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Results for “Exploratory Behavior”

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PubMed2001

Controlling the false discovery rate in behavior genetics research.

The screening of many endpoints when comparing groups from different strains, searching for some statistically significant difference, raises the multiple comparisons problem in its most severe form. Using the 0.05 level to decide which of the many endpoints' differences are statistically significant, the probability of finding a difference to be significant even though it is not real increases far beyond 0.05. The traditional approach to this problem has been to control the probability of making even one such error--the Bonferroni procedure being the most familiar procedure achieving such control. However, the incurred loss of power stemming from such control led many practitioners to neglect multiplicity control altogether. The False Discovery Rate (FDR), suggested by Benjamini and Hochberg [J Royal Stat Soc Ser B 57 (1995) 289], is a new, different, and compromising point of view regarding the error in multiple comparisons. The FDR is the expected proportion of false discoveries among the discoveries, and controlling the FDR goes a long way towards controlling the increased error from multiplicity while losing less in the ability to discover real differences. In this paper we demonstrate the problem in two studies: the study of exploratory behavior [Behav Brain Res (2001)], and the study of the interaction of strain differences with laboratory environment [Science 284 (1999) 1670]. We explain the FDR criterion, and present two simple procedures that control the FDR. We demonstrate their increased power when used in the above two studies.

Animals↗

PubMedDate not supplied

Non-associative learning in the mouse. Effect of morphine and naloxone.

The study evaluates the effect of morphine and naloxone on the process of non-associative learning in the mouse. Exploratory behavior was measured in thirty-six male albino mice (Suisse) placed on a Boissier and Simon hole-board, the procedure being repeated 24 h later after administration of naloxone and/or morphine, or bidistilled water i.p. The results show that the inhibitory effect naloxone has on the recollection process of the mnemonic traces appears to be masked by morphine.

Animals↗

PubMed2006

Midazolam inhibits neophobia-induced Fos expression in the rat hippocampus.

The effect of midazolam on expression of c-Fos protein was examined in the rat hippocampus, following the open field test of neophobia. It was found that pretreatment of rats with midazolam, at the dose of 0.5 mg/kg, enhanced rat exploratory behavior, and inhibited neophobia related stimulation of c-Fos in the CA-1 and CA-3 areas of the hippocampus. The presented results provide new immunocytochemical data on the involvement of hippocampus in emotional processes related to neophobia, and indicate a possible site of action of benzodiazepines.

Animals↗

PubMed1988

Control of responding by sounds of different quality: an evolutionary analysis.

Two experiments investigated the acquisition of discriminations between two acoustic stimuli of different quality (noise bursts vs. a 2-kHz pulsed signal) when features of the everyday environment were incorporated into the experiments. In Experiment 1, rats were trained, using food, to press a lever. Throughout all sessions, 5-s trials of noise bursts (the random stimulus) were presented, after variable intertrial intervals, through a remote speaker mounted outside the experimental enclosure. The noise burst occurred randomly with respect to reinforcement of lever pressing and had no programmed relationship to the animal's behavior. When lever pressing was established, the 2-kHz signal was presented through a speaker adjacent to the response lever according to a different set of variable intertrial intervals. A response in the presence of the 2-kHz signal terminated the trial and was reinforced. The 2-kHz signal acquired control of responding within the first few trials, whereas the random stimulus exerted no control of responding. In Experiment 2, rats were trained to press the lever in the presence of the 2-kHz signal presented through the adjacent speaker on a variable intertrial interval. After 14 sessions, 5-s trials of noise bursts (random stimulus) were presented through the remote speaker on the second variable intertrial interval. The random stimulus initially elicited exploratory behavior, which then rapidly declined. Subsequently, the random stimulus exerted no or weak control of responding. The introduction of the random stimulus had no effect on responding in the presence of the adjacent stimulus. In Experiments 3 and 4 the random stimulus was presented through the adjacent speaker, and the stimulus correlated with reinforcement was presented through the remote speaker. In both experiments, there was persistent control of responding by the random stimulus and slow development of control by the stimulus correlated with reinforcement. In Experiment 5, both stimuli were presented through the adjacent speaker. There was persistent control of responding by the random stimulus.

Animals↗

PubMed2005

Hippocampal theta rhythm: a tag for short-term memory.

