Motor Experiences Research Articles

Reduced Susceptibility to Interference in the Consolidation of Motor Memory before Adolescence

Are children superior to adults in consolidating procedural memory? This notion has been tied to “critical,” early life periods of increased brain plasticity. Here, using a motor sequence learning task, we show, in experiment 1, that a) the rate of learning during a training session, b) the gains accrued, without additional practice, within a 24 hours post-training interval (delayed consolidation gains), and c) the long-term retention of these gains, were as effective in 9, 12 and 17-year-olds and comparable to those reported for adults. However, a follow-up experiment showed that the establishment of a memory trace for the trained sequence of movements was significantly more susceptible to interference by a subsequent motor learning experience (practicing a reversed movement sequence) in the 17-year-olds compared to the 9 and 12-year-olds. Unlike the 17-year-olds, the younger age-groups showed significant delayed gains even after interference training. Altogether, our results indicate the existence of an effective consolidation phase in motor learning both before and after adolescence, with no childhood advantage in the learning or retention of a motor skill. However, the ability to co-consolidate different, successive motor experiences, demonstrated in both the 9 and 12-year-olds, diminishes after puberty, suggesting that a more selective memory consolidation process takes over from the childhood one. Only the adult consolidation process is gated by a recency effect, and in situations of multiple, clashing, experiences occurring within a short time-interval, adults may less effectively establish in memory experiences superseded by newer ones.

Movement Disorder Society‐sponsored revision of the Unified Parkinson's Disease Rating Scale (MDS‐UPDRS): Process, format, and clinimetric testing plan

This article presents the revision process, major innovations, and clinimetric testing program for the Movement Disorder Society (MDS)-sponsored revision of the Unified Parkinson's Disease Rating Scale (UPDRS), known as the MDS-UPDRS. The UPDRS is the most widely used scale for the clinical study of Parkinson's disease (PD). The MDS previously organized a critique of the UPDRS, which cited many strengths, but recommended revision of the scale to accommodate new advances and to resolve problematic areas. An MDS-UPDRS committee prepared the revision using the recommendations of the published critique of the scale. Subcommittees developed new material that was reviewed by the entire committee. A 1-day face-to-face committee meeting was organized to resolve areas of debate and to arrive at a working draft ready for clinimetric testing. The MDS-UPDRS retains the UPDRS structure of four parts with a total summed score, but the parts have been modified to provide a section that integrates nonmotor elements of PD: I, Nonmotor Experiences of Daily Living; II, Motor Experiences of Daily Living; III, Motor Examination; and IV, Motor Complications. All items have five response options with uniform anchors of 0 = normal, 1 = slight, 2 = mild, 3 = moderate, and 4 = severe. Several questions in Part I and all of Part II are written as a patient/caregiver questionnaire, so that the total rater time should remain approximately 30 minutes. Detailed instructions for testing and data acquisition accompany the MDS-UPDRS in order to increase uniform usage. Multiple language editions are planned. A three-part clinimetric program will provide testing of reliability, validity, and responsiveness to interventions. Although the MDS-UPDRS will not be published until it has successfully passed clinimetric testing, explanation of the process, key changes, and clinimetric programs allow clinicians and researchers to understand and participate in the revision process.

