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At least 199 records · Page 11Linked to original sources
PubMed2004

Exploratory behavior, trap models, and glass transitions.

A random walk is performed on a disordered landscape composed of N sites randomly and uniformly distributed inside a d-dimensional hypercube. The walker hops from one site to another with probability proportional to exp[-betaE(D)], where beta=1/T is the inverse of a formal temperature and E(D) is an arbitrary cost function which depends on the hop distance D. Analytic results indicate that, if E(D)=D(d) and N--> infinity, there exists a glass transition at beta(d)=pi(d/2)/[(d/2)Gamma(d/2)]. Below T(d), the average trapping time diverges and the system falls into an out-of-equilibrium regime with aging phenomena. A Lévy flight scenario and applications of exploratory behavior are considered.

Journal Article↗
PubMed1989

Exploratory behavior, reaction to novelty, and proactive memory in rats with temporo-entorhinal connections disrupted.

The parahippocampal cortex is ascribed a key function in mediating reciprocal connections between neocortical association areas and the hippocampal formation. Within this complex the lateral entorhinal cortex (LEC) seems to stand out as an important interface exerting modulating influence upon cognition and memory by way of its connections with the hippocampal formation and temporal cortex (TC), respectively. The purpose of the present study was to compare effects of TC/LEC disruptions in a novelty test with results previously obtained in the same test following lateral perforant path (LPP) disruptions. Further, effects of TC/LEC lesions on proactive memory were examined, since a profound impairment in retroactive memory has previously been found. Rats bearing TC/LEC lesions or LPP lesions behaved differently in the novelty test. It was also shown that the impairment in proactive memory was less severe than the one seen in retroactive memory following TC/LEC lesions. The results are discussed in terms of a highly integrative role of LEC.

Animals↗
PubMed1998

Electrophysiological responses of nucleus accumbens neurons to novelty stimuli and exploratory behavior in the awake, unrestrained rat.

To establish a physiological correlate of goal-directed and reward-seeking non-operant behaviors, we studied the electrophysiological activity of NAcc neurons in unrestrained, naive Sprague-Dawley rats. Our results showed an inhibitory response in 21% (7/34) of the recorded NAcc neurons during spontaneous nosepoking behavior and in 16% (4/25) of the NAcc neurons when rats were fed with a favorite novel food morsel (popcorn). These data suggest that a subgroup of NAcc neurons is actively modulated during motivated behavior and during consummatory events resulting in a suppression of neuronal activity.

Animal Feed↗
PubMed1978

Exploratory behavior in rats following bilateral lesions of the anterodorsal caudate nuclei.

9 rats received bilateral lesions to the anterodorsal caudate nuclei and 9 rats underwent sham operation procedures. After recovery the subjects were observed in an apparatus allowing access to familiar or novel stimuli. The caudotomized rats spent a significantly greater proportion of time exploring the novel stimuli. The results were not consistent with the suggestions that following damage to the caudate nucleus animals were unresponsive to novelty, however, they did support earlier findings implicating the caudate nucleus in learning and memory processes.

Animals↗
PubMed1998

Influence of interleukin-1beta on exploratory behaviors, plasma ACTH, corticosterone, and central biogenic amines in mice.

Systemic administration of interleukin-1beta (IL-1beta) promoted behavioral changes in an open-field exploratory test. In particular, while the cytokine suppressed locomotor activities, these behaviors were not particularly sensitive to dosage differences. In contrast, dose-dependent biphasic variations that varied over time were evident with respect to the exploration of a novel container. Within this paradigm, the behavioral changes did not appear to be related to neophobia. In addition, despite the marked effects of IL-1beta on exploratory and locomotor behaviors, habituation/exploration in a free-running spontaneous alternation task was unaffected by the cytokine. In addition to the behavioral variations, IL-1beta dose-dependently increased plasma ACTH and corticosterone concentrations, and also induced several central monoamine alterations. In particular, IL-1beta increased the utilization of norepinephrine (NE) within the paraventricular nucleus, arcuate nucleus/median eminence, locus coeruleus, and prefrontal cortex, while the turnover of dopamine (DA) was evident in the arcuate nucleus/median eminence. It is suggested that although systemic IL-1beta treatment induces some stress-like effects, the profile of central neurochemical changes induced by the cytokine can be distinguished from psychological or processive types of stressors.

Adrenocorticotropic Hormone↗
PubMed1989

Exploratory behavior and the dual activity of some psychoactive drugs. Part 5. Alcohol.

Alcohol is reported to impair acquisition and learning processes and it is considered a depressant of the brain activities impairing rapidity and consistency of some behaviors. The experiments reported here are concerned with the exploratory performances of the already described subpopulations of Albino mice under the effect of alcohols of different types.

Alcoholic Beverages↗
PubMedDate not supplied

Long-term effects of developmental exposure to zidovudine on exploratory behavior and novelty discrimination in CD-1 mice.

Long-term changes in exploratory, social and agonistic behavior have been reported in rodents following developmental exposure to zidovudine (AZT), an agent commonly administered to pregnant seropositive women and their neonates to prevent HIV-1 transmission. The present study evaluates the effects of either prenatal or prolonged AZT treatment on spatial and nonspatial novelty discrimination in mice, using an open-field test with four objects, in which responses to both spatial rearrangement of familiar objects and object novelty are assessed. AZT (160 mg/kg) or Saline was given orally twice daily to pregnant mice from gestational days (GD) 10 to 19 (Experiment 1) or from GD 10 to lactation day 10 (Experiment 2). Offspring of both sexes were tested on postnatal day (PND) 28, 45 or 70. Depending on treatment schedule, AZT altered different behavioral responses, males being more affected than females. The prenatal treatment (Experiment 1) reduced exploration of the objects at all ages considered and increased wall and top rearing at ages 45 and 70. Following prolonged treatment (Experiment 2), AZT offspring were markedly more active than controls and displayed more wall rearing at age 70 while showing lower grooming frequency at all ages. Both AZT and control mice failed to respond to object rearrangement at adulthood, a discrepancy from previous data, which is discussed in relation to perinatal stress effects.

Age Factors↗
PubMed1996

Perinatal cocaine reduces responsiveness to cocaine and causes alterations in exploratory behavior and visual discrimination in young-adult rats.

Lister hooded female rats were exposed to either saline or cocaine (20 mg/kg s.c.) from gestational day 10 every other day until weaning (postnatal day 25). The effects of maternal cocaine exposure on novelty-induced exploration and on spontaneous and cocaine-induced motor activity were evaluated in young-adult male offspring (4 weeks after weaning). Rats exposed to cocaine during development spent less time exploring two novel objects. Lack of habituation upon the second presentation of the objects and failure in the ability to discriminate between the novel and familiar object were also found in cocaine exposed offspring. Moreover, maternal cocaine treatment did not affect spontaneous motor activity (active time, average speed and rearing) in rats subjected to an open field test. Furthermore, perinatal exposure to cocaine significantly attenuated acute cocaine (15 mg/kg i.p.)-induced hyperactivity. These data indicate that developmental exposure to cocaine, at dose levels below those producing gross malformations and/or overt signs of neurotoxicity, causes behavioral changes characterized by an altered responsiveness to environmental and pharmacological challenges.

Animals↗