SEARCH · PubMed Health

Results for “Avoidance Learning”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,603 records · Page 89Linked to original sources

PubMed1990

Enhancement and impairment of memory retrieval by a vasopressin metabolite: an interaction with the accessibility of the memory.

A series of 3 experiments was conducted to determine the generalizability of the improved recall seen with pretest administration of vasopressin in aversively motivated tasks. The learning paradigm selected for this purpose assessed the transmission of a food preference between rats; retention intervals of 8, 10, and 14 days were used in the 3 experiments, respectively. Pretest subcutaneous injection of a vasopressin metabolite, AVP4-9, significantly improved recall under conditions in which memory was poor in vehicle-treated rats but significantly impaired memory at a time when good recall was evident in controls. These findings support the postulate that administration of vasopressin or its metabolites modulate memory retrieval processes and suggest that the nature of this effect depends on the degree of forgetting that has occurred.

Animals↗

PubMed1990

When pentobarbital is the conditioned stimulus and amphetamine is the unconditioned stimulus, conditioning depends on the type of conditioned response.

Injections of drugs into rats were used as conditioned stimuli (CSs) and as unconditioned stimuli (USs). With heart rate (HR) conditioning, the pentobarbital CS produces a higher HR than under control conditions. With avfail (aversion failure) conditioning, the pentobarbital CS loses much of its capacity to induce a conditioned taste aversion. HR conditioning was obtained with forward delays of up to 30 min and backward delays of up to 270 min, where the delays are defined by the interinjection interval. Avfail was obtained with forward delays of up to 270 min but not with backward delays. Neither HR conditioning nor avfail were context specific but could be demonstrated in a test apparatus after pairings that occurred in the home cage. This indicated that the external environment was not an important part of the effective stimulus complex. When HR conditioning was obtained, its latency and duration was not related to the delay between the CS and US injections or whether they were forward or backward.

Animals↗

PubMed1990

Conditioned responses to a taste conditioned stimulus paired with lithium chloride administration.

The present experiments examined whether behavioral conditioned responses (CRs) develop to lithium chloride (LiCl)-paired tastes and whether these CRs are similar to the behaviors that follow administration of the drug. Rats were exposed to a saccharin solution via intraoral infusions before being injected with either LiCl or saline. CRs were assessed after conditioning when the saccharin conditioned stimulus was delivered alone. The unconditioned response to LiCl delivery is a very distinctive posture that has been termed "lying-on-belly." The present study indicates that this behavior pattern also occurs after the delivery of a LiCl-paired taste solution. The similarity between these unconditioned and conditioned behaviors is consistent with the hypothesis that responses are conditioned during taste aversion acquisition and that CRs are similar to those that are generated by the drugs used in conditioning.

Animals↗

PubMed1991

Methodological issues in drug-drug conditioning in rats: nonassociative factors in heart rate and avfail.

Sodium pentobarbital injections followed 30 min later by d-amphetamine sulfate produce an effect over trials in the form of an increase in heart rate in response to pentobarbital in relation to rats that receive the 2 drugs 24 hr apart (long-delayed control: Revusky, Davey, & Zagorski, 1989). This study found equivalent increases in heart rate in forward and backward groups in relation to a long-delayed control regardless of whether training or testing was carried out in a heart rate recording apparatus or in the home cage, which suggests that a drug interaction due to drug administrations in forward and backward groups has yet to be eliminated in accounting for the heart rate effect. Comparison of backward and long-delayed controls in a drug-drug procedure that used a taste aversion test revealed that both forward and delayed pairings can produce attenuated aversions in relation to a backward group regardless of whether the unconditional stimulus is amphetamine (Experiment 1) or lithium chloride (Experiment 2).

Animals↗

PubMed1991

Central gustatory lesions: II. Effects on sodium appetite, taste aversion learning, and feeding behaviors.

Intake and taste reactivity tests were used to determine the effects of bilateral lesions of the gustatory portions of the nucleus of the solitary tract (NST), the parabrachial nucleus (PBN), and the ventral posteromedial nucleus of the thalamus (VPMpc) on several complex ingestive behaviors. In the 1st experiment, lesions of the PBN and the NST blocked, and VPMpc lesions impaired, the behavioral expression of salt appetite. In the 2nd experiment, alanine was paired with injections of LiCl. Control rats as well as rats with NST and VPMpc lesions acquired the taste aversion, but rats with PBN lesions did not. In the 3rd experiment, all animals increased their food intake after injections of 2 U/kg insulin and 250 mg/kg 2-deoxy-D-glucose, and their food intake was suppressed after nutritive stomach loads.

