The reorganization of bimanual movements during formation of a lateralized motor food skill in rats

After 48 h food deprivation adult Wistar rats were trained to obtain food from a narrow tube feeder using the forepaw under conditions of free choice of limb. At the initial stage of training animals use both paws: the grasping and extraction with one paw can be alternated with food grasping and extraction with another paw, and both paws can be alternately involved in movements preceding this grasping. Character of reorganization of bimanual movements was analyzed during training rats with different motor preference (right-handed and left-handed animals). It was shown that in the process of acquisition of both right- and left-hand skills, bimanual reactions in the anticipating attempts disappeared later than in the final successful movements. The disappearance of bimanual movements in the anticipating attempts is considered as an index of the maximum skill lateralization and acquisition of a novel lateralized movement coordination. The results suggest that left-handed rats more rapidly learn a novel movement coordination than right-handed animals.     

Formation of lateralized motor skills in rats

Adult Wistar rats were trained to get food with a forepaw from a narrow tube under conditions of free choice of a limb. It was shown that the presence or absence of limb preference determined by preliminary short-run testing far from always defines the character and extent of lateralization formed in the process of training. It was also found that reaching the maximal extent of lateralization requires, on average, more extended period of training for the animals, which finally constituted the group of right-handers, than for the rats finally classified as left-handers.     

The behavior of tamarin monkeys during the learning and realization of instrumental food habits in a competitive situation

Special features of competitive behavioural organization have been revealed during formation and realization of simple feeding and instrumental reflexes elaborated simultaneously in family pairs of marmoset monkeys. In contrast to other anthropoid species, male and female marmosets performed feeding reactions of different levels of complexity with equal efficiency. The differences between male and female marmosets concern the structure of competitive behaviour: males showed more active forms of competition under equal number of the given reinforcement, whereas passive forms of behaviour were more typical in females. The latter produced intensive vocalization in comparison with males. Stabilization of competitive activity was accompanied by the decrease of active forms of competition and by standardization of individual behaviour. The increase in the number of behavioural strategies was observed in family groups under sophisticated experimental conditions.     

Features of formation of new motor coordination during food retrieval movements of rats

Wistar rats were trained to retrieve a sunflower seed from a horizontal tube using a forelimb. Animals which demonstrated motor asymmetry were selected, and their training conditions were changed. The horizontal tube was replaces by that with a slot in the bottom in such a way that improperly seized seeds dropped out of the tube. Dynamic reorganization of motor coordination under these changed conditions was investigated. The appreciable individual variability of dynamics of formation of new motor coordination was revealed.     

Electromyographic biofeedback for tension control during fine motor skill acquisition

The presence of residual muscular tension has been implicated as a detrimental influence on the performance and learning of motor skills. A method for reducing muscular tension has been provided by the advent of biofeedback training. This study investigated the effects of tension-control training by electromyographic (EMG) biofeedback on learning and performance of the pursuit-rotor backing task. Thirty young adult males were pretested for pursuit-rotor (PR) tracking skill, ranked by performance scores, and divided into identical triplicates to form two experimental groups and a control group. After a total of 3 hours of EMG biofeedback training for the experimental groups, all subjects were reevaluated on the PR test. One experimental group received biofeedback during the posttests. Analysis of variance of pretest-posttest difference means andt tests of scores representing performance and tension indicated that the EMG biofeedback training (1) significantly reduced tension induced by the novel motor skill and (2) significantly improved performance of the motor skill. Transfer of tension-control training was shown to facilitate learning and performance more than direct EMG biofeedback during performance. Residual tension reduction during learning was particularly facilitated by EMG biofeedback training, a profound implication for the management of stress in a variety of situations.This investigation formed part of a Ph.D. dissertation research (1976) conducted by the author under the guidance of Dr. Donald E. Campbell, Department of Physical Education, and Dr. Carol A. Saslow, Department of Psychology, at Oregon State University.     

Stages of motor skill learning

Successful learning of a motor skill requires repetitive training. Once the skill is mastered, it can be remembered for a long period of time. The durable memory makes motor skill learning an interesting paradigm for the study of learning and memory mechanisms. To gain better understanding, one scientific approach is to dissect the process into stages and to study these as well as their interactions. This article covers the growing evidence that motor skill learning advances through stages, in which different storage mechanisms predominate. The acquisition phase is characterized by fast (within session) and slow learning (between sessions). For a short period following the initial training sessions, the skill is labile to interference by other skills and by protein synthesis inhibition, indicating that consolidation processes occur during rest periods between training sessions. During training as well as rest periods, activation in different brain regions changes dynamically. Evidence for stages in motor skill learning is provided by experiments using behavioral, electrophysiological, functional imaging, and cellular/molecular methods.     

