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At least 883 records · Page 49Linked to original sources
PubMed1978

Garter snake trailing behavior: effects of varying prey-extract concentration and mode of prey-extract presentation.

In a multiple-choice maze, garter snakes were trained to follow earthworm-extract trails for worm bit rewards. In Experiment 1, they were tested for their abilities fo follow extract trails that had been dried or extract trails that were removed from direct lingual access by a perforated floor. Snakes were able to follow the dry trails and unable to follow removed trails. In Experiment 2, snakes were tested for their behavioral responses to different concentrations of extract trails. Snakes trailed more accurately, moved more slowly, and exhibited much higher tongue flick rates on the intense concentration trails. The results are interpreted in terms of the assumption that effective trails are perceived by the tongue flick delivery of odorants to the vomeronasal organs.

Animals↗
PubMed1996

Concurrent-schedule performance in dairy cows: persistent undermatching.

Performance of dairy cows responding under concurrent variable-interval variable-interval schedules of food delivery was examined, with results analyzed in terms of the generalized matching equation. In Experiment 1, bias measures indicated that crushed barley was preferred over meatmeal when these foods were available under the alternative schedules. For whole-session data, substantial undermatching of response and time-allocation ratios to obtained reinforcement ratios was evident. Postreinforcement pause time ratios approximately matched obtained reinforcement rates. Subtracting these times from total time-allocation values yielded net time-allocation ratios that undermatched obtained reinforcement ratios to a greater degree than did whole-session time-allocation ratios. In Experiment 2, substantial undermatching was evident when the same foods (hay for 2 cows, crushed barley for 2 others) were available under the alternative schedules. Food-related activities and other defined behavior not related to food were quantified by direct observation, and were found to occupy a substantial proportion (roughly 40% to 80%) of experimental sessions. Subtracting the time spent in these activities from the time allocated to each component schedule did not reduce the degree of undermatching obtained. Across all conditions in both experiments, slopes of regression lines relating behavioral outputs to environmental inputs characteristically were below 0.6, which agrees with prior findings and suggests that, contrary to suggestions in the literature, undermatching in dairy cows is not the result of using different foods under alternative schedules or differential pausing under those schedules.

Animals↗
PubMed1994

Effects of monoamine oxidase inhibitors and dopamine agonists on the behavior of mammal- and frog-eating snakes.

Skin mucus of the frog, Xenopus laevis, induces climbing and attenuates tongue flicking in Nerodia sipedon; these effects are induced alone and are potentiated by L-deprenyl, a monoamine oxidase type B inhibitor (MAO-Bi), but not by clorgyline, an MAO type A inhibitor (MAO-Ai). Both MAO-A and MAO-B metabolize dopamine, with MAO-B having the higher affinity; MAO-A selectively metabolizes serotonin and norepinephrine and MAO-B is selective for phenylethylamine. It was hypothesized that clorgyline and L-deprenyl would differentially modulate tongue flicking and climbing in frog-eating (Nerodia erythrogaster) and mammaphagous (Elaphe o. obsoleta) snakes, based on physiological differences between the species. L-Deprenyl caused a decrease in tongue flicking and climbing by Elaphe and an increase in climbing by Nerodia, whereas clorgyline did not alter tongue flicking, climbing, or locomotor activity in either species. To further assess the role of dopamine, hybrid black/gray rat snakes, E. o. spiloides, were administered the D1 and D2 dopamine receptor agonists SKF 77434 (SKF 38393, N-allyl) and quinpirole, respectively. SKF 77434 and quinpirole attenuated climbing, but only SKF 77434 attenuated tongue flicking in Experiment 3; neither drug affected locomotor activity. Results suggest that dopaminergic stimulation by MAO-Bi and dopamine agonists modulates tongue flicking and climbing behaviors in snakes, and that the contrasting climbing reactions induced by MAO-Bi between Elaphe and Nerodia may be linked to quantitative differences in endogenous catecholamine levels and/or to the numbers and sensitivity of receptors.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed1997

Fluid intake and behavioral changes in rats associated with the distension of the small and large intestine.

