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PubMed1991

[Effects of cognitive strategies on motor-learning].

The effectiveness of cognitive strategies and the training procedure for a motor learning, which seemed difficult to control voluntarily, was examined. The task was the abduction without fluctuation of the big toe. Two experiments were conducted with 16 and 20 subjects in each. Results suggest that (1) it is necessary to provide a relatively long duration for each trial in the training session in order to let the subjects to find their appropriate strategies; and (2) the greatest facilitatory effect is obtained when they individually attempt to control the abduction of the big toe with attention to the direction of its movements which inevitably contract the M. abductor hallucis, whereas the knowledge of the location of the muscle has little effect on its motor learning. The implication of these results to the rehabilitation for physically handicapped persons was discussed.

Adult↗
PubMed1992

Expression of motor learning in the response of the primate vestibuloocular reflex pathway to electrical stimulation.

1. The vestibuloocular reflex (VOR) undergoes long-term adaptive changes in the presence of persistent retinal image motion during head turns. Previous experiments using natural stimuli have provided evidence that the VOR is subserved by parallel pathways, including some that are modified during learning and some that are not. We have used electrical stimulation of the vestibular labyrinth to investigate the temporal properties of the signals that are transmitted through the modified pathways. 2. Electrodes were implanted chronically in the superior semi-circular canal, the horizontal canal, or the vestibule for electrical activation of the vestibular afferents. Learning was induced by fitting the monkeys with spectacles that magnified or miniaturized vision. Before, during, and after motor learning, we measured the eye movements evoked by electrical stimulation of the labyrinth as well as the gain of the VOR, defined as eye speed divided by head speed during natural vestibular stimulation in the dark. 3. Trains of pulses applied to the labyrinth caused the eyes to move away from the side of stimulation with an initial rapid change in eye velocity followed by a steady-state plateau. Changes in the gain of the VOR caused large changes in the trajectory and magnitude of eye velocity during the plateau, showing that our stimulating electrodes had access to the modified pathways. 4. A single, brief current pulse applied to the labyrinth evoked an eye movement that had a latency of 5 ms and consisted of a pulse of eye velocity away from the side of the stimulation followed by a rebound toward the side of stimulation. To quantify the effect of motor learning on these eye movements, we pooled the data across different VOR gains and computed the slope of the relationship between eye velocity and VOR gain at each millisecond after the stimulus. We refer to the slope as the "modification index." 5. In comparison with the evoked eye velocity, the modification index took longer to return to baseline and showed a large peak at the time of the rebound in eye velocity. Increases in stimulus current increased both the amplitude and the duration of the modification index and revealed several later peaks. These observations suggest that the full expression of motor learning requires activation of multisynaptic pathways and recruitment of primary vestibular afferents with higher thresholds for electrical stimulation. 6. The modification index was almost always positive during the initial deflection in eye velocity, and the latency of the first change in the modification index was usually the same as the latency of the evoked eye movement.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed2004

Task-dependent role of the cerebellum in motor learning.

This chapter reviews several findings from our laboratory supporting the hypothesis that the cerebellum's role in motor learning is task-dependent. Namely, its contribution is dependent on the specific task being learned. Several studies are reviewed to demonstrate that the effect of temporary or permanent cerebellar lesions on a specific process such as storage varies depending on the behavior. Furthermore, this task-dependency is reflected also in the modulation of Purkinje cells and nuclear neurons recorded during the learning process. The behavioral correlates of this modulation are very paradigm specific. These observations support the above hypothesis and emphasize the importance of paradigm selection in designing experiments focused on elucidating the cerebellum's role in learning a specific motor behavior.

Animals↗
PubMed2006

Memory trace of motor learning shifts transsynaptically from cerebellar cortex to nuclei for consolidation.

Adaptation of ocular reflexes is a prototype of motor learning. While the cerebellum is acknowledged as the critical site for motor learning, the functional differences between the cerebellar cortex and nuclei in motor memory formation are not precisely known. Two different views are proposed: one that the memory is formed within the cerebellar flocculus, and the other that the memory is formed within vestibular nuclei. Here we developed a new paradigm of long-term adaptation of mouse horizontal optokinetic response eye movements and examined the location of its memory trace. We also tested the role of flocculus and inferior olive in long-term adaptation by chronic lesion experiments. Reversible bilateral flocculus shutdown with local application of 0.5 microl-5% lidocaine extinguished the memory trace of day-long adaptation, while it very little affected the memory trace of week-long adaptation. The responsiveness of vestibular nuclei after week-long adaptation was examined by measuring the extracellular field responses to the electrical stimulation of vestibular nerve under trichloroacetaldehyde anesthesia. The amplitudes and slopes of evoked monosynaptic field response (N1) of week-long adapted mice were enhanced around the medial vestibular nucleus compared with those of control mice. Chronic flocculus or inferior olive lesions abolished both day and week-long adaptations. These results suggest that the functional memory trace of short-term adaptation is formed initially within the cerebellar cortex, and later transferred to vestibular nuclei to be consolidated to a long-term memory. Both day and week-long adaptations were markedly depressed when neural nitric oxide was pharmacologically blocked locally and when neuronal nitric oxide synthase was ablated by gene knockout, suggesting that cerebellar long-term depression underlies both acquisition and consolidation of motor memory.

