of sperm motion parameters with the potential to reveal new mechanistic insights and improve ram semen assessment. Experimental application of these technologies is required to fully understand their potential to improve semen quality assessment and prediction of reproductive success in ovine artificial breeding programs.

Eukaryotic CRFK Cells Motion Characterized with Atomic Force Microscopy

We performed a time-lapse imaging with atomic force microscopy (AFM) of the motion of eukaryotic CRFK (Crandell-Rees Feline Kidney) cells adhered onto a glass surface and anchored to other cells in culture medium at 37 °C. The main finding is a gradient in the spring constant of the actomyosin cortex along the cells axis. The rigidity increases at the rear of the cells during motion. This observation as well as a dramatic decrease of the volume suggests that cells may organize a dissymmetry in the skeleton network to expulse water and drive actively the rear edge.

Promoting Adherence to Joint Exercise Using the Donation Model: Proof via a Motion-Detecting Mobile Exercise Coaching Application

PURPOSE

Maintaining or increasing user adherence to digital healthcare services is of great concern to service providers. This study aims to verify whether the donation model is an effective strategy to increase adherence to physical exercise using a mobile application.

MATERIALS AND METHODS

A total of 5618 users of a motion-detecting mobile exercise coaching application participated in a donation or self-reward exercise challenge with the same exercise protocol. The workout consisted of 50 squats daily for 14 days. The user's exercise was monitored through a smartphone camera, providing real-time visual and audio feedback. In the donation group, 6 USD was donated to the economically disadvantaged if a participant completed their workout each day. In the self-reward group, three people who completed the program and 20 people who completed ≥12 days of exercise were randomly selected and provided with goods worth 60 USD and 4.3 USD of online currency, respectively.

RESULTS

The average daily exercise completion rate (% of participants who completed daily exercise) in the donation group was 1.8 times higher than that of the self-reward group (donation, 41.7%; self-reward, 22.7%; p<0.0001). The donation group completed more days of the program (donation, 5.8; self-reward, 3.2; p<0.0001). The completion rate of both groups decreased with time and decreased most on day two (donation, -9.9%; self-reward, -14.5%).

CONCLUSION

The donation model effectively promoted adherence to mobile app-based exercise. This donation model is expected to effectively enhance user adherence to digital healthcare services.

The roles of motion, gesture, and embodied action in the processing of mathematical concepts

This article discusses perspective and frame of reference in the metaphorical description of mathematical concepts in terms of motions, gestures, and embodied actions. When a mathematical concept is described metaphorically in terms of gestures, embodied actions, or fictive motions, the motor system comes into play to ground and understand that concept. Every motion, gesture, or embodied action involves a perspective and a frame of reference. The flexibility in taking perspective and frame of reference allows people to embody a mathematical concept or idea in various ways. Based on the findings of past studies, it is suggested that the graphical representation of a mathematical concept may activate those areas of the motor system that are involved in the production of that graphical representation. This is supported by studies showing that when observers look at a painting or handwritten letters, they simulate the painter's or writer's hand movements during painting or writing. Likewise, the motor system can contribute to the grounding of abstract mathematical concepts, such as functions, numbers, and arithmetic operations.

Stress Distribution on Spinal Cord According to Type of Laminectomy for Large Focal Cervical Ossification of Posterior Longitudinal Ligament Based on Finite Element Method

Most studies on the ossification of the posterior longitudinal ligament (OPLL) using the finite element method were conducted in the neutral state, and the resulting decompression was judged to be good. As these studies do not reflect the actual behavior of the cervical spine, this study conducted an analysis in the neutral state and a biomechanical analysis during flexion and extension behaviors. After validation via the construction of an intact cervical spine model, the focal OPLL model was inserted into the C4–C5 segment and a simulation was performed. The neutral state was shown by applying a fixed condition to the lower part of the T1 and Y-axis fixed condition of the spinal cord and simulating spinal cord compression with OPLL. For flexion and extension simulation, a ±30-degree displacement was additionally applied to the top of the C2 dens. Accordingly, it was confirmed that spinal cord decompression did not work well during the flexion and extension behaviors, but rather increased. Thus, if patients with focal OPLL inevitably need to undergo posterior decompression, additional surgery using an anterior approach should be considered.