Effects of volumetric distension of the small and the large intestine on rats' behavior were compared. Rats were stimulated by a rubber balloon inserted into chronic isolated intestinal loops prepared from the lower duodenum-upper jejunum and from the upper colon in the same animal. Thresholds of 3 reaction classes (weak, strong, and painful) were not different from each other in the 2 loops. Distension decreased fluid intake in an intensity-dependent way, with weak and painful stimuli being less effective in the large intestine and strong stimuli less effective in the small bowel. Behavioral indexes supported intake data, satiety indexes were similar to each other and changed in time, whereas aversivity indexes differed in the 2 loops and as a function of intensity but not time. The author suggests that mild discomfort is a physiological satiety factor whereas strong and painful stimuli signal danger and induce aversivity.

Animals↗
PubMed1999

Psychophysics of remembering.

We present a new model of remembering in the context of conditional discrimination. For procedures such as delayed matching to sample, the effect of the sample stimuli at the time of remembering is represented by a pair of Thurstonian (normal) distributions of effective stimulus values. The critical assumption of the model is that, based on prior experience, each effective stimulus value is associated with a ratio of reinforcers obtained for previous correct choices of the comparison stimuli. That ratio determines the choice that is made on the basis of the matching law. The standard deviations of the distributions are assumed to increase with increasing retention-interval duration, and the distance between their means is assumed to be a function of other factors that influence overall difficulty of the discrimination. It is a behavioral model in that choice is determined by its reinforcement history. The model predicts that the biasing effects of the reinforcer differential increase with decreasing discriminability and with increasing retention-interval duration. Data from several conditions using a delayed matching-to-sample procedure with pigeons support the predictions.

Animals↗
PubMed1996

Ontogeny of copepod predation in juvenile squid (Loligo opalescens).

Copepods are the major prey of juvenile squid, and small species of squid such as Loligo opalescens face a great challenge in catching these erratically moving crustaceans. We studied the ontogeny of copepod predation in laboratory-reared animals and found that mastery of copepod capture develops progressively, starting shortly after hatch with strong attacks of a simple type. Modifications of the initial basic attack lead to more specialized strategies that effectively extend the range of capture to both longer and shorter distances. This progression culminates, by approximately 40 days post-hatching, in adult-like prey capture behavior involving tentacle extension and retraction. Squid raised exclusively on easily captured Artemia nauplii and introduced to a copepod diet 40 days after hatching displayed only basic attack behavior, characteristic of very young squid. All of these attacks were unsuccessful, and very few of these animals survived the transition. Copepod capture thus appears to be a skill that must be acquired in an experience-dependent manner early in post-hatching life.

Animals↗
PubMed1994

A microcomputer-controlled demand feeder for the study of feeding behavior in fish.

This paper describes an easy-to-make, low-cost demand feeder. The electromechanical design ensures a single-pellet delivery for each demand. The feeder, activated by a fish pressing a bar, is driven by a solenoid. A variety of pellet shapes and sizes can be used, offering broad experimental versatility. The feeder is also suitable for microcomputer control.

Animals↗
PubMedDate not supplied

Relapse to drug-seeking: neural and molecular mechanisms.

A central determinant of addictive disorders in people is increased risk of relapse to drug use even after prolonged periods of abstinence. Recent advances in animal models of relapse indicate that drug-seeking behavior can be triggered by priming injections of the drugs themselves, by drug-associated environmental stimuli, and by footshock stress. The neural mechanisms underlying this relapse can be viewed in general terms as drug-like or proponent processes. Considerable evidence points to the mesolimbic dopamine system, and more specifically to activation of D2-like dopamine receptors in the nucleus accumbens, as a crucial neural substrate utilized by various stimuli that induce relapse. Drug-associated stimuli and stress may activate this system via neural circuits from the prefrontal cortex and amygdala as well as via the hypothalamo-pituitary-adrenal axis. There is also evidence for dopamine-independent mechanisms in relapse as well. A major effort of current research is to identify the long-lasting neuroadaptations within these various brain regions that contribute to relapse in addicted people. One potential neuroadaptation is up-regulation of the cAMP pathway in the nucleus accumbens, which occurs after chronic drug exposure, and represents a drug-opposite or opponent process. Modulation of this system has been related directly to relapse to drug-seeking behavior. Given the long-lasting nature of increased risk of relapse, it is likely that the relevant neuroadaptations are mediated via drug-induced changes in gene expression. A detailed understanding of the neural and molecular basis of relapse will facilitate efforts to develop truly effective treatments and preventive measures.

