Changes In General Activity Research Articles

ACAD10 protein expression and Neurobehavioral assessment of Acad10-deficient mice.

Acyl-CoA dehydrogenase 10 (Acad10)-deficient mice develop impaired glucose tolerance, peripheral insulin resistance, and abnormal weight gain. In addition, they exhibit biochemical features of deficiencies of fatty acid oxidation, such as accumulation of metabolites consistent with abnormal mitochondrial energy metabolism and fasting induced rhabdomyolysis. ACAD10 has significant expression in mouse brain, unlike other acyl-CoA dehydrogenases (ACADs) involved in fatty acid oxidation. The presence of ACAD10 in human tissues was determined using immunohistochemical staining. To characterize the effect of ACAD10 deficiency on the brain, micro-MRI and neurobehavioral evaluations were performed. Acad10-deficient mouse behavior was examined using open field testing and DigiGait analysis for changes in general activity as well as indices of gait, respectively. ACAD10 protein was shown to colocalize to mitochondria and peroxisomes in lung, muscle, kidney, and pancreas human tissue. Acad10-deficient mice demonstrated subtle behavioral abnormalities, which included reduced activity and increased time in the arena perimeter in the open field test. Mutant animals exhibited brake and propulsion metrics similar to those of control animals, which indicates normal balance, stability of gait, and the absence of significant motor impairment. The lack of evidence for motor impairment combined with avoidance of the center of an open field arena and reduced vertical and horizontal exploration are consistent with a phenotype characterized by elevated anxiety. These results implicate ACAD10 function in normal mouse behavior, which suggests a novel role for ACAD10 in brain metabolism.

THE SUB CHRONIC TOXIC EFFECT OF VOODOO EXTRACT ON THE CENTRAL NERVOUS SYSTEM IN ADULT MALE ALBINO RATS

Abstract Introduction: Voodoo is a mixture of herbs and spices that are sprayed with a synthetic compound that mimics the effects of Cannabis. The widespread over-the-counter availability of these products made these compounds the 2nd most common frequently used recreational drug after marijuana in teenagers and young adults. This study aimed to investigate the sub chronic toxic effects of Voodoo (Voodoo abuse) on the central nervous system (CNS) in adult male albino rats. Methodology: thirty adult male albino rats were divided into three equal groups; negative control group, positive control group, and Voodoo extract treated group. Behavioral tests, neurotransmitter concentration in brain tissues and histopathological examination of brain tissues were performed. Results: general activity changes, significant decrease in food intake, feces formation and weight gain were reported between control and Voodoo treated group. The behavioral Y maze test revealed significant inhibition of the spontaneous alternation while, locomotor activity and rotarod test revealed significant inhibition of the neuromuscular coordinative function. The neurotransmitters (serotonin, dopamine, adrenaline and noradrenaline) assaying in the brain tissues of Voodoo treated group revealed significant decrease. These neurological changes were supported by the histopathological findings in the form of shrunken cells with dense nuclei and vacuolated cytoplasm in addition to the positive cytoplasmic immunoreaction for caspase -3 in the brain tissues. Conclusion: Voodoo extract was found to have a functional and structural deleterious CNS effect with sub chronic exposure in adult male albino rats.

Development of an environmental enrichment programme: case study of white Bengal tiger (Panthera tigris bengalensis) and jaguar (Panthera onca) at Moscow Zoo

Zoos are urged to implement enrichment programmes that include constant feedback to increase efficacy. However, such work is time consuming for zookeepers. The goal of this case study was to establish an enrichment programme in Moscow Zoo that could be used by keepers with minimal effort. In this brief study, an enrichment programme was established for one female white Bengal tiger (Panthera tigris bengalensis) and one female jaguar (Panthera onca). Observations were recorded from February through March 2015. The effects of three enrichment regimes were evaluated: Baseline (routine husbandry: familiar or novel items once or twice a week) compared with two novel intensive regimes: Regime 1 (enrichment provided every day) and Regime 2 (enrichment provided every other day). Two simple methods were used to evaluate the effects of regimes: the “multi-point scan” method where animals’ behaviour was recorded 6 times a day by the keepers as they passed the exhibits during their working day, and “SPIDER indirect scales”. It was found that the use of both methods for documenting behaviour improved the accuracy of evaluations. During Regimes 1 and 2, behaviour directed at enrichment increased for the tiger and jaguar, but changes in general activity were identified only for the tiger. Consequently, the keepers were able to develop an enrichment programme, including the collection of objective empirical data in a time-efficient manner. It is therefore proposed that zoological institutions use enrichment programmes that integrate both “SPI” and “DER” steps into daily work.

