[Application of high-speed video recording for investigation of food-procuring movements in rats].

Application of high-speed video recording of food-procuring movements in rats (obtaining food from a narrow horizontal tube) is described. The method was used to verify details of the performance of the movements and their temporal characteristics. This method expands the view both the single phases of food-procuring movement, and the nature of their execution. The possibilities of application this method for investigation of acquisition of lateralized motor skill in rats are discussed.

[Food-procuring skill in rats: prolongations of the extension phase in final movements of right-handed rats].

In Wistar rats with different forepaw preference trained to get food spheres from a narrow horizontal tube feeder, the duration of the paw extension phase was studied in both preliminary and final (successful) food-procuring movements. In left-handed rats, the paw extension was fastly in both preliminary and final movements than in right-handed animals. In right-handed animals, the extension phase of the final successful movements was much slower than that of preliminary movements, whereas in left-handed rats the slowing of the final extension was poorly expressed. The prolongation of the extension phase suggests a possibility of correction of the extension phase of the goal-directed movements

Characteristics of the performance of a formed motor skill by rats with different motor preferences.

Wistar rats with different motor preferences were used to study performance of a food-procuring skill--extracting food from a narrow horizontal feeder tube. These experiments showed that when the preferred limb was used, left-handed rats performed the task more quickly (including both preliminary movements and the final successful movements) than right-handed rats. Comparison of movement performance times with the preferred and non-preferred limbs showed that the task was performed more quickly using the left paw in both left- and right-handed rats, i.e., independently of whether this was the preferred paw or not. At the final stage of task performance (grasping and extracting the food), the preferred paw was more successful than the non-preferred paw in both right- and left-handed animals. It is suggested that the organization of the overall strategy for performing this complex behavioral task in rats is determined by the functional heterogeneity of the right and left hemispheres of the brain, which is not linked with limb preference. The selected preference is based on the specific motor and precision characteristics of the preferred paw, while the contralateral hemisphere--the left in right-handed animals and the right in left-handed animals--has a special role in mediating these abilities.

[Interaction of immobilization stress and food-getting learning].

The behavioral effects of emotional negative stress (immobilization) were studied in Wistar rats intact and those that had previous positive emotion experience. The food-getting learning has been chosen as positive emotion experience. Animals were trained in food pellet-reaching task by their preferred paw. It was shown that immobilization of intact rats leads to suppression of motor activity and increasing the duration of grooming. These effects indicate enhancement of passive-avoidance reactions. It was also shown that motor learning in group of rats with food reinforcement before immobilisation significantly reduces appearance of passive-avoidance reactions. It was found that immobilization stress does not inverse the initial direction of limb preference in majority of rats.

[Features of performance of acquired motor skill in rats with various motor preference].

In Wistar rats with different motor preference (right and left-handed), features of performing food-getting skill (extraction of food spheres from a narrow horizontal tube-feeder) were examined. When using preferred forepaw, left-handed rats performed the task more quickly (including both preliminary attempts and final successful movement) than the right-handed ones. This skill was more quickly performed with the left paw irrespective of whether this paw was preferred or not. At the final stage of skill performance (grasping and extraction of food), the preferred paw appeared to be more successful than the not preferred one for both the right- and left-handed rats. These results suggest that the organization of general strategy of performance of the complex behavioral task is determined by functional heterogeneity of the right and left hemispheres of the rat brain, and this heterogeneity is not connected with paw preference. Specific motor and precision abilities of a preferred paw underlie the chosen preference. A special role in realization of these abilities is played by a contralateral hemisphere.

Reorganization of bimanual motor responses on formation of a lateralized food-procuring skill in rats.

After 48-h food deprivation,Wistar rats were trained to reach a food sphere from a narrow horizontal feeder tube with one paw, with a free choice of limb. The animals used both limbs at the initial stages of training--seizing of food with one paw could alternate with seizing using the other paw, and both limbs could be involved alternately in movements preceding seizure of food. The dynamics of the reorganization of bimanual movement responses during the training of rats with different motor preferences (right-handed, left-handed) were studied. Bimanual movements in preliminary trials disappeared later than in movements ending with successful food extraction during the acquisition of both right-and left-sided skills. The disappearance of bimanual movements in preliminary trials was regarded as a measure of the maximum extent of lateralization of the skill and establishment of a new motor coordination. During training, left-handed rats reached the maximum level of lateralization of the skill earlier than right-handed rats.

[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.

[Reaching behavior of rats during realization of a lateralized motor food skill]. / Strategii dvigatel'nogo povedeniia krys pri realizatsii pishchedobyvtel'nogo lateralizovannogo navyka.

Adult Wistar rats were trained to obtain food pellets from a narrow horizontal tube with a preferred forepaw. The feeder was equipped with five photoelectric sensors with 5-mm spacing. The following parameters were recorded: total number of movements performed for a given task, amplitude (depth) of each movement, number of anticipatory movements performed with different amplitudes, and amplitude of a successful movement. It was shown that in rats with good skill acquisition, a successful food extraction was preceded by a series of differently organized sequence of preliminary movements. In some rats, such a series consisted of initial non-deep attempts followed by movements with high amplitude, whereas in other animals, it was represented, mainly, by deep attempts. Both groups of animals terminated the series by grasping and extracting food from a long distance. It is suggested that the observed organizations of the lateralized food-getting behavior of rats under the given experimental conditions represent fixed (stereotyped) action patterns.

[Nature of functional motor asymmetry in animals: state of the problem]. / Priroda funktsional'noi motornoi asimmetrii u zhivotnykh: sostoianie problemy.