The theta rhythm is the largest extracellular synchronous signal that can be recorded from the mammalian brain, and has been strongly implicated in mnemonic functions of the hippocampus. We advance the proposal that the theta rhythm represents a "tag" for short-term memory processing in the hippocampus. We propose that the hippocampus receives two main types of input, theta from ascending brainstem-diencephalo-septal systems and "information bearing" mainly from thalamocortical and cortical systems. The temporal convergence of activity of these two systems results in the encoding of information in the hippocampus, primarily reaching it via cortical routes. By analogy to processes associated with long-term potentiation (LTP), we suggest that theta represents a strong depolarizing influence on NMDA receptor-containing cells of the hippocampus. The temporal coupling of a theta-induced depolarization and the release of glutamate to these cells from intra- and extrahippocampal sources activates them. This, in turn, initiates processes leading to a (short-term) strengthening of connections between presynaptic ("information bearing") and postsynaptic neurons of the hippocampus. Theta is selectively present in the rat during active exploratory movements. During exploration, a rat continually gathers and updates information about its environment. If this information is temporally coupled to theta (as with the case of locomotion), it becomes temporarily stored in the hippocampus by mechanisms similar to the early phase of LTP (E-LTP). If the exploratory behavior of the rat goes unreinforced, these relatively short-lasting traces (1-3 h) gradually weaken and eventually fade-to be reupdated. On the other hand, if the explorations of the rat lead to rewards (or punishments), additional modulatory inputs to the hippocampus become activated and convert the short-term, theta-dependent memory, into long-term stores.

Afferent Pathways↗

PubMed1992

Housing influences exploration and social interaction of control and DSP-4-treated rats.

Exploratory behavior and social interaction were investigated in rats that were reared in different social environments following neonatal injection with either water vehicle or the norepinephrine neurotoxin, DSP-4. At weaning, they were placed in a familiar or novel bedding type and were housed in either vehicle control-only, DSP-4-only, or mixed vehicle control and DSP-4 groups for 10 days. They were then observed in three different situations: the home cage, the cage of an unfamiliar rat, and an open field. Compared to rats housed in vehicle control-only or DSP-4-only groups, rats housed in mixed DSP-4 and vehicle control groups showed elevated exploration behavior in the home cage. Also, rats housed in mixed groups in the familiar bedding, but not the novel one, showed abnormally low levels of rearing in an open field test and reduced social interaction with unfamiliar rats. The implications of these results for a new animal model of anxiety are discussed.

Adrenergic Agents↗

PubMed2005

A morphometric, neuroanatomical, and behavioral study on the effects of geometric constraint on the growing brain: the methyl 2-cyanoacrylate craniosynostosis model.

OBJECT: The effects of premature sutural synostosis on the developing brain remain unknown. A model of craniosynostosis in the perinatal rat was used to investigate the morphological and cytoarchitectural changes in the maturing brain as well as the neurobehavioral outcome. METHODS: A total of 56 perinatal rats, eight in each subgroup, were used in this study. Hypothermic arrest was induced in the rats and methyl 2-cyanocrylate was applied across the sagittal, coronal, and lambdoidal sutures at postnatal Days 0, 3, and 7. Sham rats underwent similar hypothermic arrest and application of methyl 2-cyanoacrylate but at a site different from the sutural lines. Age-matched rats that did not undergo any procedure were included as normal controls. Serial gross measurements were obtained to chart calvarial growth and computerized tomography scanning was performed to calculate mean calvarial volumes. At postnatal Day 30, the brains were fixed in situ and detailed morphological and cytoarchitectural analysis was conducted. There were no statistical differences in any of the analyses between sham rats and normal age-matched controls. In contrast, calvarial growth rates (analysis of variance, p < 0.05), mean brain weights (t-test, p < 0.01), and anterior-posterior and lateral diameter measurements (t-test, p < 0.01) were different for all synostotic rats compared with sham controls. On cytoarchitectural surveys, focal areas of nodular heterotopia and differences in cell density at the pyramidal cell layer were noted (t-test, p < 0.01). Open field testing also demonstrated excessive exploratory behavior in the synostosed animals. CONCLUSIONS: Early pan-calvarial sutural synostosis in the perinatal rat after administration of methyl 2-cyanoacrylate is associated with morphometrical and cytoarchitectural changes in the developing brain.

Animals↗

PubMed1991

A genetic-correlational study of hippocampal structural variation and variation in exploratory activities of mice.

Our previous work provided evidence that hippocampal opioid peptides form an important neurochemical substrate underlying the gene-dependent exploratory behavior of mice. A prominent hippocampal opioid is dynorphin B, which resides in the mossy fibers exclusively. In order to seek support for causal relationships between dynorphinergic hippocampal mechanisms and exploration, a quantitative-genetic method was chosen. For this purpose, mice from the inbred strains C57BL/6, DBA/2, BLN, and CPB-K were used. Their hippocampal mossy fiber projections were visualized by means of immunohistochemistry, using a highly specific anti-dynorphin B antiserum. The additive-genetic correlations that were estimated suggest pleiotropic gene effects on locomotion, rearing-up, wall-leaning, and several intra- and infrapyramidal mossy fiber (iipMF) variables. Long iipMF, in particular, were found to be associated with high exploratory activity.

