Component analyses differentiate between exploratory behaviour of spontaneously hypertensive rats and Wistar Kyoto rats in a two-compartment free-exploration open field

The present study investigated behaviour in a two-compartment free-exploration open field by means of a component analysis. Seven spontaneously hypertensive rats (SHR) and six normotensive Wistar Kyoto control rats (WKY) were tested repeatedly on eight behaviour parameters in this apparatus. A two-compartment free-exploration open field evokes less fear than the standard one-compartment forced-exploration open field, because it permits the rat to enter the field from its home cage. The data were subjected to principal component analysis and multivariate analysis of variance. The results showed that the recorded behaviour grouped into two independent components, encompassing behaviour in the cage and in the field, respectively. These components are interpreted as reflecting different kinds of exploration: (i) distant exploration when the rat explores from its home cage, and (ii) close exploration when the rat explores by entering the novel field. The SHR scored highest on both, although they mostly used close exploration. In the WKY rats, which mainly stayed in their cages, distant exploration was predominant. The present free-exploration open-field procedure discriminates between two different exploration strategies employed by SHR and WKY rats.     

An automated open-field apparatus utilizing an improved resistance detection circuit

An open-field apparatus that can be automatically operated is described. Detection of movement is electronic and based upon the fact that the S will complete a circuit path when crossing an open field. The circuit is very sensitive yet quite immune to the usual problem of 60-Hz interference.     

Conformational properties of serum albumin binding sites in rats with different behaviour in the open field test

In this study, the hypothesis was tested that behaviour of rats under the open field test condition and effects of subsequent acute stress relate to conformational properties of the main plasma carrier protein, albumin.To evaluate albumin properties, fluorescence intensity of a molecular probe CAPIDAN (N-carboxyphenylimide of dimethylaminonaphthalic acid) at N (at pH 7.4) and F (at pH 4.2) albumin conformations was measured and the N-F signal ratio was calculated. The data obtained showed that CAPIDAN fluoresces selectively from albumin in rat serum and its fluorescence is sensitive to binding of fatty acids and some other ligands to albumin. Behaviour of 78 Wistar male rats was characterized from the fraction of time taken for exploratory and ambulatory activity during the open field test. In rats not subjected to stress (n = 40), a negative correlation was revealed between open field activity and CAPIDAN N-to-F ratio for albumin (r = - 0.55, p < 0.0005). In the group of rats subjected to acute stress (immobilization plus stochastic electrocutaneous stimulation) the correlation between behavioural activity and the albumin conformational properties was significantly positive (r = 0.59, p < 0.0001): the CAPIDAN albumin fluorescence ratio increased in the highly active rats and decreased in the low-activity rats. The mechanisms of the observed effects may involve differences in nonesterified fatty acid production during stress.     

An analysis of response,direction, and place learning in an open field and T maze

Rats were trained to locate food in a response, direction, or place problem on an open field located at 2 positions. In Experiment 1, both the response and direction groups solved the problem. The place group failed to solve the task in approximately 300 trials. Experiment 2 demonstrated that rats need distinguishable start points to solve a place problem when neither a response nor a direction solution is available. Findings from Experiment 3 suggest that a combination of path traveled and distinct cues help to differentiate start points. Experiment 4 replicated the findings using a T maze. These results suggest "place" solutions are difficult for rats. The data are discussed with respect to conditional learning and modern spatial mapping theory.     

Chronic sildenafil (Viagra) administration reduces anxiety in intact and castrated male rats

Epidemiological research indicates that sildenafil (Viagra) abuse is associated with increased risk behaviors. The present study employs the open field, a standard animal model used in the field of anxiety research, to examine whether chronic exposure to sildenafil affects anxiety and risk-taking behaviors in gonadally intact and castrated male Wistar rats. Sildenafil (10 mg/kg) or saline were administered three times a week for three weeks. Animals were tested once a week in the open field during and after drug treatment. Sildenafil treatment increased the number of center entries and time spent in the center in intact and castrated animals during and after treatment, suggesting that repeated drug use decreases anxiety. Sildenafil also restored the deficits in exploration and locomotion produced by castration, indicating that sildenafil effects on open field behaviors are independent of endogenous androgens. We caution against generalizing from this study to human behaviors, but propose that the behavioral effects produced by a chronic high dose of sildenafil warrant further studies into its abuse potential.     

