The organization of instrumental food-procuring movements in rats]

The roles of the lateral hypothalamus, basolateral nucleus of the amygdalar complex, the second field of the frontal cortex, and ventromedial thalamic nucleus in organization of the fast ballistic food-procuring movements were studied in albino rats. Sequences of uni- and bilateral destruction of the brain structures were assessed by photorecording. Movement-related neuronal activity in these structures was recorded in freely moving animals. A specific involvement of each of the above listed structures in organization of food-procuring movements was shown. The lateral hypothalamus seems to participate in initiation of the motor program and its efficient realization, the basolateral amygdala appears to produce activatory, training, and stabilizing effects. The second field of the motor cortex leads in movement acquisition (i.e., in memorizing) and decision making about triggering the program. The idea about the relay role of the thalamic motor nucleus is supplemented by understanding of its more complex integrative function.     

Role of the amygdalar complex in programing of fast food-procuring movements in rats

Effects of uni- and bilateral electrolytic destruction of the basolateral nuclei of the amygdalar complex on the main parameters of fast food-procuring movements of albino rats were studied in the course of rearrangement of the motor programs; modifications of the parameters were observed both throughout the entire experiment and within each experimental day. The accuracy of the movements was significantly modified, which was manifested in an increase in the number of trials necessary for successful food capturing. An increase in the duration and a decrease in the frequency of the movements were also observed. The studied parameters underwent no complete recovery even on the tenth experimental day. Thus, the basolateral nuclei of the amygdalar complex occupy an important position in the system responsible for rearrangement of motivated automatized movements; when these nuclei are Injured, their function cannot be completely compensated by other brain structures.     

Fast ballistic food-procuring movements in rats: Phenomenology and probable controlling mechanisms

Parameters of fast ballistic food-procuring movements were studied in albino rats. With the use of video and photorecording, the number of attempts used by an animal, to get the food globula, duration of the movements, and their phasic structure were analyzed within the whole learning period and certain experimental days. When the motor skill had been formed, programed ballistic components characterized by hard-to-modify parameters and components with a considerable impact of reverse afferentation in their formation and performance were analyzed. The experimental data are interpreted in terms of the expediency of using the operant motor reactions performed by rats getting food from a narrow manger as a model of voluntary motor activity in electrophysiological, behavioral, neurochemical, and morphological studies. The regularities in formation of motor programs, initiation, realization, and control of the movements, and central mechanisms of these phenomena are discussed.     

Organization of voluntary movement.

There have recently been a number of advances in our knowledge of the organization of complex, multi-joint movements. Promising starts have been made in our understanding of how the motor system translates information about the location of external targets into motor commands encoded in a body-based coordinate system. Two simplifying strategies for trajectory control that are discussed are parallel specification of response features and the programming of equilibrium trajectories. New insights have also been gained into how neural systems process sensory information to plan and assist with task performance. A number of recent papers emphasize the feedforward use of sensory input, which is mediated through models of the external world, the body's physical plant, and the task structure. These models exert their influence at both reflex and higher levels and permit the preparation of predictive default parameters of trajectories as well as strategies for resolving task demands.     

Electrical activity of the lateral hypothalamus related to food-procuring movements of rats

On freely moving albino rats we demonstrated that, when fast food-procuring movements are performed, the mass electrical activity of the lateral hypothalamus (LH) is suppressed 1.6–2.0 sec before the movement beginning recorded with a photoelectrical device. Videorecording of the movements and recording of the spike activity of LH units showed that the latter are activated 1.0–0.1 sec before the movement initiation. The LH is considered a motivation-related structure, which serves as a source providing an increase in the excitability of the structures involved in the control of food-procuring movements and, further on, supporting this increased excitability. The LH is also a component of the mechanisms providing formation of the motor program. The role of the LH in the ensemble of motor centers, which organize and control voluntary movements, is discussed.     

Chronometric study of a posturo-kinetic program associated with voluntary movement

Posturo-kinetic programming was investigated by a simple reaction time paradigm. Standing subjects performed voluntary upper limb elevations differing by the importance of their destabilizing effect on the initial balance. It was shown that: The reaction time varied according to the destabilizing effect of the forthcoming movement. These variations were due to differences in the duration of postural adjustments which were shown to precede voluntary movement. Duration of pre-motor period, corresponding to delay between the response signal and the onset of the earliest postural adjustment, did not depend on parameters of the forthcoming movement.     

Neuronal reactions in field 2 of the frontal cortex, related to organization and performance of food-procuring movements in rats

Movement-related electrical reactions of neuronal units localized in field 2 of the frontal cortex were studied in albino rats performing fast food-procuring movements under conditions of unrestrained behavior. According to the temporal characteristics of the changes in the neuronal spike activity, three types of reactions were classified: (i) activation that forestalled the movement initiation for 1.0–1.5 sec; (ii) activation or inhibition forestalling this beginning for 0.20–0.26 sec; and (iii) activation in the course of a performed movement. Considerations about the involvement of the neurons of various cortical layers in the mechanisms of programing, switching on, and current control of the efficiency of performance of food-procuring movements are proposed, and the role of the frontal cortex in these processes is discussed.     

