Trunk Compensation During Bimanual Reaching at Different Heights by Healthy and Hemiparetic Adults

The authors explored how trunk compensation and hand symmetry in stroke survivors and healthy controls were affected by the distance and height of virtual targets during a bimanual reaching task. Participants were asked to reach to 4 different virtual targets set at: 90% of their arm length at shoulder, xiphoid process, and knee height, and 50% of their arm length at xiphoid process height. For the stroke group, for all targets, the hands’ movements were more asymmetrical than those of the healthy group, with more asymmetry observed in the direction of gravity, and trunk forward displacement values were larger and more variable. The knee targets had the largest trunk displacement values; index of curvature and trunk displacement were strongly correlated with participants’ impairment scores. A strong correlation was found between the hands’ asymmetry in the anterior or posterior direction for the shoulder targets, and the impairment scores. The results suggest that target height influences the degree of trunk compensation and hand symmetry during bimanual reaching by hemiparetic participants.     

Influence of Strategy on Muscle Activity During Impact Movements

Participants (N = 10) made flexions or extensions about the elbow. Movements either were pointing (i.e., self-terminated) or terminated by impact on a barrier. The author examined how the trajectory and the electromyographic (EMG) patterns varied according to the distance moved, the instruction provided concerning speed, or the type of termination. Variations in kinematics induced by changes in the target distance or the instruction regarding speed were the same for impact and pointing movements. In comparison with a pointing movement of similar distance and speed instruction, an impact movement (a) accelerated longer and reached a higher velocity, (b) had a longer agonist EMG burst, and (c) had a low level of contraction that started slightly after the agonist burst and continued throughout the movement but had little or no antagonist burst. Because the different types of movements required different forces from the muscles, there were systematic, task-specific differences in EMG patterns that reflected task-specific differences in central control. The results of this experiment demonstrate that impact movements share some of the rules used in the control of other tasks, such as pointing and reversing movements. The sharing is not imposed by mechanical or physiological constraints but, rather, represents the imposition of internal constraints.     

A Note on State Individual Differences in Accuracy of Response Imagery: Aftereffects and Reminiscence

In two sessions, separated by 7 days, subjects imagined themselves performing a tracking task under a massed practice schedule. After conditions of interpolated rest and no-rest, which were counterbalanced across sessions, subjects actually performed the tracking task. During imagery practice, subjects verbally reported the temporal component of the task. The temporal accuracy of verbal reports varied widely across subjects, but not within subjects. Furthermore, a performance gain was demonstrated as a function of interpolated rest versus no-rest (reminiscence effect). Finally, the accuracy of verbal reports predicted imagery aftereffects, but not reminiscence effects.     

The Impact of Segmental Trunk Support on Posture and Reaching While Sitting in Healthy Adults

The authors investigated postural and arm control in seated reaches while providing trunk support at midribs and pelvic levels in adults. Kinematics and electromyography of the arm and ipsiliateral and contralateral paraspinal muscles were examined before and during reaching. Kinematics remained constant across conditions, but changes were observed in neuromuscular control. With midribs support, the ipsilateral cervical muscle showed either increased anticipatory activity or earlier compensatory muscle responses, suggesting its major role in head stabilization. The baseline activity of bilateral lumbar muscles was enhanced with midribs support, whereas with pelvic support, the activation frequency of paraspinal muscles increased during reaching. The results suggest that segmental trunk support in healthy adults modulates ipsilateral or contralateral paraspinal activity while overall kinematic outputs remain invariant.     

Using Corticomuscular and Intermuscular Coherence to Assess Cortical Contribution to Ankle Plantar Flexor Activity During Gait

The present study used coherence and directionality analyses to explore whether the motor cortex contributes to plantar flexor muscle activity during the stance phase and push-off phase during gait. Subjects walked on a treadmill, while EEG over the leg motorcortex area and EMG from the medial gastrocnemius and soleus muscles was recorded. Corticomuscular and intermuscular coherence were calculated from pair-wise recordings. Significant EEG–EMG and EMG–EMG coherence in the beta and gamma frequency bands was found throughout the stance phase with the largest coherence towards push-off. Analysis of directionality revealed that EEG activity preceded EMG activity throughout the stance phase until the time of push-off. These findings suggest that the motor cortex contributes to ankle plantar flexor muscle activity and forward propulsion during gait.     

