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Biomedical subjects

M Domjan

Publications and source records attributed to M Domjan.

52 records · Page 3Linked to original sources
PubMed1978

Ingestional aversion learning in preweanling rats.

Ingestional aversions were conditioned in 12- and 15-day-old rats by infusing a .5% solution of saccharin into the oral cavity and following this oral infusion by the injection of lithium chloride. At both ages, subjects for which the saccharin exposure was followed by lithium injection within 2-3 min drank less when the saccharin solution was again presented by oral infusion 12 hr later; such suppressions of intake were not observed in subjects that previously received the saccharin and lithium in an unpaired fashion (Experiments 1 and 3). Ingestional aversions were also learned by 12-day-olds when a 30-min interval was introduced between saccharin exposure and lithium toxicosis but not when toxicosis was delayed by 120 min (Experiment 2). In contrast, 15-day-olds learned aversions with both the 30- and 120-min-delay intervals (Experiment 3). Despite the absence of long-delay learning in 12 day olds, ingestional aversions conditioned at 12 days of age were retained for 2 wk (Experiment 4). These results provide further evidence of the associative abilities of neonatal rats and illustrate a developmental aspect of long-delay learning.

Age Factors↗
PubMed1977

Early environmental influences on conditioned and unconditioned ingestional and locomotor behaviors.

For 34-44 days after weaning one group of rats was raised in a socially enriched environment, whereas another group was raised in isolated individual cages without handling. Following this differential rearing subjects were tested for ingestional neophobia and its attenuation, enhancement of ingestional neophobia by aversive drug administration, taste-aversion learning and extinction, open-field activity, and passive shock-avoidance learning. Although the differential rearing influenced open-field activity and shock-avoidance this manipulation did not have a significant effect on the various measures of conditioned and unconditioned ingestional behaviors. The results provide further evidence for the distinctiveness of gustatory-visceral and telereceptor-cutaneous sensory systems.

Animals↗
PubMed1977

Selective suppression of drinking during a limited period following aversive drug treatment in rats.

Administration of lithium chloride disrupted the intake of flavored solutions but not water in rats. This intake suppression was directly related to the amount of lithium administered (Experiment 1), occurred with both palatable and unpalatable novel saccharin solutions (Experiment 2), but was only observed if subjects were tested starting less than 75 min. after lithium treatment (Experiment 3). Twenty-five daily exposures to saccharin did not attenuate the effect (Experiment 4). However, in saccharin-reared and vinegar-reared rats, lithium did not disrupt consumption of the solutions these subjects had access to throughout life, even though suppressions of intake were observed when these subjects were tested with novel flavors (Experiment 5). The selective disruption of drinking is interpreted as a novelty-dependent sensitization reaction to the discomfort of aversive drug administration.

Animals↗
PubMed1977

Taste aversions conditioned by the aversiveness of insulin and formalin: role of CS specificity.

Experimenters in the past have reported that when insulin is used as the unconditioned stimulus (US), rats will learn an aversion to a sodium chloride but not a sucrose solution, whereas with formalin as the US, they will learn an aversion to a sucrose but not a saline solution. The present experiments failed to confirm these findings. Aversions to sucrose were conditioned with insulin and aversions to sodium chloride were conditioned with formalin. The use of a more concentrated sucrose solution in the present study may have been responsible for the successful sucrose-aversion conditioning with insulin. Although the source of the discrepancy in findings concerning aversion conditioning with formalin remains unclear, experiments ruled out numerous possibilities. These experiments also showed that sodium chloride aversion conditioning with formalin is a highly robust phenomenon that occurs with a variety of conditioned stimulus durations and formalin doses, with distributed and massed training, in male and female rats, and even if saline is not the only novel solution presented during conditioning. Furthermore, the aversion can be detected with both single-stimulus and choice test procedures.

Animals↗
PubMed1977

Taste-aversion conditioning with expected versus unexpected drug treatment.

Following differential conditioning in which a drug-predictive taste solution (D) infused into the oral cavity of rats was followed by a lithium injection and a no-drug-predictive solution (ND) was not reinforced, animals received a backward pairing between lithium and a novel saccharin flavor. Subjects infused with either the D solution or tap water immediately before backward conditioning learned weaker saccharin aversions than animals infused with the ND solution and animals given no infusion at this time (Experiments 1 and 3). These latter groups did not differ from each other (Experiment 3). The interference with aversion learning produced by water infusion appeared to be due to conditioned excitation that accrued to sensations of the infusion process. Extinction of the infusion sensations eliminated blocking produced by the infusion of water (Experiments 4 and 5). The blocking of saccharin-aversion learning produced by infusion of the D solution was due, to a large extent, to the conditioned aversiveness of the D taste. Extinction of the aversion to the D taste eliminated the interference with saccharin conditioning (Experiment 2), whereas extinction of the excitatory properties of the infusion process did not prevent the blocking of conditioning by infusion of the D solution (Experiment 5). These results are inconsistent with suggestions that taste-aversion learning is a primitive form of conditioning; rather, they demonstrate the influence of informational variables on conditioned taste aversions.