Linking Coordinative and Fitness Training in the Educational Context

Regular participation in physical activity in youth can promote the development of fitness and motor abilities and support the development of a physically active lifestyle, thus contributing to good health. Physical education should be the primary context for this aim, but many authors claim that the time spent in physical education is not enough to promote physical fitness for health and/or the quality of the contents is too poor to adequately promote coordinative development. PURPOSE: The purpose of this study was to assess whether an enrichment of the coordinative demands of physical education within the curricular time, as compared to the traditional physical education programme, may more efficiently improve both coordinative abilities and physical fitness. METHODS: Hundred and fifty-two middle school students aged 11–12 years were randomly assigned either to an experimental (n = 77) or to a traditional (n = 75) physical education programme lasting 5 months. The experimental intervention was structured in different modules focused on coordination abilities. Pre- and post-intervention tests assessed students' fitness (from Fitnessgram 1994 and Eurofit 1995: one mile run/walk, curl-up, flexed arm hang, trunk lift, sit and reach, 30 m run, standing long jump, basketball throw forward) and motor coordination abilities (from Hirtz' battery 1985: four field tests of kinaesthetic discrimination and response orientation). RESULTS: Scores obtained in each motor test were submitted to a 2×2×2 mixed-model ANO VA with group (experimental vs control), gender (males vs females), and treatment (pre vs post) as factors. After the training period, both groups showed a significant increment in most fitness tests. However, only the experimental group showed a significant improvement or a significantly more pronounced improvement than the control group on tests assessing coordinative abilities (i.e., upper limb kinaesthetic discrimination and lower limb response orientation ability). CONCLUSIONS: Results show that both types of physical education intervention lead to increased physical fitness levels, but only the experimental one selectively improves coordinative abilities. Thus, shifting the focus of traditional physical education didactics toward coordination training seems to add quality to students' motor experiences without reducing their effectiveness in terms of physical fitness training.

Independent coding of movement duration in a repetitive non-visually guided movement

Temporal information is an embedded feature of our sensory and motor experiences. How is temporal information encoded in the brain? In the two-stage theory of timing, an explicit representation of timing is responsible for the movement initiation while movement duration is coded implicitly. We investigated the correlation of movement duration and amplitude in a repetitive one-dimensional non-visually guided movement to find out if temporal information could be coded independently from movement. Subjects were asked to learn the distance between two points by moving their hands repeatedly along the distance between two sticks, while they could not see their hands and hand path. After a training phase, a delay of either 2 or 20 s was imposed and the subjects were asked to reproduce the learned distance. There was no correlation between distance difference and time difference in either delay condition. In the 20 s delay experiment, in comparison to the 2 s delay experiment, there was a significant increase in distance reproduction error. However, there was no significant change in time differences in either of the experiments. In addition, the time difference between the training and test trials was independent from the direction of the distance difference (i.e., overshot, undershot, or accurate). In conclusion, time may be coded as an independent measure after the delay period, so it should be a kind of explicitly coded information.

Nitric Oxide and Synaptic Dynamics in the Adult Brain: Physiopathological Aspects

The adult brain retains the capacity to rewire mature neural circuits in response to environmental changes, brain damage or sensory and motor experiences. Two plastic processes, synaptic remodeling and neurogenesis, have been the subject of numerous studies due to their involvement in the maturation of the nervous system, their prevalence and re-activation in adulthood, and therapeutic relevance. However, most of the research looking for the mechanistic and molecular events underlying synaptogenic phenomena has been focused on the extensive synaptic reorganization occurring in the developing brain. In this stage, a vast number of synapses are initially established, which subsequently undergo a process of activity-dependent refinement guided by target-derived signals that act as synaptotoxins or synaptotrophins, promoting either loss or consolidation of pre-existing synaptic contacts, respectively. Nitric oxide (NO), an autocrine and/or paracrine-acting gaseous molecule synthesized in an activity-dependent manner, has ambivalent actions. It can act by mediating synapse formation, segregation of afferent inputs, or growth cone collapse and retraction in immature neural systems. Nevertheless, little information exists about the role of this ambiguous molecule in synaptic plasticity processes occurring in the adult brain. Suitable conditions for elucidating the role of NO in adult synaptic rearrangement include physiopathological conditions, such as peripheral nerve injury. We have recently developed a crush lesion model of the XIIth nerve that induces a pronounced stripping of excitatory synaptic boutons from the cell bodies of hypoglossal motoneurons. The decline in synaptic coverage was concomitant with de novo expression of the neuronal isoform of NO synthase in motoneurons. We have demonstrated a synaptotoxic action of NO mediating synaptic withdrawal and preventing synapse formation by cyclic GMP (cGMP)-dependent and, probably, S-nitrosylation-mediated mechanisms, respectively. This action possibly involves the participation of other signaling molecules working together with NO. Brain-derived neurotrophic factor (BDNF), a target-derived synaptotrophin synthesized and released postsynaptically in an activity-dependent form, is a potential candidate for effecting such a concerted action. Several items of evidence support an interrelationship between NO and BDNF in the regulation of synaptic remodeling processes in adulthood: i) BDNF and its receptor TrkB are expressed by motoneurons and upregulated by axonal injury; ii) they promote axon arborization and synaptic formation, and modulate the structural dynamics of excitatory synapses; iii) NO and BDNF each control the production and activity of the other at the level of individual synapses; iv) the NO/cGMP pathway inhibits BDNF secretion; and finally, v) BDNF protects F-actin from depolymerization by NO, thus preventing the collapsing and retracting effects of NO on growth cones. Therefore, we propose a mechanism of action in which the NO/BDNF ratio regulates synapse dynamics after peripheral nerve lesion. This hypothesis also raises the possibility that variations in this NO/BDNF balance constitute a common hallmark leading to synapse loss in the progression of diverse neurodegenerative diseases such as amyotrophic lateral sclerosis, Alzheimer's and Parkinson's diseases.