Adaptation, Physiological↗
PubMed1990

On the role of knowledge of results in motor learning: exploring the guidance hypothesis.

Recent work on the role of knowledge of results (KR) in motor learning has challenged some traditional assumptions. In particular, the guidance hypothesis suggests that there is a detriment to learning when KR guides the learner toward correct performance. Three experiments that explored this hypothesis are reported here. These experiments contrasted the effects of relative frequency of guidance versus the relative frequency of KR. According to the guidance hypothesis, it was predicted that parallel effects of the relative frequency manipulation on motor learning and performance would result under guided and KR conditions. The movement task was a reciprocal timing task that was either paced by a metronome (Experiment 1) or augmented by auditory KR (Experiments 2 and 3). The results of Experiments 1 and 3 revealed a number of parallel effects, thus providing support for the guidance hypothesis. The contrast of Experiments 1 and 2 resulted in a number of dissociable effects, however. These findings are discussed in relation to the potential guiding properties of KR and their impact on motor performance and learning.

Journal Article↗
PubMed1984

The latency of pathways containing the site of motor learning in the monkey vestibulo-ocular reflex.

The vestibulo-ocular reflex helps to stabilize retinal images by generating smooth eye movements that are equal to and opposite each rotatory head movement. It is well known that the reflex undergoes adaptive plasticity or "motor learning" whenever there is persistent image motion during head turns: the resulting changes in the reflex occur gradually and help to restore image stability. A new approach makes it possible to identify the pathways containing the site of motor learning according to their total latency in response to natural vestibular stimuli. The fastest pathways required 14 milliseconds to initiate a vestibulo-ocular reflex, but the site of motor learning was in pathways having latencies of at least 19 milliseconds.

Animals↗
PubMed1988

Brain stem neurons in modified pathways for motor learning in the primate vestibulo-ocular reflex.

The vestibulo-ocular reflex (VOR) stabilizes retinal images by generating smooth eye movements that are equal in amplitude and opposite in direction to head turns. Whenever image motion occurs persistently during head turns, the VOR undergoes motor learning; as a result image stability is gradually restored. A group of brain stem neurons that are in the modified pathways has now been described. The neurons express changes in firing in association with motor learning in the VOR and receive monosynaptic inhibition from the flocculus of the cerebellum. The changes in firing have an appropriate magnitude and are expressed at the correct latency to account for the altered VOR. The response properties of the neurons point to their brain stem vestibular inputs for further investigation of the site of motor learning.

Action Potentials↗
PubMed2007

Aging affects motor learning but not savings at transfer of learning.

Two important components of skill learning are the learning process itself (motor acquisition) and the ability to transfer what has been learned to new task variants (motor transfer). Many studies have documented age-related declines in the ability to learn new manual motor skills. In this study, I tested whether the degree of savings at transfer of learning is similarly affected by advancing age. Young and older adults made aiming movements with a joystick to hit targets presented on a computer screen, with real-time feedback display of their movement. They adapted to three different rotations of the feedback display in a sequential fashion, with return to the normal feedback display between each. Adaptation performance was better when it was preceded by other adaptive experiences, regardless of age.

Adult↗
PubMed2003

Rapid motor learning in the translational vestibulo-ocular reflex.

