Parallel Factor Analysis of gait waveform data: A multimode extension of Principal Component Analysis

Gait data are typically collected in multivariate form, so some multivariate analysis is often used to understand interrelationships between observed data. Principal Component Analysis (PCA), a data reduction technique for correlated multivariate data, has been widely applied by gait analysts to investigate patterns of association in gait waveform data (e.g., interrelationships between joint angle waveforms from different subjects and/or joints). Despite its widespread use in gait analysis, PCA is for two-mode data, whereas gait data are often collected in higher-mode form. In this paper, we present the benefits of analyzing gait data via Parallel Factor Analysis (Parafac), which is a component analysis model designed for three- or higher-mode data. Using three-mode joint angle waveform data (subjects×time×joints), we demonstrate Parafac's ability to (a) determine interpretable components revealing the primary interrelationships between lower-limb joints in healthy gait and (b) identify interpretable components revealing the fundamental differences between normal and perturbed subjects' gait patterns across multiple joints. Our results offer evidence of the complex interconnections that exist between lower-limb joints and limb segments in both normal and abnormal gaits, confirming the need for the simultaneous analysis of multi-joint gait waveform data (especially when studying perturbed gait patterns).     

Analysis and Discrimination of Surface Electromyographic Features for Parkinson’s Disease during Elbow Flexion Movements

Abstract

Parkinson’s disease (PD) is the second most common neurodegenerative disorder. Early intervention/treatment relies on early diagnosis of PD. There is increasing interest in methods based on electromyography measurements of PD patients because of its noninvasiveness. Thus, this study was to investigate electromyographic (EMG) characteristics of the upper limb between PD patients and healthy control subjects using EMG, and to distinguish PD patients from healthy control subjects according to the EMG information using a support vector machine (SVM) classifier. Sixteen right-handed PD patients and 25 right-handed healthy subjects participated in experiments involving elbow flexion movement. The frequency power, duration, skewness, recurrence rate, and correlation dimension of EMG signals and success rate for the right hand and the skewness of EMG signals for the left hand were found to be significantly different between the two groups. This information was subsequently used to distinguish PD patients from healthy control subjects using the SVM classifier to obtain a mean accuracy of 87.02%. Although the results may not be immediately available to use in clinical applications, the safety, simplicity and speed of the system still merits further consideration. Enhancing performance accuracy and examining PD patients in different stages of disease are anticipated in future investigations.     

Effects of concurrent physical and cognitive demands on arm movement kinematics in a repetitive upper-extremity precision task

The effect of concurrent physical and cognitive demands on arm motor control is poorly understood. This exploratory study compared movement kinematics in a repetitive high-precision pipetting task with and without additional concurrent cognitive demands in the form of instructions necessary to locate the correct target tube. Thirty-five healthy female subjects performed a standardized pipetting task, transferring liquid repeatedly from one pick-up tube to different target tubes. In the reference condition, lights indicated the target tube in each movement cycle, while the target tube had to be deciphered from a row and column number on a computer screen in the condition with additional cognitive demands. Kinematics of the dominant arm was assessed using the central tendency and variability of the pipette-tip end-point trajectory and joint kinematics properties of the shoulder and elbow. Movements slowed down (lower velocities and higher area under the movement curves) and trajectory variability increased in the condition with additional cognitive demands, but there were no changes in the kinematics properties such as joint range of motion, times of acceleration and deceleration (as indicated by the time to peak velocity), average angles, or phase relationships between angle and angular velocity of shoulder or elbow movements between the two conditions. Further, there were also no differences in the size or structure of variability of the shoulder and elbow joint angles, suggesting that subjects could maintain the motor repertoire unaltered in the presence of these specific additional cognitive demands. Further studies should address motor control at other levels of concurrent cognitive demands, and with motor tasks that are less automated than the pipetting task used in the present study, so as to gain an increased understanding of the effect of concurrent cognitive demands for other activities of relevance to daily life.     

利用脑成像多体素模式分析解码认知的神经表征:原理和应用

多体素模式分析(multi-voxel pattern analysis,MVPA)是一种基于机器学习理论发展出来的新的功能磁共振数据分析技术。MVPA技术通过训练分类器,对由不同认知状态引起的多体素信号模式进行分类。与传统的基于单个体素的分析方法相比,该技术可更敏感地检测脑对认知状态的表征,并使得从神经信号解码认知状态成为可能。文章介绍MVPA技术的基本原理、分析步骤以及可以用MVPA来解决的科学问题,并对应用中可能面临的问题提供了参考建议。     

Intensity and direction of competitive state anxiety as interpreted by rugby players and rifle shooters