Independent Development of Imagination and Perception of Fitts' Law in Late Childhood and Adolescence

Recent neurophysiological and behavioral research suggests perception-action systems are tightly coupled. Accordingly, Fitts' law has been observed when individuals execute, perceive, and imagine actions. Developmental research has found that (a) children demonstrate Fitts' law in imagined actions and (b) imagined movement time (MT) becomes closer to actual MT as age increases. However, action execution, imagination, and perception have yet to be assessed together in children. The authors investigated how imagined and perceived MTs related to actual MTs in children and adolescents. It was found that imagined MTs were longer than execution MTs were. Perception MTs were lower than execution MTs for children and more consistent with execution MTs for adolescents. These results suggest potential mechanistic differences in action imagination and perception.     

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.     

Effects of Different Ratios of Physical and Mental Practice on Postural Control Improvement

Abstract

Mental practice (MP) is a reliable alternative or complement to physical practice (PP) for the training of postural control. We address how MP should ideally be combined with PP. Participants were assigned to four experimental groups where MP/PP ratios during training varied from 0 to 100%. Performance improved only for demanding postural adjustments, regardless of MP/PP ratio, and learning was partially consolidated after a night of sleep. Findings reinforce the relevance of MP for the training of weight shifting and further suggest that MP alone can be as efficient as PP for the learning of certain complex postural adjustments.     

心理健康的测量与评估:大学生与成人及住院病人的纵向横向研究

对国内有关大学生心理问题比一般成人更严重的研究结论提出了质疑。使用总量4268人的样本,应用自编的心理健康评定量表(PHS)进行了纵向与横向研究。研究发现,大学生人群与一般成人同期相比,心理问题并非更严重。5项分量表中3项(抑郁、焦虑、躯体化)成人却明显比大学生人群要高,另外两项(强迫和精神病性)二者没有显著差异。但是,10年后的大学生与10年前的大学生在所有分量表上均见非常显著的差异,说明10年的变迁中,大学生的心理问题有非常明显的增长趋势,日见复杂化,虽然不能说比成人更严重,但是也足够引起我们的高度重视。将不同人群样本的数据按心理障碍严重性进行排列,依次是:住院精神障碍患者、成人、大学生。     

健康人格研究述评

在适应现代生活的同时人们愈来愈重视人格健康问题,个体的健康人格状况一直受到学者们的关注.文章对国内外二十年来健康人格的理论和实证研究进展进行了系统综述.在此基础上,指出了健康人格研究领域存在的问题和将来进一步研究的方向.     

Age and Flexible Thinking: An Experimental Demonstration of the Beneficial Effects of Increased Cognitively Stimulating Activity on Fluid Intelligence in Healthy Older Adults

ABSTRACT

The disuse hypothesis of cognitive aging attributes decrements in fluid intelligence in older adults to reduced cognitively stimulating activity. This study experimentally tested the hypothesis that a period of increased mentally stimulating activities thus would enhance older adults' fluid intelligence performance. Participants (N?=?44, mean age 67.82) were administered pre- and post-test measures, including the fluid intelligence measure, Cattell's Culture Fair (CCF) test. Experimental participants engaged in diverse, novel, mentally stimulating activities for 10–12 weeks and were compared to a control condition. Results supported the hypothesis; the experimental group showed greater pre- to post-CCF gain than did controls (effect size d?=?0.56), with a similar gain on a spatial-perceptual task (WAIS-R Blocks). Even brief periods of increased cognitive stimulation can improve older adults' problem solving and flexible thinking.     