Animals↗

PubMed1979

Offspring open field performance following maternal lead exposure: a question of dosage and nutritional status.

Although a number of experiments has revealed offspring hyperactivity following maternal lead (Pb) exposure, a consistent correlate has been reduced pup size. The present study was designed to measure exploratory behavior employing a range of Pb dosages that allowed for the comparison between Pb and control offspring both in the presence and the absence of weight differences. Female rats were exposed to one of four dosages (0, 400, 750 or 1000 mg/kg) of Pb acetate from 21--90 days of age, mated and then continued on treatment throughout gestation and nursing. Treatment was administered via a restricted water schedule. Open field testing began on Day 22 with the pups receiving 3 min trials for 10 consecutive nights. At 120 days of age, all pups were retested. Analysis indicated that only in the presence of reduced birth and/or weaning weights (Groups 750 and 1000) did offspring exhibit exploratory patterns that were significantly different from controls. These differences were absent at retest.

Animals↗

PubMedDate not supplied

[The formation of a functional system of social exploration in the early postnatal period in rat development].

The early organization was studied of the littermate search functional system. The locomotor elements of exploratory behavior and development of social activity of single rat pups and in groups of three ones were analyzed under conditions of their isolation from mother and nest. The influence was demonstrated of the littermate presence on realization of different types of movements. The age was experimentally determined at which rat pups were capable for learning to seek for their littermates on the basis of olfactory clues.

Aging↗

PubMed1996

Systemic administration of anti-NGF antibodies to neonatal mice impairs 24-h retention of an inhibitory avoidance task while increasing ChAT immunoreactivity in the medial septum.

Neonatal mice received subcutaneous injections of either antibody against murine NGF raised in goat (3 mg, injection volume 50 microliters) or preimmune serum on postnatal days 2, 4, 6, 8, 10, and 12. They were tested on postnatal days 15-16 or 20-21 for learning and 24-h retention of a passive avoidance step-through task. Immunostaining for choline acetyltransferase (ChAT) was measured in two cholinergic forebrain areas (septum and caudate-putamen) on postnatal day 16 or 21. Locomotor activity and exploratory behavior in an open-field test were also assessed on day 17 or 22, following a single administration of either scopolamine (2 mg/kg) or saline solution. While anti-NGF treatment did not affect acquisition on day 15, impairment in retention was evident on day 16. On days 20-21, no effects were found either on acquisition or on retention capabilities. Analysis of ChAT immunostaining revealed a significant increase of ChAT-immunopositive cells in the medial septal area in 16-day-old but not in 21-day-old mice. Behavior in the open-field test and age-typical response to scopolamine were not altered by anti-NGF at either of the two ages considered. These data support the view that immunological neutralization of endogenous NGF specifically affects the maturation of retention capabilities in altricial rodents, and confirm the involvement of forebrain cholinergic mechanisms in early memory processes.

Aging↗

PubMedDate not supplied

[The pharmacology of 3,4-dihydroxyphenyl-alpha-hydroxypropionic acid sodium salt].

Sodium salt of 3,4-dihydroxyphenyl-alpha-hydroxypropionic acid inhibits exploratory behavior and induces hypothermia in mice. The compound enhances central effects of L-DOPA, such as: gross excitation in group, fighting behavior, anticataleptogenic action and hyperthermic effect. The L-DOPA central effects are mitigated by pyridoxal phosphate. The 3,4-dihydroxyphenyl-alpha-hydroxypropionic acid sodium salt abolishes the protective action of pyridoxal phosphate. In vitro this salt inhibits DOPA-decarboxylase. It is suggested that the compound under discussion is a competitive antagonist of L-DOPA, when the latter is involved in reactions with pyridoxal phosphate.

Aggression↗

PubMed1987

The effect of chlordiazepoxide on the habituation of exploration: interactions with the benzodiazepine antagonist RO 15-1788.

Rats tested on two occasions in a holeboard apparatus showed between-session habituation of exploratory activity. No habituation was observed on the measure of locomotor activity. Administration of chlordiazepoxide before the first test reduced exploratory behavior in this test and also reduced the degree of between-session habituation. Administration of RO 15-1788 reversed the effect of chlordiazepoxide on exploration in the first test, but failed to reverse the drug's effect on between-session habituation. It is unlikely that state-dependent retrieval could account for these results. The results are discussed in relation to the effects of benzodiazepines on learning and memory.

Animals↗

PubMed1987

Seven deadly sins of childhood: advising parents about difficult developmental phases.

