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Results for “Exploratory Behavior”

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PubMed1999

Calibrating space: exploration is important for allothetic and idiothetic navigation.

Allothetic and idiothetic navigation strategies rely on very different cues and computational procedures. Allothetic navigation uses the relationships between external cues (visual, auditory, and olfactory) and mapping or geometrical calculations to locate places. Idiothetic navigation relies on cues generated by self-movement (proprioceptive cues or cues from optic, auditory, and olfactory flow, or efference copy of motor commands) and path integration to locate a present location and/or a starting point. Whereas it is theorized that exploratory behavior is used by animals to create a central representation of allothetic cues, it is unclear whether exploration plays a role in idiothetic navigation. Computational models suggest that either a reference frame, calibrated by exploration, or vector addition, without reference to exploration, could support path integration. The present study evaluated the contribution of exploration in these navigation strategies by comparing its contribution to the solution of both allothetic and idiothetic navigation problems. In two experiments, rats were trained to forage on an open table for large food pellets, which they then carried to a refuge to eat. Once trained, they were given probe trials from novel locations in either normal light, which permits the use of allothetic cues, or in infrared light, which requires the use of idiothetic cues. When faced with a new problem in either lighting condition, the rats first explored the foraging table before navigating directly home with the food. That exploration is equally important for allothetic and idiothetic navigation, suggests that both navigation strategies require a calibrated representation of the environment.

Animals↗

PubMed1983

Functional supersensitivity to adrenergic agonists in the rat after DSP-4, a selective noradrenergic neurotoxin.

Rats treated with DSP-4 [N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine], a selective noradrenergic neurotoxin, showed no differences compared to control rats in the number of head dips, a measure of exploratory behavior. Since a previous neurochemical investigation had demonstrated that DSP-4 rats have supersensitive alpha 2- and beta-adrenergic receptors in certain regions of the central nervous system, the behavior of these animals was also examined after the injection of clonidine, an alpha 2 agonist, and clenbuterol, a beta agonist. These drugs reduced, in a dose-dependent manner, the head-dipping of both control and DSP-4 rats. However, this effect was of greater magnitude in DSP-4 animals. Control experiments suggested that the response to clonidine and clenbuterol was mediated centrally by alpha 2 and beta receptors, respectively. Other behavioral experiments with agonists of the dopaminergic and serotoninergic systems indicated that these neurotransmitter systems were unchanged in DSP-4 animals. The results are discussed in terms of the selective action of DSP-4 and the responsiveness of DSP-4 rats to adrenergic agonists. The DSP-4-treated rat may constitute a new model of functional supersensitivity to adrenergic agonists.

Amines↗

PubMed2003

Mechanical characteristics of rat vibrissae: resonant frequencies and damping in isolated whiskers and in the awake behaving animal.

We investigated the natural resonance properties and damping characteristics of rat macrovibrissae (whiskers). Isolated whiskers rigidly fixed at the base showed first-mode resonance peaks between 27 and 260 Hz, principally depending on whisker length. These experimentally measured resonant frequencies were matched using a theoretical model of the whisker as a conical cantilever beam, with Young's modulus as the only free parameter. The best estimate for Young's modulus was approximately 3-4 GPa. Results of both vibration and impulse experiments showed that the whiskers are strongly damped, with damping ratios between 0.11 and 0.17. In the behaving animal, whiskers that deflected past an object were observed to resonate but were damped significantly more than isolated whiskers. The time course of damping varied depending on the individual whisker and the phase of the whisking cycle, which suggests that the rat may modulate biomechanical parameters that affect damping. No resonances were observed for whiskers that did not contact the object or during free whisking in air. Finally, whiskers on the same side of the face were sometimes observed to move in opposite directions over the full duration of a whisk. We discuss the potential roles of resonance during natural exploratory behavior and specifically suggest that resonant oscillations may be important in the rat's tactile detection of object boundaries.

Animals↗

PubMed2005

Decreased anxiety levels related to aging.