Reduction of Motion Artifacts in Functional Connectivity Resulting from Infrequent Large Motion

Introduction: Subject head motion is an ongoing challenge in functional magnetic resonance imaging, particularly in the estimation of functional connectivity. Infants (1-month old) scanned during nonsedated sleep often have occasional but large movements of several millimeters separated by periods with relatively little movement. This results in residual signal changes even after image realignment and can distort estimates of functional connectivity. A new motion correction technique, JumpCor, is introduced to reduce the effects of this motion and compared to other existing techniques. Methods: Different approaches for reducing residual motion artifacts after image realignment were compared both in actual and simulated data: JumpCor, regressing out the estimated subject motion, and regressing out the average white matter, cerebrospinal fluid (CSF), and global signals and their temporal derivatives. Results: Motion-related signal changes resulting from infrequent large motion were significantly reduced both by regressing out the estimated motion parameters and by JumpCor. Furthermore, JumpCor significantly reduced artifacts and improved the quality of functional connectivity estimates when combined with typical preprocessing approaches. Discussion: Motion-related signal changes resulting from occasional large motion can be effectively corrected using JumpCor and to a certain extent also by regressing out the estimated motion. This technique should reduce the data loss in studies where participants exhibit this type of motion, such as sleeping infants.

The induced motion effect is a high-level visual phenomenon: Psychophysical evidence

Induced motion is the illusory motion of a target away from the direction of motion of the unattended background. If it is a result of assigning background motion to self-motion and judging target motion relative to the scene as suggested by the flow parsing hypothesis then the effect must be mediated in higher levels of the visual motion pathway where self-motion is assessed. We provide evidence for a high-level mechanism in two broad ways. Firstly, we show that the effect is insensitive to a set of low-level spatial aspects of the scene, namely, the spatial arrangement, the spatial frequency content and the orientation content of the background relative to the target. Secondly, we show that the effect is the same whether the target and background are composed of the same kind of local elements-one-dimensional (1D) or two-dimensional (2D)-or one is composed of one, and the other composed of the other. The latter finding is significant because 1D and 2D local elements are integrated by two different mechanisms so the induced motion effect is likely to be mediated in a visual motion processing area that follows the two separate integration mechanisms. Area medial superior temporal in monkeys and the equivalent in humans is suggested as a viable site. We present a simple flow-parsing-inspired model and demonstrate a good fit to our data and to data from a previous induced motion study.

Animal eMotion, or the emotional evaluation of moving animals

Responding adequately to the behaviour of human and non-human animals in our environment has been crucial for our survival. This is also reflected in our exceptional capacity to detect and interpret biological motion signals. However, even though our emotions have specifically emerged as automatic adaptive responses to such vital stimuli, few studies investigated the influence of biological motion on emotional evaluations. Here, we test how the motion of animals affects emotional judgements by contrasting static animal images and videos. We investigated this question (1) in non-fearful observers across many different animals, and (2) in observers afraid of particular animals across four types of animals, including the feared ones. In line with previous studies, we find an idiosyncratic pattern of evoked emotions across different types of animals. These emotions can be explained to different extents by regression models based on relevant predictor variables (e.g. familiarity, dangerousness). Additionally, our findings show a boosting effect of motion on emotional evaluations across all animals, with an additional increase in (negative) emotions for moving feared animals (except snakes). We discuss implications of our results for experimental and clinical research and applications, highlighting the importance of experiments with dynamic and ecologically valid stimuli.

The effect of rheumatoid arthritis on upper extremity functions: A kinematic perspective

AIM

To examine the global upper extremity kinematics in 3D while performing "jar opening motion" in Rheumatoid Arthritis (RA) and to compare these with healthy individuals.

METHOD

Twenty-four women (12 healthy, 12 RA) were included. Evaluations were made with a JAMAR dynamometer, Health Assessment Questionnaire, and 3D kinematic analysis of global upper extremity during "jar opening motion." The time taken during "jar opening motion" was analyzed in 2 parts (Part 1, Part 2), with total time: part 1 + part 2. In addition, shoulder-to-table distance; elbow flexion angle; wrist extension angle; the area scanned and angular rotation by arm, forearm and hand were used in the analysis.

RESULTS

Between groups, there was a statistical difference in: bilateral hand grip strength; part 1, part 2, total time; shoulder-to-table distance; elbow flexion angle; the area scanned by hand; angular rotation of arm and hand in favor of the healthy group (P < .05). In stepwise multiple regression analysis, the most predictive variable for disability was elbow flexion, explaining 53.9% of disability.

CONCLUSION

Compared to healthy individuals, individuals with RA have slower motion, more elbow flexion, less hand grip strength, circular pattern in hand, rotation in arm and hand. Increased disability may result in greater load on elbow flexion.

High Responsivity Thermopile Sensors Featuring a Mosaic Structure

This paper presents a detailed analysis of a micromachined thermopile detector featuring high responsivity and a versatile mosaic structure, based on 128 60 µm × 60 µm pixels connected in series and/or in parallel. The mosaic structure is based on the one employed for the thermal sensor known as TMOS, which consists of a CMOS-SOI transistor embedded in a suspended and thermally isolated absorbing membrane, released through microelectro mechanical system (MEMS) post-processing. Two versions of the thermopile detector, featuring different series/parallel connections, are presented and were experimentally characterized. The most performant of the two achieved 2.7 × 104 V/W responsivity. The thermopile sensors' performances are compared to that of the TMOS sensor, adopting different configurations, and their application as proximity detectors was verified through measurements.

