Biomedical subjects

P Chapillon

Publications and source records attributed to P Chapillon.

9 recordsLinked to original sources

PubMed2002

Effects of pre- and postnatal stimulation on developmental, emotional, and cognitive aspects in rodents: a review.

Interactions between the organism and its environment, during pregnancy as well as during the postnatal period, can lead to important neurobehavioral changes. We briefly review the literature, and successively present the main results from our laboratory concerning the behavioral effects of prenatal stress, differential rearing conditions, and postnatal handling. We show that submitting primiparous DA/HAN rats to an acute emotional stress (exposure to a cat) at gestational day10, 14, or 19 leads to greatly increased mortality of pups and to decreased body weight of surviving animals. The effects of such a stressor on emotional reactivity are less obvious. Cognitive processes are impaired depending on the learning task. Enriched environments restore abnormal behaviors (emotional reactivity, motor skills, motor and spatial learning) due to brain trauma or genetic deficiencies. In any case, environmental enrichment does prevent or slow down aging effects. The effects of postnatal handling noted when using classical tests of emotional reactivity also are clear when defensive reaction paradigms are used. Furthermore, pregnant females that are early handled are less anxious than nonhandled females. We hypothesize that, when subjected to a stressor, the offspring of early-handled females would be protected from the deleterious effects of this stress compared to pups of nonhandled females.

Animals↗

PubMed2001

Environmental enrichment in BALB/c mice: effects in classical tests of anxiety and exposure to a predatory odor.

Early stimulation by environmental enrichment generally leads to improved learning abilities in rodents. However, the effects of environmental enrichment on emotional reactivity remain more questionable and were mostly studied by using classical tests of anxiety based on confrontation with a novel environment. The main goal of our study was to use different tests of anxiety to compare BALB/c mice reared in either a standard condition (SC) or enriched condition (EC). Exposure to cat feces was used to assess anxiety according to an ethoexperimental approach and a comparison was made with the elevated plus maze and the open field as classical tests of anxiety. In accordance with previous works, our results show that EC mice were more active than SC mice in the elevated plus maze and the open field. Thus, possibly as a direct consequence of frequent changes in their breeding conditions, reactivity to a novel environment was reduced in EC mice. However, the cat odor test revealed no intergroup differences for behavior, although corticosterone levels were reduced in EC mice. These results indicate that classical (i.e. reaction to novel environments) and ethoexperimental-based tests (i.e. exposure to predator cues) measure different aspects of emotional reactivity. Further studies using ECs should be useful for the delineation of the neurobiological substrates of these different reactions.

Animals↗

PubMed2001

The effects of the lurcher mutation on object localization, T-maze discrimination, and radial arm maze tasks.

The Lurcher mutation is characterized by degeneration of the cerebellar cortex and cerebellar ataxia. The mutants were compared to littermate controls of the same background strain in three spatial tasks: 1) left-right discrimination in a water-filled T-maze, a reference memory task requiring a win-stay strategy; 2) the radial arm maze, a working memory task requiring a win-shift strategy; 3) object localization, a reference memory task requiring the use of cognitive mapping. Lurcher mutants were impaired in the object localization and radial arm maze tasks but not in the left-right discrimination task. These results indicate that trial-independent tasks and reference memory tasks using cognitive mapping may be particularly vulnerable to cerebellar degeneration.

Animals↗

PubMed2000

BALB/c mice are not so bad in the Morris water maze.

We compared the learning performances of BALB/c mice subjected to the Morris water spatial task under two different lighting conditions. In the first one, the experimental room was lit by neon tubes (direct and bright illumination) and in the second one by a halogen lamp directed to the roof (diffuse illumination). The scores of BALB/c mice in the diffuse illumination condition clearly demonstrated that these mice could learn to escape to a hidden platform while they could not under direct illumination condition. Moreover, they were able to acquire the task by means of spatial cues. These results are interpreted in terms of a decrease of anxiety levels.

Albinism↗

PubMed1999

Rearing environmental enrichment in two inbred strains of mice: 1. Effects on emotional reactivity.

