Mathematical Models of Central Pattern Generators in Locomotion

Possible neural connective patterns and functions with respect to interlimb coordination are studied theoretically with a mathematical model of the central pattern generating system for cat locomotion. Activities in populations of neurons controlling limb joint flexors and extensors in all four limbs are represented by a system of nonlinear differential equations. Solutions of the system for various parameter values simulate various gaits of the cat. The model is shown to be capable of generating all gaits of the cat and accounting for corresponding phase changes in interlimb coordination. The model also exhibits smooth changes of gait, and smooth initiation and termination of stepping. Further, within each limb, muscle sequencing, step cycle phases, and flexor-extensor interactions can be studied. The model suggests that one of the simplest mechanisms for a central command system to change the gait is via inhibition of specific interlimb propriospinal pathways. In a final section, properties of both proposed single limb and interlimb models are reviewed with specific reference to planning future experimental and theoretical studies.     

EDITORS' INTRODUCTION

ABSTRACT

Transsexualism implies that an anatomically normal individual feels that he or she is actually a member of the opposite sex. Treatment usually includes real-life experience along with hormone therapy and sex reassignment surgery. Voice modification surgery may be necessary, as pass ability in general is still in a large extent dependent on the aspects of voice in transsexual people. Often male-to-female patients report being addressed in telephone conversations as their genetic gender, which is experienced as a disability. The purpose of this study was to evaluate the impact of voice on the quality of life in transsexuals.

In order to detect the disability caused by a voice disorder, the validated assessment method the Voice Handicap Inventory (VHI) was used. An additional question about the way patients were addressed in a telephone conversation was added.

As part of a study describing general health in transsexual persons, done at the Ghent University Hospital Belgium, a total of 48 patients were evaluated. In female-to-male transsexuals the median scores were very low, suggesting testosterone treatment led to an acceptable voice alteration. A higher serum LH level was significantly correlated with higher total, functional and emotional VHI scores. In male-to-female transsexuals the scores were significantly higher than those of the female-to-male transsexuals, but still there was no indication of a real disability/handicap. The extra telephone question was scored higher suggesting male-to-female transsexuals did experience a disability caused by their voice. From this study it is concluded that the VHI values did not demonstrate a handicapping effect.     

威胁敏感性的概念和测量：生理和认知两种取向

对威胁敏感是人类在应对外部环境过程中不断发展的生存技能。威胁敏感性的研究主要存在两种取向：生理取向以敏感性强化理论为基础, 将行为抑制系统的敏感性界定为威胁敏感性, 量化为个体应对威胁时的生理、情绪和行为反应水平; 认知取向以信息加工的认知风格理论为基础, 将个体在对威胁信息加工过程中的敏感性偏向定义为威胁警觉, 量化为威胁刺激呈现前后的预期水平和探测水平。未来研究还需进一步整合和界定威胁敏感性的概念内涵, 验证各测量指标之间的关系, 拓展不同种类威胁敏感性的研究方法。     

女大学生体重知觉偏差及探因

以女性身体图形评定量表PFRS (the female Photographic Figure Rating Scale)作为刺激材料, 研究女大学生体重自我知觉与偏差, 以及女大学生对他人的体重知觉与偏差, 引入男性视角作为体重社会标准, 研究女大学生体重社会知觉与偏差。研究中要求女大学生选择准确代表自己胖瘦的图像, 选择自己理想胖瘦的图像, 选择他人眼里最有吸引力的图像, 估计PFRS真人照片图像体重值(假定图像中人物和自己身高相同), 并报告自己的实际体重和理想体重。研究要求男大学生选择最有吸引力的图像。在此基础上提出3种模型假设：镜像模型、泛化模型和相关模型, 进一步探索女大学生体重知觉偏差的原因。研究表明：女大学生体重自我知觉高估了对应真人图像的BMI; 女大学生对其他女性BMI知觉, 倾向于高估体重正常和偏瘦女性的BMI, 低估偏胖和肥胖女性的BMI; 女大学生体重的主观社会压力高于体重的实际社会压力, 对体重社会压力存在过度解读的倾向。女大学生对他人体重知觉偏差更有可能影响其体重自我知觉偏差; 认知评价不是造成女大学生知觉偏差的重要因素, 但两者关系需要进一步实证。     

Subjective Estimation of Task Time and Task Difficulty of Simple Movement Tasks

It has been demonstrated in previous work that the same neural structures are used for both imagined and real movements. To provide a strong test of the similarity of imagined and actual movement times, 4 simple movement tasks were used to determine the relationship between estimated task time and actual movement time. The tasks were single-component visually controlled movements, 2-component visually controlled, low index of difficulty (ID) moves and pin-to-hole transfer movements. For each task there was good correspondence between the mean estimated times and actual movement times. In all cases, the same factors determined the actual and estimated movement times: the amplitudes of movement and the IDs of the component movements, however the contribution of each of these variables differed for the imagined and real tasks. Generally, the standard deviations of the estimated times were linearly related to the estimated time values. Overall, the data provide strong evidence for the same neural structures being used for both imagined and actual movements.     

