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At least 487 records · Page 27Linked to original sources
PubMed1999

Modifications of the behavioral profile of non-competitive NMDA receptor antagonists, memantine, amantadine and (+)MK-801 after chronic administration.

Non-competitive N-methyl-D-aspartate (NMDA) receptor antagonists show antiparkinsonian-like activity in animal models, and possess neuroprotective properties. However they also induce a number of behavioral side effects in rodents at higher doses; these include learning impairment, hyperlocomotion, and ataxia. The present study focused on the possible development of tolerance, or sensitization, to any of these effects after sustained administration, either by repeated injection or continuous infusion. When memantine or (+)MK-801 (20 and 0.31 mg/kg/day respectively) were either infused or repeatedly injected for 14 days, tolerance was observed to their learning impairing effect at high doses, in a passive avoidance test. Tolerance to their ataxic effect developed after repeated administration ((+)MK-801 and memantine), or after infusion (memantine). Sensitization to the locomotor stimulation was seen following repetitive injections of memantine for 14 days, but not seen with (+)MK-801. In animals with an unilateral 6-OHDA lesion of the nigrostriatal system, acute administration of memantine caused ipsilateral rotations, which were augmented following 14 days of infusion. The potency of amantadine to antagonize neuroleptic-induced catalepsy was unchanged following either infusion or repeated injections. The various acute effects of non-competitive NMDA receptor antagonists were modified differently by sustained treatment (i.e. tolerance to learning impairment and ataxia; sensitization to memantine's locomotor stimulation). The anti-cataleptic activity of amantadine remained unaltered. However, differences between drugs and the two treatment regimens (i.e. repetitive versus continuous treatments) were apparent.

Amantadine↗
PubMed1998

Prenatal cocaine alters social competition of infant, adolescent, and adult rats.

This series of experiments examined whether gestational cocaine exposure alters later social behavior exhibited during competition for biologically relevant stimuli. Rat offspring were derived from dams that received subcutaneous injections of 40 mg/kg/3cc cocaine HCl daily on gestational Days 8-20, pair-fed dams injected with saline, or nontreated control dams. Offspring competed with peers for access to a nipple in infancy, and to water in adolescence or adulthood. Prenatal cocaine exposure resulted in a decreased ability of cocaine-exposed infant rats to compete successfully for a nipple. Although adolescent and adult cocaine-exposed rats were no less successful than controls when competing for water, they exhibited a notable increase in aggression toward competitors during testing. Data provide evidence of alterations in social behavior and social competition as a result of prenatal cocaine exposure.

Aggression↗
PubMed1983

Physical symptom reporting and health perception among type A and B college males.

This investigation studied the relationship of Type A behavior to physical symptom reporting and self-appraised health status. The student version of the Jenkins Activity Survey was administered to thirty male college seniors during a high-stress period of the semester. Results showed that Type A's reported relatively fewer physical symptoms and perceived themselves as being more healthy than Type B's. Type A individuals also rated themselves as healthier than their peers, whereas Type B individuals rated themselves as being less healthy than their peers. In addition, symptom reporting and health perception were negatively correlated in the Type B subsample; however, this relationship was not evident in the Type A subsample. In the discussion, it was suggested that the attentional style of Type A's may contribute to lower levels of symptom reporting and faulty appraisals of health status. The notion of an attributional bias whereby Type A's define internal somatovisceral states differently than Type B's was also discussed. Finally, the results were discussed in terms of their implications for understanding the mechanisms through which Type A behaviors might translate into increased coronary heart disease (CHD) risk.

Adult↗
PubMed2005

Structure of and competitive adsorption in alkyl dicarbamate two-dimensional crystals.

The potential for relatively minor structural changes to dramatically impact materials properties is one of the primary obstacles to achieving the rational design of functional materials. For example, having an odd versus an even number of carbons between functional groups in polymers can cause large variation in melting point and mechanical properties. This odd-even effect is especially pronounced in hydrogen-bonded polymers and oligomers. To shed light on the structural basis of this phenomenon, physisorbed monolayers and single crystals of alkyl dicarbamates were investigated by scanning tunneling microscopy and X-ray diffraction, respectively. The related two- and three-dimensional crystal structures both demonstrated a clear odd-even effect in packing geometry. The differing accommodation of intermolecular interactions between odd and even packing motifs was directly related to the melting point trends and further dissected through computation. In addition, these oligomers displayed unusual competitive adsorption behavior; the relative preference for adsorption of a smaller species from a binary solution was increased compared to alkanes. These results were explained in the context of hydrogen bond density effects that arise due to competition for a limited substrate surface area. This study provides a model for understanding oligourethane surface coatings and demonstrates the importance of molecular structure and hydrogen bonding in determining adsorption behavior.

