Structural Stability within the Lateral Cerebellar Nucleus of the Rat Following Complex Motor Learning

Complex motor learning, but not mere motor activity, has been previously shown to induce structural modifications within the cerebellar cortex. The present experiment examined whether similar changes occur within one of the primary output targets of the region of the cerebellar cortex in which these structural changes were described, the lateral cerebellar nucleus (LCN; dentate nucleus). Adult female rats were randomly allocated to one of three training conditions. Acrobatic condition (AC) rats were trained to complete a complex motor learning task consisting of a series of elevated obstacles while motor control (MC) condition animals were forced to traverse a flat obstacle-free runway equal in length to the AC task. Inactive condition (IC) animals received no motor training. Unbiased stereological techniques and electron microscopy were used to obtain estimates of synapse number and postsynaptic density (PSD) length within the LCN. Results showed that neither synapse number nor PSD length was significantly altered as a function of training condition. These results indicate that complex motor skill learning is associated with structural plasticity within the cerebellar cortex and with structural stability within the lateral cerebellar nucleus.     

Benefits of Blocked Over Serial Feedback on Complex Motor Skill Learning

The effects of blocked versus serial feedback (FB) on the learning of a complex motor skill-the production of slalom-type movements on a ski-simulator-were examined. FB was given about force onset, which is considered to be a measure of movement efficiency; relatively late force onsets characterize expert performance. One group of participants (blocked FB; n = 10) received FB about 1 foot per day; for example, for the right foot on Days 1 and 3 and for the left foot on Days 2 and 4. For another group (serial FB; n = 10), the foot about which FB was received was switched on consecutive trials on each of 4 days of practice. Learning was assessed on no-FB trials at the beginning of Days 2, 3, and 4, and on Day 5. Even though there were no differences between groups in force onset, the blocked FB group produced significantly larger movement amplitudes and higher movement frequencies than the serial FB group on the retention test on Day 5. Thus, contrary to the learning of more simple skills (e.g., T. D. Lee & H. Carnahan, 1990), constantly changing the movement component that FB is provided about did not seem to be beneficial for the learning of more complex skills. The findings add to the increasing evidence showing that practice variables that have been shown to enhance the learning of simple skills can actually be detrimental to the learning of complex skills.     

Effect of Analogy Instructions with an Internal Focus on Learning a Complex Motor Skill

This study examined the effects of an analogy in learning breaststroke swimming. Two groups of participants had 20 lessons on how to increase their stroke length. The participants in the experimental condition received an analogy with an internal focus of attention. Inter-limb coordination showed qualitative changes in this group: a greater increase in swimming efficiency (i.e., a coordination closer to anti-phase [?50° before learning and ?125° after] and a 10% decrease in the time spent in-phase). The findings showed that an internal focus of attention induced by analogy could be beneficial in improving the quality of inter-limb swimming coordination.     

Learning,Motor Skill,and Long-Range Correlations

Long-range correlations have been evidenced in a number of experiments, generally using overlearned and overpracticed tasks. The authors hypothesized that long-range correlation could represent the byproduct of learning. They analyzed the series of periods produced by a group of expert and a group of novices during prolonged trials on a ski simulator. Results showed a very low variability in expert's series, as compared to novices. Fractal analyses showed that fluctuations were significantly more structured and correlated in experts. These results suggest that learning could be conceived as the progressive installation of complexity in the system.     

Motor Cortex Plasticity in Children With Spastic Cerebral Palsy: A Systematic Review

A review of the literature was performed to answer the following questions: Does motor cortex excitability correlate with motor function? Do motor cortex excitability and cortex activation change after a rehabilitation program that results in improvements in motor outcomes? Can the 10–20 electroencephalography (EEG) system be used to locate the primary motor cortex when employing transcranial direct current stimulation? Is there a bihemispheric imbalance in individuals with cerebral palsy similar to what is observed in stroke survivors? the authors found there is an adaptation in the geometry of motor areas and the cortical representation of movement is variable following a brain lesion. The 10–20 EEG system may not be the best option for locating the primary motor cortex and positioning electrodes for noninvasive brain stimulation in children with cerebral palsy.     

