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Results for “Exploratory Behavior”

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PubMed1998

Fetal ethanol effects on benzodiazepine sensitivity measured by behavior on the elevated plus-maze.

Rodents prenatally exposed to ethanol demonstrate altered behavioral and hormonal responses to stressful environments. Prenatal ethanol exposure may also have long-term effects on the offspring's GABAergic system. Using the elevated plus-maze, the present study examined the sensitivity of adult Sprague-Dawley rat offspring from prenatal ethanol (E), pair-fed (PF) and ad lib-fed control (C) conditions to the effects of benzodiazepine (BZD) on plus-maze behavior and corticosterone (CORT) responses. At 60-90 days of age, E, PF, and C males and females were injected subcutaneously with either BZD or saline. Twenty minutes later animals were placed in an open field (OF) for a 5-min test and then on the plus-maze for a 5 min test; behaviors were recorded during testing and blood samples collected at the end of testing for CORT determinations. Overall, sex differences were observed in both OF and plus-maze behaviors. Females showed more ambulation and rearing in the OF than males, and exhibited increased exploratory behaviors and decreased fear-related behaviors compared to males on the plus-maze. Following BZD treatment, both males and females exhibited increased time on open arms, increased open arm entries, and decreased time on closed arms compared to saline-treated males and females, regardless of prenatal treatment. These differences did not appear to be due to altered activity levels, as BZD treatment had no effect on total ambulation in the OF. Importantly, although no significant differences in plus-maze behaviors were found among saline-injected E, PF, and C males or females. BZD treatment differentially affected E males and females compared to their PF and C counterparts. Both E males and females treated with BZD spent increased time on open arms and decreased time on closed arms compared to their PF and C counterparts, suggesting decreased fear. Further, BZD-treated E males exhibited decreased open and closed arm entries, spent significantly more time in the central area, and had lower CORT levels, another index of fear or stress, compared to BZD-treated PF and C males. These data support and extend previous work demonstrating that the plus-maze provides a reliable measure of anxiety/fear, and that plus-maze behavior is sensitive to anxiolytic agents such as BZD. Furthermore, these data suggest that prenatal ethanol exposure may alter sensitivity to the effects of BZD on plus-maze behavior and CORT responsiveness, and may do so differentially in male and females offspring.

Animals↗

PubMed1984

Preliminary report of a new rodent separation model of depression.

Phodopus sungorus, the Siberian dwarf hamster, exhibits an unusual set of behavioral changes when the members of a male-female pair bond are separated. Quantification of these behaviors reveals a significant increase in body weight, decrease in social interactions, and decrease in exploratory behaviors, predominantly in separated males. Preliminary data on antidepressant treatments to reverse the separation syndrome, and on neurochemical changes during the separation period, are presented. Separation of pair-bonded Siberian dwarf hamsters may provide a new animal model for depression, incorporating the practical advantages of a rodent model with the conceptual advantages of a naturalistic life event precipitant.

Animals↗

PubMed1980

Sexual behaviors in retarded children and adolescents.

Literature reports on the sexual behaviors of mildly retarded adolescents are reviewed. Retarded adolescents often participate in masturbation and homosexual exploratory behavior. The retarded adolescent's heterosexual interests are of great concern to parents. The retarded adolescent is vulnerable to suggestibility, poor judgment and a failure to foresee the consequences of his actions. Parents are usually acutely distressed by the retarded youth's sexual behaviors, and they may develop an attitude that these behaviors are "bad." There is a need to provide appropriate sex education for retardates and to counsel their families about the management of sexual behaviors which occur during the adolescent years.

Adolescent↗

PubMed2000

Behavioral profile of wild mice in the elevated plus-maze test for anxiety.