Journal Article↗
PubMed1970

Reinforcement of competing behavior during extinction.

Conditioned behavior declines in frequency when reinforcement is discontinued. In two experiments this extinction process was facilitated when competing behavior was reinforced as the original response was extinguished. When reinforcement for competing behavior was withdrawn, however, rats resumed their original behavior and there were no overall savings in total responses to extinction.

Animals↗
PubMed1991

Anticonvulsant and behavioral effects of two novel competitive N-methyl-D-aspartic acid receptor antagonists, CGP 37849 and CGP 39551, in the kindling model of epilepsy. Comparison with MK-801 and carbamazepine.

The orally active competitive N-methyl-D-aspartate (NMDA) receptor antagonists CGP 37849 (DL-[E]-2-amino-4-methyl-5-phosphono-3-pentenoic acid) and its ethyl ester CGP 39551 were evaluated in amygdala-kindled rats, a model for complex partial and secondarily generalized seizures. Anticonvulsant and behavioral effects of these novel compounds were compared with those of the noncompetitive NMDA receptor antagonist MK-801 [(+)-5-methyl-10,11-dihydroxy-5H-dibenzo(a,d)cyclohepten-5,10-imin e] and the antiepileptic drug carbamazepine, one of the major drugs for treatment of partial and generalized seizures in humans. For comparative evaluation, the compounds were injected i.p. at the following doses: 1 to 10 mg/kg (CGP 37849 or CGP 39551), 0.05 to 0.3 mg/kg (MK-801) and 20 to 40 mg/kg (carbamazepine), respectively. In contrast to carbamazepine, CGP 37849, CGP 39551 and MK-801 exerted only weak anticonvulsant effects in fully kindled rats and did not increase the focal seizure threshold. The weak anticonvulsant effects of the NMDA receptor antagonists in kindled rats were associated with profound untoward behavioral effects. The behavioral syndrome induced by the NMDA receptor antagonists in kindled rats was characterized by marked ataxia, hyperactivity and, in case of CGP 37849 and MK-801, stereotypies, such as head weaving. The low or absent effectiveness of the novel NMDA receptor antagonists against kindled seizures suggests that these compounds will not be clinically useful antiepileptics against partial and secondarily generalized seizures. Furthermore, in view of the recent clinical findings on psychotomimetic effects of MK-801 in epileptic patients, the similarities in the excitatory effects produced by CGP 39551, CGP 37849 and MK-801 in kindled rats may indicate that competitive NMDA receptor antagonists may also produce psychotomimetic effects in humans.

2-Amino-5-phosphonovalerate↗
PubMed2005

Effects of contrarians in the minority game.

We study the effects of the presence of contrarians in an agent-based model of competing populations. Contrarians are common in societies. These contrarians are agents who deliberately prefer to hold an opinion that is contrary to the prevailing idea of the commons or normal agents. Contrarians are introduced within the context of the minority game (MG), which is a binary model for an evolving and adaptive population of agents competing for a limited resource. The average success rate among the agents is found to have a nonmonotonic dependence on the fraction a(c) of contrarians. For small a(c), the contrarians systematically outperform the normal agents by avoiding the crowd effect and enhance the overall success rate. For high a(c), the anti-persistent nature of the MG is disturbed and the few normal agents outperform the contrarians. Qualitative discussion and analytic results for the small a(c) and high a(c) regimes are presented, and the crossover behavior between the two regimes is discussed.

Algorithms↗
PubMed1986

Competing species model with behavioral adaptation.

This paper studies the properties of a modified Lotka-Volterra model for two competing species, in which the coefficients of the interaction terms are time-dependent averages of the level of interaction over the entire past. For this model, it is shown that competitive exclusion does not occur, there are two possible stable equilibrium points, and in a certain region of parameter space numerical simulations suggest the existence of interesting oscillatory solutions.