Variability of Practice and Contextual Interference in Motor Skill Learning

The purpose of this study was to investigate whether learning benefits in multiple-task learning situations are a result of contextual interference or of schema enhancement related to the amount of variability in the practice session. Two experiments were designed that replicated and extended the experiment reported by Wulf and Schmidt (1988). In a 2 (same vs. different relative time) x 2 (blocked vs. random practice schedule) design, 48 right-handed subjects were randomly assigned to one of four experimental conditions. A tapping task was employed that required a right-handed tap of three small brass plates arranged in a diamond pattern. Each segment had a specific time requirement. Target times and response times were provided on a computer screen directly in front of the subject. Each subject participated in two acquisition sessions (i.e., 198 practice trials) and was tested for learning on several different retention and transfer tests. In Experiment 2, a control group was added that received no acquisition phase. Results of both experiments showed a typical contextual interference effect, with depressed scores by the random groups during acquisition but significantly better scores than the blocked groups on several retention and transfer tests. Certain characteristics of the tests were found to influence the demonstration of the practice schedule effects. These results were consistent with predictions from Magill and Hall (1990) that the learning benefits of contextual interference are more likely to occur when skill variations are from different classes of movement and that the amount of variability in practice is more influential when the to-be-learned tasks are parameter modifications of the same generalized motor program.     

Engaging Environments Enhance Motor Skill Learning in a Computer Gaming Task

Engagement during practice can motivate a learner to practice more, hence having indirect effects on learning through increased practice. However, it is not known whether engagement can also have a direct effect on learning when the amount of practice is held constant. To address this question, 40 participants played a video game that contained an embedded repeated sequence component, under either highly engaging conditions (the game group) or mechanically identical but less engaging conditions (the sterile group). The game environment facilitated retention over a 1-week interval. Specifically, the game group improved in both speed and accuracy for random and repeated trials, suggesting a general motor-related improvement, rather than a specific influence of engagement on implicit sequence learning. These data provide initial evidence that increased engagement during practice has a direct effect on generalized learning, improving retention and transfer of a complex motor skill.     

Dependence on Visual Feedback During Motor Skill Learning in Alzheimer's Disease

Three experiments examined the role of visual feedback on the performance of a fine motor task, namely the rotary pursuit, in patients with Alzheimer's disease (AD) and healthy older adults. After extensive practice tracking a fully visible target, participants in Experiments 1 and 2 were tested under restricted vision (RV) conditions. In both experiments, the two groups showed a drop in performance when vision was restricted, with AD patients showing a significantly larger decline. Tracking improved significantly in normal controls, but not AD patients across the RV trials after the initial drop. When difficulty of the rotary pursuit task was manipulated in Experiment 3 without restricting vision, AD patients and normal controls showed identical patterns of performance. Consequently, it could be concluded that AD patients in the first two experiments were relying more heavily on visual information for accurate performance of the tracking task than their healthy peers.     

Motor Skill Learning and the Development of Visual Perception Processes Supporting Action Identification

This study examined physical training and observational training influences on motor learning and the development of visual discrimination processes. Participants were trained on a bimanual task (relative phase of +90°) defined by a visual training stimulus. There were 2 observational contexts: 1) model-only, watch a learning model, and 2) stimulus-only, watch the visual training stimulus. After 2 d of training, the learning models performed the +90° pattern with reduced error in 2 retention tests. Each observer group showed improvement in performance of the +90° pattern, with the stimulus-only group characterized by a more significant improvement. The learning models and observer groups were characterized by an improvement in visually discriminating 2 features of the trained pattern, relative phase and hand-lead. Overall, physical practice (learning models) established a stronger link between the action and visual discrimination processes compared with the observational contexts. The results show that the processes supporting action production and the visual discrimination of actions are modified in ways specific to the trained action following both physical and observational training.     