Afferent Pathways↗

PubMed1992

Pairings of a drug or place conditioned stimulus with lithium chloride produce conditioned sickness, not antisickness.

In different experiments, pairings of a drug (pentobarbital or morphine) or place as the conditioned stimulus (CS) with lithium-induced sickness as the unconditioned stimulus (US) were given to rats to produce Pavlovian conditioning. Control rats received unpaired exposures. In the test, each rat was exposed to the CS, injected with lithium, and then offered food. If such pairings produce conditioning of antisickness (i.e., a compensatory response that opposes lithium sickness), then the experimental rats should eat more than the controls. The reverse occurred. Thus, pairings of a drug or place CS with a lithium US resulted in conditioned sickness rather than antisickness.

Animals↗

PubMed1992

Presence of conspecifics facilitates learning that food is inedible in Aplysia fasciata.

The absence of a conspecific, but not of food, interfered with learning and memory of a feeding task in Aplysia fasciata. Interference was shown by a shortened training session and by lack of savings on retraining. The shortened training is not responsible for the lack of savings because brief training in the presence of a conspecific led to savings on retraining. Animals trained in the absence of a conspecific and then tested in its presence did not show signs of having learned, which indicates that the absence of a conspecific interfered with the ability to learn, rather than with the expression of memory. Absence of a conspecific also inhibited other aspects of feeding behavior, such as the latency to respond to food and the length of time that animals respond to food, which indicate that interference with learning was apparently caused by inhibition of feeding behavior, rather than by block of the mechanisms underlying learning.

Animals↗

PubMed1992

Taste-potentiated odor aversion learning: role of the amygdaloid basolateral complex and central nucleus.

The present study examined the relative contributions of the amygdaloid basolateral complex (ABL) and central nucleus (CN) to taste-potentiated odor aversion (TPOA) learning--an associative learning task that is dependent on information processing in two sensory modalities. In Experiment 1, rats with neurotoxic lesions of these systems were trained on the TPOA task by presenting a compound taste-odor conditioned stimulus, which was followed by LiCl administration. Results showed that ABL damage caused an impairment in potentiated odor aversion learning but no deficit in the conditioned taste aversion. In contrast, rats with CN damage learned both tasks. Experiment 2 examined the effects of ABL damage on TPOA and odor discrimination learning. The odor discrimination procedure used a place preference task to demonstrate normal processing of olfactory information. Results indicated that although ABL-lesioned animals were impaired on TPOA, there was no deficit in odor discrimination learning.

Animals↗

PubMed1992

Place conditioning in a three- or four-choice apparatus: role of stimulus novelty in drug-induced place conditioning.

A series of 4 experiments examined the suggestion (Scoles & Siegel, 1986) that drug-induced place preference conditioning may be due to interference with habituation. In each experiment, rats had the opportunity to select among a drug-paired chamber, a saline-paired chamber, and a novel (or relatively novel) chamber. The drugs included the positively reinforcing drugs amphetamine, apomorphine, morphine, and nicotine and the aversive drug lithium chloride. The rats preferred chambers that were paired with amphetamine, apomorphine, and morphine more than chambers that were novel; however, they also consistently preferred novel chambers to familiar saline-paired chambers. There was no evidence of place conditioning with nicotine. The drug-induced place preference, but not the novelty preference, occurred after a single conditioning trial in a 3-choice apparatus but not a 4-choice apparatus. Lithium chloride established a place aversion after 1-3 conditioning trials. Measures of activity revealed that the rats were least active while in their most preferred chamber and most active while in their least preferred chamber.

Animals↗

PubMed1992

N-methyl-D-aspartate antagonist D-APV selectively disrupts taste-potentiated odor aversion learning.