Spontaneous facial motility in infancy: A 3D kinematic analysis

Early spontaneous orofacial movements have rarely been studied experimentally, though the motor experiences gained from these behaviors may influence the development of motor skills emerging for speech. This investigation quantitatively describes developmental changes in silent, spontaneous lip and jaw movements from 1 to 12 months of age using optically based 3D motion capture technology. Twenty-nine typically developing infants at five ages (1, 5, 7, 9, and 12 months) were studied cross-sectionally. Infants exhibited spontaneous facial movements at all ages studied. Several age-related changes were detected in lip and jaw kinematics: the occurrence of spontaneous movements increased, movement speed increased, the duration of movement epochs decreased and movement coupling among different facial regions increased. Additionally, evidence for stereotypic movements was not strong. The present findings suggest that, during the first year of life, early spontaneous facial movements undergo significant developmental change in the direction of skill development for speech.

Impact of Peripheral Nerve Injury on Sensorimotor Control

Deficits in sensorimotor control are experienced immediately after nerve injury due to changes in the periphery and central nervous system. Muscle denervation and sensory loss often disrupt prehensile coordination requiring the use of alternative strategies. To effectively foster coordination postinjury clinicians should address not only impairments and function but motor control issues through the prescription of specific sensory and motor experiences. Engagement in carefully planned, therapeutic activity can take advantage of the nervous systems' ability to regenerate and reorganize following nerve lesions. This article reviews motor control issues and neural reorganization concepts that may influence the recovery of skilled prehension following upper limb nerve injury. It also provides clinical guidelines for examining and enhancing coordination.

Neural plasticity and bilateral movements: A rehabilitation approach for chronic stroke

Stroke interferes with voluntary control of motor actions. Although spontaneous recovery of function can occur, restoration of normal motor function in the hemiplegic upper limb is noted in fewer than 15% of individuals. However, there is increasing evidence to suggest that in addition to injury-related reorganization, motor cortex functions can be altered by individual motor experiences. Such neural plasticity has major implications for the type of rehabilitative training administered post-stroke. This review proposes that noteworthy upper extremity gains toward motor recovery evolve from activity-dependent intervention based on theoretical motor control constructs and interlimb coordination principles. Founded on behavioral and neurophysiological mechanisms, bilateral movement training/practice has shown great promise in expediting progress toward chronic stroke recovery in the upper extremity. Planning and executing bilateral movements post-stroke may facilitate cortical neural plasticity by three mechanisms: (a) motor cortex disinhibition that allows increased use of the spared pathways of the damaged hemisphere, (b) increased recruitment of the ipsilateral pathways from the contralesional or contralateral hemisphere to supplement the damaged crossed corticospinal pathways, and (c) upregulation of descending premotorneuron commands onto propriospinal neurons.

