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D Treit

Publications and source records attributed to D Treit.

50 records · Page 3Linked to original sources
PubMed1986

Does effort play a role in the effect of response requirements on delayed matching to sample?

The possible role of "effort" in the accuracy of pigeons' performance on a delayed matching-to-sample procedure was investigated by examining the effects of response requirements that accompanied a trial-initiating stimulus and that accompanied a sample stimulus. In the first experiment, the effect of varying the size of a fixed-ratio requirement for responses during an initiating stimulus was compared to that of varying a similar requirement for responses during the sample stimulus. Accuracy increased reliably with increases in the ratio scheduled during the sample stimulus, but was not significantly affected by increases in the ratio scheduled on the key during the initiating stimulus. In another phase of Experiment 1, sample duration was held constant while the ratio requirement was varied during the initiating stimulus. Again, accuracy of matching to sample was not significantly affected by the size of the ratio scheduled during the initiating stimulus. Experiment 2 provided a systematic replication of these results in another group of pigeons and included a more detailed analysis of responding. These results support the view that increases in sample-response requirement facilitate accuracy of delayed matching by increasing the durations of exposure to the sample stimuli, and do not support a role of effort in the sample-response effect. In Experiment 3, the facilitative effect of responses on the sample but not of those on the initiating stimulus was replicated using a simultaneous matching-to-sample procedure. This finding provides further evidence against an interpretation of response-requirement effects that appeals to effort; the finding also suggests that sample exposure might affect initial discrimination of the sample rather than remembering the sample.

Animals↗
PubMed1985

Evidence that tolerance develops to the anxiolytic effect of diazepam in rats.

The development of tolerance to the anxiolytic effect of diazepam was studied using suppression of defensive burying as an animal model of anxiolytic action. Although tolerance to the suppressive effect of diazepam was not apparent after chronic administration of diazepam when the rats were tested with a low-intensity shock, anxiolytic tolerance was detected under exactly the same drug regimen when the rats were tested with somewhat higher intensity shocks: under the latter conditions, chronically treated rats buried significantly more than acutely treated rats. Furthermore, this tolerance effect did not appear to depend upon the injection environment, the control vehicle, or the strain of rat; under each of these experimental variations rats chronically treated with diazepam buried significantly more than acutely treated rats when they had received a moderately high intensity shock. These results suggested that tolerance to the anxiolytic effects of benzodiazepines may be detectable when the stimuli eliciting anxiety are relatively intense.

Animals↗
PubMed1985

The inhibitory effect of diazepam on defensive burying: anxiolytic vs. analgesic effects.

The hypothesis that analgesic mechanisms might account for the suppressive effect of diazepam on defensive burying was tested in four experiments. In the first experiment, 1 mg/kg of diazepam had no appreciable effect on rat's latency to escape from a painful heat stimulus, but reliably suppressed defensive burying behavior. There was no significant relationship between the diazepam-treated rats' latency to escape and their duration of burying. Rats in Experiment 2 were injected with diazepam during a delay between shock and testing, so that they could not be experiencing the putative analgesic effect of diazepam during the shock. In spite of this, diazepam produced a significant suppression of burying compared to saline control. In the next experiment, the effect of diazepam on defensive burying was assessed in the complete absence of painful stimulation by exposing the rats to a novel stimulus known to elicit burying behavior. Diazepam suppressed burying behavior to the novel stimulus in a dose-dependent fashion. Finally, the ability of 10 mg/kg of naloxone to reverse the suppressive effect of 1 mg/kg of diazepam was assessed in Experiment 4. Naloxone failed to reverse the suppressive effect of diazepam and had no significant effect on defensive burying by itself, suggesting that the modulating influence of diazepam on rats' defensive burying behavior did not depend upon endogenous opiate mechanisms. Taken together, the results of the four experiments did not support the view that benzodiazepines produce their anxiolytic effects through analgesic mechanisms.

Analgesics↗
PubMed1985

Animal models for the study of anti-anxiety agents: a review.

Animal models for the study of anxiolytic agents are reviewed and evaluated according to pharmacological and behavioral criteria. Although there are important exceptions, in general, most early animal models have not provided a reliable basis for identifying compounds with potential anxiolytic action, or for delineating the mechanisms of anxiolytic drug action. The possibility that phylogenetically 'prepared' forms of defensive learning might serve as a basis for the study of anxiolytic agents is introduced.

Aggression↗
PubMed1984

Caloric regulation in the rat: evidence for a calibration mechanism.

Rats were given access to small quantities of a 50% oil/water mixture on each of 7 baseline days. On the eighth day, a 30 min compensation test was conducted during which control rats had access to the 50% oil/water mixture and experimental rats had access to either a more concentrated or a more dilute oil/water mixture. Experimental rats given the more concentrated mixture consumed significantly less than controls, while rats given the dilute mixture consumed significantly more than controls. These results suggested that rats can immediately adjust their food intake in response to changes in the caloric density of their diets. In a second experiment, immediate adjustment for caloric change was inhibited by giving rats a supplementary meal directly after access to the 50% oil/water mixture during the baseline phase. These results were discussed in terms of a hypothetical "calibration" mechanism which allows rats to estimate the density of novel caloric concentrations on the basis of a standard concentration.