Systematic observations of the defensive behavior of wild rodents have greatly informed the experimental study of anxiety and its neural substrates in laboratory animals. However, as the former work has been almost exclusively carried out in rats, few data are available concerning the reactivity of wild mice to standardized tests of anxiety-related behavior. In the present experiments, we employed ethological measures to examine the behavioral responses of a wild-derived population of house mice (Mus musculus) in the elevated plus-maze. In direct comparisons with laboratory Swiss mice, male wild mice exhibited substantially elevated levels of exploratory activities and an overall "preference" for the open arms of the plus-maze. On re-exposure to the plus-maze, male wild mice showed further increases in open arm exploration, while Swiss mice showed a marked shift to the enclosed parts of the plus-maze. Tested over a single session, female wild mice also exhibited a profile of high open arm exploration, but showed levels of exploratory behaviors and locomotor activity similar to female Swiss counterparts. While exploratory patterns in wild mice show similarities to profiles seen in certain laboratory strains (e.g., BALB/c), wild mice displayed a number of additional behaviors that are unprecedented in plus-maze studies with laboratory mice. These included actual and attempted jumps from the maze, spontaneous freezing, and exploration of the upper ledges of the closed arms. Thus, while in conventional terms the behavior of wild mice was consistent with one of low anxiety-like behavior, the presence of these unique elements instead indicates a profile more accurately characterized by high reactivity and escape motivation. We discuss how the use of an ethological approach to measuring plus-maze behavior can support accurate interpretation of other exceptional profiles in this test, such as those possibly arising from phenotyping of transgenic and gene knockout mice.

Animals↗

PubMed1993

Metabolic mapping of the pharmacological and toxicological effects of dopaminergic drugs in experimental animals.

Functional consequences of pharmacological and toxicological manipulations of the dopaminergic systems were evaluated by means of the 2-[14C]deoxyglucose (DG) method for measuring local rates of cerebral glucose utilization. Administration of dopamine agonist drugs modifies glucose metabolism in selected brain areas. Several factors, such as the compound used, the dose, length, and modality of the treatment, and the interval of time between the end of the treatment and the measurement of glucose utilization, contribute to define the topography and intensity of the changes. The differences refer to distinct activation of subtypes of dopamine receptors, to secondary involvement of other neurotransmitter receptor systems, and to modification of the receptor sensitivity occurring during the treatment. Other variables that interfere with the motivated behavior induced by psychostimulants may also affect the metabolic pattern. A few changes in glucose utilization are, however, common to most dopamine agonist drugs. High doses, which induce stereotypic behavior, produce metabolic changes in the extrapyramidal system. Low doses of psychostimulants, which elicit locomotion and exploratory behavior and produce reinforcement, increase glucose metabolism in the limbic system, particularly in the nucleus accumbens. Metabolic mapping in monkeys bearing 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced lesions of the dopaminergic areas in the brainstem contributed to define the key role of the striatopallidal pathway in the production and maintenance of the motor abnormalities that characterize parkinsonism. Metabolic patterns associated with unilateral 6-hydroxydopamine lesion of the nigrostriatal neurons in the rat are modified by dopamine agonist drugs. Specific changes are produced by selective D1 or D2 agonists. In rats bearing unilateral 6-hydroxydopamine lesion, the DG method also revealed functional effects produced by the interaction between D1 and N-methyl-D-aspartate receptors.

Animals↗

PubMed1981

[Age related alterations of motor behavior and release of dopaminergic supersensitivity in rats].

Rats aged greater than or equal to 18 months show, aside from clearly diminished motor parameters (exploratory behavior, resting activity, nocturnal activity profile, rotation behavior), after intracerebral dopamine injection a considerably lower apomorphine hypermotility than young animals. The characteristic alteration of activity occurring in young rats during and following chronic administration of haloperidol (1 mg/kg . day, s.c. for 21 days) as an expression of developing dopaminergic supersensitivity does not appear in older animals. Repeated application of amphetamine (2 X 2 mg/kg daily) caused a significant increase in hypermotility. The results are interpreted as the consequence of a age-related reduction of the activity of central-dopaminergic transmission systems and are discussed with regard to possible differences in the realization of agonist- or antagonist-induced supersensitivity.

Age Factors↗

PubMed1989

Phenylpropanolamine and amphetamine disrupt postprandial satiety in rats.

