左侧背外侧前额叶在程序性运动学习中的作用

程序性运动学习包括序列学习和随机学习。神经影像学研究表明背外侧前额叶皮层(DLPFC)和初级运动皮层(M1)在程序性运动学习中发挥重要作用,但DLPFC和M1之间的联通性及其与不同程序性运动学习的关系尚不明确。本研究采用连续反应时间任务,结合经颅磁刺激(TMS)方法,探讨左侧DLPFC到M1的联通性在不同程序性运动学习中的差异。实验1采用两连发TMS探测DLPFC到M1的最佳投射时间点;实验2,被试分为2组,分别进行序列学习和随机学习,在学习前、后采集行为学数据,以及M1的运动诱发电位和DLPFC-M1联通性的电生理学数据。行为学结果发现序列学习组的学习效果更佳;电生理学结果发现,两组被试学习前、后M1的运动诱发电位均未发生改变;在最佳时间投射点、适当刺激强度下,序列学习组DLPFC-M1联通性发生改变,且与学习成绩相关,而随机学习组没有改变。结果说明DLPFC到M1的联通性增强可能是序列学习成绩更佳的重要原因,这一结果从电生理角度为DLPFC在运动学习中的作用提供了重要证据。     

Acquiring a Novel Coordination Skill without Practicing the Correct Motor Commands

There is evidence that experience of the sensory consequences, in the absence of practice of the required motor commands, is sufficient to learn new bimanual coordination patterns. This was shown through improvements of an incongruent group who practiced a desired 30° phase offset between the limbs while 1 limb was weighted such that the desired phase relation was achieved when synchronous motor commands were sent to the limbs (P. Atchy-Delama, P. G. Zanone, C. E. Peper, & P. J. Beek, 2005). In addition to testing a similar incongruent and congruent group (i.e., no weight), the authors extended this experiment by removing visual feedback during practice and by including an auditory modeling and passive guidance group. All groups showed improvement, except for the modeling group. The passive guidance group made more errors in posttests than the congruent and incongruent groups. Only the congruent group increased the amount of time around 30° after practice. Active experience of the sensory consequences combined with practice sending appropriate motor commands is the most effective method for learning, even though strategic improvements can be attained without experience of the latter.     

Physical and Observational Practice Afford Unique Learning Opportunities

In 2 experiments, the authors studied the effectiveness of physical and observational practice on learning and the effect on learning of combining physical practice and observation, as compared with providing physical practice alone. In Experiment 1, retention and transfer performance of 30 university students after physical, observational, or no practice were contrasted. Consistent with findings from other studies, the retention results indicated that observational practice is inferior to physical practice. The transfer data indicated no differences between observation and physical practice groups. In Experiment 2, retention and transfer performance of 30 participants in physical and combined (alternating physical and observational) practice groups were contrasted. The retention results showed no differences between the combined and physical practice groups, but the combined group performed significantly better than the physical practice group on the transfer test. Those findings suggest that a combination of observation and physical practice permits unique opportunities for learning beyond those available via either practice regimen alone.     

A Practice-Specificity-Based Model of Arousal for Achieving Peak Performance

The authors propose a practice-specificity-based model of arousal for achieving peak performance. The study included 37 healthy male physical education students whom they randomly assigned to a high-arousal (n = 19) or low-arousal group (n = 18). To manipulate participants' level of arousal, the authors used motivational techniques. They used heart rate and the Sport Competition Anxiety Test (R. Martens, 1977) to measure the level of arousal that participants achieved. At the determined and given arousal state, the 2 groups performed the task (basketball free throws) for 18 sessions. Both groups performed a retention test at the 2 arousal levels immediately after the last exercise session, in the posttest, and after 10 days. Results showed that both groups learned the task similarly and achieved their peak performance at their experienced arousal level. When tested at an arousal level that differed from the one that they experienced throughout practice sessions, participants' performance had deteriorated significantly. Performance of the task seemed to have integrated with the arousal level of the participants during the task learning. The findings of this study suggest a practice-specificity-based explanation for achieving peak performance.     

Development of Multiple Movement Representations With Practice: Specificity Versus Flexibility

The question addressed in the present experiment was whether an individual who practices a task under different conditions of afferent information develops different movement representations, each of which is based on the most accurate source of afferent information for movement control. In Experiment 1, participants (N = 23) performed a manual aiming movement in a target-only condition for 520 trials before performing in a normal vision condition for an equivalent amount of practice. Control groups performed all practice trials in either a normal vision or a target-only condition. The results revealed that the movement representation developed in the initial (target-only) practice phase remained accessible for movement planning and control. The results of Experiment 2 indicated, however, that participants did not maintain such a representation when their initial practice in the target-only condition was reduced (40 or 160 trials) before they had extensive practice in normal vision. Those results indicate that extensive practice in a target-only and then in a normal vision condition enables an individual to plan and control his or her movement on the basis of the most efficient source of available afferent information. Because visual afferent information provides optimal information for ensuring movement accuracy, however, if initial practice in the target-only condition is only modest or moderate it is likely that that information source will progressively dominate all other sources of afferent information for movement planning and control.     