Animals↗
PubMed1990

Rate-depressant effects of ethanol on fixed-ratio responding in ALKO AA and ANA rats.

The ALKO AA and ANA rats have been selectively bred for high versus low ethanol preference, respectively. AA rats have been shown to self-administer ethanol, whereas ANA rats do not. These animals also show a range of differences on tasks which measure sensitivity to ethanol, but the relationship between ethanol intake and sensitivity to this drug in these rats is not clear. This study examined sensitivity to ethanol in AA and ANA rats as determined by ethanol's rate depressant effects on schedule controlled (Fixed-Ratio (FR) 32) responding reinforced by water deliveries. Non-drug rates of responding were similar for both lines across baseline, sham injection and vehicle conditions. Ethanol produced dose-dependent decreases in responding in both the AA and ANA rats. Dose-response curves indicated that AA rats were slightly more sensitive to the acute effects of ethanol than were ANA rats, with ED50 values of 0.52 and 0.69 g/kg for AA and ANA rats, respectively. Overall, however, the effects of ethanol on rats of responding were similar across the two lines of rats. While it is possible that constraints on behavior imposed by FR schedules could be masking underlying differences in tissue sensitivity between these animals, the results indicate that ethanol intake under preference or reinforcement conditions does not appear to be highly controlled by initial sensitivity to ethanol as measured by effects on operant performance.

Alcohol Drinking↗
PubMed2003

Strict and random alternation in concurrent variable-interval schedules.

Six pigeons responded on pairs of concurrent variable-interval schedules with, in different parts, four different arrangements of alternation between schedules. Following a single switching-key response, alternation was either strict or random, and the alternative presented after a switch (the postswitch alternative) was either signaled by the location of the switching key or unsignaled. Generalized-matching analyses showed little difference in behavior among the different alternation arrangements, except the usual finding of lower sensitivity of response allocation than time allocation was eliminated by arranging random alternation. Patterns of interchangeover times were similar for all arrangements except signaled random alternation. Differences in behavior preceding the different postswitch alternatives were found in the signaled random alternation procedure. Preference was biased towards the color of the signaled postswitch alternative and showed increased sensitivity when the postswitch alternative was to be the one with the higher reinforcer rate. Interchangeover times were substantially shorter when the postswitch alternative was signaled to be different from the current alternative than when it was signaled to be the same. However, when separate reinforcer ratios were calculated for the different postswitch alternatives, those effects were eliminated or greatly reduced. We suggest that, although behavior is indeed influenced by the postswitch alternative, the mechanism is indirect. That is, the distributions of reinforcers between alternatives obtained before each postswitch alternative differ when those alternatives are signaled, and those distributions are discriminated, but the same relations between choice and relative reinforcement hold irrespective of which postswitch alternative is signaled.

Animals↗
PubMed1992

Radio-frequency lesions of the thalamus produce delayed-nonmatching-to-sample impairments comparable to pyrithiamine-induced encephalopathy in rats.