Two tests of the behavioral specificity of the anorectic effects of amphetamine (AM) and phenylpropanolamine (PPA) were done. Intraperitoneal injections of each drug reduced the size of condensed milk test meals in 30-min pellet-deprived rats. The dose-response relations in semi-log coordinates were linear and parallel, but AM (ED50, 2.0 +/- 0.1 mumol/kg) was about ten times more potent than PPA (ED50, 24.6 +/- 0.1 mumol/kg). Periprandial behaviors were observed using a time-sampling technique. Both AM and PPA disrupted the normal behavioral sequence of postprandial satiety throughout their anorectic ranges, but they did so differently. AM increased postprandial exploratory behavior, decreased or eliminated resting, and, at larger doses, elicited stereotypy. In contrast, PPA inhibited both grooming and exploration, and increased resting. The drugs' effects on water intake were tested in 17-hr water-deprived rats. AM's adipsic effect (ED50, 2.3 +/- 0.1 mumol/kg) was similar to its anorectic effect. PPA also inhibited drinking, although slightly less potently (ED50, 56.6 +/- 0.1 mumol/kg) than it did feeding. Thus, under conditions maximizing the anorectic potencies of systemically administered AM and PPA in rats, both drugs inhibited feeding nonspecifically rather than by eliciting normal postprandial satiety.

Amphetamine↗

PubMed2005

Age-dependent effects of gestational and lactational iron deficiency on anxiety behavior in rats.

Gestational iron deficiency (ID) has been linked to alterations in GABA neurotransmission, but whether these neuronal changes are mirrored in altered anxiety behavior in rats is not known. In this experiment, two tests of GABA-related affective behaviors in rats, ultrasonic vocalizations (USVs) and elevated plus maze (EPM) were used to investigate the consequences of maternal ID. Female rats were randomly assigned to one of three diet groups: low iron (10-20 ppm Fe), recommended (standard) iron control (60 ppm Fe) or lab chow (250 ppm Fe) control. Diets started 7 days prior to mating and continued until 10 days after birth (PN10). Maternal behavior and offspring growth and activity were also assessed. Blood samples taken on PN10 revealed a significant decrement in serum iron and an increase in total iron binding capacity in the low iron groups compared to the two control groups. Relative to the two control groups, the low iron group weighed less on PN1, and this weight difference persisted in adulthood. In neonates, the rate of USVs in the low iron group was significantly higher than the two control groups, and their general activity was significantly less than the controls. Maternal behavior was not significantly different across groups. By adulthood, anxiety behavior and motor activity in the low iron group were comparable to controls, although the iron deficient subjects habituated more slowly. This study shows that prenatal iron deficiency results in increased anxiety behavior in neonates that appears to be reversed with iron repletion but that some aspects of altered exploratory behavior and growth persist into adulthood.

Age Factors↗

PubMed2005

Waterborne lead exposure affects brain endocannabinoid content in male but not female fathead minnows (Pimephales promelas).

There are several similarities between the behavioral and neurochemical effects of lead (Pb2+) and the cannabinoids. Both Pb2+ exposure and cannabinoid treatment decrease exploratory behavior. Pb2+-induced hyperactivity has been observed in rats and fish. By comparison, cannabinoids increase locomotor activity at higher doses in rats. Moreover, Pb2+ exposure produces learning and memory impairments as do the cannabinoids. Many of the behavioral effects of Pb2+ are thought to be due, in part, to the ability of Pb2+ to either inhibit or mimic the actions of calcium (Ca2+). At low concentrations, Pb2+ enhances basal release of neurotransmitter from presynaptic terminals by increasing intracellular free Ca2+ concentrations. Pb2+ also decreases evoked neurotransmitter release due to blockade of voltage-gated Ca2+ channels. Interestingly, the endocannabinoids (eCBs) including N-arachidonylethanolamine (AEA) and 2-arachidonylglycerol (2-AG) are synthesized in response to increases in intracellular Ca2+ and activate the CB1 receptor that inhibits voltage-gated Ca2+ channels. We tested the hypothesis that waterborne Pb2+ exposure significantly affects whole-brain eCB content in adult male and female fathead minnows (Pimephales promelas). Waterborne Pb2+ exposure (1.0 ppm) resulted in a time-dependent accumulation of Pb2+ in bone in both males and females. Brain AEA and 2-AG content were significantly greater in females compared to males. Pb2+ exposure increased brain AEA content in males at 7 and 14 days of exposure and increased brain 2-AG content at 14 days. Pb2+ exposure had no effect on either brain AEA or 2-AG content in females at any of the time points examined. As eCBs serve as activity-dependent retrograde inhibitors of neurotransmitter release, the increase in brain eCB content would accentuate Pb2+-induced decreases in evoked neurotransmitter release in male but not female fathead minnows.