Flexible Non-contact Electrodes for Wearable Biosensors System on Electrocardiogram Monitoring in Motion

Electrocardiogram (ECG) is a critical physiological indicator that contains abundant information about human heart activities. However, it is a kind of weak low-frequency signal, which is easy to be interfered by various noises. Therefore, wearable biosensors (WBS) technique is introduced to overcome this challenge. A flexible non-contact electrode is proposed for wearable biosensors (WBS) system, which is made up of flexible printed circuits materials, and can monitor the ECG signals during exercise for a long time. It uses the principle of capacitive coupling to obtain high-quality signals, and reduces the impact of external noise through active shielding; The results showed that the proposed non-contact electrode was equivalent to a medical wet electrode. The correlation coefficient was as high as 99.70 ± 0.30% when the subject was resting, while it was as high as 97.53 ± 1.80% during exercise. High-quality ECG could still be collected at subjects walking at 7 km/h. This study suggested that the proposed flexible non-contact electrode would be a potential tool for wearable biosensors for medical application on long-term monitoring of patients' health and provide athletes with physiological signal measurements.

Dynamic Seat Assessment for Enabled Restlessness of Children with Learning Difficulties

Children with Attention-Deficit/Hyperactivity Disorder (ADHD) face a range of learning difficulties in the school environment, thus several strategies have been developed to enhance or optimise their performance in school. One possible way is to actively enable appropriate restlessness using dynamic seats. In this paper, an assessment of the efficacy of a dynamic seat while solving school task is presented and compared to classic chair and therapy ball. To test the effectiveness of active seat, a study that examined task solving performance while observing the intensity of movement, in-seat behaviour and psychophysiological responses (electrodermal activity, facial temperature) was designed. A total of 23 school-aged children participated in the study, 11 children with a combined type of ADHD and 12 children without disorders. Children with ADHD achieved the best results when sitting in the active seat, where the most intense movement and best in-seat behaviour was observed. At the same time, psychophysiological parameters indicate that when performing better at the task children with ADHD were not too challenged and were consequently less agitated. Results have suggested that for a better cognitive performance of children with ADHD, it is crucial to provide a comfortable and pleasant workspace that enables them the right amount of restlessness.

Review of Real-Time Biomechanical Feedback Systems in Sport and Rehabilitation

Real-time biomechanical feedback (BMF) is a relatively new area of research. The potential of using advanced technology to improve motion skills in sport and accelerate physical rehabilitation has been demonstrated in a number of studies. This paper provides a literature review of BMF systems in sports and rehabilitation. Our motivation was to examine the history of the field to capture its evolution over time, particularly how technologies are used and implemented in BMF systems, and to identify the most recent studies showing novel solutions and remarkable implementations. We searched for papers in three research databases: Scopus, Web of Science, and PubMed. The initial search yielded 1167 unique papers. After a rigorous and challenging exclusion process, 144 papers were eventually included in this report. We focused on papers describing applications and systems that implement a complete real-time feedback loop, which must include the use of sensors, real-time processing, and concurrent feedback. A number of research questions were raised, and the papers were studied and evaluated accordingly. We identified different types of physical activities, sensors, modalities, actuators, communications, settings and end users. A subset of the included papers, showing the most perspectives, was reviewed in depth to highlight and present their innovative research approaches and techniques. Real-time BMF has great potential in many areas. In recent years, sensors have been the main focus of these studies, but new types of processing devices, methods, and algorithms, actuators, and communication technologies and protocols will be explored in more depth in the future. This paper presents a broad insight into the field of BMF.

Exploring the Common Mechanisms of Motion-Based Visual Prediction

Human vision supports prediction for moving stimuli. Here we take an individual differences approach to investigate whether there could be a common processing rate for motion-based visual prediction across diverse motion phenomena. Motion Induced Spatial Conflict (MISC) refers to an incongruity arising from two edges of a combined stimulus, moving rigidly, but with different apparent speeds. This discrepancy induces an illusory jitter that has been attributed to conflict within a motion prediction mechanism. Its apparent frequency has been shown to correlate with the frequency of alpha oscillations in the brain. We asked what other psychophysical measures might correlate positively with MISC frequency. We measured the correlation between MISC jitter frequency and another three measures that might be linked to motion-based spatial prediction. We demonstrate that the illusory jitter frequency in MISC correlates significantly with the accrual rate of the Motion Induced Position Shift (MIPS) effect - the well-established observation that a carrier movement in a static envelope of a Gabor target leads to an apparent position shift of the envelope in the direction of motion. We did not observe significant correlations with the other two measures - the Adaptation Induced Spatial Shift accrual rate (AISS) and the Smooth Motion Threshold (SMT). These results suggest a shared perceptual rate between MISC and MIPS, implying a common periodic mechanism for motion-based visual prediction.

