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PubMedDate not supplied

Action of 6-hydroxydopamine on two parameters of motor learning.

In rats injected in the cerebral ventricle with 250 micrograms of 6-hydroxydopamine a significant blockade of the improvement of swimming performance due to training occurs. The central injection of 6-OHDA leads to a lengthening of the total latency time (LT) of active conditioned reaction in shuttle box and of the LT of netative escape responses during learning, but not of the positive avoidance responses. 6-OHDA injected after the learing schedule (12 days) has no effect on the LT during relearning and extinction. Therefore a partial destruction of central monoaminergic, and especially of dopaminergic, neurons impairs particularly the acquisition but not the retention of the motor program.

Animals↗
PubMed2000

Motor timing learned without motor training.

Improvements due to perceptual training are often specific to the trained task and do not generalize to similar perceptual tasks. Surprisingly, given this history of highly constrained, context-specific perceptual learning, we found that training on a perceptual task showed significant transfer to a motor task. This result provides evidence for a common neural architecture underlying analysis of sensory input and control of motor output, and suggests a potential role for perception in motor development and rehabilitation.

Adult↗
PubMed1996

Long-term practice effects on a new skilled motor learning: an electrophysiological study.

Cortical functions concerned with the execution of skilled movements can be studied through complex interactive tasks. Skilled performance task (SPT) offers the greatest deal of information about the electrophysiological components reflecting pre-programming, execution of the movement and control of the results. Overall, these components are indicated as "movement-related brain macropotentials' (MRBMs). Among them, Bereitschaftspotential (BP) reflects cerebral processes related to the preparation of movement and skilled performance positivity (SPP) reflects control processes on the result of performance. There is some evidence supporting a training effect on MRBMs, but less clear is whether long-term practice of a skilled activity could modify learning strategies of a new skilled task. We recorded MRBMs in subjects trained for a long time to perform a highly skillful athletic activity, i.e. gun shooting, and in a group of control subjects without any former experience in skilled motor activities. Our findings demonstrated the existence of a relationship between pre-programming and performance control, as suggested by decrease of BP amplitude and increase of SPP amplitude in presence of high levels of performance. Long-term practice seems to develop better control models on performance, that reduce the need of a high mental effort in pre-programming a skilled action.

Adult↗
PubMedDate not supplied

Participation of the nigro-striatal and mesolimbic dopaminergic systems of the brain in the control of components of learned motor responses in dogs.

We studied the role of the striatal and limbic dopaminergic systems in the regulation of instrumentally conditioned avoidance behavior and postural adjustment in chronic experiments on dogs. Dopamine in doses of 3 micrograms was introduced bilaterally into the caudate nucleus head and the nucleus accumbens of the forebrain through implanted cannuli. Predominantly unidirectional effects were demonstrated, but a clear acceleration of the initiations of both conditioned-reflex postural adjustment and voluntary movement were obtained from the caudate nucleus; there was a marked degree of expressiveness to this movement. The greatest effects were obtained during simultaneous, bilateral introduction of dopamine into both structures in dogs with an akinetic form of motor pathology. We conclude that the integration of the striatal and limbic dopaminergic systems is of critical necessity for the initiation and regulation of the components of voluntary movement.

Animals↗
PubMed1998

Improved ankle function in children with cerebral palsy after computer-assisted motor learning.

The effect of biofeedback training on ankle function was studied in young children with cerebral palsy (CP) during a pilot study and a 6-week follow-up study. Patients underwent range of motion (ROM) and ankle dorsiflexor (DF) strength training in a laboratory 3 days per week, receiving auditory and visual feedback. An at-home programme used portable EMG units to help train DF muscle recruitment on the remaining days. Independent outcome measures included DF strength, active ROM, and tapping ability pretraining and 6 weeks and 14 months posttraining. Tapping ability increased significantly in the trained leg posttraining. It then fell significantly at the 6-weeks posttraining test, but remained significantly higher than pretest levels, and returned to pretraining levels by 14 months. Passive ROM was unchanged, but active ROM increased significantly in the trained leg. DF strength increased in most children posttraining in both the pilot and main study. Increased motor-unit recruitment is believed to explain the increases in DF strength and active ROM. These results suggest that biofeedback training can improve ankle function, and the implications for gait are discussed.

Ankle↗
PubMed1987

[Participation of the nigro-striatal and mesolimbic dopaminergic systems of the brain in the control of components of learned motor reactions in the dog].

Microinjections of dopamine (3 micrograms) into the caudate nucleus head and into the nucleus accumbens produced unidirectional effects on the motor components of avoidance behaviour and posture adjustment in two groups of the dogs (intact ones and dogs with different degree of caudate pathology). However, each of these dopaminergic systems can regulate mainly certain components of motor program, i.e. nigrostriatal system--the initiation of both the conditioned postural adjustment and the voluntary movement and mesolimbic system--the degree of this movement manifestation in amplitude and stability of realization. The greatest effect was shown after combined microinjection of dopamine bilaterally into both structures in the dogs with akinetic form of caudate pathology. The obtained data suggest that the integration of the striatal and limbic dopaminergic mechanisms seems to be critical for initiation and control of components of voluntary movement in the dog.

Animals↗
PubMed2000

The relation between movement parameters and motor learning.