Animals↗

PubMed2000

Differential basis of strain and rearing effects on open-field behavior in Fawn Hooded and Wistar rats.

Open-field behavior was examined under several conditions in isolation-reared, and socially reared, Fawn Hooded (FH) and Wistar rats. Lighting conditions (red or white light) and complexity (object or no object) were varied: Experiment 1, white light, no object; Experiment 2, red light, no object; Experiment 3, white light, object; Experiment 4, red light, object. The plasma corticosterone (CORT) response to open-field exposure was examined two further experiments. Observation of differences in open-field behavior, resulting from strain or rearing condition, was dependent on both lighting condition and complexity. Differences in exploratory behavior exhibited by isolation-reared rats were best explained by changes in response to novelty, while those in FH, relative to Wistar, rats were primarily due to increased anxiety. Supporting these conclusions, FH rats had enhanced stimulated CORT levels, while isolation rearing was without effect.

Animals↗

PubMed1994

Measuring impulsivity and examining its relationship to delinquency.

A multimethod, multisource assessment of impulsivity was conducted in a sample of more than 400 boys who were members of a longitudinal study of the development of antisocial behavior. Exploratory and confirmatory factor analysis of the 11 different impulsivity measures revealed two impulsivity factors: Cognitive and Behavioral. Cognitive and behavioral impulsivity had similar correlations with socioeconomic status. Cognitive impulsivity was more strongly related to IQ than was behavioral impulsivity. Behavioral impulsivity was more strongly related to delinquency at ages 10 and 12-13 than was cognitive impulsivity. Consistent with theoretical prediction, our results also indicate that behavioral impulsivity was especially related to serious delinquency that is stable over time.

Adolescent↗

PubMed1997

Hippocampal electrical activity and behavior in the rabbit.

Different approaches to the study of the relationship between hippocampal electrical activity and behavior have shown that hippocampal EEG varies according to different behavioral aspects. In particular, a rhythmic slow activity (RSA, Theta rhythm) can be recorded during voluntary movements and to a lesser degree during immobility. In laboratory experiments, we tried to evaluate the influence on the hippocampal EEG of external stimuli evoking emotional or cognitive responses. Similar electrical responses were observed during animal hypnosis and in the presence of threatening stimuli, while some electrical parameters, such as frequency and rhythmicity, varied according to the nature of the stimulus. In order to have greater and clearer information, we adopted a neuro-ethological approach ch. which allowed us to classify behavior into several categories and to record the hippocampal EEG during natural behavior. The influence exerted on hippocampal electrical activity by novel stimuli and the electrical profiles recorded during exploratory behavior or alert or quiet immobility allowed us to classify the hippocampal EEG on the basis of frequency and rhythmicity. Moreover, the study of social behavior showed that the variations of the electrical parameters of the hippocampal activity depended on the characteristics of the stimulus and that typical electrical profiles could be observed in immobile or motor activities caused by specific stimuli. Socially dominant and subordinate rabbits could also be distinguished on the basis of hippocampal electrical parameters.

Animals↗

PubMed2000

Applications of video mixing and digital overlay to neuroethology.