Two experiments examined the effects of the competitive N-methyl-D-aspartate (NMDA) antagonist D-APV (D-2-amino-5-phosphonovalerate) on rats' ability to acquire potentiated aversions to the odor element of a taste-odor compound. In Experiment 1, pretreatment with D-APV (2.5 micrograms/side icv) caused stereospecific deficits in potentiated odor aversion learning but left simple taste and odor aversion learning intact. In Experiment 2, pretreatment with D-APV had no effect on rats' acquisition of an illness-based odor discrimination task. These results parallel those previously obtained using a noncompetitive NMDA antagonist (Robinson, Crooks, Shinkman, & Gallagher, 1989) and show that interference with NMDA receptors can selectively impair potentiated odor aversion learning. These results suggest that NMDA receptors play a critical role in some, but not all, forms of learning and memory.

2-Amino-5-phosphonovalerate↗

PubMed1992

Chronic exposure to morphine does not alter the neural tissues subserving its acute rewarding properties: apparent tolerance is overshadowing.

Drug-naive, but not morphine-dependent, rats preferred places paired with morphine (2 mg/kg) over unfamiliar neutral places. Both drug-naive and morphine-dependent rats preferred places paired with higher doses of morphine (20 mg/kg) over unfamiliar places. Lesions of the tegmental pedunculopontine nucleus (TPP) blocked the conditioned place preferences produced by both 2 and 20 mg/kg morphine in drug-naive rats but not the preferences produced by 20 mg/kg morphine in dependent rats. When morphine-dependent animals received withdrawal-alleviating doses of morphine (20 mg/kg) 3.5 hr before pairing one environment with 2 mg/kg morphine, they showed morphine-conditioned place preferences that were abolished by TPP lesions. The apparent behavioral tolerance to the TPP-mediated rewarding effects may have resulted from overshadowing by separate withdrawal-related motivational mechanisms.

Animals↗

PubMed1992

Odors can induce feeding motor responses in the terrestrial mollusc Limax maximus.

Highly developed odor learning was shown in the terrestrial slug Limax maximus. In addition, several key cellular elements of the neural network that controls ingestive feeding have been identified. The results of 3 experiments demonstrate an interaction between odor input and ingestive feeding in that olfactory stimulation with behaviorally attractive odors summed with tactile stimulation from plain agar to produce ingestion of plain agar. Agar ingestion did not occur in the absence of attractive odor stimulation. The adequacy of odor stimulation to trigger agar ingestion was altered by associative learning. Innately attractive odors rendered repellent by associative learning no longer triggered agar ingestion, whereas innately repellent odors rendered attractive by conditioning triggered agar ingestion. The newly discovered feeding command cells in the Limax cerebral ganglion are a logical cellular locus for this interaction.

Animals↗

PubMed1992

Biophysical and behavioral correlates of memory storage, degradation, and reactivation.

Neural correlates of associative memory and "forgetting" were observed 1, 6, and 14 days after acquisition of a conditioned response (CR) in the marine snail Hermissenda. Behavioral expression of a light-rotation association, as indexed by contraction of the animal's foot in response to light, dissipated throughout the 14-day interval such that a CR was observed 1 and 6 days after conditioning but was absent 14 days later. In relation to naive or pseudoconditioned animals, membrane resistance (inversely related to neuronal membrane conductance and directly related to excitability) of the isolated Type B photoreceptor (B cell) was elevated in conditioned animals on Days 1 and 6, whereas no elevation was detectable on Day 14. However, both the behavioral response and the elevated membrane resistance in conditioned animals were hypersensitive to light-rotation pairings (i.e., exhibited "savings") on Day 14, which is indicative of a latent memory trace. In a second experiment, a current-induced depolarization of the B cell after 14 retention days resulted in an increase in input resistance of the B cell membrane in previously conditioned animals but a weaker, transient rise in resistance in B cells from animals exposed to the nonassociative control procedure 14 days earlier. This effect was Ca(2+)-dependent because no rise in resistance was observed if Ca2+ was removed from the extracellular bath. These results indicate that modification of membrane conductance (i.e., elevated resistance), although apparently critical for the behavioral expression of the memory, is not essential for the maintenance of the latent memory trace, whereas Ca2+ hypersensitivity may be a principal contributor to the storage of a latent memory trace and memory reactivation.

Animals↗

PubMed1993

The parabrachial nucleus: a brain stem substrate critical for mediating the aversive motivational effects of morphine.