The effects of an enriched rearing environment on two types of anxiety-like behavior (designated "trait" and "state" anxiety) and on spontaneous activity were investigated in two inbred strains of mice, BALB/c (C) and C57BL/6(B6). Subjects were socially reared from birth to 56 days of age under enriched or standard rearing conditions. The enriched environment consisted of an assembly of plastic boxes in which a various number of objects (running wheels, pieces of plastic, etc.) offered the possibility of multiple activities. The subjects were subsequently tested in three situations: a spontaneous activity recorder, an elevated plus-maze test (a model of state anxiety), and a free exploration test (a model of trait anxiety). No group differences could be found in spontaneous activity. Environmental enrichment, however, decreased the level of both types of anxiety-like behavior in the C strain. In contrast, the level of trait anxiety of the B6 mice was not modified. The results were discussed in relation to possible CNS modifications, especially in the limbic system.

Analysis of Variance↗

PubMed1998

Timed active avoidance learning in lurcher mutant mice.

Lurcher mutant mice (+/Lc) which exhibit a massive loss of neurons in the cerebellar cortex and in the inferior olivary nuclei were subjected to an active avoidance learning task; the animals' avoidance response must occur within a small time window after a short or a long delay. The control mice needed a mean of 8.3 sessions of 10 trials (short delay group) and of 11.8 sessions (long delay group) and showed good retention after a 24 h interval. When subjected to the same number of sessions, the +/Lc mice were unable to learn the timing task. However, a subgroup of lurcher mutants was able to learn after a high number of sessions (25.4 sessions as a mean). There was no intergroup difference in the standard version of one-way active avoidance. These results indicate that the cerebellar cortex is involved in time processing during active avoidance. The cerebellum may be part of a loop including the cerebral cortex known to be involved in time perception. An alternative explanation is that the cerebellar mutant animals had persevering tendencies acquired during performance of the one-way avoidance task.

Animals↗

PubMed1998

Early development of synchronized walking on the rotorod in rats. Effects of training and handling.

There is considerable improvement of motor coordination on the rotorod during the first 3 weeks of development in rats. The purpose of the present study was to determine some factors implicated in this improvement. From days 15-22 of age, rats were: (1) extensively trained on the rotorod; (2) minimally trained on the rotorod; (3) handled daily but not trained on the rotorod; and (4) neither handled nor trained. All animals were tested on the rotorod on day 23, with separate groups of the naive rats also being tested on days, 19, 20, 21 or 22. Latencies before falling and the percentage of time spent walking in time to the movement of the rotating rod were recorded. There was a close correspondence between these two scores during ontogeny. The percentage of time spent walking was similar among extensively trained, minimally trained, and handled rats and significantly higher than that measured in rats tested only on 1 day. These results indicate that the emergence of this postural sensorimotor skill is more dependent on the maturation of sensorimotor brain region than on previous training on the apparatus.

Aging↗

PubMed1996

Use of proximal and distal cues in place navigation by mice changes during ontogeny.

The ontogeny of the ability of C57BL/6 mice to use different cues for spatial learning was examined in several Morris water maze tasks. In the first two studies, three learning procedures were used, in which only distal cues (place learning), only proximal cues (cue learning), or both proximal and distal cues (cue + place learning) were pertinent to localize the platform. The results indicated that whatever the procedure, 22-day-old mice showed the same capabilities as adults. Moreover, in the cue + place-learning procedure, although the distal cues were not necessary to solve the task, both young and adult mice demonstrated the integration of distal information by exhibiting a strong spatial bias during a probe test. However, in the third experiment, it was shown that nonpertinent proximal cues perturbed 22-day-old mice in a place-learning procedure. Taken together, these results suggest that while even the youngest mice show striking spatial navigation abilities, young mice give greater importance to proximal cues for orientation whereas adults preferentially use distal information.

Animals↗

PubMed1995

Ontogeny of orientation and spatial learning on the radial maze in mice.

The development of the orientation capacities of C57BL/6 mice has been studied on the radial maze in several procedures allowed to dissociate the different types of cues used by the mouse for solving the task with two intersession delays (2 and 24 hr). The results of the first two studies show that performance is independent of intersession delay regardless of the age of the subject. Mice as early as 23 days old obtain good performances when they can develop an algorithmic strategy or when they dispose of both proximal and distal cues during learning. At 37 days of age, however, mice can efficiently solve the radial maze task with distal cues alone. However, in the third experiment, 23-day-old mice were able to use distal cues for orientation at the end of the learning session if, at the onset, they also had access to proximal cues. These results suggest that, on weaning, mice use several types of information for task performance and that, as they mature, they turn more often to distal cues for orientation.

Aging↗