Neuroethological experiments often require video images of animal behavior and recordings of physiological data to be acquired simultaneously, synchronized with each other, stored, and analyzed together. The use of inexpensive multimedia computers offers new possibilities for mixing video images, analog voltages, and computer data, storing these combined signals to videotape, and extracting quantitative data for analysis. In this paper, we summarize methods for mixing images from multiple video cameras and a Macintosh computer display to facilitate manipulation of data generated during our neurophysiological and behavioral research. These technologies enhance accuracy, speed, and flexibility during experiments, and facilitate selecting and extracting quantitative data from the videotape for further analysis. Three applications are presented: (A) we used an analog video mixer to synchronize neurophysiological recordings with ongoing behaviors of freely moving rats; (B) we used a chroma keyed digital overlay to generate positional data for the rat's face during drinking behavior; and (C) we combined a computer model of a rat's head and whiskers with videos of exploratory behaviors to better track and quantify movements in three dimensions. Although the applications described here are specific to our neuroethological work, these methods will be useful to anyone wishing to combine the signals from multiple video sources into a single image or to extract series of positional or movement data from video frames without frame grabbing.

Animals↗

PubMed1992

Electromyographic studies of neck muscles in the intact cat. I. Patterns of recruitment underlying posture and movement during natural behaviors.

Natural head movements in alert, unrestrained cats were studied using video-filming, videofluoroscopy and electromyographic (EMG) recording methods. In each cat, up to sixteen neck muscles or neck-muscle compartments were implanted with recording electrodes. Patterns of muscle recruitment were examined during systematically-selected behavioral epochs in which the cat held a range of stationary postures, and when it performed volitional and exploratory behaviors such as flexion-extension or turning, grooming, eating, or headshaking. Patterns of muscular activity were interpreted with reference to simultaneous video images of head and neck movements. In separate, videofluoroscopic analysis, flexion-extension movements were examined to gain insight into the underlying movements of the skull and cervical vertebrae. These and other movements were found commonly to depend upon changes in joint angles between lower as well as upper cervical joints. Stationary postures in which the neck was held vertically were consistently associated with tonic EMG activity in only two long dorsal muscles, biventer cervicis and occipitoscapularis. Less consistent activity was also present in dorsal intervertebral muscles crossing lower cervical joints. When the neck was held horizontally, the long dorsal muscles increased their EMG activity and moderate activity was also recorded in deeper intervertebral and suboccipital muscles. When flexion-extension occurred around upper cervical joints, greatest activity was recorded in rectus capitis posterior and complexus, but when it involved the lower cervical joints, large changes in EMG activity could also be detected in biventer cervicis, occipitoscapularis, and the intervertebral muscles crossing lower cervical joints. During specialized, sagittal-plane movements such as grooming, well-defined patterns of synergy could be recognized that varied according to the degree of involvement of upper and lower cervical joint-sets. Movements in the horizontal plane were associated with EMG activity in a largely different subset of neck muscles including splenius, longissimus capitis and obliquus capitis inferior. The levels of EMG activity during flexion-extension or turning movements were much lower than those observed during other more vigorous behaviors, such as head shaking. Some neck muscles, such as clavotrapezius and sternomastoideus, could only be recruited during forceful or ballistic head movements. Results showed that the patterns of muscular activation were linked not only to the speed and trajectory of the movements of the skull, but also to the kinematics of the motion occurring across different parts of the cervical column.

Animals↗

PubMed2007

Effects of mild early life stress on abnormal emotion-related behaviors in 5-HTT knockout mice.

A low-expressing polymorphic variant of the serotonin transporter (5-HTT) gene has been associated with emotional disorders in humans and non-human primates following exposure to early life trauma. 5-HTT gene knockout (KO) mice exhibit increased anxiety- and depression-related behaviors, and provide a model to study interactions between 5-HTT gene variation and early life stress. The present study assessed the effects of postnatal footshock stress on the development of emotion-related behaviors in 5-HTT KO mice. Results showed that 5-HTT KO mice displayed a profile of suppressed exploratory behavior and increased anxiety-like behavior in the light/dark, elevated plus-maze and open field tests, as well as increased depression-related behavior in the forced swim test following repeated exposure to the test. Postnatal exposure to footshock stress did not affect emotion-related behaviors in non-mutant C57BL/6J mice or modify phenotypic abnormalities in 5-HTT KO. Data provide further evidence of emotional abnormalities following genetic disruption of the 5-HTT.

