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At least 919 records · Page 51Linked to original sources
PubMed2004

Effects of odor flux and pulse rate on chemosensory tracking in turbulent odor plumes by the blue crab, Callinectes sapidus.

The ability of animals to track through chemical plumes is often related to properties of evanescent odor bursts and to small-scale mixing process that determine burst properties. However, odor plumes contain variation over a range of scales, and little is known about how variation in the properties of the odor signal on the scale of one to several seconds affects foraging performance. We examined how flux and pulse rate interact to modulate the search behavior of blue crabs, Callinectes sapidus, locating odor sources in controlled flume flows. Experimental treatments consisted of continuous plumes and plumes with discrete odor pulses at intervals of 2.5 s and 4 s at two fluxes. Crabs experienced diminished search success and reduced search efficiency as flux decreased and the inter-pulse interval lengthened. There often were significant interactions between flux and pulse length, and neither property completely determined search behavior. Thus, over the time span of several seconds, the blue crab chemosensory system is not a simple flux detector. The sensitivity of blue crabs to inter-pulse intervals in the range of several seconds indicates that larger-scale mixing processes, which create odor variation on comparable scales, may exert a significant impact on foraging success in nature.

Analysis of Variance↗
PubMed1997

Cocaine impairs acquisition of an autoshaped lever-touch response.

The effects of daily peripheral (IP) post-session injection of cocaine on the development of an autoshaped lever-touch response in rats were investigated. Male Sprague-Dawley rats received ten daily pairings of a retractable lever (conditioned stimulus; CS) and food delivery (unconditioned stimulus; UCS). Food delivery occurred if the subjects contacted the extended lever within 10 s, or, if the subjects failed to contact the lever, at the end of the 10-s stimulus interval. These contingencies resulted in increased lever-touch responses over 10 days of conditioning. Cocaine (5.6-19.0 mg/kg) impaired development of the lever-touch response, as compared to saline-treated control subjects. Because the injections were given immediately after each conditioning session, we suggest that cocaine affects the neural processes involved in consolidation. Three additional control experiments support this suggestion. The effect of cocaine on lever-touch acquisition was time-dependent as daily injection of cocaine (5.6 mg/kg) 3 h after each conditioning session did not affect lever-touch acquisition. In addition, the effect of cocaine was dependent upon the explicit pairing of lever extension (CS) and food delivery (UCS) as immediate post-session cocaine (5.6 mg/kg) administration did not alter responding when the presentation of both the CS and the UCS was uncorrelated. Cocaine (5.6 mg/kg) administered to subjects previously trained to a performance criterion did not affect lever-touch responding, indicating that cocaine administration (5.6 mg/kg) impairs the development, but not the maintenance, of autoshaped lever-touch responding. In contrast, the highest dose of cocaine tested, 19.0 mg/kg, did decrease lever-touch responding in well-trained subjects, indicating that post-session administration of higher doses of cocaine can produce aversive effects that may affect both the acquisition and maintenance of appetitively motivated behavior in the rat. The relative contributions of the instrumental and classical associations inherent in the autoshaping procedure were investigated by altering response contingencies. Rats showed no evidence of learning the lever-touch response when lever insertion and food delivery were positively correlated, and no explicit response contingency was present (classical conditioning); further, cocaine-treated subjects did not differ from saline-treated subjects. However, cocaine did impair lever-touch responding in the instrumental version of the task. Taken together, these results show that the post-session administration of cocaine can impair the acquisition of a multi-trial, multi-session appetitively motivated response.

Animals↗
PubMed2000

Recovery from early cortical damage in rats, VIII. Earlier may be worse: behavioural dysfunction and abnormal cerebral morphogenesis following perinatal frontal cortical lesions in the rat.