Animals↗
PubMed1984

The effect of d-amphetamine on short-term memory for time in pigeons.

The effect of d-amphetamine on pigeons' perception and short-term memory of time was investigated within a delayed symbolic matching to sample paradigm in which pigeons were rewarded for choosing one color after a 1-sec sample and another color after a 5-sec sample. On trials with no delay between sample offset and onset of the choice phase, d-amphetamine produced a bias toward choosing the color that was correct after long samples, suggesting that the birds overestimated the sample durations under amphetamine. With a 20-sec retention delay, d-amphetamine lowered choice accuracy to chance level, suggesting that it impaired the bird's short-term memory for sample durations. It was postulated that an amphetamine-induced increase in the rate of perceptual processing could mediate the effects of amphetamine on both time perception and memory.

Animals↗
PubMed1983

Variety in the flavor of food enhances eating in the rat: a controlled demonstration.

The effect of variety in the flavor of food on rats' consumption of a meal was examined in two experiments in which the confounding factors of diet composition and palatability could be ruled out. Experiment 1 showed that rats ate more of a four-course meal when each course was flavored differently than when each course was flavored the same; furthermore, this "variety effect" did not appear to depend upon the rats' prior experience with the flavors. Experiment 2 replicated and extended these findings by showing that the enhancement of eating by variety did not depend critically upon the rat's level of food motivation. The results were discussed in terms of their implications for the etiology and control of obesity, as well as for theories of satiety. It was suggested that the "variety effect" may represent an adaptive mechanism in the control of feeding.

Animals↗
PubMed1982

The inhibitory effect of diazepam on conditioned defensive burying is reversed by picrotoxin.

The ability of picrotoxin to reverse the effect of diazepam was studied using the conditioned defensive burying paradigm. Although picrotoxin alone had no detectable effect on the conditioned defensive burying response of rats, picrotoxin was able to reverse the usual inhibitory effect of diazepam on defensive burying. These results suggest that the anxiolytic effect of diazepam may depend upon the integrity of GABAergic neural systems.

Animals↗
PubMed1981

Conditioned defensive burying: a new paradigm for the study of anxiolytic agents.

Behavioral paradigms that have been designed to mimic forms of learning that are important for the survival of animals in the wild, rather than to minimize the contributions of adaptive predispositions, may prove to be particularly useful for studying the behavioral effects of drugs. In the present experiments, the propensity of rats to bury sources of aversive stimulation was disrupted in a dose-dependent fashion by a single injection of the anxiolytic drug, diazepam. This suggested that the conditioned defensive burying paradigm could prove to be a valuable addition to the paradigms available for studying anxiolytic effects. Supporting this view were two additional observations. First, the relative potencies of diazepam, chlordiazepoxide, and pentobarbital in the burying paradigm compared favorably with their relative potencies in clinical settings. Second, the effects of anxiolytics on conditioned burying appeared to be dissociable from the effects of other drugs that disrupt this behavior.

Animals↗
PubMed1977

Temporal lobe aggression in rats.

Although reports of aggressive behavior in temporal lobe epileptics are common, it has proven difficult in clinical settings to gain the experimental control necessary to systematically investigate temporal lobe aggression or even to provide unequivocal evidence of its existence. Increases in aggressive behavior were observed in rats with experimentally induced epileptic foci in temporal lobe structures but not in control rats or those with foci in the caudate.

Aggression↗
PubMedDate not supplied

Septal GABAergic and hippocampal cholinergic systems modulate anxiety in the plus-maze and shock-probe tests.

According to Gray [The neuropsychology of anxiety: an inquiry into the function of the septo-hippocampal system. Oxford: Oxford Univ. Press, 1982; Neural systems, emotion and personality. In: Madden VJ, editor. Neurobiology of learning, emotion, and affect. New York: Raven Press, 1991. p. 273-306.] the septum and hippocampus act in concert to control anxiety. In the present study we examined the roles of these structures in two animal models of anxiety: the elevated plus-maze and the shock-probe burying tests. We found that microinfusions (20 ng/0.4 microl) of the GABA(A) agonist muscimol into either the lateral or the medial septum increased rats' open-arm exploration in the plus-maze test, and decreased their burying behavior in the shock-probe test. We also found that infusions of the acetylcholinesterase inhibitor physostigmine (10 microg/microl) into the dorsal hippocampus, like intraseptal muscimol (20 ng/0.4 microl), increased open-arm exploration in the plus-maze test, and decreased burying behavior in the shock-probe test. Although combined infusions of intraseptal muscimol and intrahippocampal physostigmine did not increase the magnitude of anxiolysis, this may have been due to "ceiling" effects. Overall, the results confirm that septal GABAergic and hippocampal cholinergic systems are both involved in the modulation of anxiety.

Animals↗