Animals↗

PubMed1985

Brain monoamine metabolism and behavior in portacaval-shunted rats.

Animals with a portacaval shunt exhibit several biochemical abnormalities in plasma and brain similar to patients with portal-systemic encephalopathy, i.e., hyperammonemia, amino acid imbalance, and neurotransmitter disturbances. We investigated behavior and brain monoamine metabolism in operated, sham-operated, and nonoperated rats 1 day and 2, 4, and 6 weeks after operation. In order to quantitate the turnover in the brain indoleamine and catecholamine systems, 5-hydroxytryptophan (5-HTP) and dihydroxyphenylalanine were measured after decarboxylase inhibition with NSD 1015. The brains were dissected into five regions. All rats with the shunt had high plasma ammonia concentrations. Behavioral tests revealed a reduction in spontaneous locomotion 2, 4, and 6 weeks after portacaval shunt and reduced exploratory behavior compared with control rats. These changes coincided with profound alterations of the indoleaminergic system. As early as 1 day after surgery, rats with the shunt showed a marked increase in the accumulation of 5-HTP in all brain regions, indicating an enhanced tryptophan hydroxylase activity. The changes in indoleamine synthesis were most profound in the cortex and the midbrain. Only minor alterations of the catecholaminergic system could be detected. The alterations in behavior and indoleamine neurotransmitter metabolism may be pathophysiologically interrelated and may serve as the basis for experimental studies of portal-systemic encephalopathy.

Animals↗

PubMed1984

Temporal matching of sensory-motor behavior and limbic theta rhythm deteriorates in aging rats.

The correlations between investigatory sniffing and rhythmic slow-wave activity (RSA) in the dorsal hippocampal formation were studied during free behavior in Fischer 344 rats aged 3, 18, 30, and 36 months. The amount and vigor of spontaneous exploratory behavior was reduced in older animals, and the frequency distributions of investigatory sniffing and hippocampal RSA both shifted with age toward the lower end of their normal ranges. In the youngest animals, the dominant frequency of sniffing matched that of hippocampal RSA (frequency entrainment) more often than would be predicted by chance; preferred phase differences between sniffing and hippocampal RSA were reliably observed in the 5-9 Hz range; and these preferred phase differences varied linearly as a function of frequency, implying an underlying latency relationship. These correlations changed progressively with age as follows: the incidence of frequency entrainments decreased; the frequency range within which preferred phase differences were observed became lower and narrower; and the incidence of preferred phase differences decreased. However, animals of all ages exhibited similar preferred phase differences for those frequencies at which significant preferences were expressed. These findings are discussed in relation to the hypothesis that alterations of forebrain theta rhythms may accompany aberrations of the medial septum-diagonal band-nucleus basalis complex and may be importantly involved in aging-related impairments of cognitive and learning abilities.

Aging↗

PubMed2000

Predator odor as an unconditioned fear stimulus in rats: elicitation of freezing by trimethylthiazoline, a component of fox feces.

Four experiments tested whether an odor from a rat predator can unconditionally elicit a fear response in rats. In a large chamber, rats displayed fear-related behaviors to trimethylthiazoline (TMT, a volatile compound isolated from fox feces), including avoidance and immobility, while showing less exploratory behavior. In a smaller chamber, TMT induced a species-typical fear response, freezing, whereas other odors did not. In addition, TMT systematically elicited more freezing as the amount of TMT increased. Moreover, there was no within-sessions or between-sessions habituation of freezing to TMT, nor did TMT promote contextual conditioning. The results indicate that the predator odor, TMT, can induce a fear-related behavioral response in rats that is controllable and quantifiable, suggesting that TMT-induced freezing may be a useful paradigm for a neurobehavioral system analysis of ecologically relevant, unconditioned fear.

Animals↗