Caricatured facial movements enhance perception of emotional facial expressions

Although faces “in the wild” constantly undergo complicated movements, humans adeptly perceive facial identity and expression. Previous studies, focusing mainly on identity, used photographic caricature to show that distinctive form increases perceived dissimilarity. We tested whether distinctive facial movements showed similar effects, and we focussed on both perception of expression and identity. We caricatured the movements of an animated computer head, using physical motion metrics extracted from videos. We verified that these “ground truth” metrics showed the expected effects: Caricature increased physical dissimilarity between faces differing in expression and those differing in identity. Like the ground truth dissimilarity, participants’ dissimilarity perception was increased by caricature when faces differed in expression. We found these perceived dissimilarities to reflect the “representational geometry” of the ground truth. However, neither of these findings held for faces differing in identity. These findings replicated across two paradigms: pairwise ratings and multiarrangement. In a final study, motion caricature did not improve recognition memory for identity, whether manipulated at study or test. We report several forms of converging evidence for spatiotemporal caricature effects on dissimilarity perception of different expressions. However, more work needs to be done to discover what identity-specific movements can enhance face identification.

The Role of Specular Reflections and Illumination in the Perception of Thickness in Solid Transparent Objects

Specular reflections and refractive distortions are complex image properties of solid transparent objects, but despite this complexity, we readily perceive the 3D shapes of these objects (e.g., glass and clear plastic). We have found in past work that relevant sources of scene complexity have differential effects on 3D shape perception, with specular reflections increasing perceived thickness, and refractive distortions decreasing perceived thickness. In an object with both elements, such as glass, the two optical properties may complement each other to support reliable perception of 3D shape. We investigated the relative dominance of specular reflection and refractive distortions in the perception of shape. Surprisingly, the ratio of specular reflection to refractive component was almost equal to that of ordinary glass and ice, which promote correct percepts of 3D shape. The results were also explained by the variance in local RMS contrast in stimulus images but may depend on overall luminance and contrast of the surrounding light field.

Measuring Strain in Diffusion-Weighted Data Using Tagged Magnetic Resonance Imaging

Accurate strain measurement in a deforming organ has been essential in motion analysis using medical images. In recent years, internal tissue's in vivo motion and strain computation has been mostly achieved through dynamic magnetic resonance (MR) imaging. However, such data lack information on tissue's intrinsic fiber directions, preventing computed strain tensors from being projected onto a direction of interest. Although diffusion-weighted MR imaging excels at providing fiber tractography, it yields static images unmatched with dynamic MR data. This work reports an algorithm workflow that estimates strain values in the diffusion MR space by matching corresponding tagged dynamic MR images. We focus on processing a dataset of various human tongue deformations in speech. The geometry of tongue muscle fibers is provided by diffusion tractography, while spatiotemporal motion fields are provided by tagged MR analysis. The tongue's deforming shapes are determined by segmenting a synthetic cine dynamic MR sequence generated from tagged data using a deep neural network. Estimated motion fields are transformed into the diffusion MR space using diffeomorphic registration, eventually leading to strain values computed in the direction of muscle fibers. The method was tested on 78 time volumes acquired during three sets of specific tongue deformations including both speech and protrusion motion. Strain in the line of action of seven internal tongue muscles was extracted and compared both intra- and inter-subject. Resulting compression and stretching patterns of individual muscles revealed the unique behavior of individual muscles and their potential activation pattern.

Extension of Dancer's Legs: Increasing Angles Show Motion

Usain Bolt’s Lightning Bolt pose, one arm highly extended to one side, suggests action. Likewise, static pictures of animals, legs extended, show animation. We tested a new cue for motion perception—extension—and in particular extension of dancer’s legs. An experiment with pictures of a dancer finds larger angles between the legs suggest greater movement, especially with in-air poses and in lateral views. Leg positions graded from simply standing to very difficult front and side splits. Liking ratings (a small range) were more related to Difficulty ratings (a large range) than Movement ratings (a moderate range).

The Validity of Wireless Earbud-Type Wearable Sensors for Head Angle Estimation and the Relationships of Head with Trunk, Pelvis, Hip, and Knee during Workouts

The present study was performed to investigate the validity of a wireless earbud-type inertial measurement unit (Ear-IMU) sensor used to estimate head angle during four workouts. In addition, relationships between head angle obtained from the Ear-IMU sensor and the angles of other joints determined with a 3D motion analysis system were investigated. The study population consisted of 20 active volunteers. The Ear-IMU sensor measured the head angle, while a 3D motion analysis system simultaneously measured the angles of the head, trunk, pelvis, hips, and knees during workouts. Comparison with the head angle measured using the 3D motion analysis system indicated that the validity of the Ear-IMU sensor was very strong or moderate in the sagittal and frontal planes. In addition, the trunk angle in the frontal plane showed a fair correlation with the head angle determined with the Ear-IMU sensor during a single-leg squat, reverse lunge, and standing hip abduction; the correlation was poor in the sagittal plane. Our results indicated that the Ear-IMU sensor can be used to directly estimate head motion and indirectly estimate trunk motion.