The influence of LPS and zinc on interaction between mother and offspring

IntroductionThe maternal behavior consists of a set of behavioral and physiological changes in adults, performed around the reproductively immature individuals, ensuring their survival and propagation of the species. Offsprings give signal to be collected when separated from their mother through olfactory, visual and sound signals. Infection and its influence in the context of the interaction between mother and offspring is poorly investigated. The classic disease model, which is widely used, involves the treatment with lipopolysaccharide (LPS), the major component of the cell wall of Gram‐negative bacteria. The infections can activate a chain of nonspecific host responses, including the immune response and levels of zinc.ObjectiveTo investigate the behavioral and neuroimmunological adaptations of rats and their offspring resulting from experimental inflammation produced by LPS and the possible influence of zinc treatment on these adaptations.MethodsIn this study, virgin, pregnant and lactating female rats received LPS (100 μg/kg, ip) and then were treated with zinc (2 mg/kg, sc). Temperature, body weight, water and food consumption were measured for ninety‐six hours, starting two hours after LPS administration. On the fifth day of lactation, maternal behavior, the overall activity in the open field and ultrasonic vocalization in offsprings were observed. On the day of weaning, pups of these females received a challenge with LPS (50 μg/kg, ip) and two hours after administration were observed for general activity in the open field. The burst and phagocytosis of leukocytes in the blood of pups was also studied.Results1) in virgin, pregnant and lactating rats, the exposure to LPS and the treatment with zinc modified the temperature, body weight, water and food consumption, and the general activity observed in the open field. Virgin, pregnant or lactating rats responded differently to this treatment. 2) In the lactation period the latency to search the first pup was reduced. 3) In the offspring, a change in the pattern of vocalization of the offspring, changes in general activity observed in the open field and changes in the burst and phagocytosis of leukocytes on the twenty‐first day of lactation after challenge with endotoxin were detected.Conclusionthe results indicate that administration of LPS and treatment with zinc have effects modulated according to the physiological stage of the female. These effects interfere with the interaction between a mother and her offspring, resulting in short and long term effects in offspring's behavior. Exposure of mothers to bacterial endotoxin modulates the effects caused by zinc and programs the inflammatory responses in the offspring.Support or Funding InformationCoordination for the Improvement of Higher Education Personnel (CAPES)Natural Sciences and Engineering Research Council (NSERC)Canadian Centre for Health and Safety in Agriculture (CCHSA)This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Primary-Care Weight-Management Strategies: Parental Priorities and Preferences

ObjectiveTo examine parental perspectives/rankings of the most important weight-management clinical practices and to determine whether preferences/rankings differ when parents disagree that their child is overweight. MethodsWe performed mixed-methods analysis of a 32-question survey of parents of 2- to 18-year-old overweight children assessing parental agreement that their child is overweight, the single most important thing providers can do to improve weight status, ranking American Academy of Pediatrics–recommended clinical practices, and preferred follow-up interval. Four independent reviewers analyzed open-response data to identify qualitative themes/subthemes. Multivariable analyses examined parental rankings, preferred follow-up interval, and differences by agreement with their child's overweight assessment. ResultsThirty-six percent of 219 children were overweight, 42% obese, and 22% severely obese; 16% of parents disagreed with their child's overweight assessment. Qualitative analysis of the most important practice to help overweight children yielded 10 themes; unique to parents disagreeing with their children's overweight assessments was “change weight-status assessments.” After adjustment, the 3 highest-ranked clinical practices included, “check for weight-related problems,” “review growth chart,” and “recommend general dietary changes” (all P < .01); parents disagreeing with their children's overweight assessments ranked “review growth chart” as less important and ranked “reducing screen time” and “general activity changes” as more important. The mean preferred weight-management follow-up interval (10–12 weeks) did not differ by agreement with children's overweight assessments. ConclusionsParents prefer weight-management strategies that prioritize evaluating weight-related problems, growth-chart review, and regular follow-up. Parents who disagree that their child is overweight want changes in how overweight is assessed. Using parent-preferred weight-management strategies may prove useful in improving child weight status.