Imaging brain plasticity during motor skill learning

The search for the neural substrates mediating the incremental acquisition of skilled motor behaviors has been the focus of a large body of animal and human studies in the past decade. Much less is known, however, with regard to the dynamic neural changes that occur in the motor system during the different phases of learning. In this paper, we review recent findings, mainly from our own work using fMRI, which suggest that: (i) the learning of sequential finger movements produces a slowly evolving reorganization within primary motor cortex (M1) over the course of weeks and (ii) this change in M1 follows more dynamic, rapid changes in the cerebellum, striatum, and other motor-related cortical areas over the course of days. We also briefly review neurophysiological and psychophysical evidence for the consolidation of motor skills, and we propose a working hypothesis of its underlying neural substrate in motor sequence learning.     

Application of Variability of Practice Hypothesis in Alzheimer Patients

This study examined the effects of constant versus variable practice on learning a simple motor task in eight patients diagnosed with Alzheimer's Disease (AD). According to the variability of practice hypothesis, variations in practice of a motor skill result in superior learning as evidenced by better ability to transfer the skill. Eight AD patients were matched for Mini-Mental State Exam and baseline scores and then randomly assigned to a constant or variable practice group. Then, the participants were trained in hitting a tennis ball with a small racquet against a horizontal target (practice task) over 12 sessions. Finally, they were asked to aim at a vertical target (transfer task). All participants showed improvement on the practice task. On the transfer task, three of four participants in the variable practice group outperformed their matched counterparts, suggesting learning benefits of variable practice.     

Offline Improvement during Motor Sequence Learning Is Not Restricted to Developing Motor Chunks

Robust offline performance gains, beyond those that would be anticipated by being exposed to additional physical practice, have been reported during procedural learning and have been attributed to enhancement consolidation, a process by which memory is transformed in such a way that it is not only more resistant to forgetting but may also involve a reorganization of information that supports superior task execution. The authors assessed the impact of increasing within-session practice extent on the emergence of offline performance gains. Practice-dependent improvements occurred across 12 and 24 30-s practice trials of a 5-element motor sequencing task. Offline improvements were observed following both 12 and 24 trials. The improvement following 12 trials was associated with the formation of motor chunks important for establishing movement sequence structure. In contrast, the offline improvement after 24 trials was not related to further changes in movement structure beyond those that had emerged during practice. These data suggest that additional memory operations, beyond those needed to amalgamate subsequences of the SRT task, are susceptible to enhancement consolidation.     

Specificity of Learning in a Video-Aiming Task: Modifying the Salience of Dynamic Visual Cues

The authors investigated whether the salience of dynamic visual information in a video-aiming task mediates the specificity of practice. Thirty participants practiced video-aiming movements in a full-vision, a weak-vision, or a target-only condition before being transferred to the target-only condition without knowledge of results. The full- and weak-vision conditions resulted in less endpoint bias and variability in acquisition than did the target-only condition. Going from acquisition to transfer resulted in a large increase in endpoint variability for the full-vision group but not for the weak-vision or target-only groups. Kinematic analysis revealed that weak dynamic visual cues do not mask the processing of other sources of afferent information; unlike strong visual cues, weak visual cues help individuals calibrate less salient sources of afferent information, such as proprioception.     

The Schematic Representation of Effector Function Underlying Perceptual-Motor Skill

Conceptual and methodological problems related to Schmidt’s (1975) motor schema theory are discussed. In particular, the motor schema is interpreted as representing the dynamics of the system being controlled, which may or may not be associated with a referent movement pattern. Furthermore, it is suggested that prior familiarity with a control system’s dynamics is a critical but uncontrolled factor in tests of the theory, and largely accounts for their equivocal findings. These ideas are examined by two experiments in which subjects had to bimanually control the movement of a computer-displayed cursor along a track on a CRT screen. Different track orientations required different patterns of movement not entailing a single generalized motor program. Experiment 1 shows that variable track performance with a given control system, results in better transfer to novel tracks than does fixed practice. Experiment 2 demonstrates that altering the control system disrupts performance whether or not the required movements remain the same. These results indicate the need for a fundamental modification of schema theory, such that a schematic representation of effector-environment relations (effector function) is available independently of particular movement patterns used in its acquisition.     

