Measures Of Exploratory Behavior Research Articles

Acute Administration of Ethanol and of a D1-Receptor Antagonist Affects the Behavior and Neurochemistry of Adult Zebrafish.

Alcohol abuse represents major societal problems, an unmet medical need resulting from our incomplete understanding of the mechanisms underlying alcohol's actions in the brain. To uncover these mechanisms, animal models have been proposed. Here, we explore the effects of acute alcohol administration in zebrafish, a promising animal model in alcohol research. One mechanism via which alcohol may influence behavior is the dopaminergic neurotransmitter system. As a proof-of-concept analysis, we study how D1 dopamine-receptor antagonism may alter the effects of acute alcohol on the behavior of adult zebrafish and on whole brain levels of neurochemicals. We conduct these analyses using a quasi-inbred strain, AB, and a genetically heterogeneous population SFWT. Our results uncover significant alcohol x D1-R antagonist interaction and main effects of these factors in shoaling, but only additive effects of these factors in measures of exploratory behavior. We also find interacting and main effects of alcohol and the D1-R antagonist on dopamine and DOPAC levels, but only alcohol effects on serotonin. We also uncover several strain dependent effects. These results demonstrate that acute alcohol may act through dopaminergic mechanisms for some but not all behavioral phenotypes, a novel discovery, and also suggest that strain differences may, in the future, help us identify molecular mechanisms underlying acute alcohol effects.

Urban Individuals of Three Rove Beetle Species Are Not More Exploratory or Risk-Taking Than Rural Conspecifics.

Simple SummaryUrbanization-derived disturbances and threats, as well as changes in environmental and habitat parameters act as selection pressures on various features of urban-dwelling animals, including their behavior. Earlier studies on vertebrates showed that urban individuals are more exploratory and bolder than their rural counterparts. Similar analyses on invertebrates are rare, therefore we studied the exploratory and risk-taking behavior of individuals of three rove beetle species from rural and urban populations during their main reproductive period. Beetles of all three studied species responded consistently in the different behavioral tests. The exploratory behavior of beetles was consistent over time indicating the existence of personalities, but did not differ in differently urbanized habitats. Ocypus nitens males, however, were significantly more exploratory than females which can be explained by the active searching of males for mating partners.Urbanization is creating changes in environmental and habitat conditions, as well as creating disturbance and threats to urban-associated species. Some traits, such as high exploratory and risk-taking behavior, are beneficial to allow colonization of urban habitats and coping with urbanization-derived pressures. In this study the exploratory and risk-taking behavior of rural and urban individuals of three forest-associated rove beetle species were tested during their main reproductive period by five frequently used behavioral measures. Individuals of all studied species were similarly ranked by all behavioral measures, indicating that the studied rove beetles responded consistently in the different contexts. However, the behavior of beetles was consistent over time for all/most studied species only by using two measures of exploratory behavior. These provide evidence for the existence of the exploratory dimension of personality in rove beetles. We found a higher exploratory behavior in males than females in Ocypus nitens which can be explained by the active searching of males for mating partners. There were no urbanization-related differences in the exploratory behavior of individuals, suggesting that behavioral changes (being more exploratory) may not yield additional fitness benefits in these rove beetle species with good dispersal capacity.

Cardiovascular, Cerebral and Behavioral Response to Anti‐Hypertensive Treatment in Female Dahl Salt Sensitive Rats