Handedness in skilled movements of animals is a result of interaction of innate motor preference and learning. The nature of the innate preference is not clear. Breeding of right-handed and left-handed mice revealed that the degree rather than direction of motor preference is an inherited feature. There is, however, a correlation between the direction of preference and a number of morphological, functional, and neurochemical characters. Shifts of a preference direction were found in some strains of mice. Differences between right-handed and left-handed rats were revealed in social behavior, learning, and resistance to forced retraining. Strains of rats with different forms of genetic epilepsy were characterized by the predominance of animals with a certain direction of the motor preference. This evidence suggests some genetic influence on a direction of the motor preference. Perhaps, genetic and environmental factors closely interact in determining motor preference in animals.

The formation of lateralized motor habits in rats.

Wistar rats were trained to obtain food from a narrow tube feeder using the forepaw in conditions of free choice of which limb to use. It was found that the presence or absence of limb preference, identified in short preliminary tests, often did not coincide with the nature and degree of lateralization formed during the process of prolonged training. Achievement of the maximum degree of lateralization by the animals finally forming the right-handed group was found to require longer average training periods than was the case for left-handed rats.

[Various resistance of motor preference in rats exposed to forced retraining]. / Razlichnaia ustoichivost' dvigatel'nogo predpochteniia u krys k prinuditel'nomu pereobucheniiu.

Adult Wistar rats were trained to get food from a narrow tube under conditions of free choice of a limb. After reaching a stable level of using the preferred limb, rats (n = 35) were forced to relearn the acquired skill for reaching food with a unpreferred paw. When afterwards the rats returned to the initial conditions of free choice of a limb, 12 animals (34%) did not recover their initial preference, 8 rats (23%) were ambidextrous, and 15 animals (43%) returned to the originally preferred paw. The results demonstrated different resistance of the initial limb preference to forced retraining in different animals. It is suggested that the process of retraining per se is not the only and sufficient condition of the change in "handedness". It also suggested that the different resistance of initial preference to forced retraining reflects individual differences in a degree (intensity) of this preference, which are predetermined by internal, probably by genetic factors.

[Formation of lateralized motor skills in rats]. / K voprosu o formirovanii lateralizovannogo dvigatel'nogo navyka u krys.

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.

[Sensory information--an important factor in ontogeny]. / Sensornaia informatsiia--vazhnyi faktor ontogeneza.

Ontogenetic process reveals a row of consecutive stages characterized by the gradual increase in complexity and by the changing specificity of sensory mechanisms basic for the adaptive behavior of the young. The study examines the mechanisms of interaction among different sensory systems during the formation of early behavioral patterns and analyzes why, at a certain stage of development, a particular sensory stimulus loses its efficacy in the organization of a given behavior and is substituted by another one, previously ineffective. A special attention is paid to formation of behavior based on sensory information within the limits of ontogenetically fixed developmental critical periods and to the role of the early sensory experience in learning in adult animals.

[The effect of moderate doses of ethanol on the evoked neuronal activity of the sensorimotor cortex]. / Vliianie umerennykh doz étanola na vyzvannuiu aktivnost' neironov sensomotornoi kory.

Influence of acute administration of ethanol in moderate doses (170-1200 mg/kg, intraperitoneally) on the evoked activity of sensorimotor cortical neurons in response to electrical stimulation of the contralateral forelimb was studied in outbred rats never earlier exposed to ethanol action. During the first 20-25 min of ethanol action whether augmentation or attenuation in the level of neuronal reactivity could occur as well which in both cases could be accompanied by significant variability of latencies in poststimulus discharges and destabilization of their patterns. Expressed modifications in neuronal patterns at the first stage of ethanol action suggest that ethanol destabilizes evoked reactions of sensorimotor cortical neurons to afferent stimulation. This underlines the need for more complete approach to investigation of primary CNS reactions to ethanol paying more attention to temporal succession of origin and flow of these effects. Possible relations between oppositely directed primary reactions of single cortical neurons and individual characteristics of perception of different animals are discussed.

[The effect of moderate doses of ethanol on the nature of the background neuronal impulse activity of the sensorimotor cortex in rats]. / Vliianie umerennykh doz étanola na kharakter fonovoi impul'snoi aktivnosti neironov sensomotornoi kory krys.

The influence of acute administration of moderate doses of ethanol (170-1200 mcg/kg, intraperitoneally) on the spontaneous impulse activity of motor cortex neurons was studied in outbred rats never earlier exposed to alcohol. Initial reactions of the cortical neurons were shown to be characterized by the changes in the frequency of spontaneous activity which could be increased or decreased during the first 20-25 min after the injection. The changes in the mean frequency of spontaneous discharges were accompanied by the changes in their patterns. Both increase and decrease of the mean frequency at the initial stage of ethanol action was accompanied by significant variability of interspike intervals. It is emphasized that examination of the initial reactions of the cortical neurons to ethanol administration demands studying their temporal duration.

[The single administration of ethanol and the amplitude of the action potentials of the neocortical neurons in rats: extracellular studies]. / Odnokratnoe vvedenie étanola i amplituda potentsialov deistviia neironov neokorteksa krys: ékstrakletochnye issledovaniia.

On outbred rats the influence was studied of acute administration of moderate dozes of ethanol (150 mg--1.2 g/kg, intraperitoneally) on the motor cortex neurones. It was shown that ethanol in the range of these dozes led to a change of the amplitude of extracellularly recorded action potentials, which could be directed to an increase or decrease. In the used range minimum as well as maximum dozes in various animals might elicit contrary effects, i.e. no dependence was observed of the direction of reaction of the studied neurones on the administrated doze. Possible mechanisms are discussed which may be the basis of the change of the amplitude of extracellular action potentials. Conclusion is made that use of moderate dozes of ethanol is a useful condition for studies directed to a search of mechanisms of initial reaction to alcohol action.