Continuous Cognitive Tasks Improve Postural Control Compared to Discrete Cognitive Tasks

Research suggests that postural control synergies are sensitive to cognitive manipulations; however, the impact of different types of cognitive tasks on postural control remains inconclusive. The authors examined the effect of discrete and continuous tasks on postural control. Sixteen healthy young adults (M age = 22.7 ± 2.2 years) stood with feet together on a force platform while performing randomly assigned discrete and continuous cognitive tasks. Results demonstrated marked improvements in the area of 95% confidence ellipse and the standard deviation of the center of pressure in the anterior-posterior and medial-lateral directions for continuous compared to discrete tasks. This reinforces the notion that continuous tasks are sufficient in providing less opportunity to consciously attend to postural control, thereby facilitating automatic postural control.     

Sensitivity analysis of structural equation models

The main purpose of this paper is to investigate the sensitivity analysis of structural equation model when minor perturbation is introduced. Some influence measure that based on the general case weight perturbation is derived for the generalized least squares estimation. An influence measure that related to the Cook's distance is also developed for the special case deletion perturbation scheme. Using the proposed methodology, the influential observation in a data set can be detected. Moreover, the general theory can be applied to detect the influential parameters in a model. Finally, some illustrative artificial and real examples are presented. The research of the first author was supported by a Hong Kong UPGC grant. The authors are greatly indebted to two reviewers for some very valuable comments for improvement of the paper.     

Vis‐à‐vis the Couch: Where is Psychoanalysis?

The author discusses ways in which the couch or chair (lying down versus sitting up) may be used to maintain safety and defend against perceived dangers in the analytic process. Several dialectics are relevant as they intersect with that of danger and safety, including engagement/privacy, interiority/exteriority and subject/object. The author discusses these dialectics in terms of the ways in which the analyst is used at different points in time, i.e. as an objectifi ed other, a subjective object or part-object, or as a subject with an internal world. The therapeutic action associated with sitting up (versus lying down on the couch) has been undertheorized, despite the fact that many, if not most, analysands sit up for some portion of their analysis. Through the use of a heuristic visual-spatial metaphor as represented by the use of the couch or chair, the author discusses the signifi cance of lying down and sitting up for therapeutic action.     

Sudden gains in group cognitive-behavioral therapy for panic disorder

The current study investigates sudden gains (rapid symptom reduction) in group cognitive-behavioral therapy for panic disorder. Sudden gains occurring after session 2 of treatment predicted overall symptom reduction at treatment termination and some changes in cognitive biases. Meanwhile, sudden gains occurring immediately following session 1 were not associated with symptom reduction or cognitive change. Together, this research points to the importance of examining sudden gains across the entire span of treatment, as well as the potential role of sudden gains in recovery from panic disorder.     

Sudden gains in interpersonal psychotherapy for depression

Sudden, precipitous improvements in depressive symptom severity have been identified as occurring among unipolar depressed individuals. These "sudden gains" have been associated with superior acute treatment outcome in several treatment modalities, including cognitive therapy. A better understanding of sudden gains may provide insight into the mechanisms of action in these and other psychotherapies. One efficacious therapy that has been overlooked in sudden gains research is interpersonal psychotherapy (IPT; Weissman, M. M., Markowitz, J. C., & Klerman, G. L. (2000). Comprehensive guide to interpersonal psychotherapy. New York: Basic Books). The present research examined the rates and concomitant features of sudden, precipitous improvements in depressive symptomotology among 185 women receiving IPT for recurrent depression. Sudden gains, defined using extant criteria for the Beck Depression Inventory, were assessed over 12 weeks of acute IPT treatment for depression and occurred for 33.5% of the sample. Sudden gains were not associated with diagnostic and demographic characteristics or with differential likelihood of achieving depression remission with IPT monotherapy during active treatment. Further, those with sudden gains were no more likely to maintain their recovery through maintenance treatment. The lack of impact of sudden gains on eventual outcome is discussed in terms of potentially disparate emphases and mechanisms of change between IPT and cognitive-behavioral therapy (CBT).     