Form and Function in Information for Visual Perception

Visual perception involves spatially and temporally coordinated variations in diverse physical systems: environmental surfaces and symbols, optical images, electro-chemical activity in neural networks, muscles, and bodily movements—each with a distinctly different material structure and energy. The fundamental problem in the theory of perception is to characterize the information that enables both perceptual awareness and real-time dynamic coordination of these diverse physical systems. Gibson's psychophysical and ecological conception of this problem differed from that of mainstream science both then and now. The present article aims to incorporate Gibson's ideas within a general conception of information for visual perception. We emphasize the essential role of spatiotemporal form, in contrast with symbolic information. We consider contemporary understanding of surface structure, optical images, and optic flow. Finally, we consider recent evidence about capacity limitations on the rate of visual perception and implications for the ecology of vision.

Visual search in naturalistic scenes from foveal to peripheral vision: A comparison between dynamic and static displays

How important foveal, parafoveal, and peripheral vision are depends on the task. For object search and letter search in static images of real-world scenes, peripheral vision is crucial for efficient search guidance, whereas foveal vision is relatively unimportant. Extending this research, we used gaze-contingent Blindspots and Spotlights to investigate visual search in complex dynamic and static naturalistic scenes. In Experiment 1, we used dynamic scenes only, whereas in Experiments 2 and 3, we directly compared dynamic and static scenes. Each scene contained a static, contextually irrelevant target (i.e., a gray annulus). Scene motion was not predictive of target location. For dynamic scenes, the search-time results from all three experiments converge on the novel finding that neither foveal nor central vision was necessary to attain normal search proficiency. Since motion is known to attract attention and gaze, we explored whether guidance to the target was equally efficient in dynamic as compared to static scenes. We found that the very first saccade was guided by motion in the scene. This was not the case for subsequent saccades made during the scanning epoch, representing the actual search process. Thus, effects of task-irrelevant motion were fast-acting and short-lived. Furthermore, when motion was potentially present (Spotlights) or absent (Blindspots) in foveal or central vision only, we observed differences in verification times for dynamic and static scenes (Experiment 2). When using scenes with greater visual complexity and more motion (Experiment 3), however, the differences between dynamic and static scenes were much reduced.

Real-Time Exercise Feedback through a Convolutional Neural Network: A Machine Learning-Based Motion-Detecting Mobile Exercise Coaching Application

PURPOSE

Mobile applications are widely used in the healthcare market. This study aimed to determine whether exercise using a machine learning-based motion-detecting mobile exercise coaching application (MDMECA) is superior to video streaming-based exercise for improving quality of life and decreasing lower back pain.

MATERIALS AND METHODS

The same 14-day daily workout program consisting of five exercises was performed by 104 participants using the MDMECA and another 72 participants using video streaming. The Medical Outcomes Study Short Form 36-Item Health Survey (SF-36) and lower back pain scores were assess as pre- and post-workout measurements. Scores for the treatment-satisfaction subscale of the visual analog scale (TS-VAS), intention to use a disease-oriented exercise program, intention to recommend the program to others, and available expenses for a disease-oriented exercise program were determined after the workout.

RESULTS

The MDMECA group showed a higher increase in SF-36 score (MDMECA, 9.10; control, 1.09; p<0.01) and a greater reduction in lower back pain score (MDMECA, -0.96; control, -0.26; p<0.01). Scores for TS-VAS, intention to use a disease-oriented exercise program, and intention to recommend the program to others were all higher (p<0.01) in the MDMECA group. However, the available expenses for a disease-oriented program were not significantly different between the two groups.

CONCLUSION

The MDMECA is more effective than video streaming-based exercise in increasing exercise adherence, improving QoL, and reducing lower back pain. MDMECAs could be promising tools of use to achieve better medical outcomes and higher treatment satisfaction.

Multimodal neuroimaging in pediatric type 1 diabetes: a pilot multisite feasibility study of acquisition quality, motion, and variability