Organization of a complex movement: fixed and variable components of the cockroach escape behavior

The escape behavior of the cockroach Periplaneta americana was studied by means of high speed filming (250 frames/s) and a computer-graphical analysis of the body and leg movements. The results are as follows: 1. The behavior begins with pure rotation of the body about the posteriorly located cerci, followed by rotation plus forward translation, and finally pure translation (Figs. 1, 2). 2. A consistent inter-leg coordination is used for the entire duration of the turn (Fig. 3A). At the start of the movement, five or all six legs execute their first stance phase (i.e. leg on the ground during locomotion) simultaneously. By the end of the turn the pattern has changed to the alternate 'tripod' coordination characteristic of insect walking. The change-over from all legs working together, to working alternately, occurs by means of a consistent pattern of delays in the stepping of certain legs. 3. The movements made by each leg during its initial stance phase are carried out using consistent movement components in the anterior-posterior (A-P) and the medial-lateral (M-L) axes (Fig. 4A). The movement at a particular joint in each middle leg is found to be diagnostic for the direction of turn. 4. The size and direction of a given leg's M-L movement in its initial stance phase depends on the same leg's prior A-P position (Fig. 5). No such feedback effects were seen among different legs. 5. Animals that are fixed to a slick surface on which they make slipping leg movements show the same inter-leg coordination (Fig. 3B), direction of initial stance movement (Fig. 4B) and dependence of the leg's initial M-L movement on its prior A-P position (Fig. 6), as did free-ranging animals. 6. Cockroaches that are walking at the moment they begin their escape reverse those ongoing leg movements that are contrary to escape movements. 7. These results are discussed in terms of the overall coordination of the complex movements, and in terms of the known properties of the neural circuitry for escape. Possibilities for neurobiological follow-up of certain of the findings presented here are also addressed.     

Asymmetry of movement direction as a tactic in the feeding behavior of rats

The sign and degree of spatial-motor asymmetry in rats were studied in conditions both of spontaneous or signalled choice in an U-maze and spontaneous multiple choice in a radial labyrinth. It was shown that during investigation of a new environment, motor asymmetry in rats was feebly expressed in all conditions of experiments, irrespective of the labyrinth scheme and experimental procedures. In the process of training, adequate behaviour was formed and in some conditions a distinctly expressed spatial asymmetry appeared, while in other cases it was absent. Apparently, while investigating an "unknown" situation (where rats can move rightwards and leftwards), the strategy of "displacement" is characteristic of them. Later the rate of asymmetry manifestation depends on concrete spatial and temporal characteristics of already "familiar" surroundings.     

Effects of reorganization of the food-procuring behavior in the time deficit situation in primates

The organization of the food-procuring behavior inMacaca mulatto was studied under conditions of the time deficit. It has been shown that if the duration of performance of the alimentary behavior in the animals is restricted by 8 s, four ways of individual arrangement of their activity are observed: (1) stabilization of time intervals between the acts performed; (2) shift of the effectiveness of performance from the instrumental phase to the consumatory one of the reflex in the same animal in different experiments; (3) in the case of an individual experiment: an increased effectiveness of performance of one act (the instrumental or consumatory one) and a decreased effectiveness of the other; (4) an abrupt change in the tactics of motor responsiveness. All the behavioral phenomena revealed are believed to be connected with a voluntary and goal-oriented strive of the monkeys to obtain the maximal amount of food under the conditions of time deficit by way of the active (directly in the experiment) or latent (at the intersignal period) reorganization of their activity program. Deceased.     

Formation of lateralization of manipulatory food-procuring behavior in the white rat early ontogenesis

Study of peculiarities of formation of preference in use of one of forepaws at learning of the manipulatory food-procuring skill has been carried out at different stages of early ontogenesis of white rats. It was established that as early as at the 3-week age the rat pups were already able to learn getting food from a narrow test-tube; however, no expressed preference in using one of the extremities was revealed. After repeated testing of adult rats at the age of 4 months the number of ambidexters was significantly higher than in the control animal group. At learning of the 30-day old rat pups of this manipulatory skill, in the majority of the rat pups, no significant lateralization also was found in using the forepaw. At repeated testing of adult rats the amount of ambidexters did not differ from that in the control group of animals. The obtained results indicate the existence of critical periods in formation of lateral preference in performance of the manipulatory food-procuring skill. There also was shown effect of learning in early ontogenesis of the capability for lateralization of this skill in the adult state in rats.     