The size of cortical removal was varied in rats that were given medial frontal lesions on postnatal day 2. In adulthood, the animals were trained on the Morris water task and Whishaw reaching task following which the brains were harvested and dendritic arborization and spine density was examined in the layer III pyramidal cells in Zilles' area Par1. There was a small relationship between lesion size and behavioral outcome as smaller lesions produced somewhat smaller deficits. In contrast, both small and large lesions produced large reductions in brain weight, dendritic arborization, and spine density. The cortex of newborn rats appears to be especially vulnerable to even restricted injury. This contrasts to the effects of similar injury a week later when animals show extensive functional recovery and anatomical compensation.

Analysis of Variance↗
PubMed2000

Prefrontal cortical manipulations alter the effects of intra-ventral striatal dopamine antagonists on fixed-interval performance in the rat.

The nature of the functional relationships between areas of prefrontal cortex and ventral striatum remain undefined. This study was designed to examine functional interactions between activity in two areas of prefrontal cortex, the prelimbic (PL) and agranular insular (AI) areas, and ventral striatal (VS) dopamine (DA) function. Interactions were assessed using a Fixed Interval (FI) schedule of reinforcement shown previously in our laboratory to be modulated by VS DA function. The study compared changes in FI performance following intra-VS DA antagonist injections alone (SCH23390 + eticlopride) to those observed when either saline or saline + lidocaine were injected into prefrontal cortex after the intra-VS DA antagonist injections. The intra-VS DA antagonists alone decreased FI response rates and increased postreinforcement pause times at both dose combinations (1/0.1 and 3/0.3 microg of SCH23390/eticlopride per side). Neither saline nor saline + lidocaine injected into the PL area of prefrontal cortex altered the effects of intra-VS DA antagonists on FI performance. Saline administration into the AI area of prefrontal cortex, however, eliminated the FI rate-decreasing effects of intra-VS DA antagonists. The agent or mechanism of this effect, whether it be saline, the act of inserting the cannulae into the cortical tissue, or the act of injecting fluid into this tissue, is not clear. This effect of AI saline was prevented by coadministration of lidocaine with saline into AI. These results, coupled with those from a previous experiment examining lesion effects in PL and AI on FI performance (Evans SB, Cory-Slechta DA. The effects of temporary lesions of the insular and medial prefrontal cortex on fixed-interval schedule-controlled behavior in the rat, Soc Neurosci Abstr 1996;22(1):159) suggest that PL might exert a tonic influence on VS DA function, since FI response rates gradually increase over a 2-week period following lesions of PL. In contrast, AI, although not normally modulating FI performance, can apparently influence VS DA function, possibly when alterations in activity are invoked in AI.

Animals↗
PubMed1975

Ethological studies in the ant Tetramorium caespitum Mayr. II. Interspecific relationships.

The structure of relationships between the neighboring species of ants is characterized by great variability. What happens when particular individuals meet - depends upon considerable differences between individual behaviors of ants and a number of variable factors determining the actual emotional state of the workers. From these factors, it is the general structure of forces between the nests that changes slowest, and may be responsible for reaching temporary stabilization of the interspecific relationships. Invariable hierarchical structure between the species occurs very rarely: when there is an enormous supremacy of one of the species.

Animals↗
PubMed1992

Failure of a chlordiazepoxide to reproduce the behavioral effects of muscimol administered into the basal forebrain.

Bilateral infusion of the GABAA-receptor agonist muscimol into the basal forebrain was previously found to impair visual conditional discrimination performance in rats. In order to examine whether the GABAergic input into the basal forebrain is active during performance of this task, the benzodiazepine receptor agonist chlordiazepoxide (15, 25, 40 micrograms/0.5 microliters/hemisphere) was bilaterally infused. Surprisingly, chlordiazepoxide did not affect performance. The impact of this result for the understanding of basal forebrain GABAergic functions is discussed.

Animals↗
PubMed2001

Cytokine-induced sickness behavior: mechanisms and implications.