Type 1 diabetes (T1D) affects over 200,000 children and is associated with an increased risk of cognitive dysfunction. Prior imaging studies suggest the neurological changes underlying this risk are multifactorial, including macrostructural, microstructural, and inflammatory changes. However, these studies have yet to be integrated, limiting investigation into how these phenomena interact. To better understand these complex mechanisms of brain injury, a well-powered, prospective, multisite, and multimodal neuroimaging study is needed. We take the first step in accomplishing this with a preliminary characterization of multisite, multimodal MRI quality, motion, and variability in pediatric T1D. We acquire structural T1 weighted (T1w) MRI, diffusion tensor MRI (DTI), functional MRI (fMRI), and magnetic resonance spectroscopy (MRS) of 5-7 participants from each of two sites. First, we assess the contrast-to-noise ratio of the T1w MRI and find no differences between sites. Second, we characterize intervolume motion in DTI and fMRI and find it to be on the subvoxel level. Third, we investigate variability in regional gray matter volumes and local gyrification indices, bundle-wise DTI microstructural measures, and N-acetylaspartate to creatine ratios. We find the T1-based measures to be comparable between sites before harmonization and the DTI and MRS-based measures to be comparable after. We find a 5-15% coefficient of variation for most measures, suggesting ~150-200 participants per group on average are needed to detect a 5% difference across these modalities at 0.9 power. We conclude that multisite, multimodal neuroimaging of pediatric T1D is feasible with low motion artifact after harmonization of DTI and MRS.

Differences in the Optimal Motion of Android Robots for the Ease of Communications Among Individuals With Autism Spectrum Disorders

Android robots are employed in various fields. Many individuals with autism spectrum disorders (ASD) have the motivation and aptitude for using such robots. Interactions with these robots are structured to resemble social situations in which certain social behaviors can occur and to simulate daily life. Considering that individuals with ASD have strong likes and dislikes, ensuring not only the optimal appearance but also the optimal motion of robots is important to achieve smooth interaction and to draw out the potential of robotic interventions. We investigated whether individuals with ASD found it easier to talk to an android robot with little motion (i.e., only opening and closing its mouth during speech) or an android robot with much motion (i.e., in addition to opening and closing its mouth during speech, moving its eyes from side to side and up and down, blinking, deeply breathing, and turning or moving its head or body at random). This was a crossover study in which a total of 25 participants with ASD experienced mock interviews conducted by an android robot with much spontaneous facial and bodily motion and an android robot with little motion. We compared demographic data between participants who answered that the android robot with much motion was easier to talk to than android robot with little motion and those who answered the opposite. In addition, we investigated how each type of demographic data was related to participants' feeling of comfort in an interview setting with an android robot. Fourteen participants indicated that the android robot with little motion was easier to talk to than the robot with much motion, whereas 11 participants answered the opposite. There were significant differences between these two groups in the sensory sensitivity score, which reflects the tendency to show a low neurological threshold. In addition, we found correlations between the sensation seeking score, which reflects the tendency to show a high neurological threshold, and self-report ratings of comfort in each condition. These results provide preliminary support for the importance of setting the motion of an android robot considering the sensory traits of ASD.

Evaluation of motion artifacts in brain magnetic resonance images using convolutional neural network-based prediction of full-reference image quality assessment metrics

Purpose: Motion artifacts in magnetic resonance (MR) images mostly undergo subjective evaluation, which is poorly reproducible, time consuming, and costly. Recently, full-reference image quality assessment (FR-IQA) metrics, such as structural similarity (SSIM), have been used, but they require a reference image and hence cannot be used to evaluate clinical images. We developed a convolutional neural network (CNN) model to quantify motion artifacts without using reference images. Approach: The brain MR images were obtained from an open dataset. The motion-corrupted images were generated retrospectively, and the peak signal-to-noise ratio, cross-correlation coefficient, and SSIM were calculated. The CNN was trained using these images and their FR-IQA metrics to predict the FR-IQA metrics without reference images. Receiver operating characteristic (ROC) curves were created for binary classification, with artifact scores < 4 indicating the need for rescanning. ROC curve analysis was performed on the binary classification of the real motion images. Results: The predicted FR-IQA metric having the highest correlation with the subjective evaluation was SSIM, which was able to classify images requiring rescanning with a sensitivity of 89.5%, specificity of 78.2%, and area under the ROC curve (AUC) of 0.930. The real motion artifacts were classified with the AUC of 0.928. Conclusions: Our CNN model predicts FR-IQA metrics with high accuracy, which enables quantitative assessment of motion artifacts in MR images without reference images. It enables classification of images requiring rescanning with a high AUC, which can improve the workflow of MR imaging examinations.

Functionally Assessing the Age-Related Decline in the Detection Rate of Photons by Cone Photoreceptors

Age-related decline in visual perception is usually attributed to optical factors of the eye and neural factors. However, the detection of light by cones converting light into neural signals is a crucial intermediate processing step of vision. Interestingly, a novel functional approach can evaluate many aspects of the visual system including the detection of photons by cones. This approach was used to investigate the underlying cause of age-related visual decline and found that the detection rate of cones was considerably affected with healthy aging. This functional test enabling to evaluate the detection of photons by cones could be particularly useful to screen for retinal pathologies affecting cones such as age-related macular degeneration. However, the paradigm used to functionally measure the detection of photons was complex as it was evaluating many other properties of the visual system. The aim of the current mini review is to clarify the underlying rationale of functionally evaluating the detection of photons by cones, describe a simpler approach to evaluate it, and review the impact of aging on the detection rate of cones.