Le cycle journée/nuit : étude du développement des connaissances chez l’enfant français et comparaison de méthodes

The aim of this work is to study the knowledge development process about night and day cycle during ontogeny, by comparing two diverging theoretical and methodological approaches, on 178 elementary school children (6-7 years old, 8-9 years old and 10-11 years old). We hypothesis that the dimension (2D/3D) of the representation, the question type (open versus forced choice) and the age of the student have an effect on the amount of correct answers and on the coherence between the answers. The results show that the knowledge acquisition process regarding night and day cycle follows a gradual path during ontogeny and that the method used has a significant effect on the number of correct answers given by the children. Indeed, heliocentric model is given minority when children are asked with open questions (only 31% of the children). On the contrary 76% of them choose the heliocentric perspective when asked with forced-choice questions. The support's dimension (2D/3D) has no effect.     

The relationship of attitudes,habit and loyalty to market share in relation to a staple good in a local grocery store: An exploratory study

The influence of brand attitudes, brand loyalty and habit on market share is analyzed. The data were generated from a sample of bar soap purchasers in a store, where there were no variations in price or promotional displays during the field study. Results indicate that brand attitudes and habit are both directly and indirectly related to market share with the indirect path occurring through brand loyalty. The results are discussed in terms of their significance for researchers and managers.     

The spontaneously hypertensive rat as an animal model of attention-deficit hyperactivity disorder: effects of methylphenidate on exploratory behavior

Spontaneously hypertensive rats (SHR) show a pervasive hyperactivity in several paradigms. Thus, these rats may be used as an animal model of childhood hyperactivity also called Attention-Deficit Hyperactivity Disorder. This disorder is frequently treated with psychomotor stimulant drugs, but little is known about the effects of such drugs on behavior. The present study investigated the behavioral effects of 1-24 mg/kg methylphenidate (Ritalin) on the exploratory behavior of male SHR and Wistar-Kyoto control rats (WKY) in a two-compartment free-exploration open field. Except following very high doses. SHR spent most of the session time in the field while WKY stayed in the home cage. Low and medium doses were followed by increased activity in the field for SHR and increased activity in the cage for WKY. The response-stimulatory effects of low to medium doses of methylphenidate are less in SHR than in WKY. Starting at medium doses, activity decreased and stereotyped behavior increased progressively by increasing dose. Locomotor activity in the field decreased following lower doses than locomotor activity in the cage, and vertical activity (rearing) was reduced by lower doses than horizontal activity (crossing). The following conclusions were drawn. (i) There is no "paradoxical" inhibition of SHR hyperactivity following methylphenidate. On the contrary, SHR activity is in fact stimulated, albeit to a lesser degree than that of WKY. (ii) The stimulatory effects of low to medium doses are, in general, most pronounced for the kind of exploratory behavior most frequently used by the rat during baseline conditions. (iii) Rearing might be more susceptible to adverse effects of methylphenidate than ambulation.     

The marriage and family counseling profession (An editorial)

Abstract

Marriage and family counseling must become an autonomous profession because it is socially necessary, open to those who are qualified to practice it and for those who need it, and consultative. Legally recognized in only five states, it is struggling through growing pains in the rat of the US. The special field of this profession is the procesr of interpersonal dynamics in the intimate setting of the family and its effects on the individual. The clinical work of the marriage and family counselor becomes “adaptive,” “therapeutic” or “maturational,” depending on different variables.     

CNTF对应激大鼠行为障碍和海马CA1神经元损害的作用

实验采用 ｏｐｅｎ ｆｉｅｌｄ测定、 Ｎｉｓｓｌ染色、 Ｂｉｅｌｓｃｈｏｗｓｋｙ－Ｇｒｏｓ－Ｌａｗｒｅｎｔｊｅｗ染色和常规透射电镜技术,观察急性和慢性足底电击应激大鼠的ｏｐｅｎ ｆｉｅｌｄ行为和海马ＣＡ１神经元形态的变化,及双侧海马注射睫状神经营养因子（ＣＮＴＦ）对它的影响。结果表明,急性应激大鼠ｏｐｅｎ ｆｉｅｌｄ行为活动增加,海马ＣＡ１神经元形态无明显变化;慢性应激大鼠ｏｐｅｎ ｆｉｅｌｄ行为活动减少,海马ＣＡ１神经元出现明显的损伤性形态变化;睫状神经营养因子对对照组大鼠和急性应激大鼠的ｏｐｅｎ ｆｉｅｌｄ行为和海马ＣＡ１神经元形态均无明显作用,但可显著减轻慢性应激大鼠海马ＣＡ１神经元损伤程度,改善其行为障碍。实验结果提示睫状神经营养因子可能通过保护海马神经元从而改善慢性应激大鼠的行为障碍。     

On the border: perimeter patrolling as a transitional exploratory phase in a diurnal rodent,the fat sand rat (<Emphasis Type="Italic">Psammomys obesus</Emphasis>)