The Effect of Auditory Cueing on the Spatial and Temporal Gait Coordination in Healthy Adults

Walk ratio, defined as step length divided by cadence, indicates the coordination of gait. During free walking, deviation from the preferential walk ratio may reveal abnormalities of walking patterns. The purpose of this study was to examine the impact of rhythmic auditory cueing (metronome) on the neuromotor control of gait at different walking speeds. Forty adults (mean age 26.6 ± 6.0 years) participated in the study. Gait characteristics were collected using a computerized walkway. In the preferred walking speed, there was no significant difference in walk ratio between uncued (walk ratio = .0064 ± .0007 m/steps/min) and metronome-cued walking (walk ratio = .0064 ± .0007 m/steps/min; p = .791). A higher value of walk ratio at the slower speed was observed with metronome-cued (walk ratio = .0071 ± .0008 m/steps/min) compared to uncued walking (walk ratio = .0068 ± .0007 m/steps/min; p < .001). The walk ratio was less at faster speed with metronome-cued (walk ratio = .0060 ± .0009 m/steps/min) compared to uncued walking (walk ratio = .0062 ± .0009 m/steps/min; p = .005). In healthy adults, the metronome cues may become an attentional demanding task, and thereby disrupt the spatial and temporal integration of gait at nonpreferred speeds.     

Behavioural and ERP Effects of Cognitive and Combined Cognitive and Physical Training on Working Memory and Executive Function in Healthy Older Adults

Cognitive and physical training have been shown to be effective in improving older adults’ cognition. However, it is not yet clear whether combined cognitive and physical training offers an advantage compared to cognitive training alone. Twenty-two older adults performed cognitive or combined cognitive and physical training in order to compare their effects on working memory event-related potentials (ERPs) and on working memory and executive function performance. Before and after eight weeks of training, performance in Plus Minus, Flanker, Updated Span, and Complex Span tasks was measured, and ERPs were registered during performance of an n-back task (0-back, 2-back, and 3-back). Post-training behavioural improvement was observed in Updated Span, Complex Span, and n-back tasks. During the n-back task, the N2/P3 complex was modulated by training, with a decrease in N2 amplitude and an increase in P3 amplitude in the posttraining session compared to the pretraining session. These changes in ERP components suggest that both types of training potentially reduce the need for attentional control to perform the tasks correctly and increase working memory capacity. Thus, based on our data, no conclusion can be reached on the direct advantage of combined training, either at behavioural or at neural level. However, the present study might suggest an indirect advantage of such a combined training, because the cognitive benefit was found to be highly similar in both types of training. Using combined cognitive and physical training may produce a potential improvement in general fitness and an increased appeal of training.     

Combination Effects of Forced Mild Exercise and GABAB Receptor Agonist on Spatial Learning,Memory, and Motor Activity in Striatum Lesion Rats

Basal ganglia (BG) lesions cause impairments of different mammalian’s movement and cognition behaviors. Motor circuit impairment has a dominant role in the movement disorders. An inhibitory factor in BG is GABA neurotransmitter, which is released from striatum. Lesions in GABAergic neurons could trigger movement and cognition disorders. Previous evidence showed that GABA_B receptor agonist (Baclofen) administration in human improves movement disorders and exercise can improve neurodegenerative and cognitive decline; however, the effects of both Baclofen and mild forced treadmill exercise on movement disorders are not well known. The main objective of this study is to investigate the combined effects of mild forced treadmill exercise and microinjection of Baclofen in the internal Globus Pallidus on striatum lesion-induced impairments of spatial learning and motor activity. We used Morris water maze and open filed tests for studying spatial learning, and motor activity, respectively. Results showed that mild exercise and Baclofen microinjection could not lonely affect the spatial learning, and motor activity impairments while the combination of them could alleviate spatial learning, and motor activity impairments in striatum-lesion animals. Our results suggest that striatum lesion-induced memory and motor activity impairments can improve with combination interaction of GABA_B receptor agonist and exercise training.