Does Sound Influence Perceived Duration of Visual Motion?

Multimodal perception is a key factor in obtaining a rich and meaningful representation of the world. However, how each stimulus combines to determine the overall percept remains a matter of research. The present work investigates the effect of sound on the bimodal perception of motion. A visual moving target was presented to the participants, associated with a concurrent sound, in a time reproduction task. Particular attention was paid to the structure of both the auditory and the visual stimuli. Four different laws of motion were tested for the visual motion, one of which is biological. Nine different sound profiles were tested, from an easier constant sound to more variable and complex pitch profiles, always presented synchronously with motion. Participants' responses show that constant sounds produce the worst duration estimation performance, even worse than the silent condition; more complex sounds, instead, guarantee significantly better performance. The structure of the visual stimulus and that of the auditory stimulus appear to condition the performance independently. Biological motion provides the best performance, while the motion featured by a constant-velocity profile provides the worst performance. Results clearly show that a concurrent sound influences the unified perception of motion; the type and magnitude of the bias depends on the structure of the sound stimulus. Contrary to expectations, the best performance is not generated by the simplest stimuli, but rather by more complex stimuli that are richer in information.

Hand Motion Analysis Illustrates Differences When Drilling Cadaveric and Printed Temporal Bone

OBJECTIVE

Temporal bone simulation is now commonly used to augment cadaveric education. Assessment of these tools is ongoing, with haptic modeling illustrating dissimilar motion patterns compared to cadaveric opportunities. This has the potential to result in maladaptive skill development. It is hypothesized that trainee drill motion patterns during printed model dissection may likewise demonstrate dissimilar hand motion patterns.

METHODS

Resident surgeons dissected 3D-printed temporal bones generated from microCT data and cadaveric simulations. A magnetic position tracking system (TrakSTAR Ascension, Yarraville, Australia) captured drill position and orientation. Skill assessment included cortical mastoidectomy, thinning procedures (sigmoid sinus, dural plate, posterior canal wall) and facial recess development. Dissection was performed by 8 trainees (n = 5 < PGY3 > n = 3) using k-cos metrics to analyze drill strokes within position recordings. K-cos metrics define strokes by change in direction, providing metrics for stroke duration, curvature, and length.

RESULTS

T-tests between models showed no significant difference in drill stroke frequency (cadaveric = 1.36/s, printed = 1.50/s, P < .40) but demonstrate significantly shorter duration (cadaveric = 0.37 s, printed = 0.16 s, P < .01) and a higher percentage of curved strokes (cadaveric = 31, printed = 67, P < .01) employed in printed bone dissection. Junior staff used a higher number of short strokes (junior = 0.54, senior = 0.38, P < .01) and higher percentage of curved strokes (junior = 35%, senior = 21%, P < .01).

CONCLUSIONS

Significant differences in hand motions were present between simulations, however the significance is unclear. This may indicate that printed bone is not best positioned to be the principal training schema.

What you see is what you get: visual scanning failures of naturalistic social scenes in schizophrenia

BACKGROUND

Impairments in social cognition contribute significantly to disability in schizophrenia patients (SzP). Perception of facial expressions is critical for social cognition. Intact perception requires an individual to visually scan a complex dynamic social scene for transiently moving facial expressions that may be relevant for understanding the scene. The relationship of visual scanning for these facial expressions and social cognition remains unknown.

METHODS

In 39 SzP and 27 healthy controls (HC), we used eye-tracking to examine the relationship between performance on The Awareness of Social Inference Test (TASIT), which tests social cognition using naturalistic video clips of social situations, and visual scanning, measuring each individual's relative to the mean of HC. We then examined the relationship of visual scanning to the specific visual features (motion, contrast, luminance, faces) within the video clips.

RESULTS

TASIT performance was significantly impaired in SzP for trials involving sarcasm (p < 10-5). Visual scanning was significantly more variable in SzP than HC (p < 10-6), and predicted TASIT performance in HC (p = 0.02) but not SzP (p = 0.91), differing significantly between groups (p = 0.04). During the visual scanning, SzP were less likely to be viewing faces (p = 0.0001) and less likely to saccade to facial motion in peripheral vision (p = 0.008).

CONCLUSIONS

SzP show highly significant deficits in the use of visual scanning of naturalistic social scenes to inform social cognition. Alterations in visual scanning patterns may originate from impaired processing of facial motion within peripheral vision. Overall, these results highlight the utility of naturalistic stimuli in the study of social cognition deficits in schizophrenia.