The present experiment investigated the effects of aging on emotional behavior, without concomitant influences from any previous behavioral manipulation apart from weighing the rats. Anxiety-related behaviors were measured in the elevated plus-maze (EPM). Performance in the open field (OF) was also assessed to control for any effect of aging on exploratory behavior that could account for changes in emotional behavior. Fifty-two naïve male Wistar rats of 3 (3MO), 17 (17MO), or 24 (24MO) months, were submitted to two sessions (5 min each) of EPM, followed by two sessions (2 min each) of OF, on 4 consecutive days. The main emotional indices (open arm entries, ratio of open arm entries to total entries, time spent in open arms, ratio of time in open arms to time in four arms, open arm ends, and head dips) measured in the EPM indicated a lower level of anxiety in aged (24MO) than in young (3MO) rats, whereas middle-aged (17MO) rats showed intermediate values between those of 3MO and 24MO rats; 3MO rats showed higher general motor activity (number of rearings in closed arms of EPM and in OF, and higher number of areas crossed in OF) than 17MO and 24MO rats. We conclude that aging is associated with a decrease in anxiety and in general motor activity.

Aging↗

PubMed2002

The development of behavioral abnormalities in the motor neuron degeneration (mnd) mouse.

The motor neuron degeneration (mnd) mouse, which has widespread abnormal accumulating lipoprotein and neuronal degeneration, has a mutation in CLN8, the gene for human progressive epilepsy with mental retardation (EPMR). EPMR is one of the neuronal ceroid lipofuscinoses (NCLs), a group of neurological disorders characterized by autofluorescent lipopigment accumulation, blindness, seizures, motor deterioration, and dementia. The human phenotype of EPMR suggests that, in addition to the motor symptoms previously categorized, various types of progressive behavioral abnormalities would be expected in mnd mice. We have therefore examined exploratory behavior, fear conditioning, and aggression in 2-3 month and 4-5 month old male mnd mice and age-matched C57BL/6 (B6) controls. The mnd mice displayed increased activity with decreased habituation in the activity monitor, poor contextual and cued memory, and heightened aggression relative to B6 controls. These behavioral deficits were most prominent at 4-5 months of age, which is prior to the onset of gross motor symptoms at 6 months. Our results provide a link from the mutation via pathology to a quantifiable multidimensional behavioral phenotype of this naturally occurring mouse model of NCL.

Aggression↗

PubMed2002

Validation of a behavioral recording automated system in the elevated plus-maze test.

The elevated plus-maze test has been widely used for screening of anxiolytic drugs and for exploring neurobiological bases of anxiety. In this study, we validated a new automated system that enables to record exploratory behavior in the elevated plus-maze test. This system, called cyberplus, consisted of ten pairs of photoelectric cells strategically located in several parts of the apparatus, and seemed to be sensitive to the position of the animal's forepaws, so it would yield scores in anxiety measurements and locomotor activity similar to those obtained by following the traditional procedure, that is, by analyzing videotapes by experienced observers. In order to assess this hypothesis, we exposed rats to the elevated plus-maze test and compared the scores obtained by cyberplus with the values recorded by two independent observers, conducting a correlational study with both kinds of recording procedures. The results obtained suggest the utility of cyberplus as a behavioral recording automated system in the elevated plus-maze test, making data collection and data analysis easier in exploring pharmacological and neurobiological bases of anxiety.

Animals↗

PubMed1997

Oil enriched diets and behavioral parameters in rats' recovery from early undernutrition.

The effect of oil enriched diets on sexual and exploratory behavior has been studied in male rats undernourished in utero and during lactation. At 20 days of age, for a period of 4 months, these animals were fed with 3 different diets: standard diet, standard diet enriched with 7% soybean oil, and standard diet enriched with 7% olive oil. A control group eating standard diet was also studied. Sexual behavior, open-field and nocturnal spontaneous locomotor activity were studied at 16-20 weeks of age. Undernutrition produced decreased body weight, and the experimental diets were not effective in growth recovery. Undernourished animals eating oil-enriched diets displayed lower nocturnal spontaneous locomotor activity, less time spent in central squares, and a lower number of rearing episodes than undernourished animals eating the standard diet; the number of peripheral squares entered was, however, significantly increased. Experimental groups eating oil diets showed a statistically significant increase in the number of ejaculating males and in the total number of ejaculations compared with experimental rats eating standard diet. These findings suggest that early undernutrition produces permanent behavioral alterations in male rats, but that the sexual behavior deficit could be reversed by feeding our oil-enriched diets from weaning. The diet enriched with soybean oil seems more effective in the rehabilitation of sexual behavior.