Bilateral ibotenic acid lesions of the lateral, but not the medial, parabrachial nucleus (PBN) blocked conditioned taste aversion (CTA) induced by morphine but not conditioned place preference induced by morphine. The same lateral PBN lesions also blocked conditioned place aversion produced by low intraperitoneal doses of morphine (shown to produce aversion, instead of preference, due to a restricted action on gut opiate receptors). Lateral PBN lesions did not block CTA produced by LiCl. Cerebral peduncle lesions that destroyed the direct descending projections from the visceral cortex to the PBN did not block CTA induced by morphine, nor did ibotenic acid lesions of the tegmental pedunculopontine nuclei (shown to block place preference produced by even high morphine doses). It is suggested that the lateral PBN is a critical link in the neural pathway carrying the aversive motivational effects of opiates from the gut into the central nervous system, independent of the neural pathway carrying the rewarding motivational effects of morphine.

Animals↗

PubMed1993

Antisickness conditioning using a nausea-producing nondrug cue.

Most drugs induce conditioned taste aversions and are therefore commonly supposed to produce nausea or sickness. Paradoxically, some drugs appear to lose induction capability when made to serve as a cue for a second drug that produces more severe sickness, perhaps through selective association with a hypothetical homeostatic or antisickness aftereffect of sickness. Using drug-drug pairings had made antisickness conditioning theory difficult to validate. We report here that rotation serves in lieu of a drug cue in rats. Rotation-drug pairings eliminate drug interactions and enable the sorts of parametric manipulations required to validate the theory. By postulating a common sickness mechanism to explain both taste aversion and aversion failure, the theory places the phenomenon within an adaptive evolutionary framework. Successful application could yield a direct countermeasure to severe nausea in clinical settings.

Animals↗

PubMed1993

Drug-induced hypothermia and conditioned place aversion.

This study examined the relationship between ethanol's thermal and motivational effects in a place conditioning task. In three experiments, male albino rats were exposed to a differential conditioning procedure that paired a distinctive tactile stimulus with ethanol (1.2 or 1.8 g/kg) or lithium chloride (3 meq/kg); a different stimulus was paired with saline. Different groups were exposed to ambient temperatures (Ta) of 5 degrees, 21 degrees or 32 degrees C during each 60-min conditioning trial. Both ethanol and lithium chloride produced hypothermia and conditioned place aversion in rats conditioned at normal Ta. Exposure to high Ta reduced drug-induced hypothermia, increased activity, and decreased conditioned place aversion. Exposure to low Ta did not enhance drug-induced hypothermia or change conditioned place aversion. In general, these findings support the suggestion that the hedonic effects of ethanol and lithium chloride interact with their thermal effects.

Animals↗

PubMed1993

Ibotenate lesions of the hippocampus enhance latent inhibition in conditioned taste aversion and increase resistance to extinction in conditioned taste preference.

In 2 experiments, the effects of axon-sparing lesions of the hippocampus on performance in aversive and appetitive taste conditioning tasks were investigated. In Experiment 1, hippocampally lesioned rats showed no impairment of conditioned taste aversion learning relative to control subjects, but they did display an increased sensitivity to latent inhibition (LI). In Experiment 2, the same hippocampectomized rats acquired a conditioned taste preference but failed to show any evidence of extinction. The influence of the neurotoxic lesion on LI is in the opposite direction to the effect typically found following hippocampal damage induced by traditional methods. Accordingly, the data present challenges for most current theories of hippocampal function.

Animals↗

PubMed1994

Acquisition of conditional discriminations in hippocampal lesioned and decorticated rats: evidence for learning that is separate from both simple classical conditioning and configural learning.

This study examined whether hippocampal or neocortical lesions would impair acquisition of a discrimination task using taste aversions. Rats were injected with a drug 15 min before a flavored solution-lithium chloride pairing. On alternate days, vehicle injections preceded and followed access to the same flavored solution. Rats learned to consume significantly more of the flavored solution after vehicle injections than after drug injections. Rats with hippocampal lesions or neonatal decortication performed as well as controls. Rats with hippocampal lesions also learned a similar task in which visual and textural cues predicted whether access to a flavored solution would be followed by an injection of lithium chloride or vehicle. However, these hippocampal lesions did impair performance in the Morris water task. Occasion setting may involve a type of learning dissociated from both simple classical conditioning and configural learning.

Animals↗