This study reports the findings of part of an ongoing research program examining sports performers' interpretations of competitive anxiety prior to competition. The notion of 'directional perceptions' has questioned the limited utility of examining only the intensity of competitive anxiety responses as has Jones. The purpose of this study was to examine intensity and direction, i.e., interpretation of intensity as facilitative or debilitative, of anxiety symptoms as a function of two types of sport. The types of sport were explosive (rugby league) versus fine motor skills (target rifle shooting). The sample comprised 50 male rugby league participants and 50 target rifle shooters who completed a modified version of the Competitive State Anxiety Inventory-2 prior to competition. Contingency analysis yielded a significant difference in the number of rugby players who reported somatic anxiety as facilitative and the number of rifle shooters who reported somatic states as debilitative. No such differences were evident for cognitive anxiety. Analysis of variance indicated no differences between the two groups on the intensity of cognitive and somatic anxiety, but the performers competing in rugby league interpreted both states as being more facilitative to performance; the rugby league players also had higher scores on self-confidence than the shooters. These findings provide continuing support for the measurement of directional perceptions of competitive anxiety and highlight the importance of examining individual sports.     

The long arm of time pressure at work: Cognitive failure and commuting near-accidents

This study tests whether cognitive failures mediate effects of work-related time pressure and time control on commuting accidents and near-accidents. Participants were 83 employees (56% female) who each commuted between their regular place of residence and place of work using vehicles. The Workplace Cognitive Failure Scale (WCFS) asked for the frequency of failure in memory function, failure in attention regulation, and failure in action execution. Time pressure and time control at work were assessed by the Instrument for Stress Oriented Task Analysis (ISTA). Commuting accidents in the last 12 months were reported by 10% of participants, and half of the sample reported commuting near-accidents in the last 4 weeks. Cognitive failure significantly mediated the influence of time pressure at work on near-accidents even when age, gender, neuroticism, conscientiousness, commuting duration, commuting distance, and time pressure during commuting were controlled for. Time control was negatively related to cognitive failure and neuroticism, but no association with commuting accidents or near-accidents was found. Time pressure at work is likely to increase cognitive load. Time pressure might, therefore, increase cognitive failures during work and also during commuting. Hence, time pressure at work can decrease commuting safety. The result suggests a reduction of time pressure at work should improve commuting safety.     

The relation between preparatory stance and trunk rotation movements

The influence of preparatory stance on rotation movement reaction time of the trunk by bending of the knee and hip joint(s) was examined in 12 subjects. Four preparatory stances were examined: straight knee and hip extension (STAND), slight flexion of knee joints and hip joint (LIGHT), deep flexion (DEEP), and free initial position, i.e. that felt to be the most comfortable and effective (FREE). There was no significant influence of the preparatory stance on hip latency, but there were significant differences between the preparatory stances on response time (RT) and movement time (MT). Furthermore, using a quadratic curve fitting technique, knee joint angles of 24.8 degrees and a hip joint angle of 23.3 degrees were shown to be the optimum flexion angles in the preparatory stance for the initiation of quick trunk rotation movements. It is proposed that mechanical factors have considerably more effects on trunk rotation movements than does the nervous system.     

Finding words for feelings: The relationship between personality disorders and alexithymia

This study examined whether personality disorders (PDs) are associated with alexithymic features at varying levels of comorbid psychopathology distress. 167 psychiatric outpatients completed the Toronto Alexithymia Scale (TAS) and the General Severity Index (GSI) of the SCL90-revised. Bootstrapping analyses were performed to test whether the PD/alexithymia relationship was moderated by psychopathology distress (GSI). The overall number of PD criteria was associated with cognitive aspects of alexithymia (i.e., Externally Oriented Thinking, EOT) only at low/moderate levels of distress. Borderline criteria predicted EOT only when distress was low, while avoidant and dependent criteria were independently related with EOT. No association was found between other PDs and alexithymia facets. Thus, within clinical samples the alexithymia/PD association is mainly explained by comorbid psychopathology; however, individuals with avoidant, dependent and borderline features might have a specific difficulty with focusing on internal reality, even when their current symptom distress is low.     

Exploring the Within-Person Coupling of Reading Vision and Cognition in the Elderly

ABSTRACT

This study examined the within-person relationship between reading vision and cognitive functioning. Analysis was conducted on 36 community-dwelling elderly (age range?=?60–87) who completed a reading vision task and three cognitive tests (i.e., Rey Auditory Verbal Learning Task (AVLT), Letter Series, and Number Comparison) twice a day over 60 consecutive days. Significant within-person variability was found for the reading vision measure. Additionally, a main effect was found for reading vision and performance on the AVLT and Number Comparison task; such that on occasions when reading vision was poor, cognitive performance suffered.     