Exploration is an initial phase of constructing spatial representation. In an illuminated environment, exploration by nocturnal rodents takes the form of home-base behavior, with the rodents organizing their activity in relation to the base, repeatedly orienting and returning to it. In the dark, home base behavior in gerbils is preceded by looping exploration, in which travel paths tangle into loops that close at various locations so that the gerbils pilot from one loop to the next. In the present study we tested a diurnal gerbil, the fat sand rat, Psammomys obesus, in both a lit and a dark open field in order to compare its exploratory behavior with that of nocturnal rodents. We found that under lit conditions, fat sand rats used perimeter patrolling, traveling mainly along the walls of the open field. In perimeter patrolling the animal probably monitors its location in relation to the perimeter (arena walls), and not to a specific location as in home base. In the dark, fat sand rats first used looping, and gradually shifted to perimeter patrolling exploration. We suggest that perimeter patrolling is a transient phase in which the animal evaluates possible locations for a home base. Thus, perimeter patrolling is an intermediate phase between looping, which is based on piloting from one landmark to the next, and home base exploration, in which the animal continuously orients to a specific location. This spatial behavior of perimeter patrolling may shed light on phases of information processing and spatial representation during exploration and navigation.     

Conditioned increases in locomotor activity produced with morphine as an unconditioned stimulus, and the relation of conditioning to acute morphine effect and tolerance

Rats administered 5 mg/kg morphine SO4, through subcutaneously implanted catheters, during each of several daily sessions in an open field showed a progressive increase in locomotor activity measured in the open field prior to each morphine administration. Since the increases in activity were not observed in rats given morphine in a different environment (home cage) and saline in the open field, it is concluded that the increases were due to conditioning. In addition, the increases in activity were retained over a 7-day rest period; they were also produced when a second opiate (5 microgram/kg etorphine HCl) was substituted for morphine, were not seen when 2 mg/kg naloxone HCl (ip) was administered during treatment, and were present in rats showing tolerance to opiate-produced hypoactivity. Morphine's direct effect on activity is believed to have a biphasic dose-response curve; therefore, the relation of dose to conditioning was also studied. Increases in activity were the only conditioned behaviors observed; they were present only at the higher doses (16, 4, and 1 vs. .25, .065, and 0 mg/kg), and they occurred whether or not the dose was associated with unconditioned hypoactivity. The discussion deals with the relation of conditioning and morphine tolerance, the question of whether the unconditioned stimulus of morphine conditioning is a compensatory or a direct effect of morphine, and the similarity of conditioned increases in activity produced by morphine and by other stimuli that are reinforcing.     

Short cuts by dogs in natural surroundings

We studied the capacity of seven Alsatian dogs to use a short cut in experiments carried out in a large (3-ha) meadow. The animals' task was to find meat hidden at two points (A and B) when released from a third (D). The dogs had each been taken previously on a lead to the two baited points by a different path that led indirectly from A to B via D (line segment AD = 24 m; DB = 40 m). The experiment was carried out in two different fields, one nearly homogeneous (covered mainly in thyme), and the other heterogeneous, containing visual features such as bushes, puddles and trails. In 96% of the 224 trials, the animals took a reasonably good short cut between the baited points rather than return to the start. The animals took the shortest possible path—a straight line directly from A to B—more frequently in the homogeneous than in the heterogeneous field. In the heterogeneous field, the animals had a greater tendency to use an “inside short cut”, heading for a point that intersected the path from the start to the second baited point rather than going directly to the point or returning to the start. The trials in which the shortest path was taken suggest that dogs are capable of evaluating along a continuum the direction of an invisible goal by integrating motor and sensory cues obtained during an early but indirect visit to the same goal. Some hypotheses are presented concerning the use of the inside short cut in this experiment, especially in an heterogeneous field.     

Undernutrition during suckling and latent learning ability of rehabilitated adult male rats

The present report investigates the effects of early undernutrition on the latent learning ability of rehabilitated adult male rats in a simple maze task. Rats were undernourished during suckling by feeding their dams an 8% casein diet. Well-nourished dams received a 25% casein diet during the same period. Rats were weaned at 21 days of age and nutritionally rehabilitated until they became adults, when behavioral task was conducted. Under a nonappetitive condition, rats were exposed either to an open field or to a maze apparatus. They were thereafter deprived of water and tested in the maze apparatus. Both well-nourished and undernourished rats that had been previously exposed to the maze performed better than those exposed to the open field. Nutritional treatment had no effect on performance of either the latent learning or of the open-field groups. These results suggest that rehabilitated adult rats are able to learn about the environment when no immediate reinforcement is involved. The discrepancy between our findings and results reported by others may be due to differences in task complexity and/or perhaps to the fact that nutritional rehabilitation also plays a role in reversing some of the deleterious effects of early undernutrition on learning ability of rats.     