Effect of Forelimb Use on Postnatal Development of the Forelimb Motor Representation in Primary Motor Cortex of the Cat

In the cat, the motor representation in motor cortex develops between wk 8 and wk 13. Motor map development is accompanied by a decrease in the current thresholds for evoking movements with a concomitant increase in the number of effective sites, an increase in the distal representation, and the representation of multijoint synergies. In this study we used intracortical microstimulation in anesthetized cats to examine how forelimb motor experiences influence development of map characteristics. To promote skilled movements during wks 8-13, animals were engaged in daily performance of a prehension task. Forelimb movements were prevented by intramuscular botulinum toxin injection or restraint. To determine whether experience-dependent changes were permanent, we examined the map in different animals between 1 wk and 1 yr after cessation of testing. Promoting forelimb use resulted in an increase in the number of sites from which multiple joint effects were produced by stimulation and the number of joints represented at those sites. The effect was maximal at 1 wk after cessation of testing, and became progressively less at 1 mo and at 4 mo. Preventing limb use resulted in a decreased number of effective sites, an increase in current thresholds for evoking responses, and a decreased representation of joints at multijoint sites. Our findings show that the motor map can respond to novel motor demands as it is forming during development but that it reverts back to one with the properties of a map in a control animal if those demands are not maintained in the animal's behavioral repertoire.

Espaces psychiques et cognition de l'espace chez des enfants atteints d'infirmité motrice d'origine cérébrale

Cerebral Palsy (CP) involves disabilities which influence the psychological development. CP changes the relationship with social environment and the organisational role plays by caretakers. CP prevents the sensori-tonic dialog of the maternal function and it affects the dialectical link between psychic schema of transformation and psychic schema of envelope [2]. Therefore, children with CP develop psychic envelopes which are strong and inflexible, impairing in this way the passage between the real world to the mental life. We can also find this phenomenon in the cognitive area. Children with CP instantiate analogical depictive representations built on motor experiences which involve the whole body. Motor impairments influence the construction of analytical, sequential representations which are constructed by internalizing and coordinating motor manipulations [29,30]. We think that the features of mental spaces and spatial cognition are organized on the same model and it means a difficulty to think about transformations.

Corticospinal system development depends on motor experience.

Early motor experiences have been shown to be important for the development of motor skills in humans and animals. However, little is known about the role of motor experience in motor system development. In this study, we address the question of whether early motor experience is important in shaping the development of the corticospinal (CS) tract. We prevented limb use by the intramuscular injection of botulinum toxin A into selected forelimb muscles to produce muscle paralysis during the period of development of CS connection specificity, which is between postnatal weeks 3 and 7. CS terminations were examined using an anterograde tracer. Preventing normal forelimb use during CS axon development produced defective development of CS terminations at week 8 and in maturity. There were reductions in the topographic distribution of axon terminals, in terminal and preterminal branching, and in varicosity density. This suggests that limb use is needed to refine CS terminals into topographically specific clusters of dense terminal branches and varicosities. To determine correlated effects on motor behavior, cats were tested in a prehension task, to reach and grasp a piece of food from a narrow food well, when the neuromuscular blockade dissipated (by week 10) and in maturity (week 16). Preventing normal limb use also produced a prehension deficit later in development and in maturity, in which there was a loss of the supination component of grasping. This component of prehension in the cat depends on CS projections from the paw representation of rostral motor cortex to the cervical enlargement. Our findings show that motor experiences are necessary for normal development of CS terminations and function.

Theoretical simulation of a rotary motor driven by surface acoustic waves

A simulation model for theoretically studying the operation behavior of a rotary motor driven by surface acoustic waves (SAWs) is proposed. According to the model, some simulation results are obtained as follows: (1) as the rotor is excited by the SAWs, the motor experiences two phases, i.e., the acceleration phase and the steady phase; (2) the normal vibration amplitude A of SAWs has a very weak effect on the acceleration in the first phase but an enhancing effect on the steady velocity of the rotary motor; (3) as the number of the contact points between the rotor and the stator increases, the motor rotates more steadily; (4) as the rotor radius becomes smaller, both the acceleration and the steady angular velocity become greater. These features are in agreement with the experimental results.