Ankle dorsiflexion range of motion is associated with kinematic but not kinetic variables related to bilateral drop-landing performance at various drop heights

Limited evidence is available concerning ankle dorsiflexion range of motion (DF ROM) and its relationship with landing performance from varying drop heights. The aim of this investigation was to determine the relationship between ankle DF ROM and both kinetic and kinematic variables measured during bilateral drop-landings from 50%, 100% and 150% of countermovement jump height. Thirty-nine participants were measured for their ankle DF ROM using the weight-bearing lunge test, after which five bilateral drop-landings were performed from 50%, 100% and 150% of maximal countermovement jump height. Normalized peak vertical ground reaction force (vGRF), time to peak vGRF and loading rate was calculated for analysis, alongside sagittal-plane initial contact angles, peak angles and joint displacement for the hip, knee and ankle. Frontal-plane projection angles were also calculated. Ankle DF ROM was not related to normalized peak vGRF, time to peak vGRF or loading rate (P > 0.05), regardless of the drop height. However, at drop heights of 100% and 150% of countermovement jump height, there were numerous significant (P < 0.05) moderate to large correlations between ankle DF ROM and initial contact angles (r = −0.34 to −0.40) and peak angles (r = −0.42 to −0.52) for the knee and ankle joint. Knee joint displacement (r = 0.39–0.47) and frontal-plane projection angle (r = 0.37–0.40) had a positive relationship with ankle DF ROM, which was consistent across all drop heights. Ankle DF ROM influences coordination strategies that allow for the management of vGRF during bilateral drop-landings, with alterations in alignment for the knee and ankle joints at both initial contact and peak angles.     

Decoding the Large-Scale Structure of Brain Function by Classifying Mental States Across Individuals

ABSTRACT— Brain-imaging research has largely focused on localizing patterns of activity related to specific mental processes, but recent work has shown that mental states can be identified from neuroimaging data using statistical classifiers. We investigated whether this approach could be extended to predict the mental state of an individual using a statistical classifier trained on other individuals, and whether the information gained in doing so could provide new insights into how mental processes are organized in the brain. Using a variety of classifier techniques, we achieved cross-validated classification accuracy of 80% across individuals (chance = 13%). Using a neural network classifier, we recovered a low-dimensional representation common to all the cognitive-perceptual tasks in our data set, and we used an ontology of cognitive processes to determine the cognitive concepts most related to each dimension. These results revealed a small organized set of large-scale networks that map cognitive processes across a highly diverse set of mental tasks, suggesting a novel way to characterize the neural basis of cognition.     

Mind-reading without the scanner: Behavioural decoding of working memory content

ABSTRACT

Sophisticated machine learning algorithms have been successfully applied to functional neuroimaging data in order to characterize internal cognitive states. But is it possible to “mind-read” without the scanner? Capitalizing on the robust finding that the contents of working memory guide visual attention toward memory-matching objects, we trained a multivariate pattern classifier on behavioural indices of attentional guidance. Working memory representations were successfully decoded from behaviour alone, both within and between individuals. The current study provides a proof-of-concept for applying machine learning techniques to simple behavioural outputs (e.g., response times) in order to decode information about specific internal cognitive states.     

Theory of mind and joint action in Parkinson’s disease

It has been suggested that the Theory of Mind (ToM) may rely on more basic processes of social cognition, such as action control (e.g., joint action), even if little is known about this relationship. The relationship between ToM and joint action can be studied in patients with Parkinson’s disease (PD), because they are characterized not only by a deficit in ToM (and in its cognitive and affective subcomponents) but also by a deficit in the inhibition of competing responses. Sixty PD patients and 60 matched healthy controls (HCs) performed a go/no-go Flanker task in both joint and individual conditions. Cognitive (Advanced Test or AT) and affective (Emotion Attribution Task or EAT) ToM also were measured. Thirty-five PD patients and matched HCs also performed the standard Flanker task, as a control measure. In patients, only individuals with high AT scores exhibited a joint Flanker effect, whereas in HCs the joint effect was found irrespectively of AT score. Patients with low EAT scores showed a greater interference effect than patients with high scores, whereas the opposite pattern was found for HCs. In regression analysis AT and EAT scores predicted the Flanker effect in the joint condition only. In the standard task, both groups showed a Flanker effect. The role of different fronto-striatal circuits, especially in PD patients, could explain the different involvement of cognitive and affective ToM in joint tasks. The Flanker effect is discussed considering the referential coding account and the attention-focus account as possible candidates to explain joint action effects.     