Animals↗

PubMedDate not supplied

[The action of ACTH 4-10 on the behavior of mice from different inbred strains].

We found that the administration of ACTH4-10 fragment to newborn mice of several strains (DBA/2, CBA, C57BL/6J, CBARb, and BLRb) for 5 days from the second day of life led to changes of several behavioral characteristics of adult animals. The effect of peptide administration on exploratory behavior of mice and on following the direction of stimulus movement are opposite to those induced by pain stimulation, i.e., administration of a solvent. The results are interpreted as a possible antistress effect of the peptide, which is realized during the period of neurodifferentiation. These data are discussed in terms of a possible effect of the used peptide on differentiation of the nervous system.

Adaptation, Physiological↗

PubMed2002

Anxiolytic-like effects of substance P fragment (SP(1-7)) in non-human primates (Callithrix penicillata).

The behavioral effects of the amino (N)-terminal fragment of substance P (SP(1-7)) on the marmoset (Callithrix penicillata) predator confrontation test of fear/anxiety were investigated. The test apparatus consisted of a figure-eight maze with three parallel arms interconnected at each extremity to a perpendicular arm. A taxidermized oncilla cat (Felis tigrina) was placed outside the maze facing one of its corners. Subjects were submitted to seven 30 min maze habituation trials (HTs), in the absence of the 'predator', and then to six 30 min treatment trials (TTs), in the presence of the 'predator', consisting of four doses of SP(1-7) (5, 50, 250 and 500 microg/kg; IP), saline and sham injection. SP(1-7) treatment reversed, in a dose-dependent way, the fear-induced avoidance behavior due to the predator's presence and increased the frequency of exploratory behaviors. Locomotor activity decreased during successive HTs, yet increased after all SP(1-7) treatments. These results indicate that systemic administration of SP(1-7) produces anxiolytic-like effects in marmosets tested in the predator confrontation model of fear/anxiety.

Animals↗

PubMed1975

The effect of vasectomy and oviduct section on mouse behavior (38554).

The spontaneous movement of vasectomized adult Swiss Webster male mice was 60% less than sham-operated controls 45 days after the operation. A similar trend was recorded for tubectomized frmales. Exploratory behavior as measured by the open field test was not significantly influenced by either surgical proceedure.

Animals↗

PubMed2000

Phenotypic characterization of an alpha 4 neuronal nicotinic acetylcholine receptor subunit knock-out mouse.

Neuronal nicotinic acetylcholine receptors (nAChR) are present in high abundance in the nervous system (Decker et al., 1995). There are a large number of subunits expressed in the brain that combine to form multimeric functional receptors. We have generated an alpha(4) nAChR subunit knock-out line and focus on defining the behavioral role of this receptor subunit. Homozygous mutant mice (Mt) are normal in size, fertility, and home-cage behavior. Spontaneous unconditioned motor behavior revealed an ethogram characterized by significant increases in several topographies of exploratory behavior in Mt relative to wild-type mice (Wt) over the course of habituation to a novel environment. Furthermore, the behavior of Mt in the elevated plus-maze assay was consistent with increased basal levels of anxiety. In response to nicotine, Wt exhibited early reductions in a number of behavioral topographies, under both unhabituated and habituated conditions; conversely, heightened levels of behavioral topographies in Mt were reduced by nicotine in the late phase of the unhabituated condition. Ligand autoradiography confirmed the lack of high-affinity binding to radiolabeled nicotine, cytisine, and epibatidine in the thalamus, cortex, and caudate putamen, although binding to a number of discrete nuclei remained. The study confirms the pivotal role played by the alpha(4) nAChR subunit in the modulation of a number of constituents of the normal mouse ethogram and in anxiety as assessed using the plus-maze. Furthermore, the response of Mt to nicotine administration suggests that persistent nicotine binding sites in the habenulo-interpeduncular system are sufficient to modulate motor activity in actively exploring mice.