Nickel deficiency diminishes sperm quantity and movement in rats

Early studies on nickel essentiality with rats and goats indicated that nickel deprivation impaired reproductive performance. Nickel also has been found to influence cyclic nucleotide gated channels (CNG); these types of channels are important in sperm physiology. Thus, two experiments were conducted to test the hypothesis that nickel deficiency affects sperm physiology in a manner consistent with nickel having an essential function related to CNG channel functions. The experiments were factorially arranged with four treatment groups of eight weanling rats in each. In experiment 1, the treatments were supplemental dietary nickel of 0 and 1 mg/kg and N ^ω -nitro-l-arginine methyl ester (l-NAME, a nitric oxide synthase inhibitor) added to the drinking water (50 mg/100 mL) the last 3 wk of an 8-wk experiment. In experment 2, the treatments were supplemental dietary nickel at 0 and 1 mg/kg and supplemental dietary sodium chloride (NaCl) at 0 and 80 g/kg. The NaCl and l-NAME variables were included to act as stressors affecting CNG channel activity. The basal diet contained per kilogram about 27 μg of nickel and 1 g of sodium. After 8 wk in experiment 1 and 16 wk in experiment 2, urine while fasting and testes and epididymis in both experiments, and seminal vesicles and prostates in experiment 2 were harvested for analysis. Nickel deprivation significantly decreased spermatozoa motility and density in the epididymides, epididymal transit time of spermatozoa, and testes sperm production rate. Nickel deficiency also significantly decreased the weights of the seminal vesicles and prostate glands. Excessive NaCl had no effect on sperm physiology; however, it decreased prostate gland weights. The findings support the hypothesis that nickel has an essential function that possibly could affect reproductive performance in higher animals, perhaps through affecting a CNG channel function. Part of the data was presented at the Experimental Biology 2001 Meeting, Orlando, FL, March 31–April 4, 2001. (F. H. Nielsen, E. O. Uthus and K. Yokoi, Dietary nickel deprivation decreases sperm motility and evokes hypertension in rats, FASEB J. 15, A972 (2001), and K. Yokoi, E. O. Uthus and F. H. Nielsen, Nickel deficiency induces renal damages and hypertension in rats which is augmented by sodium chloride, FASEB J. 15, A973 (2001). The US Department of Agriculture, Agricultural Research Service, Northern Plains Area, is an equal opportunity/affirmative action employer and all agency services are available without discrimination. Mention of a trademark or proprietary product does not constitute a guarantee or warranty of the product by the US Department of Agriculture and does not imply its approval to the exclusion of the products that may also be suitable.     

Study of bone remodeling in corticotomy-assisted orthodontic tooth movement in rats

The goal of this study was to determine the structure change of the alveolar bone and the expression of a group of bone remodeling-related factors. Sixty healthy male Wistar rats were randomly divided into three groups. Selective alveolar decortication (SAD), tooth movement (TM), and “combined therapy” (SAD+TM) was performed in group I, II, and III, respectively. On days 0, 7, 14, 21, and 42, a Micro-CT scan was performed on the maxillary alveolar bone and tooth. In addition, on days 0, 7, 14, 21, 28, and 42, some of the rats were killed by cervical dislocation and tissues were harvested. Analysis of scan data revealed a significant decrease in bone density of the alveolar bone at 14 days post-surgery, and increased at 42 days post-surgery to a level higher than that before the surgery. Microarray and bioinformatics analysis were performed to explore gene expression profile in three groups (SAD, TM, and SAD+TM), and a large number of differentially expressed genes were identified. In addition, real-time polymerase chain reaction was performed to determine the expression of bone remodeling-related factors. The expression of osteoblast-related cytokines, including osteopontin, bone sialoprotein, and osteocalcin, and osteoclast regulators macrophage-colony stimulating factor (M-CSF) and RANKL (activator of nuclear factor KB receptor ligand) were increased in group III, suggesting that there was increased bone synthesis and activation of bone absorption. Moreover, group III had a unique alveolar bone remodeling pattern: RANKL and osteoprotegerin-promoted alveolar remodeling. In conclusion, during the early stage of orthodontic tooth movement, corticotomy can accelerate the movement of teeth, modulate the state of bone metabolism, and activate osteogenesis and osteoclast, which support the theory of regional acceleratory phenomenon.     

A program for the study of long-term adaptation to a weightless environment providing three-dimensional freedom of movement

The mechanical details of a working model of a proposed small-animal space station which is currently undergoing bench tests are briefly described together with supporting evidence pointing to the feasibility of the program. The one-third cubic meter canister weighs less than 250 kg when loaded for a 9-month period. It would transmit by slow-scan television data concerning mice which it is proposed would be born in the weightless state. Observation of their silhouettes would indicate their growth rates and study of the picture sequence their activity patterns. For example, their use and defense of the feeding and nesting areas and their care of their young.The device would also be used to determine whether the weightless state affected the development of a circadian rhythm or the periodicity of any rhythm that was observed. Recovery of the animals' special living compartment by rendezvous in orbit would permit testing of those born in the device in the earth's gravity field by familiar methods such as those that have been used for the assessment of negative geotactic responses and for the evaluation of rodents living in vertical, as opposed to horizontal mazes.This work was jointly supported by the National Aeronautics and Space Administration, Office of Advanced Research and Technology, and the United States Air Force's Aerospace Medical Division through United States Air Force Contract F29600-67-C-0010.