Social effects on rat spatial choice in an open field task

Pairs of rats foraged in trials either together or separately in an open field apparatus for pellets hidden in discreet locations in a 5 × 5 matrix. Trial duration was either 1 or 4 min. The tendency to choose locations that had earlier been visited by another rat was examined by comparing the choices made in the presence and absence of the other rat. Rats avoided visits to locations that had earlier been visited by the other rat, but only if they had also visited the same location earlier in a short duration trial. This pattern of results is consistent with earlier findings from experiments using the radial arm maze. Furthermore, when rats did visit locations that had earlier been visited by the other rat in a long duration trial, they tended to be locations that had been visited longer ago by the other rat than would be expected. This suggests a forgetting function for social memories. These data provide evidence that the social memory reported in earlier studies using the radial-arm maze can be found in other experimental paradigms and that at least some of its properties are common in the two paradigms.     

Immune stress in late pregnant rats decreases length of gestation and fecundity, and alters later cognitive and affective behaviour of surviving pre-adolescent offspring

Immune challenge during pregnancy is associated with preterm birth and poor perinatal development. The mechanisms of these effects are not known. 5α-Pregnan-3α-ol-20-one (3α,5α-THP), the neuroactive metabolite of progesterone, is critical for neurodevelopment and stress responses, and can influence cognition and affective behaviours. To develop an immune challenge model of preterm birth, pregnant Long-Evans rat dams were administered lipopolysaccharide [LPS; 30?μg/kg/ml, intraperitoneal (IP)], interleukin-1β (IL-1β; 1?μg/rat, IP) or vehicle (0.9% saline, IP) daily on gestational days 17-21. Compared to control treatment, prenatal LPS or IL-1β reduced gestational length and the number of viable pups born. At 28-30 days of age, male and female offspring of mothers exposed to prenatal IL-1β had reduced cognitive performance in the object recognition task compared to controls. In females, but not males, prenatal IL-1β reduced anxiety-like behaviour, indicated by entries to the centre of an open field. In the hippocampus, progesterone turnover to its 5α-reduced metabolites was lower in prenatally exposed IL-1β female, but not in male offspring. IL-1β-exposed males and females had reduced oestradiol content in hippocampus, medial prefrontal cortex and diencephalon compared to controls. Thus, immune stress during late pregnancy reduced gestational length and negatively impacted birth outcomes, hippocampal function and central neurosteroid formation in the offspring.     

Optimal combination of environmental cues and path integration during navigation

Navigation is influenced by body-based self-motion cues that are integrated over time, in a process known as path integration, as well as by environmental cues such as landmarks and room shape. In two experiments we explored whether humans combine path integration and environmental cues (Exp. 1: room shape; Exp. 2: room shape, single landmark, and multiple landmarks) to reduce response variability when returning to a previously visited location. Participants walked an outbound path in an immersive virtual environment before attempting to return to the path origin. Path integration and an environmental cue were both available during the outbound path, but experimental manipulations created single- and dual-cue conditions during the return path. The response variance when returning to the path origin was reduced when both cues were available, consistent with optimal integration predicted on the basis of Bayesian principles. The findings indicate that humans optimally integrate multiple spatial cues during navigation. Additionally, a large (but not a small) cue conflict caused participants to assign a higher weight to path integration than to environmental cues, despite the relatively greater precision afforded by the environmental cues.     

Dominance-subordinance in cohabiting pairs of adult rats: Effects on Aggressive behavior

Following an initial intruder aggression test, 10 pairs of adult male rats matched on aggressiveness were formed. The first 20 min of paired cohabitation were used to determine dominance and subordinance between pau members. Residents judged to be dominant from this observation session gained significantly more weight during cohabitation and exhibited significantly more aggression on the second aggression test than their subordinate counterparts. Significant correlations among various measures of aggression were found, but open field performance did not correlate, with the measures of aggression nor did changes in open field scores reflect changes in aggression.     

Open field activity after learning in mice

The possible increase of open field activity after learning in mice was examined in five experiments, where the following factors were assessed: (1) and (2) the duration of an open field activity increase (3) the influence of the familiarity of the environment (4) the influence of floor texture during activity measurements and (5) the result of motor activation per se compared to the result of learning. The results indicate that the activity increase lasted 60 min. The phenomenon was related to the learning paradigm used and to the familiarity of the environment and was affected by floor texture. Motor activation per se did not activate the mice as much as the learning of a task. It is suggested that an open field activity increase in mice after learning is associated both with the strain due to the acquisition of a new response and with the strain due to the activity measurement.