Aggression↗

PubMed1997

Antagonism of non-NMDA receptors in the dorsal periaqueductal grey induces anxiolytic effect in the elevated plus maze.

Microinjections of glutamate into the dorsal periaqueductal grey (DPAG) of rats induce flight behavior, and blockade of glutamate NMDA receptors in the same region increases exploratory behavior of rats tested on the elevated plus maze. To investigate a possible role of other glutamate receptors in the DPAG on anxiety modulation, rats (n = 6-10) received microinjections into this structure of CNQX (1 and 3 nmol/0.5 microl), an AMPA/kainate antagonist, or GDEE (80 or 160 nmol/0.5 microl), a non-selective glutamate antagonist, and were tested on the elevated plus-maze, an ethologically based animal model of anxiety. Both drugs increased the percentage of entries into open arms, as compared to rats receiving vehicle, without changing the number of enclosed arm entries. Injections of the active compounds outside the DPAG were not effective. The anxiolytic effect of CNQX (3 nmol/0.5 microl) was not reversed by glycine (10 nmol/0.5 microl), injected into the DPAG 5 min after CNQX administration. These results suggest that, in addition to NMDA receptors, non-NMDA glutamate receptors may also modulate anxiety in the DPAG.

6-Cyano-7-nitroquinoxaline-2,3-dione↗

PubMedDate not supplied

Age-dependent cognitive and behavioral deficits after kainic acid seizures.

The long-term behavioral and cognitive effects of seizures at different ages were studied using the kainic acid (KA) seizure model. Rats of postnatal (P) ages (in days) 5, 10, 20, 30, and 60 were administered KA intraperitoneally (i.p.), which induced status epilepticus for several hours, or an equivalent volume of saline. Occurrence of spontaneous recurrent seizures (SRS) was then monitored for 3 months by a closed-circuit videotaping system. Rats began behavioral testing on P80; a separate group of rats that received KA on P60 began testing on P120. Behavioral tests included the Morris water maze (visuospatial learning and memory), the open field test (response to a novel environment), and the handling test (emotionality). When tested on P80, KA-treated P5 and P10 rats had no demonstrable deficits on any test as compared with controls. KA-Treated P20 rats differed from controls only on the water maze spatial bias test. KA-Treated P30 rats had deficits in spatial bias, were more active in the open field, and were more aggressive when handled. KA-Treated P60 rats, whether tested on P80 or P120, had deficits in learning platform position and spatial bias in the water maze, were more active in the open field, and were more aggressive when handled. P60 rats with SRS performed poorer in water maze place learning and spatial bias testing, although the number of SRS did not correlate with overall task acquisition. Our findings suggest age-related behavioral and cognitive deficits after KA-induced seizures. Pubescents and adults had alterations in learning, memory, exploratory behavior, and response to handling, whereas younger animals had no obvious behavioral or cognitive deficits.

Age Factors↗

PubMed1977

Effects of withdrawal from chronic amphetamine intoxication on exploratory and stereotyped behaviors in the rat.

Rats were administered 3, 6, and 12 mg/kg of d-amphetamine s.c. twice daily on a weekly increasing staircase schedule. On days 1, 7, 14, and 28 after the last injection of amphetamine the animals were challenged with 1 and 3 mg/kg of d-amphetamine and their behavior was observed. The 7-, 14-, and 28-day withdrawn animals required less amphetamine than controls to induce stereotyped behaviors. However, it was found that withdrawn animals and control animals were equally sensitive to the effects of apomorphine. Reserpine pretreatment eliminated the differences between control and withdrawn animals. alpha-Methyl tyrosine pretreatment blocked the effects of 1 but not 3 mg/kg of d-amphetamine in the withdrawn animals. Possible chemical mechanisms underlying the change in amphetamine sensitivity in the withdrawn animals are discussed.

Animals↗

PubMed1992

Role of the cerebellum in spatial orientation in the rat.

