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Critical period. --- Emotional reactivity. --- Infantile stimulation. --- Periods. --- Reactivity. --- Stimulation. --- Stimulus. --- Theory.

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In this study, we tested the ability of risk assessment and exploration behaviours to emphasise PH effects. Indeed, postnatal handling (PH) decreases emotional reactivity in rats but inconsistent behavioural results can be observed and may be due to false negative (i.e. existing effects are not detected). Risk assessment behaviours were measured in the elevated plus maze, in the free exploration paradigm and in the open field. In addition, we measured object exploration behaviours towards familiar/new objects in the open field. PH increased general activity in the elevated plus maze and in the free exploration paradigm and risk assessment behaviours allowed demonstrating that these effects were specific to emotional reactivity. In the open field, PH increased object exploration as early as first exposition while general activity was unaffected. PH also decreased behavioural inhibition in response to the introduction of a novel object. On the whole, our results show that risk assessment and object exploration behaviours are valuable tools to measure more precisely emotional reactivity in rodents. This reinforces the idea that these behaviours should be used more frequently in order to avoid false negative when emotional reactivity changes are expected in unconditioned conflict tests. (C) 2004 Elsevier B.V. All rights reserved

Ability. --- Activity. --- Animal-models. --- Anxiety-like behaviors. --- Assessment. --- Behaviour. --- Boxes. --- Conflict. --- Corticosterone response. --- Elevated plus maze. --- Elevated plus-maze. --- Emotional reactivity. --- Environmental enrichment. --- Ethological analysis. --- Exploration. --- Female rats. --- Field. --- Free exploration. --- Handling stimulation. --- Handling. --- Inhibition. --- Object exploration. --- Object. --- Objects. --- Open field. --- Open fields rats. --- Open-field. --- Ph. --- Postnatal handling. --- Prenatal stress. --- Rat. --- Rats. --- Reactivity. --- Response. --- Risk assessment. --- Risk. --- Rodent. --- Rodents. --- Test. --- Tests. --- Time. --- Tool.

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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 mite was not modified. The results were discussed in relation to possible CNS modifications, especially in the limbic system

Activity. --- Age. --- Animal-models. --- Anxiety disorders. --- Anxiety-like behavior. --- Anxiety. --- Behavior. --- Birth. --- Boxes. --- Elevated plus maze. --- Elevated plus-maze test. --- Elevated plus-maze. --- Emotional reactivity. --- Enriched environment. --- Enriched. --- Enrichment. --- Environment. --- Environmental enrichment. --- Exploration. --- Free-exploratory paradigm. --- Group. --- Hippocampal mossy fibers. --- Inbred strains. --- Level. --- Limbic system. --- Mice. --- Model. --- Novelty reactions. --- Object. --- Objects. --- Rats. --- Rattus-norvegicus. --- Reactivity. --- Rearing. --- Running wheel. --- Situations. --- Spontaneous activity. --- System. --- Test. --- Trait anxiety,state anxiety,environmental enrichment,balb c,c57bl/6. --- Validation.

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Human performance on diverse tests of intellect are impacted by a "general" regulatory factor that accounts for up to 50% of the variance between individuals on intelligence tests. Neurobiological determinants of general cognitive abilities are essentially unknown, owing in part to the paucity of animal research wherein neurobiological analyses are possible. We report a methodology with which we have assessed individual differences in the general learning abilities of laboratory mice. Abilities of mice on tests of associative fear conditioning, operant avoidance, path integration, discrimination, and spatial navigation were assessed. Tasks were designed so that each made unique sensory, motor, motivational, and information processing demands on the animals. A sample of 56 genetically diverse outbred mice (CD-1) was used to assess individuals' acquisition on each task. Indicative of a common source of variance, positive correlations were found between individuals' performance on all tasks. When tested on multiple test batteries, the overall performance ranks of individuals were found to be highly reliable and were "normally" distributed. Factor analysis of learning performance variables determined that a single factor accounted for 38% of the total variance across animals. Animals' levels of native activity and body weights accounted for little of the variability in learning, although animals' propensity for exploration loaded strongly ( and was positively correlated) with learning abilities. These results indicate that diverse learning abilities of laboratory mice are influenced by a common source of variance and, moreover, that the general learning abilities of individual mice can be specified relative to a sample of peers