Antidepressant-like effect of Hoodia gordonii in a forced swimming test in mice: evidence for involvement of the monoaminergic system.

Hoodia gordonii is a plant species used traditionally in southern Africa to suppress appetite. Recently, it has been associated with a significant increase in blood pressure and pulse rate in women, suggesting sympathomimetic activity. The present study investigated the possible antidepressant-like effects of acute and repeated (15 days) administration of H. gordonii extract (25 and 50 mg/kg, po) to mice exposed to a forced swimming test (FST). Neurochemical analysis of brain monoamines was also carried out to determine the involvement of the monoaminergic system on these effects. Acute administration of H. gordonii decreased the immobility of mice in the FST without accompanying changes in general activity in the open-field test during acute treatment, suggesting an antidepressant-like effect. The anti-immobility effect of H. gordonii was prevented by pretreatment of mice with PCPA [an inhibitor of serotonin (5-HT) synthesis], NAN-190 (a 5-HT1A antagonist), ritanserin (a 5-HT2A/2C antagonist), ondansetron (a 5-HT3A antagonist), prazosin (an α1-adrenoceptor antagonist), SCH23390 (a D1 receptor antagonist), yohimbine (an α2-adrenoceptor antagonist), and sulpiride (a D2 receptor antagonist). A significant increase in 5-HT levels in the striatum was detected after acute administration, while 5-HT, norepinephrine and dopamine were significantly elevated after chronic treatment. Results indicated that H. gordonii possesses antidepressant-like activity in the FST by altering the dopaminergic, serotonergic, and noradrenergic systems.

Cattle Responses to a Type of Virtual Fence

Interest in developing more flexible fencing technology to improve pasture and rangeland management is increasing. The objective of this study was to test the efficacy of a new virtual fencing product and measure impact on behavior, thus potentially allowing positive development of virtual fence systems. The Boviguard (Agrifence, Henderson Products Ltd., Gloucester, UK) invisible fence is now commercially available, consisting of cow collars, a battery-based transformer, and an induction cable laid on the ground or buried in the ground. As the Boviguard collar comes close to the induction cable, a warning sound is triggered and if the animal continues to move closer, an electrical stimulus is triggered. We tested this novel system on 10 cows wearing global positioning system (GPS) collars to pinpoint location and activity sensors to gather behavioral data. Two separate exclusion zones were created consecutively in different areas of a test field, with alternate periods of control, with no fence activity, and virtual fence activation. The system successfully prevented the animals from crossing the virtual fence line. No changes in general activity or lying behavior were found. There were significant changes in the pattern of use of the rest of the field area when the fencing system was activated. When only the unactivated cable was left on the ground in a final control period, the visual cue alone deterred animals from entering the exclusion area. The trial showed the effectiveness of a collar-based electrical stimuli system. This approach to virtual fencing could provide solutions for management systems where moving fences frequently is required, such as for strip grazing, nature conservation management of specific areas and habitats, and grazers of land where physical fences are not preferred or feasible.

Rapid behavioural gregarization in the desert locust, Schistocerca gregaria entails synchronous changes in both activity and attraction to conspecifics