Motor learning was induced in the translational vestibulo-ocular reflex (TVOR) when monkeys were repeatedly subjected to a brief (0.5 sec) head translation while they tried to maintain binocular fixation on a visual target for juice rewards. If the target was world-fixed, the initial eye speed of the TVOR gradually increased; if the target was head-fixed, the initial eye speed of the TVOR gradually decreased. The rate of learning acquisition was very rapid, with a time constant of approximately 100 trials, which was equivalent to <1 min of accumulated stimulation. These learned changes were consolidated over >or=1 d without any reinforcement, indicating induction of long-term synaptic plasticity. Although the learning generalized to targets with different viewing distances and to head translations with different accelerations, it was highly specific for the particular combination of head motion and evoked eye movement associated with the training. For example, it was specific to the modality of the stimulus (translation vs rotation) and the direction of the evoked eye movement in the training. Furthermore, when one eye was aligned with the heading direction so that it remained motionless during training, learning was not expressed in this eye, but only in the other nonaligned eye. These specificities show that the learning sites are neither in the sensory nor the motor limb of the reflex but in the sensory-motor transformation stage of the reflex. The dependence of the learning on both head motion and evoked eye movement suggests that Hebbian learning may be one of the underlying cellular mechanisms.

Animals↗
PubMed2001

Knowledge of results for motor learning: relationship between error estimation and knowledge of results frequency.

The authors of the present study investigated the apparent contradiction between early and more recent views of knowledge of results (KR), the idea that how one is engaged before receiving KR may not be independent of how one uses that KR. In a 2 &times: 2 factorial design, participants (N = 64) practiced a simple force-production task and (a) were required, or not required, to estimate error about their previous response and (b) were provided KR either after every response (100%) or after every 5th response (20%) during acquisition. A no-KR retention test revealed an interaction between acquisition error estimation and KR frequencies. The group that received 100% KR and was required to error estimate during acquisition performed the best during retention. The 2 groups that received 20% KR performed less well. Finally, the group that received 100% KR and was not required to error estimate during acquisition performed the poorest during retention. One general interpretation of that pattern of results is that motor learning is an increasing function of the degree to which participants use KR to test response hypotheses (J. A. Adams, 1971; R. A. Schmidt, 1975). Practicing simple responses coupled with error estimation may embody response hypotheses that can be tested with KR, thus benefiting motor learning most under a 100% KR condition. Practicing simple responses without error estimation is less likely to embody response hypothesis, however, which may increase the probability that participants will use KR to guide upcoming responses, thus attenuating motor learning under a 100% KR condition. The authors conclude, therefore, that how one is engaged before receiving KR may not be independent of how one uses KR.

Adult↗
PubMed1996

Acquisition of a runway motor learning task is impaired by a beta adrenergic antagonist in F344 rats.

Performance of rats on a motor learning paradigm that has been demonstrated to be dependent upon cerebellar norepinephrine (NE) was studied in male F344 rats treated with an alpha 1 antagonist (prazosin), an alpha 2 antagonist (yohimbine) or a beta noradrenergic antagonist (propranolol). The ability of propranolol-treated rats (10 mg/kg i.p. 30 min prior to daily testing) to acquire proficiency on the novel motor task was impaired while prazosin-treated rats' (0.5 mg/kg i.p. 30 min prior to daily testing) and yohimbine-treated rats' (1 mg/kg i.p. 30 min prior to daily testing) rates of acquisition of the novel motor task were not different from controls. In an attempt to distinguish between alterations in motor coordination and motor learning, additional tests of psychomotor performance were assessed for all groups of rats. These examinations included a walking test on 2.5 and 5 cm rods and speed of running on the motor task. The data indicate that drug-treated rats show no difference from controls on the above parameters. Some differences, however, were observed between propranolol and controls in the time spent in the goal box. Overall, the data are consistent with our hypothesis that the beta noradrenergic receptor is involved in the ability to acquire novel motor tasks.

Adrenergic alpha-1 Receptor Antagonists↗
PubMed2002

Cerebellum activation associated with performance change but not motor learning.

The issue of whether the cerebellum contributes to motor skill learning is controversial, principally because of the difficulty of separating the effects of motor learning from changes in performance. We performed a functional magnetic resonance imaging investigation during an implicit, motor sequence-learning task that was designed to separate these two processes. During the sequence-encoding phase, human participants performed a concurrent distractor task that served to suppress the performance changes associated with learning. Upon removal of the distractor, participants showed evidence of having learned. No cerebellar activation was associated with the learning phase, despite extensive involvement of other cortical and subcortical regions. There was, however, significant cerebellar activation during the expression of learning; thus, the cerebellum does not contribute to learning of the motor skill itself but is engaged primarily in the modification of performance.

Brain↗
PubMed1995

The locus of visual-motor learning at the task or manipulator level: implications from intermanual transfer.