Adaptation, Psychological↗
PubMed1985

Age and sex differences in the cooperative and noncooperative behavior of pairs of American children.

Game playing behavior of same and mixed sex pairs of 5-, 8-, and 11-year-old American children was compared, using a game in which cooperative behavior maximized reward. Pairs of 8- and 11-year-old children were relatively more cooperative and attained significantly more Joint Reward Goals than 5-year-old pairs. Older pairs were not maximally cooperative, however, in terms of all the dependent measures; in adjusting for initial differences on practice trials, 5-year-olds and 8-year-olds took less time than the 11-year-olds, and 11-year-old pairs of boys took significantly more time than all other pairs. In addition, cooperative behavior increased across trials, especially for the 11-year-old children.

Child↗
PubMed1994

Methyl farnesoate levels in male spider crabs exhibiting active reproductive behavior.

The concentration of methyl farnesoate (MF) in the hemolymph and its synthesis by the mandibular organs (MOs) were investigated to determine whether this compound is related to the differences in the size of the reproductive system and the mating behavior among male morphotypes of the spider crab, Libinia emarginata. Large-claw abraded males displayed mating behavior under competitive conditions. They have the largest reproductive systems, their MOs synthesize large amounts of MF in vitro, and the concentration of MF in their hemolymph is high. Small-claw abraded males displayed mating behavior with receptive females only when isolated. These smaller crabs have intermediate-sized reproductive systems, their MOs synthesize the most MF, and they have the highest circulating level of MF relative to their body size. The unabraded males did not display mating behavior; their reproductive systems are smaller; their MO activity is low, as is their circulating level of MF. The strong relationship between MF levels and the intensity of reproductive behavior suggests that MF may be one of the driving forces behind mating behavior in Crustacea.

Animals↗
PubMed2005

Mosquito behavior and vector control.

Effective indoor residual spraying against malaria vectors depends on whether mosquitoes rest indoors (i.e., endophilic behavior). This varies among species and is affected by insecticidal irritancy. Exophilic behavior has evolved in certain populations exposed to prolonged spraying programs. Optimum effectiveness of insecticide-treated nets presumably depends on vectors biting at hours when most people are in bed. Time of biting varies among different malaria vector species, but so far there is inconclusive evidence for these evolving so as to avoid bednets. Use of an untreated net diverts extra biting to someone in the same room who is without a net. Understanding choice of oviposition sites and dispersal behavior is important for the design of successful larval control programs including those using predatory mosquito larvae. Prospects for genetic control by sterile males or genes rendering mosquitoes harmless to humans will depend on competitive mating behavior. These methods are hampered by the immigration of monogamous, already-mated females.

Animals↗
PubMed1984

Brain serotonergic neurons: their role in a form of dominance-subordination behavior in rats.

The present study evaluated the possible role of brain serotonergic neurons in dominant-subordinate (D-S) behavior in Wistar male rats competing for water. Treatment of D rat with drugs that stimulate serotonergic neurons of receptors (tryptophan, 5-hydroxytryptophan, quipazine, femoxetine) resulted in D-S reversal. A similar effect was observed when the S animal was treated with drugs that blocked serotonin synthesis (p-chlorophenylalanine) or receptors (metergoline). The D-S relationship was unchanged when serotonergic drugs were given to the S subject (tryptophan or quipazine) or when D animal received p-chlorophenylalanine. None of the drugs tested influence the water intake and the general activity of rats. Rats with lesioned midbrain raphe nuclei were always dominant when paired with sham lesioned counterparts. Our results indicate that one form of dominance behavior can be inversely related to the activity of brain 5-HT system.

Animals↗
PubMed2005

Suicide in athletes: a review and commentary.

Not only are athletes at risk for psychiatric illness, but they are at risk of suicide. In an effort to learn more about suicide in athletes and those connected to the sports arena, a review of the medical literature from 1960 to 2000 was conducted through Medline, and a review of the periodical literature from 1980 to 2000 was conducted through Infotrac. These reviews revealed 71 cases of athletes who have either contemplated, attempted, or completed suicide. In this article, these cases are analyzed by sport, gender, and age. Through inference, an attempt to establish the etiologic basis for these behaviors is undertaken. Intervention and prevention strategies are discussed, based on the available data.

Adolescent↗