不同强迫倾向个体信息加工方式的特点研究

采用Flanker范式,通过考察高低强迫倾向个体在Flanker任务上的差异,来研究强迫倾向个体信息加工方式的特点。研究结果显示,在Flanker任务中,高强迫倾向个体显示出较慢的反应速度,表现为更多的犹豫不觉的特性;高强迫倾向个体的信息加工方式以集中加工为主;高强迫倾向个体在信息加工的灵活性上存在不足,对情景的变化较不敏感。通过对强迫倾向个体的信息加工方式的研究,有助于丰富和发展强迫症的理论,同时为强迫症的临床治疗提供依据。     

高血压患者对称动态动脉硬化指数与尿NAG的相关性研究

对称动态动脉硬化指数(S-AASI)是一种评价动脉顺应性的检测技术,具有无创、易操作、有效的特点,在预测高血压靶器官损害、心血管事件和死亡方面具有广阔的应用前景。本文通过探讨S-AASI与尿N-乙酰-β-D-氨基葡萄糖苷酶(NAG)之间的相关性,为临床使用S-AASI作为一种预测和评价高血压靶器官损害的指标提供科学的依据。     

A Critical Test of the Waist-to-Hip Ratio Hypothesis of Women's Physical Attractiveness in Britain and Greece

Body mass index (BMI) and body shape as measured by the waist-to-hip ratio (WHR) have been reported to be the major cues to women's bodily attractiveness. The relative importance of each of these cues was examined cross-culturally in two distinct countries, Greece and Britain. Fifty Britons, 25 British-Greeks, and 25 participants in Greece were asked to rate a set of images of real women with known BMI and WHR. The results showed that, regardless of the cultural setting, BMI is the primary determinant of women's physical attractiveness, whereas WHR emerged as a significant predictor for the Greek groups but not the British group. This finding is discussed in terms of the different gender roles occupied by Britons and Greeks. The discussion critically evaluates evolutionary psychological and sociocultural explanations of preferences for body weight.     

Body mass index,peer victimization,and body dissatisfaction across 7 years of childhood and adolescence: Evidence of moderated and mediated pathways

Numerous studies have reported that children and adolescents who are overweight are more likely to get bullied, yet the literature is replete with methodological limitations. We examined the transactional associations between peer victimization and body mass index (BMI), considering potential mediating (body dissatisfaction) and moderating (biological sex) factors. Participants (n = 631) came from the McMaster Teen Study, where students were assessed annually between Grades 5–11, approximately half were girls (53.9%), and the majority were white (76.4%). Peer victimization (from Grade 5) and body dissatisfaction (from Grade 6) were self‐reported by students, while parents reported their child's height and weight (from Grade 5). Cascade models were built up sequentially using path analysis across 2‐year increments (Grades 5, 7, 9, and 11). The final model had excellent fit to the data (χ² = 73.961, df = 66, p = 0.234). Grade 5 peer victimization had a direct effect on BMI across a 2‐year period in girls (b = 0.59, SE = 0.21, p = 0.005) and boys (b = 0.82, SE = 0.30, p = 0.006), and an indirect effect on BMI via body dissatisfaction across a 4‐year period (b = 0.074, 95% CI = 0.012–0.152, p = 0.036). At no point did BMI directly increase risk for peer victimization, yet there were indirect effects via body dissatisfaction among girls but not boys. Peer victimization and body dissatisfaction were proximally and longitudinally related at every time point and there was a transactional association in late‐adolescence among girls but not boys. Targeting modifiable factors in the social (peer victimization) and psychological (body dissatisfaction) domains may limit accelerated weight gain and the health risks associated with excess adiposity.     

Human walk-to-run transition in the context of the behaviour of complex systems

This study had two main aims: 1) to investigate if the walk-to-run (WR-) transition occurs when the speed of locomotion is kept constant below the WR-transition speed (speed clamp) and the stride rate is increased monotonously using a metronome and 2) to investigate if diversion of attention and awareness from the locomotion process influences the position of the WR-transition in stride rate, stride length, and locomotion speed (SrSlLs) space.Eighteen healthy individuals (13 men and 5 women) were recruited (age: 23.9 ± 1.5 years, height: 1.77 ± 0.10 m and body mass: 77.3 ± 12.8 kg). Stride-by-stride stride rates, stride lengths, locomotion speeds, and duty factors were determined on a treadmill in 4 different tests: 1) reference WR-transition, 2) preferred walking speed, 3) dual-task test including arithmetic calculations and 4) four speed clamp bouts with different initial velocities.Walk-to-run transitions were elicited in all participants in the speed clamp bouts. When the stride rate ramp was clamped at preferred walking speed the WR-transition stride rate was not significantly different from the WR-transition stride rate during the reference test (t = 2.2, p = 0.312). However, in the SrSlLs space the speed clamp WR-transitions all deviated from the position of the reference WR-transition. Additionally, it was demonstrated that intensive attentional diversion using a dual-task paradigm had very little influence on the position of the WR-transition in the SrSlLs space.It is argued that these observations can be explained in the context of the behavior of complex systems.