In a recent paper, Flament et al. (1999) studied the process of learning to flex the elbow faster. They concluded from their data that time-related parameters (e.g. movement time) changed faster during learning than magnitude-related parameters (e.g. peak velocity) and discussed this finding in terms of neural substrates responsible for the apparently different learning mechanisms. In this paper, I will argue that finding different time constants does not imply different learning mechanisms and will give a theoretical example of the development of parameters during learning to move faster. Despite the fact that only one learning process is modelled, various kinematic parameters show different time courses of learning. The differences the model predicts are comparable with the experimental results.

Biomechanical Phenomena↗
PubMed1995

On associative motor learning by the cerebellar cortex: from Purkinje unit to network with variational learning rules.

This paper is an attempt to describe the ability of the cerebellar cortical network to coordinate movement on the basis of the continuous behavior of individual neural networks, the so-called "Purkinje units." The problem is considered from the point of view of a hierarchical network with two levels of organization: the level of Purkinje units including Purkinje, star and basket cells, and the level of granule cells and Golgi cells which is a network with a specific architecture. We suggest that the coordination of movements is based on a new class of learning rules between Purkinje units, called variational learning rules (VLR), which are mathematically deduced from the dynamics of a Purkinje unit. This network is driven by two functions H0 and H, defined for each Purkinje unit, which depend on external signals for this unit. Specifically, the proposed interpretation of the coordination of movement depends on three main features: (i) The definition of a unit of function, the Purkinje unit, made up of a Purkinje cell and closely associated cells and connections; (ii) a new learning rule called the "Variational Learning Rule" (VLR), operating at the level of the Purkinje units; (iii) the interpretation of the coordination of movements in terms of excitatory and inhibitory interactions between Purkinje units. An emergent property of the model is that Purkinje units occur in groups which act in opposition in the sense that when the output of one group increases, that of the other decreases.

Association Learning↗
PubMed1989

Qualitative differences in tactuo-spatial motor learning by left-handers.

Tactuo-spatial performance was studied as a function of subject handedness and hand employed in learning and transfer. Seventy-eight dextral and 75 sinistral blindfolded subjects learned a finger-maze with either dominant or nondominant hand. Transfer to the untrained hand was assessed with either an identical or a mirror-image version of the maze. Left hand acquisition required fewer trials; latencies were shorter when the dominant hand was used. All dextrals and those sinistral subjects who used the right hand in acquisition showed superior transfer to the identical maze. Sinistral subjects who used the left hand in acquisition demonstrated facilitated transfer to the mirror image maze. Results are suggested to provide evidence of two qualitatively different hemispheric strategies for encoding tactuo-spatial information.

Attention↗
PubMed1986

'Error' potentials in limbic cortex (anterior cingulate area 24) of monkeys during motor learning.

Two monkeys were trained to lift a lever with wrist extension in response to a visual cue. The animals were chronically implanted with electrodes for recording transcortical field potentials. Unique 'error' potentials were observed in the anterior cingulate cortical area 24 during a transitional learning-stage when the animals were uncertain about fulfilling the required task appropriately. At that stage (III) about 40-60% of the movements were made appropriately within the required cue-time. Error potentials followed inappropriate lever lifts made with wrist movements that were self-paced and hence non-rewarded, but such potentials did not follow appropriately made, i.e. visually initiated, and rewarded lifts.

Animals↗
PubMed2006

alphaCaMKII Is essential for cerebellar LTD and motor learning.

Activation of postsynaptic alpha-calcium/calmodulin-dependent protein kinase II (alphaCaMKII) by calcium influx is a prerequisite for the induction of long-term potentiation (LTP) at most excitatory synapses in the hippocampus and cortex. Here we show that postsynaptic LTP is unaffected at parallel fiber-Purkinje cell synapses in the cerebellum of alphaCaMKII(-/-) mice. In contrast, a long-term depression (LTD) protocol resulted in only transient depression in juvenile alphaCaMKII(-/-) mutants and in robust potentiation in adult mutants. This suggests that the function of alphaCaMKII in parallel fiber-Purkinje cell plasticity is opposite to its function at excitatory hippocampal and cortical synapses. Furthermore, alphaCaMKII(-/-) mice showed impaired gain-increase adaptation of both the vestibular ocular reflex and optokinetic reflex. Since Purkinje cells are the only cells in the cerebellum that express alphaCaMKII, our data suggest that an impairment of parallel fiber LTD, while leaving LTP intact, is sufficient to disrupt this form of cerebellar learning.

Animals↗
PubMed2005

Relation between methamphetamine-induced monoamine depletions in the striatum and sequential motor learning.

Methamphetamine (METH) use results in depletion of monoamines in the striatum. The purpose of this study was to evaluate the relation between the degree of METH-induced monoamine depletion in the striatum and impairment on a striatally-dependent learning task in rats. Male Sprague-Dawley rats received four injections of METH (10 mg/kg) or saline at 2-h intervals. METH treatment produced a 38.5% (+/-5.6) and 46.7% (+/-6.7) dopamine (DA) depletion in the medial and lateral striatum, respectively. Serotonin (5-HT) was depleted 15.6% (+/-10.4) and 21.1% (+/-8.2) in the medial and lateral striatum, respectively. One month after treatment, rats were trained on a sequential-memory task on an 8-arm radial maze. METH-treated rats made significantly fewer direct movements between arms in the maze sequence across days of trials. The learning impairment was significantly correlated with the degree of DA depletion in the medial striatum, as well as serotonin tissue content in striatum. Only rats with a greater than 40% DA depletion in medial striatum showed significant impairments. These results provide additional evidence for METH-induced learning impairments and suggest that this impairment is dependent on the striatal monoamine loss, in general, and the degree of DA loss in medial striatum, in particular.

Animals↗