Seven of the more difficult developmental phases for any parent to deal with are colic, awakening at night, separation anxiety, normal exploratory behavior, normal negativism, normal poor appetite, and toilet training resistance. For the child living in a high-risk family, these innocent acts can trigger dangerous or even deadly abuse. The two behaviors most commonly associated with fatal abuse are colic and toilet training. When we recognize a child who is going through a provocative phase, we should be prepared to advise the parents on some practical alternatives to a physical response. Such advice is welcomed by most types of families. Any treatment plan for an abusive family that fails to include this type of problem solving may be inadequate.

Anxiety, Separation↗

PubMed1998

Seizure patterns of Mongolian gerbils subjected to a prolonged weekly test schedule: evidence for a kindling-like phenomenon in the adult population.

PURPOSE: Mongolian gerbils (Meriones unguiculatus) seize in response to sensory stimulation and forced exploratory behavior, but the incidence and severity of their seizures are variable. We wished to characterize the seizure pattern of gerbils from our breeding colony. METHODS: Ninety-three gerbils aged 1-16 months were tested for a mean of 24 consecutive weeks and assigned to a category according to their seizure pattern. Frequency distribution histograms of the mean scores assigned every 5 weeks were plotted for each category. Mean age, number of seizures, onset of the first facial and forelimb myoclonus, and of the first generalized tonic-clonic seizure (GTCS) were compared among categories. We performed correlation analysis between onset of seizures and animal age. RESULTS: From the 93 tested, no seizure-resistant gerbils could be isolated. Four major categories were distinguished. Category 1, highly seizure-sensitive gerbils (39%), exhibited seizures from the first few weeks of test on. Category 2, consisting of approximately 37%, were seizure-free for the first three to six consecutive tests, later developing facial and forelimb myoclonus and eventually GTCS. Because such progressive development of seizures was similar to that occurring upon electrical kindling, the gerbils were classified as kindled-like (KL). Among KL gerbils, older individuals were significantly more refractory to seizures. In category 3, gerbils (10%) exhibited inconsistent seizure behavior. Category 4 consisted of significantly younger animals (11%) with rapid progress to generalized seizures. CONCLUSIONS: Seizures of progressive severity can be induced in adult gerbils with a prolonged test regimen. As a consequence, the number of regularly seizing gerbils in a colony can be increased. Prolonged tests starting at a defined age may help characterize seizure development better in this genetic model of limbic epilepsy.

Age Factors↗

PubMed1991

Treatment with methylazoxymethanol at different gestational days: two-way shuttle box avoidance and residential maze activity in rat offspring.

Pregnant rats were injected with a single dose of methylazoxymethanol (MAM, 25 mg/kg) on gestational days 14, 15, 16, 17, 18 or 19 which resulted in various degrees of microencephaly. Offspring were tested on a two-way shuttle box avoidance and residential maze activity at 60-90 days of age. Rats treated on gestational day 19 (GD19) were severely impaired in the acquisition of the two-way shuttle box task whereas the other groups did not show any significant difference from controls. Spontaneous activity measured for 23 hr in the residential maze was altered as total, time-course and pattern depending on the time of MAM administration: treatment on GD14 prolonged exploratory behavior, treatment on GD15 and GD16 increased nocturnal activity, treatment on GD16 and GD17 induced changes in locomotion patterns and treatment on GD18 and GD19 decreased total activity. These findings indicate that treatment with MAM results in selective deficits in the acquisition of a shuttle box avoidance and alterations of locomotion patterns in the offspring which are dependent on the time of administration.

Alkylating Agents↗

PubMed1984

Deviations on exploration, attachment, and fear of strangers in high-risk and control infants at one year of age.

Exploratory behavior and deviations on three dimensions--fear of strangers, attachment to mother, and exploration--were studied in 46 infants of mothers with a history of psychosis and 80 control infants. While high-risk infants did not differ from controls on exploration alone, they showed multiple deviations on the three dimensions more frequently than did controls, especially in the case of offspring of schizophrenic mothers.

Affective Disorders, Psychotic↗

PubMed1985

Effect of trichloroethylene on the exploratory and locomotor activity of rats exposed during development.

Trichloroethylene (TCE) is a common contaminant of underground water supplies. To examine the effect of TCE on the developing central nervous system, rats were exposed to TCE throughout gestation until 21 days postpartum via their dams' drinking water. TCE concentrations of 312 mg/l, 625 mg/l and 1250 mg/l were tested. Exploratory behavior was higher in 60- and 90-day old male rats which were exposed to any level of TCE. The effect of TCE-exposure on locomotor activity (running wheel) was also examined in 60-day old males (625 and 1250 ppm exposure groups). Locomotor activity was significantly higher in rats exposed to 1250 ppm TCE. These data suggest that TCE has long-term effects on behaviour.

Aging↗