Rats were trained and matched on a delayed-nonmatching-to-sample (DNMTS) task and randomly assigned to treatment. In Experiment 1, radio-frequency (RF) lesions were aimed at lateral portions of the internal medullary lamina (L-IML), midline thalamus (MT), mammillary bodies (MB), and the combination of MT and MB. In Experiment 2, RF lesions were aimed at the fornix. After recovery, DNMTS was retrained at retention intervals retention interval of 3.0-18.0 s, the critical retention interval for 75% DNMTS accuracy was determined by a staircase procedure, and spontaneous exploration was observed in an open field. L-IML lesions produced significant deficits on DNMTS and exploratory behavior that were comparable to deficits on the same tasks in rats recovered from pyrithiamine-induced thiamine deficiency. Fornix lesions produced significant DNMTS deficits that were substantially smaller than for the L-IML group. The MT, MB, and MT+MB treatments had no significant effect on DNMTS.

Alcohol Amnestic Disorder↗
PubMed1999

Modulation of taste reactivity by intestinal distension in rats.

Discomfort created by intestinal distension may play a role in controlling intake behavior. We analyzed these effects in details by the taste reactivity test in Long-Evans rats. A balloon inserted into a separated Thiry-Vella intestinal loop was distended with different volumes of water (0.05, 0.09, 0.12, and 0.28 mL, respectively). Saccharin solution (0.001 M) was infused into the mouth via an implanted oral cannula nine times for 30 s, with 5-min intertrial intervals. The balloon was distended after the second and released following the seventh trial. Taste reactivity (TR) elements were videotaped and later analyzed for appetitive and aversive responses. The number of appetitive responses decreased after gut distension, whereas aversive elements were infrequent and stable. It is suggested that pleasantness of the taste stimulus decreased independently of the discomfort, which remained mild but steady; that is, sweet taste gradually lost its hedonic value but was not accompanied by an acquired aversion of the same taste. This finding may point to the difference of the motivational and discriminative effects of the internal stimuli.

Animals↗
PubMed1994

Endogenous opioids are differentially involved in appetitive and consummatory aspects of sexual behavior of male rats.

The sexual activity of 40 male Wistar rats was tested weekly in a bilevel test chamber to evaluate the involvement of endogenous opioids in the appetitive and consummatory aspects of sexual behavior. It has been suggested that the increase of the anticipatory level-changing behavior over repeated testing, displayed before the introduction of a receptive female, is sexually motivated. Two doses of the opioid antagonist naloxone, 1 and 10 mg/kg, prevented the increase of the anticipatory level-changing over four repeated tests of sexually experienced rats without prior experience in the bilevel test chamber and decreased the number of level changes of rats displaying a high number of level changes. Analysis of the pattern of inhibition suggested that the lower dose of naloxone may reduce sexual reward and that, in addition, the higher dose may block the expression of motivation. In contrast, naloxone treatment facilitated the efficiency of the sexual performance, with less mounts and intromissions preceding ejaculation and a shorter ejaculation latency, implying an inhibitory role of endogenous opioids in the neural control of some aspects of sexual performance (e.g., ejaculatory threshold). These results suggest that endogenous opioids may increase sexual appetite and diminish sexual performance.

Analysis of Variance↗
PubMed1993

Neurochemical correlates of the Klüver-Bucy syndrome by in vivo microdialysis in monkey.

The Klüver-Bucy syndrome is a well known consequence of lesions of the temporal lobe, but the neural mechanisms remain obscure. To elucidate the neurochemical changes in this syndrome, we utilized in vivo microdialysis of amygdala and hypothalamus in two Cebus monkeys (C. apella) before and after bilateral lesions of the temporal pole (TP). Both subjects were housed and observed in a social group when not being dialyzed. Behavioral changes consequent to the TP lesion included early postoperative anorexia, adipsia, hunched posture, tameness, and lethargy. Subsequently loss of fear, hyperorality, loss of social rank, and social withdrawal were observed. Neurochemical changes in amygdala included fall in DA metabolites, increase in NE, and fall in 5-HIAA. The amino acids glutamate and aspartate were both lower postoperatively but more so in the subject with the greatest behavioral changes. Similar changes were noted in hypothalamus except for DA metabolites which remained unchanged. The Klüver-Bucy syndrome consequent to ablation of the temporal pole appears related to a partial deafferentation of excitatory projections to amygdala, along with a lowering of DA and 5-HIAA and an increase in NE.