To assess the functional locus of visual-motor learning, the computational concepts of "task level" programming (determination of the trajectory of a hand during arm reaching in the Cartesian coordinates) and "manipulator level" programming (determination of the joint coordinates) was adopted. Because the former is likely to be hand nonspecific and the latter is hand specific, it is assumed that learning at the task level should be transferred to the unpracticed hand, whereas that at the manipulator level it should not. Under this assumption, the paradigm of intermanual transfer was used in an aiming task under rotated visual feedback. Nearly 100% intermanual transfer from the practiced hand to the unpracticed hand in the performance time of aiming was found, concluding that the locus of visual-motor learning should be at the task level rather than at the manipulator level.

Adolescent↗
PubMed2005

Electromyographic study of motor learning for a voice production task.

PURPOSE: This study's broad objective was to examine the effectiveness of surface electromyographic (EMG) biofeedback for motor learning in the voice production domain. The specific objective was to examine whether concurrent or terminal biofeedback would facilitate learning for a relaxed laryngeal musculature task during spoken reading. METHOD: Twenty-two healthy adult speakers were randomly assigned to 1 of 2 groups. One group received real-time EMG waveform displays of muscle activation from bilateral thyrohyoid sites during reading trials (concurrent feedback group). The other group received static terminal EMG waveform displays about activation levels for the same sites on completion of successive trials (terminal feedback group). All participants were instructed to minimize EMG amplitudes from the thyrohyoid sites during phonation in an oral reading task. Signals were also collected from control, orofacial sites, but participants received neither instructions nor feedback for those sites. RESULTS: The pooled data (2 feedback groups x 2 electrode sites) showed that, overall, muscle activation levels did decrease across baseline, training, and no-feedback test phases. However, no clear evidence was seen of reliable changes in the targeted laryngeal muscle activation levels across the phases, for either the concurrent or the terminal feedback groups. Paradoxically, and entirely unanticipated, reliable decreases were seen in muscle activation for the orofacial, no-feedback control sites. Those decreases were equivalent across concurrent and terminal feedback groups. CONCLUSIONS: The unanticipated findings indicate that the provision of biofeedback for a target muscle group facilitated incidental learning in another, untargeted muscle group. Discussion focuses on the possible role of locus of attention in motor learning. Building on literature from other domains, the hypothesis is advanced that attention to muscular contractile force during training trials may suppress intentional learning for attended target sites but may benefit incidental learning for nearby, unattended sites.

Adult↗
PubMed1977

Motor learning and control: a working hypothesis.

There is mounting evidence that motor learning and control are not a process of accretion but depend on patterning of inhibition in motor neurons. Electromyographic studies in health and disease indicate that the acquisition of skills occurs through selective inhibition of unnecessary muscular activity rather than the activation of additional motor units.

Electromyography↗
PubMed1991

Knowledge of results and motor learning--implications for physical therapy.

Relevant to this special series on movement science, a brief overview of research in the field of motor learning is provided. A distinction between learning and performance is emphasized with respect to experimental design and the evaluation of laboratory and clinical intervention techniques. Intrinsic and extrinsic feedback are defined. Basic principles of motor learning pertaining to the use of augmented feedback or knowledge of results (KR) are reviewed. Particular emphasis is placed on recent research regarding the effects of selected KR variations (KR relative frequency, bandwidth KR, and KR delay) on motor performance and learning in healthy young adults. Results are discussed in terms of short-lasting temporary performance effects and relatively long-lasting learning effects. Theoretical and practical implications from this research are discussed. It is suggested that it is appropriate to use the principles obtained through laboratory experimentation as guidelines rather than as exact recommendations when applying basic research findings to clinical practice.

Feedback↗
PubMed2000

Motor learning and Parkinson's disease: refinement of within-limb and between-limb coordination as a result of practice.

Even though the basal ganglia have been assigned a role in motor learning, few studies have addressed motor learning capabilities in Parkinson patients. In the present experiment, improvement of bimanual figure drawing across practice was compared between Parkinson patients and normal age-matched controls. At regular intervals during acquisition, performance was assessed under normal vision and blindfolded conditions. At initiation of practice, the typical signs associated with Parkinson's disease became evident, such as bradykinesia and hypometria. Moreover, reduced synchronization between the force-time specifications of both limbs was observed. When vision was withdrawn, Parkinson patients showed a larger drift of drawing performance across the workspace, indicative of a decline in proprioception. In spite of the aforementioned deficits, Parkinson patients made marked improvements in the speed of execution, the consistency of the spatial trajectories, and the synchronization between the limbs across practice, even though they never reached the performance levels obtained in elderly controls. The findings demonstrate that Parkinson patients do benefit from practice to refine their upper limb control and to alleviate their most basic motor deficits.

Aged↗