Background Cerebrovascular disease is associated with central arterial stiffness (CAS), which can lead to reduced brain blood supply, neuronal density loss and cognitive impairment. Dahl salt sensitive (DSS) rats represent a model of vascular dementia and have a compromised renin-angiotensin system, develop CAS, hypertension, and hippocampal memory decline with age on a normal salt (NS) diet. Lisinopril (LIS), an angiotensin converting enzyme inhibitor, effectively treated this pathology in aged male DSS rats. We investigated the relationship between systolic blood pressure (SBP), pulse wave velocity (PWV), a marker of CAS, hippocampal blood flow (CBF), neuronal density and anxiety in female DSS rats treated with LIS. Methods Female DSS rats (n=23) were fed a NS diet (0.5% NaCl) for the duration of the study. Rats were administered LIS (15mg/kg BW/day in drinking water, n=12) or control treatment (CTRL; n=11) for 7-mo beginning at 6-mo of age. The following measurements were assessed at 6-mo (baseline; BL) and at 13-mo of age: SBP (by plethysmography), PWV (by echocardiography), CBF (by continuous arterial spin labeling), and hippocampal N-acetyl aspartate concentration (NAA; by proton magnetic resonance spectroscopy). In open field test (OFT; a metric of anxiety, a precursor to symptoms of dementia) travel activity (distance) and rearing durations (vertical activity; VA) in the center of the field were collected as measures of exploratory behavior. Pearson's correlation matrix and 2-way ANOVA mixed effects model analyses were performed. Results At BL, the treatment groups were not different in any parameters except heart rate (HR). At 13-mo CTRL, SBP and PWV increased, CBF, total distance, total VA and distance in center of the OFT decreased compared to BL. In 13-mo LIS group, SBP and PWV were lower compared to 13-mo CTRL; 13-mo LIS group had higher HR and lower SBP, CBF and total VA in OFT compared to BL (Table 1). At 6-mo, NAA and VA were marginally correlated. HR and central distance were significantly correlated (Table 2A). For 13-mo CTRL, SBP positively correlated with PWV and NAA. NAA negatively correlated with distance in center. HR negatively correlated with distance in center and VA in center (Table 2B). This relationship with HR was reversed for 13-mo LIS group, for which PWV and CBF were negatively associated with central distance and central VA, while NAA was negatively correlated with central VA only (Table 2C). Conclusion In both CTRL and LIS groups, advancing age adversely affected hippocampal perfusion, but not neuronal density. ChronicLIS treatment reduced hypertension and PWV but did not affect cerebral parameters in aged female DSS rats. Increased level of anxiety, known to predate cognitive decline, was associated with PWV for LIS group, suggesting that CAS can adversely affect brain structures and function. CTRL and LIS groups showed differences in associations between cerebral, behavioral, and cardiovascular parameters. Further analyses will be conducted to investigate the role of sex hormones and their associations with age in the patterns observed.

Fear expression is reduced after acute and repeated nociceptin/orphanin FQ (NOP) receptor antagonism in rats: therapeutic implications for traumatic stress exposure.

Evaluation of pharmacotherapies for acute stress disorder (ASD) or post-traumatic stress disorder (PTSD) is challenging due to robust heterogeneity of trauma histories and limited efficacy of any single candidate to reduce all stress-induced effects. Pursuing novel mechanisms, such as the nociceptin/orphanin FQ (NOP) system, may be a viable path for therapeutic development and of interest as it is involved in regulation of relevant behaviors and recently implicated in PTSD and ASD. First, we evaluated NOP receptor antagonism on general behavioral performance and again following a three-species predator exposure model (Experiment 1). Then, we evaluated effects of NOP antagonism on fear memory expression (Experiment 2). Adult, male rats underwent daily administration of NOP antagonists (J-113397 or SB-612,111; 0-20mg/kg, i.p.) and testing in acoustic startle, elevated plus maze, tail-flick, and open field tests. Effects of acute NOP antagonism on behavioral performance following predator exposure were then assessed. Separately, rats underwent fear conditioning and were later administered SB-612,111 (0-3mg/kg, i.p.) prior to fear memory expression tests. J-113397 and SB-612,111 did not significantly alter most general behavioral performance measures alone, suggesting minimal off-target behavioral effects of NOP antagonism. J-113397 and SB-612,111 restored performance in measures of exploratory behavior (basic movements on the elevated plus maze and total distance in the open field) following predator exposure. Additionally, SB-612,111 significantly reduced freezing behavior relative to control groups across repeated fear memory expression tests, suggesting NOP antagonism may be useful in dampening fear responses. Other measures of general behavioral performance were not significantly altered following predator exposure. NOP antagonists may be useful as pharmacotherapeutics for dampening fear responses to trauma reminders, and the present results provide supporting evidence for the implication of the NOP system in the neuropathophysiology of dysregulations in fear learning and memory processes observed in trauma- and stress-related disorders.

Linking Colony Size with Foraging Behavior and Brain Investment in Odorous Ants (Formicidae: Dolichoderinae)

Superorganisms represent a unique level of biological organization in which the phenotype of the reproductive unit, the colony, results from traits expressed at the level of individual workers. Because body size scaling has important consequences for cell diversity and system complexity in solitary organisms, colony size is a trait of particular interest in superorganism evolution. In some instances, division of labor and worker polymorphism scale with colony size, but in general little is known about how colony size drives differences in individual-level behavior or neural traits. Ants represent the greatest diversity of superorganisms and provide a manner of natural experiment to test trends in trait evolution across multiple instances of colony size expansion. In this study, we control for environmental differences and worker size polymorphism to test if colony size correlates with measures of foraging behavior and brain size in dolichoderine ants. We present data from 3 species ranked by colony size. Our results suggest colony size correlates with measures of exploratory behavior and brain investment, with small-colony ants showing higher exploratory drive and faster exploration rate than the larger colony species, and greater relative investment in the primary olfactory brain region, the antennal lobe, than the larger colony species.