Animals↗
PubMed1998

NPY and food intake: discrepancies in the model.

The evidence that NPY is an endogenous neurotransmitter that modulates both sides of the energy equation is clear and compelling. While agreeing with this (and indeed contributing to the growing literature supporting the concept), we have found that the interpretation of the increased food intake stimulated by intraventricular (i.v.t.) NPY is more complex than first appears. We discuss evidence suggesting that NPY additionally (and presumably at other receptor populations in the brain) causes sensations that produce aversion or illness. Specifically, the i.v.t. administration of NPY at doses that stimulate eating also cause the formation of a conditioned taste aversion and the animal engages in a form of pica behavior (kaolin consumption). It also suppresses an otherwise robust increase of sodium consumption. We discuss evidence suggesting that whereas NPY activates feeding behavior by stimulating the complex sequence of behaviors beginning with the seeking and finding of food and ending with food ingestion, NPY does not stimulate increased eating in the absence of the anticipatory preliminary behaviors. Finally, we briefly review evidence suggesting that whatever sensation is aroused by i.v.t. NPY, it is not necessarily the same sensation that is aroused when animals are food-deprived. Hence, one must be cautious in interpreting NPY as solely an orexigen.

Animals↗
PubMedDate not supplied

Extinction training regulates neuroadaptive responses to withdrawal from chronic cocaine self-administration.

Cocaine produces multiple neuroadaptations with chronic repeated use. Many of these neuroadaptations can be reversed or normalized by extinction training during withdrawal from chronic cocaine self-administration in rats. This article reviews our past and present studies on extinction-induced modulation of the neuroadaptive response to chronic cocaine in the mesolimbic dopamine system, and the role of this modulation in addictive behavior in rats. Extinction training normalizes tyrosine hydroxylase levels in the nucleus accumbens (NAc) shell, an effect that could help ameliorate dysphoria and depression associated with withdrawal from chronic cocaine use. Extinction training also increases levels of GluR1 and GluR2/3 AMPA receptor subunits, while normalizing deficits in NR1 NMDA receptor subunits, in a manner consistent with long-term potentiation of excitatory synapses in the NAc shell. Our results suggest that extinction-induced increases in AMPA and NMDA receptors may restore deficits in cortico-accumbal neurotransmission in the NAc shell and facilitate inhibitory control over cocaine-seeking behavior. Other changes identified by gene expression profiling, including up-regulation in the AMPA receptor aggregating protein Narp, suggest that extinction training induces extensive synaptic reorganization. These studies highlight potential benefits for extinction training procedures in the treatment of drug addiction.

Adaptation, Physiological↗
PubMed1997

Memory processes in delayed spatial discriminations: response intentions or response mediation?

Pigeons were trained on a pair-comparison task in which left versus right choices were reinforced following different sequences of two center-key stimuli. Choice accuracy was higher when retention intervals occurred after the entire sequence than when they separated the two stimuli comprising it, and this effect occurred independently of whether the initial and terminal stimuli came from the same or different dimensions. The initial stimulus from the prior trial was a source of proactive interference only in groups for which the retention interval separated the two sequence stimuli. By contrast, differential delay-interval behavior was observed only in groups for which the retention interval followed presentation of the entire sequence. These results indicate that coding processes in delayed discriminations are influenced by the location of the retention interval, and that response mediation affects retention performances if the reinforced choice can be determined prior to the interval.

Animals↗
PubMed1982

Models of the influence of predation on aspect diversity in prey populations.

By considering a model incorporating behavioral changes by predators and prey evolution, we demonstrate how under certain conditions apostatic predation influences the maintenance of diversity within prey populations, and among different prey species. Further, we estimate the intrinsic "diversity" wavelength of the system when apostasy combines with other factors to lead to nonuniform distributions of prey along aspect gradients.

Animals↗