Neurocognitive Contributions to Motor Skill Learning: The Role of Working Memory

ABSTRACT

Researchers have begun to delineate the precise nature and neural correlates of the cognitive processes that contribute to motor skill learning. The authors review recent work from their laboratory designed to further understand the neurocognitive mechanisms of skill acquisition. The authors have demonstrated an important role for spatial working memory in 2 different types of motor skill learning, sensorimotor adaptation and motor sequence learning. They have shown that individual differences in spatial working memory capacity predict the rate of motor learning for sensorimotor adaptation and motor sequence learning, and have also reported neural overlap between a spatial working memory task and the early, but not late, stages of adaptation, particularly in the right dorsolateral prefrontal cortex and bilateral inferior parietal lobules. The authors propose that spatial working memory is relied on for processing motor error information to update motor control for subsequent actions. Further, they suggest that working memory is relied on during learning new action sequences for chunking individual action elements together.     

干扰情境下类比习得运动技能的稳定性表现

本实验以高尔夫推杆技能学习为任务,采用双因素混合设计,通过对24名高尔夫新手的研究比较了类比和外显两种学习方式获得的运动技能在干扰情境下的操作表现。结果发现:(1)类比学习和外显学习在运动技能形成过程中的效果是相当的;(2)类比学习获得的运动技能在干扰情境下操作表现稳定,而外显学习获得的运动技能表现却下降。类比学习是一种具有实践应用价值的内隐学习方法。     

Examining the Preferred Self-Controlled KR Schedules of Learners and Peers During Motor Skill Learning

In many practical situations, learners are provided with feedback in the form of knowledge of results (KR) by a peer. However, when peers provide KR is currently unknown. When given the opportunity to request KR in a self-controlled manner, some participants have reported a preference for requesting KR after good performances. Alternatively, peers may provide KR in a different fashion. Subsequently, a discrepancy between the learner's desire to receive KR and when a peer provides KR may arise. In our study, peer- and self-controlled KR schedules were compared. Participants were peers who controlled KR (PC; 8), learners with peers (P-L; 8), or learners with self-control (SC; 8). Participants in the two learning groups (P-L and SC groups) completed a serial-timing task with a goal time of 2500 ms. Absolute error data on KR and no-KR trials along with self-reports indicate that participants with self-control preferred KR after good trials and peers preferred to provide KR after both good and bad trials equally. Results from the delayed retention test indicated that peer-controlled learners were more consistent (i.e., in terms of variable error) than the self-control group.     

条件性恐惧大鼠边缘下区Cdk5激酶活性、caspase-3表达以及突触结构的变化

探讨条件性恐惧大鼠内侧前额叶皮层边缘下区(IL区)Cdk5激酶活性、凋亡因子caspase-3表达和突触结构的变化。采用声音结合足底电击的方法对大鼠建立条件性恐惧模型后, 在不同时间点测定IL区Cdk5激活剂P35和P25的蛋白表达水平、Cdk5激酶活性、caspase-3的阳性细胞数, 并观察突触结构的变化。结果发现, 大鼠在条件性恐惧建立后第2、4和8天, IL区的P25蛋白表达和Cdk5激酶活性均明显高于正常; caspase-3的免疫反应阳性细胞数在3个时间点也均多于正常; 透射电镜下观察到：在恐惧建立后的第8天, IL区突触的突触后致密物质(PSD)厚度变薄, 在恐惧建立后第22天突触数密度减少、PSD厚度仍小于正常。推测条件性恐惧的建立, 使大鼠IL区的P25水平和Cdk5活性高于正常, 引起IL区的突触结构发生改变, 导致大鼠的恐惧反应持续存在。     

Signaling Mechanisms Mediating BDNF Modulation of Synaptic Plasticity in the Hippocampus