Desert Locusts can change reversibly between solitarious and gregarious phases, which differ considerably in behaviour, morphology and physiology. The two phases show many behavioural differences including both overall levels of activity and the degree to which they are attracted or repulsed by conspecifics. Solitarious locusts perform infrequent bouts of locomotion characterised by a slow walking pace, groom infrequently and actively avoid other locusts. Gregarious locusts are highly active with a rapid walking pace, groom frequently and are attracted to conspecifics forming cohesive migratory bands as nymphs and/or flying swarms as adults. The sole factor driving the onset of gregarization is the presence of conspecifics. In several previous studies concerned with the mechanism underlying this transformation we have used an aggregate measure of behavioural phase state, Pgreg, derived from logistic regression analysis, which combines and weights several behavioural variables to characterise solitarious and gregarious behaviour. Using this approach we have analysed the time course of behavioural change, the stimuli that induce gregarization and the key role of serotonin in mediating the transformation. Following a recent critique that suggested that using Pgreg may confound changes in general activity with genuine gregarization we have performed a meta-analysis examining the time course of change in the individual behaviours that we use to generate Pgreg. We show that the forced crowding of solitarious locusts, tactile stimulation of the hind femora, and the short-term application of serotonin each induce concerted changes in not only locomotion-related variables but also grooming frequency and attraction to other locusts towards those characteristic of long-term gregarious locusts. This extensive meta-analysis supports and extends our previous conclusions that solitarious locusts undergo a rapid behavioural gregarization upon receiving appropriate stimulation for a few hours that is mediated by serotonin, at the end of which their behaviour is largely indistinguishable from locusts that have been in the gregarious phase their entire lives.

Cognitive dysfunction syndrome in dogs and cats.

Abstract Some ageing pets developed cognitive dysfunction syndrome (CDS), which is equivalent to dementia or Alzheimer's disease (AD) in people. Both CDS and AD share similar pathological changes including cortical atrophy with irreversible loss of brain cells, cerebral amyloid angiopathy and ventricular enlargement. Clinical signs of CDS include disorientation, social interaction changes, sleep/wake disturbances, house soiling and general activity changes. The risk factors and causes of CDS in dogs and cats have not been fully investigated, but age, gender, oxidative stress and sex hormone deficiency appear to be associated with increased risk of CDS in dogs. Both AD and CDS are incurable diseases currently, therefore greater efforts should be focused on preventing or reducing brain atrophy, and minimizing the risk of AD in people and CDS in pets. A number of nutritional approaches for enhancing cognitive function and promoting healthy brain ageing are briefly discussed.

A pheromone mechanism for swaying female mate choice: enhanced affinity for a sexual stimulus in a woodland salamander

Traditionally, male signals have been thought to function in satisfying female choice by conveying meaningful information about a potential mate. However, the male signal, rather than merely providing raw material for female evaluation, may actively modulate a female’s intrinsic preferences or decision-making capabilities in favour of a given male. We propose two broad mechanisms by which male signals could modulate female behaviour: (1) specific augmentation of sexual motivation or (2) heightened general arousal. Specifically, we investigated the ability of a generic male pheromone mix to elicit changes in general activity or affinity for different classes of stimuli in female terrestrial salamanders ( Plethodon shermani ). Attraction to male olfactory stimuli was significantly increased by pheromones, but attraction to visual stimuli and nonsexual olfactory stimuli remained unaffected, as did locomotor activity. These results are consistent with the hypothesis that sex pheromones activate specific behavioural subsystems associated with augmented sexual motivation. This pheromone action may still function within the context of information-transfer signalling, for example, if pheromones influence female choice by affecting (1) sensory processing of relevant stimuli, (2) the value assigned to a set of sexual stimuli, or (3) the criteria used to decide whether to mate.

Anxiolytic- and antidepressant-like properties of ketamine in behavioral and neurophysiological animal models