Associating quantitative behavioral traits with gene expression in the brain: searching for diamonds in the hay

Gene expression and phenotypic functionality can best be associated when they are measured quantitatively within the same experiment. The analysis of such a complex experiment is presented, searching for associations between measures of exploratory behavior in mice and gene expression in brain regions. The analysis of such experiments raises several methodological problems. First and foremost, the size of the pool of potential discoveries being screened is enormous yet only few biologically relevant findings are expected, making the problem of multiple testing especially severe. We present solutions based on screening by testing related hypotheses, then testing the hypotheses of interest. In one variant the subset is selected directly, in the other one a tree of hypotheses is tested hierarchical; both variants control the False Discovery Rate (FDR). Other problems in such experiments are in the fact that the level of data aggregation may be different for the quantitative traits (one per animal) and gene expression measurements (pooled across animals); in that the association may not be linear; and in the resolution of interest only few replications exist. We offer solutions to these problems as well. The hierarchical FDR testing strategies presented here can serve beyond the structure of our motivating example study to any complex microarray study. Supplementary data are available at Bioinformatics online.

Behavioral impairment of APP V717F mice in fear conditioning: is it only cognition?

Alzheimer's Disease (AD) is a devastating human neurodegenerative disorder associated with progressive deterioration of cognitive abilities. The APP V717F mouse, an animal model of AD showing robust overexpression of the human amyloid precursor protein (APP) carrying the mutation 717 V→F, was also shown to exhibit learning and memory performance deficits. However, AD patients suffer from other abnormalities including altered emotionality. Emotionality has not been analyzed in AD mouse models. Here, motor and posture patterns exhibited by APP V717F mice are described in a detailed manner in fear conditioning, a paradigm that allows one to test both mnemonic and emotional characteristics of mice. Our results revealed a complex set of behavioral alterations in APP V717F mice in measures of exploratory behavior and fear suggesting that the effects of APP V717F overexpression in this mouse model are not limited to cognition and may need to be thoroughly examined in the future in a broad range of behavioral tests.

The influence of stimulus deviance on electrophysiologic and behavioral responses to novel events.

This study investigated the role of stimulus deviance in determining electrophysiologic and behavioral responses to "novelty." Stimulus deviance was defined in terms of differences either from the immediately preceding context or from long-term experience. Subjects participated in a visual event-related potential (ERP) experiment, in which they controlled the duration of stimulus viewing with a button press, which served as a measure of exploratory behavior. Each of the three experimental conditions included a frequent repetitive background stimulus and infrequent stimuli that deviated from the background stimulus. In one condition, both background and deviant stimuli were simple, easily recognizable geometric figures. In another condition, both background and deviant stimuli were unusual/unfamiliar figures, and in a third condition, the background stimulus was a highly unusual figure, and the deviant stimuli were simple, geometric shapes. Deviant stimuli elicited larger N2-P3 amplitudes and longer viewing durations than the repetitive background stimulus, even when the deviant stimuli were simple, familiar shapes and the background stimulus was a highly unusual figure. Compared to simple, familiar deviant stimuli, unusual deviant stimuli elicited larger N2-P3 amplitudes and longer viewing times. Within subjects, the deviant stimuli that evoked the largest N2-P3 responses also elicited the longest viewing durations. We conclude that deviance from both immediate context and long-term prior experience contribute to the response to novelty, with the combination generating the largest N2-P3 amplitude and the most sustained attention. The amplitude of the N2-P3 may reflect how much "uncertainty" is evoked by a novel visual stimulus and signal the need for further exploration and cognitive processing.

Effects of chronic nicotine administration on locomotion depend on rat sex and housing condition.