Sickness behavior refers to a coordinated set of behavioral changes that develop in sick individuals during the course of an infection. At the molecular level, these changes are due to the brain effects of proinflammatory cytokines such as interleukin-1 (IL-1) and tumor necrosis factor alpha (TNFalpha). Peripherally released cytokines act on the brain via a fast transmission pathway involving primary afferent nerves innervating the bodily site of inflammation and a slow transmission pathway involving cytokines originating from the choroid plexus and circumventricular organs and diffusing into the brain parenchyma by volume transmission. At the behavioral level, sickness behavior appears to be the expression of a central motivational state that reorganizes the organism priorities to cope with infectious pathogens. There is evidence that the sickness motivational state can interact with other motivational states and respond to nonimmune stimuli probably by way of sensitization and/or classical conditioning. However, the mechanisms that are involved in plasticity of the sickness motivational state are not yet understood.

Adaptation, Physiological↗
PubMed2004

Sign-tracking (autoshaping) in rats: a comparison of cocaine and food as unconditioned stimuli.

A series of experiments was performed to determine whether sign-tracking would occur in rats with intravenous (i.v.) cocaine as the unconditioned stimulus. In Experiment 1, a retractable lever paired with food produced strong sign-tracking, but a lever paired with one of three doses of i.v. cocaine did not elicit any approach or contact behavior. Experiment 2 demonstrated that doses of cocaine that did not elicit sign-tracking would function as a positive reinforcer for a lever contact operant. In Experiment 3, an artificial consummatory response was added to make the cocaine reinforcement episode more behaviorally comparable to that occasioned by food. Although the rats readily performed this response when it was required to receive cocaine infusions, they still did not contact a lever that signaled the availability of these infusions. It appears that cocaine is different from other positive reinforcers (e.g., food, water, warmth, or intracranial stimulation) in that it will not produce sign-tracking in rats.

Animal Feed↗
PubMed1987

The spontaneous interconnection of four repertoires of behavior in a pigeon (Columba livia).

A pigeon was trained to peck a small facsimile of a banana placed within its reach, to climb onto a box, to open a door, and to push a box toward targets. When confronted with a new situation-the banana was placed out of reach, and the box was placed behind the door-the four repertoires came together rapidly to produce a humanlike solution to the problem. A tentative account of the performance is offered in terms of empirically validated principles.

Animals↗
PubMed1983

Functional heterogeneity of single neuronal activity in the monkey dorsolateral prefrontal cortex.

Extracellular single unit recording during high fixed ratio bar press behavior, guided by multimodal cue stimuli for food intake, revealed functional heterogeneity in the monkey dorsolateral prefrontal cortex. Cells were found significantly more often in the ventral arcuate concavity, the dorsal arcuate concavity, the principal sulcal area and the inferior convexity which responded, respectively, to visual events, auditory events, visual plus auditory events and bar press.

Animals↗
PubMed2006

Is brain estradiol a hormone or a neurotransmitter?

Mounting evidence indicates that, besides their well-known hormonal mode of action at the genetic level, estrogens such as 17beta-estradiol also influence brain function by direct effects on neuronal membranes. Experimentally induced rapid changes in estradiol bioavailability in the brain have been shown to alter the expression of male sexual behavior significantly within minutes--probably too quickly to be accounted for by conventional genetic mechanisms. In parallel, recent studies indicate that aromatase, the enzyme that converts testosterone to estradiol in the brain, is expressed in presynaptic terminals and modulated within minutes by Ca(2+)-dependent phosphorylation. In this article, we develop the hypothesis that brain estrogens display many, if not all, functional characteristics of neuromodulators or even neurotransmitters.

Animals↗
PubMed1979

Effects of d-amphetamine, maprotiline, L-dopa, and haloperidol on the components of the predatory behavior of the ferret, Putorius furo L.