Neuromodulation during motor development and behavior

Important recent advances have been made in understanding the role of aminergic modulation during the maturation of Xenopus larvae swimming rhythms, including effects on particular ion channel types of component neurons, and the role of peptidergic modulation during development of adult central patterns generators in the stomatogastric ganglion of crustaceans. By recording from octopaminergic neuromodulatory neurons during ongoing motor behavior in the locust, new insights into the role of this peripheral neuromodulatory mechanism have been gained. In particular, it is now clear that the octopaminergic neuromodulatory system is automatically activated in parallel to the motor systems, and that both excitation and inhibition play important functional roles.     

The characteristics of the intragroup behavior of rhesus macaques and hamadryas baboons during the realization of food motivation in a competitive situation]

The aim of the present work is to consider the specific interrelations in "family" units of macaques (Macaca mulatta) and baboons (Papio hamadryas) during food-getting reactions in competitive conditions. Detailed analysis of dyadic interactions revealed that competing partners demonstrate more various types of behaviour tactics at the initial stage of learning. At the final one, only males of both investigated species performed instrumental reactions and received the food reward. All females demonstrated much more vocal reactions in comparison with males. Thus the variety of competing interactions between heterosexual partners, learning and possibility to realize its motivation correspond ro novelty of experimental situation and degree of intraspecies social subordination.     

Lysosomal behavior during lateral motor column neurogenesis

Modulations in the total and free activities of acid phosphatase, acid protease, aryl sulfatase, and β-glucuronidase reveal that maximum lysosomal activity accompanies histogenetic cell death within the lateral motor column (LMC) of Rana pipiens larvae. LMC neurogenesis is separable into three distinct periods. In the first, hydrolytic activity remains low through the initial half of the period only to exhibit an exponential rise in the latter half. This increase in acid hydrolase activity continues well into the period of histogenetic cell death (Period 2). At this juncture, lysosomal activity (total and free) reaches a maximum. Subsequently, hydrolytic activity declines with the cessation of neuronal death (Period 3). Activation experiments indicate that lysosomal granules isolated during the cell death period are extremely sensitive to a variety of procedures which disrupt membranes, whereas preparations from younger or older larvae are more stable. Alterations in lysosomal properties are discussed in terms of our present knowledge on lysosomal packaging, activation, and heterogeneity during the course of neural maturation.     

Central mechanisms of motor skill learning

Recent studies have shown that frontoparietal cortices and interconnecting regions in the basal ganglia and the cerebellum are related to motor skill learning. We propose that motor skill learning occurs independently and in different coordinates in two sets of loop circuits: cortex-basal ganglia and cortex-cerebellum. This architecture accounts for the seemingly diverse features of motor learning.     

Differential corticostriatal plasticity during fast and slow motor skill learning in mice

BACKGROUND: Motor skill learning usually comprises "fast" improvement in performance within the initial training session and "slow" improvement that develops across sessions. Previous studies have revealed changes in activity and connectivity in motor cortex and striatum during motor skill learning. However, the nature and dynamics of the plastic changes in each of these brain structures during the different phases of motor learning remain unclear. RESULTS: By using multielectrode arrays, we recorded the simultaneous activity of neuronal ensembles in motor cortex and dorsal striatum of mice during the different phases of skill learning on an accelerating rotarod. Mice exhibited fast improvement in the task during the initial session and also slow improvement across days. Throughout training, a high percentage of striatal (57%) and motor cortex (55%) neurons were task related; i.e., changed their firing rate while mice were running on the rotarod. Improvement in performance was accompanied by substantial plastic changes in both striatum and motor cortex. We observed parallel recruitment of task-related neurons in both structures specifically during the first session. Conversely, during slow learning across sessions we observed differential refinement of the firing patterns in each structure. At the neuronal ensemble level, we observed considerable changes in activity within the first session that became less evident during subsequent sessions. CONCLUSIONS: These data indicate that cortical and striatal circuits exhibit remarkable but dissociable plasticity during fast and slow motor skill learning and suggest that distinct neural processes mediate the different phases of motor skill learning.     

Distractor Interference during a Choice Limb Reaching Task

According to action-centered models of attention, the patterns of distractor interference that emerge in selective reaching tasks are related to the time and effort required to resolve a race for activation between competing target and non-target response producing processes. Previous studies have only used unimanual aiming tasks and, as such, only examined the effects of competition that occurs within a limb. The results of studies using unimanual aiming movements often reveal an “ipsilateral effect” - distractors on the same side of space as the effector cause greater interference than distractors on the opposite side of space. The cost of the competition when response selection is between the limbs has yet to be addressed. Participants in the present study executed reaching movements to 1 of 4 (2 left, 2 right) possible target locations with and without a distractor. Participants made ipsilateral reaches (left hand to left targets, right hand to right targets). In contrast to studies using unimanual aiming movements, a “contralateral effect” was observed; distractors affording responses for the other hand (in contralateral space) caused more interference than distractors affording responses for the same hand. The findings from the present research demonstrate that when certain portions of response planning must be resolved prior to response initiation, distractors that code for that dimension cause the greatest interference.     