Administration, Oral↗
PubMed1977

Paradoxical effects of proximal unconditioned stimulus preexposure: interference with and conditioning of a taste aversion.

Taste aversions were conditioned in rats by giving the subjects an injection of lithium following exposure to saccharin. Treatment with lithium shortly (30 to 60 min.) before such a conditioning trial disrupted the taste-aversion learning produced by the postsaccharin drug injection. In Experiment 1, this interference effect was found to be a monotonically decreasing function of the preexposure-to-conditioning interval. The greatest disruption of conditioning was observed with a 30-min. preexposure-to-conditioning interval, and no interference occurred if the preexposure was administered 1 or 2 days before conditioning. These results suggest that in addition to the more durable effects of unconditioned stimulus (US) preexposure emphasized by previous investigators, US preexposure also activates temporary mechanisms that likewise attenuate subsequent conditioning. Experiment 2 demonstrated that lithium given before saccharin exposure disrupts the conditioning produced by a postsaccharin drug injection even if the presaccharin injection would itself otherwise be effective in producing a "backward" conditioned saccharin aversion. This outcome indicates that proximal US preexposure can have two opposite and paradoxical effects: It can interfere with as well as condition a taste aversion.

Animals↗
PubMed1977

Aftereffects of lithium-conditioned stimuli on consummatory behavior.

Exposure to taste or spatial cues previously paired with lithium administration resulted in more drinking during a test session started 15 min. later than did exposure to stimuli previously presented in the absence of drug treatment (Experiments 1, 2, 4, and 5). This outcome reflected an elevation of intake above baseline levels (Experiment 1) and required the presence of the lithium-paired cues rather than merely a history of lithium injections (Experiments 1, 2, 4, and 5). The increased drinking was evident in tests with novel (Experiments 1, 4, and 5) as well as familiar (Experiment 2) palatable solutions and was not attributable to a greater degree of thirst in subjects exposed to the lithium-predictive cues (Experiments 4 and 5). The phenomenon was attenuated by extinction of the lithium-conditioned stimuli (Experiment 3). However, the increased drinking aftereffect probably was not a result of the conditioned aversiveness of lithium-predictive cues, since shock-conditioned stimuli did not elicit enhanced consumption (Experiment 5). Various explanations of the effect are discussed.

Animals↗
PubMed1976

Determinants of the enhancement of flavored-water intake by prior exposure.

The intake of a 2.0% sodium saccharin solution in rats was observed to increase as a function of both the number (Experiment 1) and the duration (Experiment 3) of prior periods of access to the saccharin flavor, but did not increase when subjects were maintained on a fluid deprivation procedure in the absence of saccharin exposure (Experiment 2). The enhancement of intake was further influenced by the schedule of saccharin preexposures in the absence of variations in the amount of solution tasted (Experiment 4). The effect was not a function of the opportunity for subjects to determine their own pattern of contact with the saccharin flavor, the opportunity for association of the flavor with hunger and thirst reduction, or the amount of saccharin swallowed during preexposure (Experiment 5). These results suggest that mere exposure to a flavored solution is sufficient to increase subsequent intakes. The phenomenon is discussed in terms of the attenuation of neophobia elicited by the novelty of flavored solutions.

Animals↗
PubMed1975

The nature of the thirst stimulus: a factor in conditioned taste-aversion behavior.

Independent groups of rats were compared drinking in response to either water deprivation or osmotic thirst induced by intraperitoneal injections of hypertonic saline. When water or a palatable saccharin solution served as the drinking fluid, deprivation and osmotic thirst produced comparable fluid intakes. In contrast, when a saccharin solution previously associated with the aversive effects of lithium served as the drinking fluid, animals injected with hypertonic saline drank substantially less than water deprived animals. Experiment 2 indicated that this hyperreactivity to a conditioned aversive flavor in animals suffering from osmotic thirst was due to the reduced palatability of the saccharin flavor rather than the previous experience with lithium. Experiment 3 showed that the effect also could not be attributed to differential taste-aversion learning, handling, food deprivation or weight loss before the test sessions. The phenomenon is discussed in terms of various differences between thirst induced by water deprivation and thirst induced by acute cellular dehydration.

Animals↗