Ability. --- Acquisition. --- Activity. --- Analysis. --- Animal. --- Animals. --- Avoidance. --- Body weight. --- Body-weight. --- Brain. --- Cognitive-ability. --- Conditioning. --- Demand. --- Discrimination. --- Enhancement. --- Exploration. --- Expression. --- Fear. --- Genetics. --- Human. --- Individual difference. --- Individual differences. --- Individual-differences. --- Intelligence,general intelligence,fluid intelligence,associative learning,memory,spatial learning,emotional learning,learning systems,genetic variation,behavioral phenotypes. --- Intelligence. --- Laboratory mice. --- Laboratory. --- Learning ability. --- Learning-ability. --- Learning. --- Level. --- Memory. --- Methodology. --- Mice. --- Navigation. --- Performance. --- Rank. --- Rat. --- Research. --- Sensory. --- Spatial. --- System. --- Task. --- Tasks. --- Test. --- Tests. --- Variability. --- Weight.

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The present study investigated the effects of post-weaning social isolation (SI) on behavioural and neuroendocrine reactivity to stress of male and female rats. Innate aspects of fear and anxiety were assessed in the open field and elevated plus maze tests. Spontaneous startle reflex and conditioned fear response were further investigated. The neuroendocrine response of isolates was examined by measuring basal and stress release of ACTH and corticosterone and by evaluating the mRNA expression of mineralocorticoid (MR) and glucocorticoid (GR) receptors using in situ hybridization. Locomotor activity in the open field was not modified by chronic SI. In males, but not females, SI produced an anxiogenic profile in the elevated plus maze. Male isolates showed a trend towards increased startle reflex amplitude relative to socially-reared controls. Moreover, SI in males produced alterations of the HPA axis functioning as reflected by higher basal levels of ACTH, and enhanced release of ACTH and corticosterone following stress. In contrast, startle response or HPA axis functioning were not altered in female isolates. Social isolates from both genders showed reduced contextual fear-conditioning. Finally, the mRNA expression of MR and GR was not modified by SI. The results of the present study suggest that chronic SI increases emotional reactivity to stress and produces a hyperfunction of the HPA axis in adult rats, particularly in males. (C) 2003 Elsevier B.V. All rights reserved

Acoustic startle response. --- Acth. --- Activity. --- Adult rats. --- Adult-rat. --- Adult-rats. --- Adult. --- Anxiety. --- Conditioned fear. --- Control. --- Corticosterone. --- Differentially reared rats. --- Elevated plus maze. --- Elevated plus-maze. --- Emotional reactivity. --- Expression. --- Fear. --- Female rats. --- Female. --- Females. --- Field. --- Gender. --- Glucocorticoid receptors. --- Glucocorticoid. --- Hpa axis. --- Hybridization. --- Increase. --- Increases. --- Innate. --- Isolation. --- Latent inhibition. --- Level. --- Locomotor activity. --- Locomotor-activity. --- Male lewis. --- Male. --- Males. --- Maternal separation. --- Mineralocorticoid receptors. --- Neuroendocrine. --- Open field. --- Open-field. --- Post weaning. --- Prepulse inhibition. --- Rat. --- Rats. --- Reactivity. --- Receptor. --- Receptors. --- Reflex. --- Release. --- Response. --- Social isolation. --- Social-isolation. --- Social. --- Sprague-dawley. --- Startle. --- Strain differences. --- Stress. --- Switzerland. --- Test. --- Tests. --- Time.