Effects of Pointing Rate and Availability of Visual Feedback on Visual and Proprioceptive Components of Prism Adaptation

The withdrawal of vision of the arm during a manual aiming task has been found to result in a large increase in aiming error, regardless of the amount of practice in normal vision before its withdrawal. In the present study, the authors investigated whether the increase in error reflects the domination of visual afferent information over the movement representation developed during practice to the detriment of other sources of afferent information or whether it reflects only transformation errors of the location of the target from an allocentric to an egocentric frame of reference. Participants (N = 40) performed aiming movements with their dominant or nondominant arm in a full-vision or target-only condition. The results of the present experiment supported both of those hypotheses. The data indicated that practice does not eliminate the need for visual information for optimizing movement accuracy and that learning is specific to the source or sources of afferent information more likely to ensure optimal accuracy during practice. In addition, the results indicated that movement planning in an allocentric frame of reference might require simultaneous vision of the arm and the target. Finally, practice in a target-only condition, with knowledge of results, was found to improve recoding of the target in an egocentric frame of reference.     

Performance and Learning of Generalized Motor Programs: Relative (GMP) and Absolute (Parameter) Errors

The effects of practice (Experiment 1) and parameter variability (Experiment 2) on the learning of generalized motor programs (GMPs) and movement parameterization were investigated In each experiment, 2 tasks with different relative force-time structures were tested. Participants (N = 32, Experiment (N = 40, Experiment 2) attempted to exert a pattern of force that resembled in force and time a waveform that was displayed on a computer monitor. In both experiments, the analysis suggested that the GMP, although refined over practice, was relatively stable (i.e., resistant to decay and interference), even early in practice (after 20 trials). In addition, the results indicated that constant and variable parameter practice did not differentially affect GMP learning but did degrade the learning of the parameter that was not varied. The data provided additional evidence for the dissociation of the GMP and the parameterization processes proposed in GMP theory. Contrary to schema theory, the present data suggest an interdependence between the force and the time parameters: The manipulation of 1 of the parameters has a negative effect on the learning of the other parameter.     

Investigating speech motor practice and learning in people who stutter

In this exploratory study, we investigated whether or not people who stutter (PWS) show motor practice and learning changes similar to those of people who do not stutter (PNS). To this end, five PWS and five PNS repeated a set of non-words at two different rates (normal and fast) across three test sessions (T1, T2 on the same day and T3 on a separate day, at least 1 week apart). The results indicated that PWS and PNS may resemble each other on a number of performance variables (such as movement amplitude and duration), but they differ in terms of practice and learning on variables that relate to movement stability and strength of coordination patterns. These findings are interpreted in support of recent claims about speech motor skill limitations in PWS.

Educational objectives: The reader will be able to: (1) define oral articulatory changes associated with motor practice and learning and their measurement; (2) summarize findings from previous studies examining motor practice and learning in PWS; and (3) discuss hypotheses that could account for the present findings that suggest PWS and PNS differ in their speech motor learning abilities.     

Motor Learning through Induced Variability at the Task Goal and Execution Redundancy Levels

The authors examined the influence of introducing variability at two different levels in the learning of a striking task. Variability at the task goal level was introduced by changing target location, whereas variability at the execution redundancy level was introduced by using an intermediate target that constrained participants to use different paths from trial to trial to strike the same target. After practice, participants were transferred to 2 test conditions: (a) a fixed-target test, where the position of the target was unchanged; and (b) a variable-target test, where the position of the target was varied from trial to trial. The results from the manipulation at the task goal level were consistent with predictions from the specificity of practice hypothesis. In both the fixed- and variable-target tests, the best performance was achieved by the group that had practiced in the condition matching the test condition. At the execution-redundancy level, practicing multiple solutions to achieve the task goal did not improve performance in either the fixed- or variable-target tests. These results show that introducing variability at the task goal and execution redundancy levels has different effects on learning and generalization and that practice schedules that constrain the participant to use redundant solutions may not facilitate learning.     

学习与脑可塑性的研究进展及其教育意义

脑可塑性是指脑在外界环境和经验的作用下不断塑造其结构和功能的能力.本文阐述了神经科学与认知神经科学关于学习影响动物脑与人脑结构与功能的研究进展.研究表明,学习与经验可以改变脑皮层的厚度与树突的结构,增加树突棘的数量,修饰其形状,对脑的功能代表区产生影响.学习与脑可塑性的多层面研究为理解学习的本质规律以及教育研究与实践提供重要的启示.