Evaluating Lower Limb Kinematics Using Microsoft's Kinect: A Simple, Novel Method

Purpose: Our aim was to evaluate the Microsoft Kinect sensor (MKS) as a markerless system for motion capture and analysis of lower limb motion, compare it with a state-of-the-art marker-based system (MBS), and investigate its accuracy in simultaneously capturing several lower limb joint movements on several planes while participants walked freely. Method: Participants were asked to walk while gait data were simultaneously recorded by both the MKS and the MBS. Software for analysing the Kinect data stream was developed using Microsoft Visual Studio and Kinect for Windows software development kits. Visual three-dimensional (3D) C-Motion software was used to calculate 3D joint angles of the MBS. Deviation of the joint angles calculated by the two systems was calculated using root-mean-square error (RMSE) on the basis of a designated formula. Results: The calculated RMSE average was <5° between the two systems, a level of difference that has practically no clinical significance. Conclusions: Quantitative measurements of the joint angles of the knee and hip can be acquired using one MKS with some accuracy. The system can be advantageous for clinical use, at the pre- and post-treatment stages of rehabilitation, at significantly lower costs. Further evaluation of the MKS should be performed with larger study populations.

Prevalence of Locomotive Organ Impairment and Associated Factors among Middle-Aged and Older People in Nan Province, Thailand

While locomotive organ impairment among older people is attracting worldwide attention, this issue has not yet been widely investigated in Thailand. This study aimed to measure locomotive organ impairment prevalence and identify the determinants of locomotive function decline among middle-aged and older people in Nan Province, Thailand. This cross-sectional study included anthropometric measurements, a two-step test to investigate locomotive function, and a structured questionnaire to obtain socio-demographic and related information. Logistic regression analysis and multiple regression analysis were used to identify the determinants of locomotive organ impairment. The study participants were aged 50–87 years old (n = 165), and 71.5% of them had begun experiencing declining locomotive function; < 6 years of school education (adjusted odds ratio: 4.46), body mass index ≥25 kg/m² (AOR: 3.06), comorbidities (AOR: 2.55), and continuous walking for <15 min (AOR: 2.51) were identified as factors associated with locomotive organ impairment. Moreover, age, knee pain, anxiety about falling in daily life, and difficulty with simple tasks were identified as factors significantly associated with exacerbated locomotive organ impairment (p < 0.05). Appropriate interventions such as guidance or follow-up and recommendations for exercises are needed to prevent locomotive organ impairment and improve treatment.

Modeling Physiological Sources of Heading Bias from Optic Flow

Human heading perception from optic flow is accurate for directions close to the straight-ahead and systematic biases emerge in the periphery (Cuturi and Macneilage, 2013; Sun et al., 2020). In pursuit of the underlying neural mechanisms, primate brain dorsal medial superior temporal (MSTd) area has been a focus because of its causal link with heading perception (Gu et al., 2012). Computational models generally explain heading sensitivity in individual MSTd neurons as a feedforward integration of motion signals from medial temporal (MT) area that resemble full-field optic flow patterns consistent with the preferred heading direction (Britten, 2008; Mineault et al., 2012). In the present simulation study, we quantified within the structure of this feedforward model how physiological properties of MT and MSTd shape heading signals. We found that known physiological tuning characteristics generally supported the accuracy of heading estimation, but not always. A weak-to-moderate overrepresentation of peripheral headings in MSTd garnered the highest accuracy and precision out of the models that we tested. The model also performed well when noise corrupted high proportions of the optic flow vectors. Such a peripheral MSTd model performed well when units possessed a range of receptive field (RF) sizes and were strongly direction tuned. Physiological biases in MT direction tuning toward the radial direction also supported heading estimation, but the tendency for MT preferred speed and RF size to scale with eccentricity did not. Our findings help elucidate the extent to which different physiological tuning properties influence the accuracy and precision of neural heading signals.

Stretchable and Highly Permeable Nanofibrous Sensors for Detecting Complex Human Body Motion

Wearable strain sensors have been attracting special attention in the detection of human posture and activity, as well as for the assessment of physical rehabilitation and kinematics. However, it is a challenge to fabricate stretchable and comfortable-to-wear permeable strain sensors that can provide highly accurate and continuous motion recording while exerting minimal constraints and maintaining low interference with the body. Herein, covalently grafting nanofibrous polyaniline (PANI) onto stretchable elastomer nanomeshes is reported to obtain a freestanding ultrathin (varying from 300 to 10 000 nm) strain sensor that has high gas permeability (10-33 mg h^-1 ). The sensor demonstrates a low weight and can be directly laminated onto the dynamic human skin for long periods of time. The sensor, which produces an intimate connection with solid or living objects, has a stable performance with excellent sustainability, linearity, durability, and low hysteresis. It exibits excellent performance for continuous interrogation of complex movements, mimicking muscle activities, and resembling brain activity. This includes a very precise discrimination of bending and twisting stimuli at different angles (1-180°) and speeds (3-18 rpm) and very low exertion of counter-interference. These results imply the utility of this appraoch for advanced developments of robotic e-skins or e-muscles.