Nicotine's behavioral actions in the human smoker by self-report depend, in part, on the individual's gender and environment. The purpose of the present experiment was to determine whether effects of nicotine on unconditioned behaviors of rats also depend on sex and environmental conditions. Long-Evans rats (96 males and 96 females) living in individual or grouped housing were administered saline or 12 mg/kg/day nicotine via osmotic minipump for 14 days. Horizontal activity (a measure of overall activity and arousal), vertical activity (a measure of exploratory behavior), and center time (a possible index of anxiety) were measured on Day 10 of drug administration and on Day 2 of nicotine cessation. Group housing decreased horizontal and vertical activity and center time, with effects occurring sooner in females. Nicotine's effects depended on housing and sex. For males, nicotine altered indices of arousal and exploration, increasing these variables for group-housed males but decreasing them for individually housed males. For females, nicotine altered possible indices of anxiety, reducing anxiety for group-housed females. In cessation, housing effects continued in females and appeared more robustly in males. Results indicate that nicotine's chronic effects depend on subjects' sex and living environment.

Responses to Stress and Novelty in Adult Rats Born Vaginally, by Cesarean Section or by Cesarean Section with Acute Anoxia

The aim of this study was to test the hypothesis that alterations in birth conditions, specifically vaginal birth vs. birth by Cesarean section (C-section) vs. birth by C-section with an added period of acute global anoxia, produces long-term differences in behavioral responses to stress or novelty in the rat at adulthood. In comparison to animals born by rapid C-section alone, animals born by C-section with 10 or 15 min of added anoxia were significantly more immobile during forced swim stress administered for 6 trials over several weeks. In a step-down passive avoidance task, there were no group differences in acquisition or retention of the avoidance response. However, when initially placed in the passive avoidance apparatus before delivery of shock, animals born by C-section with 15 min of anoxia required significantly more pretrials to step down from the wooden platform, than did vaginally born or C-sectioned animals. No group differences were observed on measures of exploratory behavior in an elevated plus-maze or of approach behavior either to food or to a novel object in an open field. These findings suggest that birth conditions which include a degree of perinatal hypoxia can contribute to variability in selective responses to stress and novelty in the adult rat.

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.

Behavioral Toxicity of Trihalomethane Contaminants of Drinking Water in Mice

The behavioral toxicity of trichloromethane (TCM), dichlorobromomethane (DCBM), dibromochloromethane (DBCM) and tribromomethane (TBM) was evaluated following oral administration in mice. A variety of dosage regimens and behavioral measures were used. Studies included acute dose effect, 14-and 90-day treatments at 300 and 3000 times the estimated average human daily intake of contaminated drinking water, 30 days of 100 mg/kg/day, and 60 days of 100 and 400 mg/kg/day. In addition, TCM was tested for the production of taste aversions with 10-day administration and for behavioral teratology in offspring following extensive perinatal exposure. The ED50 for acute effects on a screen test of motor performance was about 500 mg/kg for all four trihalomethanes. The 14-day treatments had no effect on swimming behavior and the 90-day treatments had no effect on bar clinging, a test of motor coordination, and a measure of exploratory behavior. None of the compounds produced effects on passive-avoidance learning following 100 mg/kg/day for 30 days. TCM, DBCM and TBM elicited clear effects at both 100 and 400 mg/kg/day on operant behavior when administered for 60 days. DBCM elicited clear effects at 400 mg/kg/day. These effects on operant behavior were seen following the first dose and tolerance tended to develop. Thus, there was no evidence from these studies for a progressive neurotoxicity from trihalomethanes in adult mice. A behavioral teratology study was also conducted with TCM. Both parents were treated with 31.1 mg/kg/day TCM, and treatment of the dam continued throughout gestation and lactation. No clear evidence for behavioral effects in the offspring were observed. The most sensitive measure for the effects of TCM was the taste aversion paradigm in which saccharin aversions were produced after a single treatment of 30 mg/kg.

Behavioral toxicity of trihalomethane contaminants of drinking water in mice.