Disentangling the relationship between hemispheric asymmetry and cognitive performance

It is widely believed that advantages of hemispheric asymmetries originated in better cognitive processing, hence it is often implied that the relationship between hemispheric asymmetry and cognitive performance is linearly positive: the higher the degree of lateralization in a specific cognitive domain, the better the performance in a corresponding task. Yet, the empirical evidence for this notion is mixed and the statistical methods to analyze this relationship have been criticized. The present study therefore investigated the relationship between hemispheric asymmetries and cognitive performance in two behavioral tasks (a left-lateralized word-matching task and a right-lateralized face-decision task) in 230 participants (140 women, 90 men) by using two different approaches. Both methods correspondingly revealed that a relationship between hemispheric asymmetries and cognitive performance does exist. Contrary to a positive (linear) relationship however, the data could be best described by an inverted U-shaped curve. Although the optimal degree of lateralization seemed to be task-specific, a slight or moderate degree of hemispheric asymmetry achieved best cognitive performance in all tasks. Moreover, performances deteriorated towards extreme ends of lateralization (i.e., participants with either extreme left or right hemispheric biases). Taken together, the present study provides evidence against the notion that higher lateralization is related to enhanced cognitive performance.     

Human factors in GIScience laboratory at the Pennsylvania State University

The human factors in GIScience Laboratory (Human Factors Lab) of The Pennsylvania State University’s Department of Geography is located in University Park, PA (USA). University Park and bordering State College, PA are found in the heart of PA between the cities of New York City, NY, Philadelphia, PA, and Pittsburgh, PA. The laboratory is directed by Dr. Alexander Klippel and is part of the GeoVISTA Center. The Human Factors Lab contributes to Penn State Geography’s strong tradition as a leader in research on map perception, spatial cognition, and behavior in spatial environments. This report focuses upon basic research topics in spatial cognition, including: (1) perceptual and cognitive factors in map symbolization and design, (2) the creation of cognitively ergonomic route directions for next generation location based services (LBS), (3) You-Are-Here maps and the creation of a sense of place through map-like representations, (4) the conceptualization and representation of dynamic phenomena (i.e., geographic movement pattern), and (5) the relationship between linguistic and non-linguistic conceptualization.     

The Influence of Goal Orientation on Task Performance: A Substantively Meaningful Suppressor Variable1

The present study investigated the relationship between performance goal orientation and performance on a complex task. It was hypothesized that cognitive interference would mediate this relationship. In addition, it was hypothesized that cognitive ability would moderate the relationship between cognitive interference and task performance. A three-variable suppressor relationship indicated that, although the direct effect of performance goal orientation on performance was one that produced better performance, the indirect effect of performance goal orientation indicated that performance orientations were associated with increases in cognitive interference, and these increases in cognitive interference were associated with poorer performance. Thus, the beneficial aspect of performance goal orientation (i. e., the direct effect) was counterbalanced by the dysfunctional aspects of performance goal orientation (i. e., the associated increase in cognitive interference). Support was also found for the proposed moderation of ability on the cognitive interference-task performance relationship for final, but not initial performance. The results are interpreted in light of recent discussions regarding the influence of goal orientation on task performance and cognitive interference.     

Unnoticed intrusions: Dissociations of meta-consciousness in thought suppression

The current research investigates the interaction between thought suppression and individuals’ explicit awareness of their thoughts. Participants in three experiments attempted to suppress thoughts of a prior romantic relationship and their success at doing so was measured using a combination of self-catching and experience-sampling. In addition to thoughts that individuals spontaneously noticed, individuals were frequently caught engaging in thoughts of their previous partner at experience-sampling probes. Furthermore, probe-caught thoughts were: (i) associated with stronger decoupling of attention from the environment, (ii) more likely to occur under cognitive load, (iii) more frequent for individuals with a desire to reconcile, and (iv) associated with individual differences in the tendency to suppress thoughts. Together, these data suggest that individuals can lack meta-awareness that they have begun to think about a topic they are attempting to suppress, providing novel insight into the cognitive processes that are involved in attempting to control undesired mental states.     

运动习惯与社区老年人认知功能的关系

为评估社区老年人运动习惯与认知功能的关系,在北京市通过分层、方便取样的方法选取60岁以上的老年人732名,采用自编调查表收集一般人口学资料及运动习惯情况（包括有无运动习惯,运动频率,运动持续时间）,使用简明精神状态评估量表（MMSE）和北京版蒙特利尔认知评估量表（MoCA-BJ）评估认知功能。结果发现：（1）运动组整体认知功能及视空间定向能力得分均高于无运动组;（2）有无运动习惯可正向预测整体认知功能及视空间定向能力得分;（3）运动持续10年及以上组整体认知功能得分高于运动持续10年以下组。结果表明：相对于无运动习惯的社区老年人,有运动习惯的社区老年人的整体认知功能及视空间定向能力更好;运动持续年数较长,对社区老年人的认知功能起到促进作用。