Ferret predation on rats was examined in an arena. One hour before the test one of the following drugs was administered. d-Amphetamine (0.8 and 1.4 mg/kg IM), MAPROTILINE (10 AND 40 Mg/kg orally), L-dopa (30 and 60 mg/kg orally), or haloperidol (0.14 and 0.6 mg/kg IM). Provided that capture was successful, the sequence of the behavioral components was not changed by these drugs. With the exceptions of paw movements and rolling over, which were not affected by the drugs, the components of predatory behavior were influenced differently. This leads to the assumption that a drug affects different mechanisms which control behavior. It is assumed that dopamine is involved in the control of capture elicitation as well as in the control of pursuit and biting. Capture elicitation was inhibited by d-amphetamine and L-dopa, but not by maprotiline, and was even facilitated by haloperidol. The orientation of pursuit movements and biting was impaired by L-dopa and improved by haloperidol, whereas maprotiline did not influence these components.

Animals↗
PubMed2000

Sucrose and quinine intake by maternally-deprived and control rhesus monkeys.

Clinical depression is often characterized by a loss of interest or pleasure in formerly enjoyable activities. Analogs of anhedonia are established in rats, but the generality of this phenomenon to other species is unknown. Maternally-deprived rhesus macaques show a wide range of behavioral abnormalities that are reversed by chronic antidepressant treatment. We tested consumption by maternally deprived versus control macaques of sweetened (seven sucrose concentrations) or bitter water (four quinine concentrations) versus plain water to evaluate a non-human primate model of depression for signs of anhedonia. All monkeys consumed more sweetened than tap water, but maternally-deprived monkeys had a diminished preference for sweetened water than did controls. However, maternally deprived animals consumed more bitter water than did controls. Baseline fluid consumption did not differ. The data suggest that 'anhedonia' in animal models may be secondary to a generally attenuated responsiveness to stimuli, rather than a unitary reduction in responsiveness to the appetitive properties of stimuli. We conclude that maternally-deprived rhesus monkeys do not display gustatory signs of anhedonia, but rather of insensitivity to gustatory stimuli.

Animals↗
PubMed2005

Effects of day-length and food availability on food caching, mass and fat reserves in black-capped chickadees (Poecile atricapillus).

Many animals seasonally change energy stores such as food caches and fat deposits. Two factors that potentially influence energy stores are changes in day-length and food availability. We investigated food storing and fat levels in black-capped chickadees to determine how they are affected by changes in duration of light period and duration of food availability. Because previous studies have confounded the effects of photoperiod and the effects of duration of access to food we manipulated these variables independently. Birds were exposed to either long days (15 h light with 15 h of food availability), long day light exposure with short day food availability (15 h light, 9 h food), or short days (9 h light, 9 h food). We measured mass, body fat and the number of sunflower seeds stored in 1-h test sessions for 2 weeks prior and 3 weeks following this manipulation. Neither photoperiod nor food availability had an effect on food storing behavior. Fat and body mass transiently increased in both groups exposed to short duration of food availability, regardless of photoperiod, but did not increase in birds exposed to long days with long duration food availability. These results indicate that duration of time to feed may affect seasonal changes in energy reserves in addition to any effects of photoperiod.

Adipose Tissue↗
PubMed2004

Ethanol-maintained responding of rats is more resistant to change in a context with added non-drug reinforcement.

Alternative non-drug reinforcers reliably decrease drug-maintained responding in self-administration procedures. Studies of the resistance to change of food-maintained behavior, however, have found that responding in the presence of a stimulus associated with an alternative reinforcer is more resistant to disruption. This increase in persistence occurs despite lower response rates when the alternative reinforcer is present. The present experiment examined if, in addition to decreasing response rates, an alternative non-drug reinforcer also increases the persistence of drug-maintained responding. Rats self-administered oral ethanol in a multiple schedule of reinforcement in which responding was reinforced in two components signaled by different stimuli. In one component, response-independent food was delivered in addition to the earned ethanol. The effects of the alternative food reinforcer on response rates and resistance to extinction in the two components were examined. As in previous experiments on the resistance to change of food-maintained operant behavior, response rates were lower, but more resistant to extinction in the presence of the stimulus associated with the alternative reinforcer. These findings suggest that all the reinforcers obtained in a context in which drugs are consumed may contribute to the persistence of drug seeking in that context. This increase in persistence may occur even if the alternative reinforcers interfere with drug seeking.