Although recent studies indicate that brain-derived neurotrophic factor (BDNF) plays an important role in hippocampal synaptic plasticity, the underlying signaling mechanisms remain largely unknown. Here, we have characterized the signaling events that mediate the BDNF modulation of high-frequency synaptic transmission. Mitogen-associated protein kinase (MAPK), phosphotidylinositol-3 kinase (PI3K), and phospholipase C-γ (PLC-γ) are the three signaling pathways known to mediate neurotrophin signaling in other systems. In neonatal hippocampal slices, application of BDNF rapidly activated MAPK and PI3K but not PLC-γ. BDNF greatly attenuated synaptic fatigue at CA1 synapses induced by a train of high-frequency, tetanic stimulation (HFS). Inhibition of the MAPK and PI3K, but not PLC-γ, prevented the BDNF modulation of high-frequency synaptic transmission. Neurotrophin-3 (NT-3), a close relative of BDNF, did not activate MAPK or PI3K and had no effect on synaptic fatigue in the neonatal hippocampus. Neither forskolin, which activated MAPK but not PI3 kinase, nor ciliary neurotrophic factor (CNTF), which activated PI3K but not MAPK, affected HFS-induced synaptic fatigue. Treatment of the slices with forskolin together with CNTF still had no effect on synaptic fatigue. Thus, although the activation of MAPK and PI3K is required, the two together are not sufficient to mediate the BDNF effect. Inhibition of new protein synthesis by anisomycin or cycloheximide did not prevent the BDNF effect. These data suggest that BDNF modulation of high-frequency transmission is independent of protein synthesis but requires MAPK and PI3K and yet another signaling pathway to act together in the hippocampus.     

Interindividual Variability in Use-Dependent Plasticity Following Visuomotor Learning: The Effect of Handedness and Muscle Trained

Motor learning has been linked with increases in corticospinal excitability (CSE). However, the robustness of this link is unclear. In this study, changes in CSE associated with learning a visuomotor tracking task were mapped using transcranial magnetic stimulation (TMS). TMS maps were obtained before and after training with the first dorsal interosseous (FDI) of the dominant and nondominant hand, and for a distal (FDI) and proximal (biceps brachii) muscle. Tracking performance improved following 20 min of visuomotor training, while map area was unaffected. Large individual differences were observed with 18%–36% of the participants revealing an increase in TMS map area. This result highlights the complex relationship between motor learning and use-dependent plasticity of the motor cortex.     

Self-Regulated Learning of a Motor Skill Through Emulation and Self-Control Levels in a Physical Education Setting

This study examined the effectiveness of the second and third level of Zimmerman's (2000) model of self-regulated learning development. Participants were 72 (28 boys and 44 girls) fifth- and sixth-grade students who practiced the novel task of dart-throwing. Results showed that sixth-grade Greek students who proceeded sequentially from the emulation to the self-control level improved their dart-throwing performance more than students who missed one or both of these levels, but fifth-grade students benefited equally either from the sequential practice at the emulation and the self-control level or from the experience at one of these self-regulatory levels. No differences were found in self-efficacy, although sixth-grade students who practiced at the emulation level reported higher satisfaction, and sixth-grade students who practiced at the self-control level reported higher intrinsic motivation compared to control group students. These results attest to the effectiveness of learning at the emulation and self-control levels and are discussed with reference to the social cognitive model of self-regulation development.     

汉字输入中认知技能与动作技能的分离

通过20名大学生在采用目光注视屏幕上的键盘完成汉字输入任务的眼动研究,将汉字输入中的认知技能与动作技能实现分离,从而探究关于键盘布局图式的认知技能的发展.结果发现:(1)在标准键盘显示下,汉字输入技能水平高分组与低分组在完成时间上没有显著差异,而空白键盘显示下高分组的完成时间显著快于低分组;(2)两种键盘显示方式下,低分组的眼动指标都没有显著差异,而高分组在空白键盘显示下的平均注视时间要显著多于标准键盘显示下的.