Changes in stimulus control during guided skill learning in rats

We examined the changes in stimulus control occurring during guided skill learning in rats. Twenty rats were trained to complete a left-right sequence of lever presses guided by the onset and offset of panel lights over their respective levers. Once sequence accuracy was high and stable, the rats were divided into two groups. For the No-Lights group, the lights were eliminated without changing the response requirements. Sequence accuracy decreased in all subjects, but accuracy was higher than that predicted by random chance. More practice produced greater autonomy and reduced dependence on the guiding lights. For the Reversed-Lights group, the lights were presented in reversed order without changing the response requirements. Sequence accuracy immediately plummeted and did not recover, violating expectations of automatization. The guiding lights appeared to overshadow other sources of stimulus control.     

Neural substrates of intermanual transfer of a newly acquired motor skill

In healthy humans, the two cerebral hemispheres show functional specialization to a degree unmatched in other animals, and such strong hemispheric specialization contributes to unimanual skill acquisition [1, 2]. When most humans learn a new motor skill with one hand, this process results in performance improvements in the opposite hand as well [3-6]. Despite the obvious adaptive advantage of such intermanual transfer, there is no direct evidence identifying the neural substrates of this form of skill acquisition [7-9]. Here, we used functional magnetic resonance imaging (fMRI) to study brain regions activated during intermanual transfer of a learned sequence of finger movements. First, we found that the supplementary motor area (SMA) has more activity when a skill has transferred well than when it has transferred poorly. Second, we found that fMRI activity in the ventrolateral posterior thalamic nucleus correlated with successful future intermanual transfer, whereas activity in the ventrolateral anterior thalamic nucleus correlated with past intermanual transfer. Third, we found that repetitive transcranial magnetic stimulation applied over the SMA blocked intermanual transfer without affecting skill acquisition. These findings provide direct evidence for an SMA-based mechanism that supports intermanual transfer of motor-skill learning.     

Intranasal administration of testosterone increased immobile-sniffing, exploratory behavior, motor behavior and grooming behavior in rats

Currently, testosterone (T) replacement therapy is typically provided by oral medication, injectable T esters, surgically implanted T pellets, transdermal patches and gels. However, most of these methods of administration are still not ideal for targeting the central nervous system. Recently, therapeutic intranasal T administration (InT) has been considered as another option for delivering T to the brain. In the present study, the effects of 21-day InT treatment were assessed on open field behavior in gonadectomized (GDX) rats and intact rats. Subcutaneous injections of T at same dose were also tested in GDX rats. A total of 12 behavioral events were examined in GDX groups with or without T and in intact groups with or without InT. Significant decreases in open field activity were observed in rats after GDX without InT compared to sham-operated rats. The open field activity scores for most tests significantly increased with InT treatment in GDX rats and in intact rats compared with the corresponding GDX rats and intact rats. Intranasal administration of T improved the reduced behaviors resulted from T deficiency better than subcutaneous injection of T, demonstrating that T can be delivered to the brain by intranasal administration. Our results suggest that intranasal T delivery is an effective option for targeting the central nervous system.     

Ritualized behavior during competition for food between two formicinae

Summary Polyrhachis laboriosa andCamponotus brutus are two syntopic ants of the African equatorial forest. Although they occupy two different ecological niches (nesting area, diet, rhythms of activity), they are in competition for the exploitation of large permanent food sources. C. brutus, which is nocturnal, changed its rhythm of activity in the presence of large permanent food sources to exploit it day and night, whileP. laboriosa, diurnal, did not change its rhythm of activity. Encounters between workers of the two species at the food source always resulted in duels, even though several other workers were present. When attacked byC. brutus, P. laboriosa workers showed a novel flee-return strategy (fleeing over a 20-cm distance and returning to the source) instead of escaping definitively from the source and displayed ritualized behavior (i.e., fleeing, raising the gaster, flexing the gaster). These types of behavior appeasedC. brutus workers and enabledP. laboriosa to avoid overt aggression and to exploit the source in spite of the presence of a competitor. C. brutus also exhibited ritualized behavior during the duels (i.e., back-and-forth jerking of the body, series of light bites on a leg).C. brutus intimidatedP. laboriosa rather than really attacking it. This ritualization, used at an interspecific level, may be the result of a coevolutionary process or the effect of learning that certain types of behavior are beneficial. In any case, both species benefit from the possibility of exploiting large permanent food sources through confrontations that never lead to overt aggression.