Administration, Oral↗
PubMed1995

The effects of intrahippocampal grafts, training, and postoperative housing on behavioral recovery after septohippocampal damage in the rat.

This study examined whether the expression of behavioral effects of grafts rich in cholinergic neurons placed into the hippocampus of rats with septohippocampal damage may be modulated by postoperative housing or training conditions. Among 91 Long-Evans female rats, 61 sustained a bilateral aspirative lesion of the fimbria-fornix fibers and all overlying tissue, while 30 were given sham operations. Ten days after surgery, fetal septal suspension grafts were performed in the hippocampus of half the lesioned rats. Two days later, all rats were randomly assigned to one of three housing or training conditions: standard, standard with daily training, and enriched. Two and 5 months later, the rats were tested for learning using a Hebb-Williams maze. At both these delays, performance was clearly impaired in lesioned rats and was found to be ameliorated by grafts only in rats which had received daily training. Cresyl violet staining and acetylcholinesterase histochemistry showed that, irrespective of the housing or training conditions, all grafts had survived and provided the denervated hippocampus with a substantial cholinergic reinnervation. Our results suggest that the beneficial behavioral effects of intrahippocampal suspension grafts of septal cells may depend on the postsurgical training or handling conditions of the graft recipients. This result might be of importance for interpreting some behavioral effects of grafts, since in most studies in which grafts were found to induce beneficial behavioral effects (especially on learning capacity), these effects were generally observed at the end of a rather long testing period. Moreover, the present findings show that this delay, before graft function is expressed, might be linked not only to the time needed by grafts to establish a functional reinnervation in the host brain, but also to the training and/or handling conditions of the graft recipient.

Animals↗
PubMed1990

The time window of feeding.

This paper contrasts the traditional depletion/repletion model of food intake with a longer-term perspective which focuses on function rather than mechanism. We review naturalistic observations as well as the economic relationships we have discovered in the laboratory by a cost/benefit analysis of feeding in a closed economy. We have manipulated feeding costs by means of operant methodology and have explored two classes of cost, the cost of initiating meals and the cost of consuming food. We conclude that when an animal can detect the cost/benefit structure of its habitat, its feeding behavior will tend to maximize benefits relative to cost in apparent anticipation of its nutritional requirements and environmental conditions. The time window over which these feeding decisions are integrated may be minutes, hours, months, or seasons depending upon the animal's niche and current habitat. Feeding mechanisms based on momentary deficits and repletions are inadequate to explain these strategies, leaving the field of feeding mechanisms open for major discovery and revision.

Animals↗
PubMed1981

Differential effects of prefrontal cortex ablation in neonatal, juvenile, and young adult rats.

Rats sustaining lesions restricted to the medial (MF) or the orbital (OF) pre-frontal cortex at various ages (10, 25, 40, or 60 days postnatally) were tested as adults on a series of behavioral tasks that are known to be sensitive to such lesions in adults. On spatial alternation learning, both the 40- and 60-day MF operates were seriously impaired, whereas neither the 10- nor the 25-day MF operates differed from control. On a hoarding task, 25- and 60-day MF operates hoarded less food than either controls or 10-day MF operates. Lesions of OF cortex in males at 40 or 60 days of age produced a significant increase in running-wheel activity; OF lesions in both sexes at 25 days of age or later produced a decrease in the rate of continuous reinforcement reacquisition (following experience with differential reinforcement of low rates of responding and bar-press extinction) relative to controls, whereas 10-day OF operates did not differ from controls on either task. Thus, rats with lesions of either frontal area at 10 days of age showed complete behavioral sparing on all measures. The effects of lesions at later ages varied with the behavioral tasks employed and with lesion locus. Although the 10-day operates received a somewhat longer postoperative recovery interval than most of the later operates, these results cannot be explained on the basis of recovery time alone. A control group of 60-day operates with the same recovery interval as the 10-day operates did not differ on any measure from the 60-day operates with shorter recovery intervals.

Aging↗