姿势干扰强度的心理预期效应

本研究基于经典快速举臂试验与落球试验范式, 采用表面肌电信号分析技术, 研究内、外姿势干扰强度的心理预期对腰部姿势肌肉和上肢动作肌肉预期姿势调节(APAs)和补偿姿势调节(CPAs)的影响, 探讨中枢神经系统(CNS)对内、外姿势干扰的控制策略。20名健康受试者先后完成不同负荷强度的快速举臂试验和落球试验, 同步采集腰部竖脊肌、腰部多裂肌和上肢肱二头肌的表面肌电信号, 计算肌肉预激活时间和APAs与CPAs积分肌电值, 观察内、外姿势干扰强度的心理预期对中枢APAs和CPAs控制机制的影响。结果显示内部姿势干扰条件下, 干扰强度的心理预期对腰部多裂肌、腰部竖脊肌和上肢肱二头肌的APAs强度有显著影响, 而对预激活时间和CPAs强度无显著影响; 外部姿势干扰条件下, 干扰强度的心理预期对腰部多裂肌、腰部竖脊肌和肱二头肌的APAs强度有显著影响, 对肱二头肌和腰部多裂肌预激活时间有显著影响, 而对CPAs强度无显著影响。突发可预期姿势干扰条件下姿势的快速反应是一个由CNS主导的神经肌肉运动控制过程。受姿势干扰强度心理预期的影响, CNS对内、外突发姿势干扰条件下腰部姿势肌肉的活动采取了不同的控制策略。在内部姿势干扰条件下, 干扰刺激发生时间明确, CNS主要通过对APAs强度的调节来实现姿势肌肉的优化控制; 而在外部姿势干扰条件下, 干扰刺激时间不明确, CNS则通过对局部稳定肌APAs预激活时间以及局部稳定肌和整体稳定肌APAs强度的双重调节实现姿势肌肉的优化控制。干扰强度的心理预期对姿势肌肉APAs和CPAs的作用表明, 心理预期效应主要源自于CNS对局部和整体稳定肌APAs控制机制的调制。     

Effects of Visual Error Timing on Smooth Pursuit Gain Adaptation in Humans

Smooth pursuit (SP) is one of the precise oculomotor behaviors when tracking a moving object. Adaptation of SP is based on a visual-error driven motor learning process associated with predictable changes in the visual environment. Proper timing of a sensory signal is an important factor for adaptation of fine motor control. In this study, we investigated whether visual error timing affects SP gain adaptation. An adaptive change in SP gain is produced experimentally by repeated trials of a step-ramp tracking with 2 different velocities (double-velocity paradigm). The authors used the double-velocity paradigm where target speed changes 400 or 800 ms after the target onset. The results show that SP gain changed in a certain time window following adaptation. The authors suggest that SP adaptation shown in this study is associated with timing control mechanisms.     

A Cognitive-Behavioral Model of Persistent Postural-Perceptual Dizziness

Persistent postural-perceptual dizziness (PPPD; previously termed “chronic subjective dizziness”) is a frequently observed disorder in patients who present with dizziness to audiology; ear, nose, and throat; or neurology clinics. The primary symptoms are persistent nonvertiginous dizziness, and hypersensitivity to motion and visual stimuli. These occur either in the absence of any active neuro-otologic illness or, where an episodic vestibular disorder exists, symptoms cannot be fully explained by the disorder alone. Diagnosis is necessarily multidisciplinary and proceeds by identification of primary symptoms and exclusion of other neurological or active medical disorders requiring treatment. Psychological processes are implicated in the development and maintenance of PPPD, with similarities to cognitive models of health anxiety and panic disorder, and there is evidence that cognitive-behavioral therapy is an effective treatment. A cognitive-behavioral model of PPPD is presented along with a case example. It is suggested that dizziness becomes persistent when it is processed as a threat, and that it is maintained by (a) unhelpful appraisals, (b) avoidance and safety behaviors, and (c) attentional strategies including selective attention to body sensations associated with dizziness. Once PPPD is identified techniques for its effective treatment fall within the skills mix of qualified cognitive-behavioral therapists or vestibular clinical scientists who have received additional training in cognitive and behavioral treatment.     

Age-related Changes in Postural Sway During Sit-to-stand in Typical Children and Children with Cerebral Palsy

Objective: To assess age-related changes in postural sway during sit-to-stand (STS) in typical children (TC) and children with mild cerebral palsy (CP). Methods: Thirty-five TC and 23 children with mild CP were allocated in four different age groups: 5–6, 7–9, 10–12, and 13–15 years; they all performed STS movements over a force plate. Anterior-posterior and medial-lateral amplitude of center of pressure (CoP) displacement, area and velocity of CoP sway were analyzed and compared between the age groups for TC and children with CP. Results: TC at 5 to 6 years of age showed higher values of anterior-posterior CoP displacement and Area of CoP sway than at 10–12 years, during the stabilization phase. There were no age-related changes for CP. Conclusion: TC change their postural sway during the last STS phase over the years, reducing their body sway. Children with CP did not show age-related changes in sway during STS, reflecting a distinct rhythm of postural control development in this population.     

The Influence of Motor Imagery on Postural Sway: Differential Effects of Type of Body Movement and Person Perspective

The present study examined the differential effects of kinesthetic imagery (first person perspective) and visual imagery (third person perspective) on postural sway during quiet standing. Based on an embodied cognition perspective, the authors predicted that kinesthetic imagery would lead to activations in movement-relevant motor systems to a greater degree than visual imagery. This prediction was tested among 30 participants who imagined various motor activities from different visual perspectives while standing on a strain gauge plate. The results showed that kinesthetic imagery of lower body movements, but not of upper body movements, had clear effects on postural parameters (sway path length and frequency contents of sway). Visual imagery, in contrast, had no reliable effects on postural activity. We also found that postural effects were not affected by the vividness of imagery. The results suggest that during kinesthetic motor imagery participants partially simulated (re-activated) the imagined movements, leading to unintentional postural adjustments. These findings are consistent with an embodied cognition perspective on motor imagery.