The role of handedness in graphic production: Interactions between biomechanical and cognitive factors in drawing development

In this study, the interaction of biomechanical and cognitive factors in drawing development was explored. Children (4‐ to 6‐year‐olds) and adults copied four shapes (two familiar and two novel) six times alternating between their dominant and non‐dominant hands (starting hand was counterbalanced). Similarity in the production sequences within and across hands was compared. The results suggest that production sequences are influenced by specific motor experiences yet highlight the importance of cognitive constraints on the drawing process.

Activity-dependent development of cortical axon terminations in the spinal cord and brain stem.

Corticospinal (CS) axon terminations in several species are widespread early in development but are subsequently refined into a spatially more restricted distribution. We studied the role of neural activity in sensorimotor cortex in shaping postnatal development of CS terminations in cats. We continuously infused muscimol unilaterally into sensorimotor cortex to silence neurons during the postnatal CS refinement period (weeks 3-7). Using anterograde transport of WGA-HRP, we examined the laterality of terminations from the muscimol-infused (i.e., silenced) and active sides in the spinal cord, as well as in the cuneate nucleus and red nucleus. We found that CS terminations from the muscimol-infused cortex were very sparse and limited to the contralateral side, while those from the active cortex maintained an immature bilateral topography. Controls (saline infusion, noninfusion) had dense, predominantly contralateral, CS terminations. There was a substantial decrease in the spinal gray matter area occupied by terminations from the side receiving the blockade and a concomitant increase in the area occupied by ipsilateral terminations from the active cortex. Optical density measurements of HRP reaction product from the active cortex in muscimol-infused animals showed substantial increases over controls in the ratio of ipsilateral to contralateral CS terminations for all laminae examined (IV-V, VI, VII). Our findings suggest that ipsilateral dorsal horn terminations reflect new axon growth during the refinement period because they are not present there earlier in development. Those in the ventral horn are present earlier in development and thus could reflect maintenance of transient terminations. Increased ipsilateral terminations from active cortex were due to recrossing of CS axons in lamina X and not to an increase in labeled CS axons in the ipsilateral white matter. Examination of brain stem terminations suggested that, between postnatal weeks 3 and 7, development of corticocuneate terminations also is activity-dependent but that development of corticorubral terminations is not. Activity-dependent CS development is a plausible mechanism by which early motor experiences could shape the anatomical and functional organization of the motor systems during a critical postnatal period.

Limiting induction motor transient shaft torques following source discontinuities

When an induction motor experiences a momentary discontinuity in source power, the motor shaft is subjected to potentially damaging re-energization transients caused by transient electromagnetic torques from the motor, and by the dynamic mechanical shaft response. Source discontinuities may be the unavoidable result of supply dips and outages, or of planned motor bus transfers. Although it is possible to estimate the reconnection electromagnetic torque peak by general principles, without detailed simulation, there is currently no simple way to estimate the shaft reclosure torque peak in the worst case of a resonant shaft and load. In this paper, a general result on the magnitude of resonant shaft torque is given and the effect of reclosure delay and stator damping is shown.

Effects of oral experience on rewarding properties of oral stimulation

The oropharyngeal sensory and motor experiences of ingestion have long been considered to be rewarding or motivating. Recent work has suggested that the reinforcing properties of oral stimulation are modulated by experience with an ingestive bout. Two processes that result from the repeated oral experience that occurs during an ingestive bout, sensitization and oral habituation, may influence the reinforcing or rewarding properties of oral stimulation. The first process, sensitization, describes an initial increase in responsiveness following the first presentation of a stimulus; such an increase in responding has been noted in the ingestive behavior of both rats and humans. The second process, oral habituation, occurs after sensitization of responding, and results from continued repeated exposure to oral stimulation. During oral habituation, ingestive responsiveness declines; decreased ingestive responding to oral stimulation is demonstrated even in the absence of substantial post-ingestive signals. Both oral habituation and sensitization reflect processes through which experience may modulate the rewarding properties of oral stimulation.