The behavioral toxicity of trichloromethane (TCM), dichlorobromomethane (DCBM), dibromochloromethane (DBCM) and tribromomethane (TBM) was evaluated following oral administration in mice. A variety of dosage regimens and behavioral measures were used. Studies included acute dose effect, 14-and 90-day treatments at 300 and 3000 times the estimated average human daily intake of contaminated drinking water, 30 days of 100 mg/kg/day, and 60 days of 100 and 400 mg/kg/day. In addition, TCM was tested for the production of taste aversions with 10-day administration and for behavioral teratology in offspring following extensive perinatal exposure. The ED50 for acute effects on a screen test of motor performance was about 500 mg/kg for all four trihalomethanes. The 14-day treatments had no effect on swimming behavior and the 90-day treatments had no effect on bar clinging, a test of motor coordination, and a measure of exploratory behavior. None of the compounds produced effects on passive-avoidance learning following 100 mg/kg/day for 30 days. TCM, DBCM and TBM elicited clear effects at both 100 and 400 mg/kg/day on operant behavior when administered for 60 days. DBCM elicited clear effects at 400 mg/kg/day. These effects on operant behavior were seen following the first dose and tolerance tended to develop. Thus, there was no evidence from these studies for a progressive neurotoxicity from trihalomethanes in adult mice. A behavioral teratology study was also conducted with TCM. Both parents were treated with 31.1 mg/kg/day TCM, and treatment of the dam continued throughout gestation and lactation. No clear evidence for behavioral effects in the offspring were observed. The most sensitive measure for the effects of TCM was the taste aversion paradigm in which saccharin aversions were produced after a single treatment of 30 mg/kg.

Strain differences in neophilia in the rat

Latencies to approach a novel physical object and a novel human hand placed in the home cage were obtained for 599 rats from 12 inbred strains: ACI, A990, A35322, F344, INR, IR, MNR/Har, MNRA, MR/Har, TS1, TS3, WAG. Comparison with results of other studies of these strains show consistencies among different measures of exploratory behavior where differences might have been expected. The results also provide parametric data for methodological use and add to the standardization of these strains as behaviorally defined lines.

Dimensions in the perception of architecture:II. Measures of exploratory behavior

Four experiments were conducted with 20 slides of buildings representing major architectural styles. The purpose of the experiments was to determine interrelations of verbal and non‐verbal measures. The experiments were concerned with: (1) Looking Time, (2) Reward Value, (3) Judgments indicative of Exploratory Tendencies, and (4) Exploratory Choice. The findings were consistent with previous studies in experimental aesthetics. It was concluded that exploratory reactions to the architectural environment may be expressed in at least two types of behavior. First, exploratory behavior was found to be related to perceptual curiosity aroused by a building. Secondly, behavior could be predicted from the hedonic aspects of the building. These two underlying variables were also found to merge frequently.

Direct contact with enriched environment is required to alter cerebral weights in rats.

To test the relative effectiveness of direct vs. indirect interaction with an enriched environment, some rats were housed in groups of 12 in large enriched condition (EC) cages while littermate "observer" (OC) rats were placed singly in small wire-mesh cages within EC. A third group was housed singly in an impoverished condition (IC) where stimulation was minimal. After 30 days, the animals were killed and the brains dissected. In both experiments the usual pattern of EC-IC differences in brain weights appeared, whereas OC showed no significant differences from IC. On measures of exploratory behavior taken during the last 2 days of the second experiment, IC fell significantly below EC, and OC was somewhat below IC. Thus EC differen from both IC and OC in brain and in behavior. Active contact with an enriched environment appears necessary for development of EC effects.

Enhancement of exploratory behavior by strychnine sulfate.

An experiment was conducted to study the effect of strychnine sulfate on the exploratory behavior of male, Wistar rats in an open field. The number of times S reared in a stimulus square and the number of stimuli to which a S reared were recorded for both experimental and control Ss. Analyses of covariance performed on both measures of exploratory behavior showed that exploratory behavior was significantly increased by strychnine sulfate.

Exploratory behavior in children.

60 children representing equally two age groups (2nd and 6th graders) and three ability groups (IQs of 92–108, 112–128, and 132+) served as Ss in studies of the effects of stimulus characteristics on exploratory behavior and the effect of novelty on immediate and delayed recall. In Exp. 1, significant effects were obtained for complexity, abstractness, and incongruity but not ambiguity of tachistoscopically presented stimulus materials. Age affected exploration of incongruous and ambiguous but not complex and abstract materials. Ability level had no significant effects. In Exp. II, exploratory time and judged intensity of exploration were influenced by the characteristics of stimulus objects presented in an array for free exploration. Novelty facilitated exploration but neither age nor ability had a significant effect. In Exp. III, both immediate and delayed recall by the younger Ss were greater for objects they identified as “novel” but recall by the older Ss was somewhat greater for “not-novel” objects. Factor analysis of all the behavioral scores derived in these experiments along with scores from a creativity test indicated that the various measures of exploratory behavior and creativity used here were sampling different aspects of behavior and no one of such measures can be assumed to be an adequate index of exploratory behavior in general.