Adult DA/HAN strain rats were submitted to a spatial orientation task consisting of finding a reward in an open field. They were first submitted to an initial learning session and 10 days later to a retrieval test. The animals were divided into four groups of five rats each: animals that were cerebellectomized before the initial learning session or after the initial learning session, sham-operated rats, and control (intact) animals. Different parameters that characterize the spatiotemporal organization of the rat's exploratory behavior were quantified. From the results, it can be concluded that the cerebellum is not absolutely necessary in the processes that sustain spatial learning but that it is involved in the mechanisms sustaining focused spatial memory and in the cognitive processes of the motor program elaboration and not only in the regulation of the movement being done.

Animals↗

PubMed1993

Two types of motivation revealed by ibotenic acid nucleus accumbens lesions: dissociation of food carrying and hoarding and the role of primary and incentive motivation.

Rats with dopamine-depleting lesions of the nucleus accumbens (NAcc) no longer carry food and leave it in a refuge (carry-to-leave or hoard). The present study replicates this finding and extends it to rats with ibotenic acid lesions. The same rats, however, were found to carry food to a refuge to eat it (carry-to-eat). Thus, within a test session, control rats would first carry food to eat it, and when sated, carry the remaining food to leave it in the refuge. NAcc food-deprived rats carried food to eat it but when sated engaged mainly in exploratory behavior. When carrying-to-eat, NAcc rats modulated responses normally to food size and eating time, their movement speed and motor patterns were normal, and their eating times were normal. Nevertheless, they were slower to return for food after eating, and they did not show normal slowing of eating times with successively presented food pellets. The failure of NAcc rats to carry-to-leave when sated was not related to general inactivity. In activity tests, they were as active in the light, more active in the dark, and did not differ from control rats under amphetamine (1.25 and 2.5 mg/kg). Their impairments were also not related to damage to other forebrain related structures, as they displayed normal neocortical and hippocampal atropine-sensitive and atropine-resistant electroencephalograms (EEG). The finding that NAcc rats carry-to-eat when hungry but do not carry-to-leave when sated suggests two separate conclusions. First, food carrying can be dissociated into two separate actions with respect to neural control, carrying-to-eat and carrying-to-leave. Second, the selective involvement of the NAcc in only carrying-to-leave suggests that it is associated with recruiting actions in response to the secondary incentive features of food but is not required for behaviors associated with food consumption. Other structures are presumably activated by the primary drive-reducing features of food. The results are discussed in relation to two-factor theories of motivation.

Animals↗

PubMed2006

Long-term memory for aversive training is impaired in Idua(-/-) mice, a genetic model of mucopolysaccharidosis type I.

Mucopolysaccharidosis type I (MPS I) is a lysosomal storage disease that leads to neurodegeneration and neurological deficits, among other pathological and clinical consequences. The aim of the present study was to evaluate neurobehavioral parameters in a genetic mouse model of mucopolysaccharidosis type I (MPS I). During exploration of an open field, adult MPS I (Idua(-/-)) mice showed normal locomotion and anxiety but reduced number of rearings. Idua(-/-) mice performed normally in a novel object recognition memory task and showed normal short-term retention of inhibitory avoidance training. By contrast, long-term retention of inhibitory avoidance was impaired in Idua(-/-) mice. The deficit in inhibitory avoidance memory could not be attributed to reduced footshock reactivity. The results indicate that Idua(-/-) mice present deficits in long-term memory for aversive training and reduced exploratory behavior.

Animals↗

PubMed2004

A genetic analysis of avian personality traits: correlated, response to artificial selection.

Individuals in a range of species consistently differ in their behavior towards mild challenges, over age and time. Differences have been found for several personality traits in a range of species. In great tits these traits have a genetic basis and are phenotypically correlated. Estimates of genetic correlations are, however, fundamental to understanding the evolution of consistent individual differences in behavior. This study analyzed two selection experiments on two avian personality traits, early exploratory behavior and risk-taking behavior. The selection lines used were both started using wild great tits (Parus major) from two natural populations. Genetic correlations were calculated using the response and the correlated response to artificial selection. We found genetic correlations ranging from 0.51 to 0.66, based on individual values, and from 0.84 to 1.00 based on nest means. Genetic correlations can be due to pleiotropic effects or to linkage disequilibrium. The different behavioral traits might therefore have a common genetic basis, possibly constraining independent evolution of personality traits in natural populations. These results are discussed in relation to domain generality and domain specificity of personalities.

Animals↗