Hypnosis in Sport: An Isomorphic Model

Hypnosis in sport can be applied according to an Isomorphic Model. Active-alert hypnosis is induced before or during practice whereas traditional hypnosis is induced after practice to establish connections between the two experiences. The fundamental goals are to (a) develop mental skills important to both motor and hypnotic performance, (b) supply a wide range of motor and hypnotic bodily experiences important to performance, and (c) induce alert hypnosis before or during performance. The model is based on the assumption that hypnosis and motor performance share common skills modifiable through training. Similarities between hypnosis and peak performance in the model are also considered. Some predictions are important from theoretical and practical points of view.

Appropriation of the Environment, Motor Experiences and Sporting Activities of Girls and Women

In the Western world women, if they are interested in sport at all, are mostly engaged in physical activities which allow an aesthetic presentation and/or a modelling of the body. They arc relatively seldom active in types of sport in which the body is employed as an instrument in trials of strength with others or with the environment. At the same time women do not claim much space in many respects—their presence does not fill a room, they do not prowl the streets, they seldom appropriate and use the natural environment for sport. The differences between men and women in sport orientation and the use of physical space begins in childhood. The results of the research can be summed up as follows: 1. The space used by boys was much larger than the space used by girls. 2. Girls are underrepresented on public sporting grounds. 3. Boys and girls differ in the way they use play grounds and other areas appropriated for free movement. 4. Boys' activities tend to contain sporting elements while girls' leisure time activities are more sedentary. The causes for these different play and motor preferencies lay in different areas: the family, peer-groups, sporting facilities and so on. Here are the possible sites for change.

Situated fraternization: The eudaemonic sublimation of religion

The drabness and routineness of the ordinary outside world of the working and lower-middle classes contrasts sharply with the excite? ment, opportunities for expressiveness and possibilities for exotic experiences in a lounge, a live music bar. Closeted in the lounge the individual is separated from the mundane world and brought into a real world of make-believe wherein each may become what he or she wishes. The lounge is like a cocoon simultaneously enveloping the entire range of the individual's sensory, motor, tactile and auditory experiences. In particular it is the total musical ambiance that serves as a spectacular agency for evoking the spirit of an enchanted land. In addition, status enhancement is provided by extravagant tip? ping, valet parking, and association with lounge owners. The cardi? nal rule of etiquette of a lounge is the prevention of intrusions that might break the fantasy of lounge life, meaning no conflict, no disagreeableness, only lovingness, sweetness, happiness, person ableness. The lounge, abandoning the real, outside world, like a Salvationist religion called for a rejection of the world, serves as a sanctuary creating exalted moods and new personae. In the case of the lounge, it creates a milieu for working and lower-middle class, hard-working, ordinary people seeking ultimate if only temporary fulfillment in their own make-believe world. The actors in the lounge believe that their experience is credibly fulfilling, shared by others and unique in its heightened spiritual state.*

Some new results of chuffing in composite solid propellant rockets

Chuffing is one of the low-frequency instabilities in solid propellant rockets functioning at low chamber pressures. In chuffing, the rocket motor experiences brief spurts of combustion and consequent pressure buildup, followed by periods of near ambient pressures in the combustion chamber. This period of dormancy can extend up to a few seconds. According to many earlier workers,1-3 during the low-pressure induction period, slow reactions take place in a subsurface layer of the propellant which eventually reaches the temperature where a thermal explosion can occur. Rapid burning of this preheated layer is followed by a sudden ceasing of propellant combustion as the layers beneath it, being at low temperature, cannot sustain the process. While this theory projects the condensed phase reactions as solely responsible for chuffing, there are also those which bring in the importance of gas phase processes.