Ketamine, a dissociative anesthetic agent, appears to have rapid antidepressant effects at sub-anesthetic doses in clinically depressed patients. Although promising, these results need to be replicated in double-blind placebo-controlled studies, a strategy thwarted by the psychoactive effects of ketamine, which are obvious to both patients and clinicians. Alternatively, demonstrations of the psychotherapeutic effects of ketamine in animal models are also complicated by ketamine's side-effects on general activity, which have not been routinely measured or taken into account in experimental studies. In this study we found that ketamine decreased “behavioral despair” in the forced swim test, a widely used rats model of antidepressant drug action. This effect was not confounded by side-effects on general activity, and was comparable to that of a standard antidepressant drug, fluoxetine. Interestingly, ketamine also produced anxiolytic-like effects in the elevated-plus-maze. Importantly, the effective dose of ketamine in the plus-maze did not affect general locomotion measures, in either the plus-maze or in the open field test. While the selective N-methyl-d-aspartic acid (NMDA) receptor antagonist MK-801 also produced antidepressant-like and anxiolytic-like effects, these were mostly confounded by changes in general activity. Finally, in a neurophysiological model of anxiolytic drug action, ketamine reduced the frequency of reticularly-activated theta oscillations in the hippocampus, similar to the proven anxiolytic drug diazepam. This particular neurophysiological signature is common to all known classes of anxiolytic drugs (i.e. benzodiazepines, 5-HT1A agonists, antidepressants) and provides strong converging evidence for the anxiolytic-like effects of ketamine. Further studies are needed to understand the underlying pharmacological mechanisms of ketamine's effects in these experiments, since it is not clear they were mimicked by the selective NMDA antagonist MK-801.

Effects of the essential oils of Lippia turbinata and Lippia polystachya (Verbenaceae) on the temporal pattern of locomotion of the mosquito Culex quinquefasciatus (Diptera: Culicidae) larvae

The essential oils (EO) of Lippia turbinata (TUR) and Lippia polystachya (POL) have shown lethal effects against mosquito larvae. The present work evaluated whether these EO at doses ranging from sublethal to lethal (20, 40 and 80 ppm) modify the temporal pattern of locomotion of Culex quinquefasciatus larvae. Larvae were individually placed in glass boxes, and their activity recorded at 0.3 s intervals during 40 min. Individuals treated with doses >40 ppm of either EO significantly decreased their ambulation speed and the percentage of total time ambulating compared to controls. TUR 80 ppm decreased their ambulation even sooner than POL 80 ppm, when compared to their respective controls. These findings are consistent with the neurotoxic effect against insects attributed to alpha-Thujone, a main component of both EO. A detrended fluctuation fractal analysis evaluating the complexity and organisation of the temporal pattern of locomotion showed fractal patterns in all animals. Both sublethal and lethal doses of TUR and POL increased the complexity of ambulation. Interestingly, for POL 20 ppm, an increase in complexity was observed, while no changes in general activity were detected, suggesting that fractal analysis may be more sensitive to detect behavioural changes than general activity evaluation.

A conscious mouse model of gastric ileus using clinically relevant endpoints

BackgroundGastric ileus is an unsolved clinical problem and current treatment is limited to supportive measures. Models of ileus using anesthetized animals, muscle strips or isolated smooth muscle cells do not adequately reproduce the clinical situation. Thus, previous studies using these techniques have not led to a clear understanding of the pathophysiology of ileus. The feasibility of using food intake and fecal output as simple, clinically relevant endpoints for monitoring ileus in a conscious mouse model was evaluated by assessing the severity and time course of various insults known to cause ileus.MethodsDelayed food intake and fecal output associated with ileus was monitored after intraperitoneal injection of endotoxin, laparotomy with bowel manipulation, thermal injury or cerulein induced acute pancreatitis. The correlation of decreased food intake after endotoxin injection with gastric ileus was validated by measuring gastric emptying. The effect of endotoxin on general activity level and feeding behavior was also determined. Small bowel transit was measured using a phenol red marker.ResultsEach insult resulted in a transient and comparable decrease in food intake and fecal output consistent with the clinical picture of ileus. The endpoints were highly sensitive to small changes in low doses of endotoxin, the extent of bowel manipulation, and cerulein dose. The delay in food intake directly correlated with delayed gastric emptying. Changes in general activity and feeding behavior were insufficient to explain decreased food intake. Intestinal transit remained unchanged at the times measured.ConclusionFood intake and fecal output are sensitive markers of gastric dysfunction in four experimental models of ileus. In the mouse, delayed gastric emptying appears to be the major cause of the anorexic effect associated with ileus. Gastric dysfunction is more important than small bowel dysfunction in this model. Recovery of stomach function appears to be simultaneous to colonic recovery.

Absence of anxiolytic response to chlordiazepoxide in two common background strains exposed to the elevated plus-maze: importance and implications of behavioural baseline.

Although genetic background is acknowledged as a potentially important determinant of mutant phenotypes, publications on genetically modified mice far outnumber those on progenitor strains. We have recently reported major differences in basal anxiety levels (elevated plus-maze & light/dark exploration) among three strains (C57BL/6JOlaHsd, 129/SvEv and 129S2/SvHsd) employed as progenitor stock in European laboratories (Rodgers et al. in press). Furthermore, the phenotypes of these inbred strains differed significantly from that of an outbred strain (Swiss-Webster) commonly used in behavioural pharmacology. In view of these findings, the present study assessed possible differences in the anxiolytic efficacy of chlordiazepoxide (0, 7.5 & 15.0 mg/kg, IP) in three of these strains (Swiss-Webster (SW), C57BL/6JOIaHsd (C57) & 129S2/SvHsd (129)). Experimentally naive mice were exposed to the elevated plus-maze, sessions were videotaped and behaviour analysed using ethological software. The performance of control subjects confirmed significant strain differences in basal levels of activity (SW > C57 > 129) and anxiety-related behaviours (129 = SW > C57), with hypolocomotion dominating the 129 profile. SW mice displayed an anxioselective response to both doses of chlordiazepoxide (CDP), with significant reductions in open arm avoidance and risk assessment observed in the absence of any change in general activity. In direct contrast, the lower dose of CDP (7.5 mg/kg) was without effect in either inbred strain, whereas treatment with 15.0 mg/kg induced a profile indicative of muscle relaxation/mild sedation in C57 mice and virtually abolished all behavioural activity in 129 mice. Although the absence of an anxiolytic response to CDP in C57 mice may be attributed to their low basal anxiety levels, the profile of 129 mice strongly suggests an abnormality in benzodiazepine/GABAA receptor function. The implications of these findings for research on mutant mice are discussed.

Effects of excitotoxic lesions of the basolateral amygdala on cocaine-seeking behavior and cocaine conditioned place preference in rats

Incentive motivation for cocaine, elicited by cocaine-associated stimuli, is thought to be involved in craving and relapse. To examine the role of the basolateral amygdala complex (BLC) in this phenomenon, we assessed the effects of post-training BLC lesions on extinction of cocaine-seeking behavior and cocaine-conditioned place preference (CPP) and the effects of pre-training BLC lesions on acquisition of cocaine-CPP. In Experiment 1, rats were first trained to self-administer cocaine and then received bilateral infusions of the excitotoxin, N-methyl- d-aspartic acid (NMDA, 0.12 M; 0.3 μl/side), or vehicle into the BLC. They were then tested repeatedly for extinction of cocaine-seeking behavior (i.e. nonreinforced responses in the presence of cocaine-paired stimuli). Subsequently, they were trained and tested for acquisition of cocaine-CPP (i.e. increased time spent in a previously cocaine-paired, relative to a saline-paired, environment). Locomotion and compartment entries were also measured. In Experiment 2, rats were first trained and tested for cocaine-CPP, and then received NMDA or vehicle infusions into the BLC. Subsequently, they were tested repeatedly for extinction of cocaine-CPP. Post-training BLC lesions retarded extinction of cocaine-seeking behavior and cocaine-CPP, whereas pre-training lesions disrupted acquisition of cocaine-CPP. These effects did not appear to be related to changes in general activity. We suggest that pre-training BLC lesions disrupted acquisition of cocaine-CPP by impairing assignment of incentive value to cocaine-paired stimuli, whereas post-training BLC lesions disrupted extinction of cocaine-conditioned behaviors by impairing the assessment of the current incentive value of cocaine-paired stimuli.

Behavioural changes in Schistocerca gregaria following infection with a fungal pathogen: implications for susceptibility to predation

Summary1. Field observations have indicated that infection of locusts and grasshoppers by the fungal entomopathogen Metarhizium anisopliae var. acridum may result in a substantial increase in the host's susceptibility to predation, before death is caused directly by the disease.2. Laboratory experiments were conducted to examine how the behaviour of the desert locust Schistocerca gregaria Forskål changes following infection by M. anisopliae var. acridum to explore some potential mechanisms underlying this phenomenon.3. In the first experiment, which involved monitoring general locust activity in small cages throughout the disease incubation period, infected locusts were observed to increase locomotion and bodily movement from 3 days after infection until death (average survival time of 11 days). There was some evidence of reduced feeding and mating behaviour following infection.4. In a second experiment, locusts were exposed individually to a simulated predator attack and the initiation and strength of any escape responses were measured. Infected locusts were observed to have a reduced escape capability (both the propensity to escape and the strength of the response). In contrast to the relatively early changes in general activity observed in the first experiment, this was only apparent at the late stages of infection shortly before death.5. Both an increase in movement and general apparency early in the infection process, and reduced escape capability late on, suggest mechanisms whereby the susceptibility of locusts and grasshoppers to predation might be enhanced following infection with M. anisopliae var. acridum.

Diurnal Variation of Plasmatic Melatonin, Corticosterone and Variation of General Activity in Pigeons under Light-Dark Cycle and Constant Light

This work analyzed the diurnal variation of general activity and plasmatic levels of melatonin and corticosterone in pigeons submitted to a 12:00:12:00 h light-dark cycle (lights on at 6:00 a.m.) or to constant light. In both conditions pigeons were observed in 5-min sessions at times 03:00, 06:00, 09:00, 12:00, 15:00, 18:00, 21:00 and 24:00 h during two successive days. Behavior was video taped in the home cages for posterior categorization and quantification. Radioimmunoassays were used to evaluate plasmatic levels of melatonin and corticosterone. Blood samples were obtained at the times of behavioral observation. In the light-dark condition the results showed day-night variation of general activity (p < 0.001) and a robust diurnal rhythm of plasmatic melatonin (p < 0.001). Both of these variations as well as the oscillatory secretion of corticosterone disappeared under constant light condition. The parallel changes in general activity and blunting of melatonin rhythm secretion in constant light condition agree with previous evidences that melatonin may regulate behavioral oscillations in the pigeon. The present data are related to the proposition that the timing system in pigeons may involve neuroendocrine relations characterized by interactions between blood born signalization by melatonin and corticosterone.

Does Foraging Activity Change with Ontogeny? An Assessment for Six Sympatric Species of Postmetamorphic Litter Anurans in Central Amazonia

Does Foraging Activity Change with Ontogeny? An Assessment for Six Sympatric Species of Postmetamorphic Litter Anurans in Central Amazonia

Within-Session Patterns of Pigeons' General Activity

The study investigates the idea that within-session changes in responding are produced by arousal and satiation. General activity, measured by the displacement of floor panels, was used as an index of these variables. In Experiment 1, pigeons pecked a key on a simple variable-interval schedule and general activity was also recorded. In Experiment 2, pigeons received response-independent reinforcers. In Experiment 3, the pigeons' general activity was reinforced on a variable-interval schedule. Although significant within-session changes in operant key pecking were observed in Experiment 1, within-session changes in general activity were seldom observed in either Experiment 1 or Experiment 2. Significant within-session changes in general activity were observed in Experiment 3, when activity was the operant. The present results can potentially be explained by arousal and satiation. However, the predictive power of this explanation is severely limited. Regardless of whether one accepts arousal and satiation as the theoretical explanation for within-session changes in responding, the present results suggest that aspects of the response–reinforcer relation may determine the within-session pattern of responding.

Illness-induced context aversion learning in rats with lesions of the dorsal hippocampus.

In 2 experiments, rats with electrolytic lesions of the dorsal hippocampus and sham-operated control subjects were given injections of lithium chloride after exposure to a distinctive context. This procedure establishes a context-illness association in intact subjects. In Experiment 1, the strength of the context aversion was assessed by measuring the subjects' willingness to consume a novel flavor in the context. It was found that lesioned subjects showed less suppression of consumption than controls. Experiment 2 tested the ability of the context to block subsequent flavor-aversion learning and revealed less effective blocking in lesioned rats. These results are consistent with the view that hippocampal lesions retard context conditioning; unlike previous work that has made use of conditioned freezing as the measure of context conditioning, the present results are not explicable in terms of lesion-induced changes in general activity.