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Biomedical subjects

A R Wagner

Publications and source records attributed to A R Wagner.

17 recordsLinked to original sources
PubMed1994

Discriminated lateralized eyeblink conditioning in the rabbit: an experimental context for separating specific and general associative influences.

Four experiments are reported that demonstrate discriminated lateralized eyeblink conditioning in rabbits and show how the phenomenon may be used to differentiate between the reflexive and emotive consequences of Pavlovian conditioning. Experiments 1, 2, and 3 characterized how 2 conditioned stimuli (CSs), contemporaneously trained with left vs. right paraorbital unconditioned stimuli (USs), can produce different conditioned reflexes (CRs), each involving predominant closure of the eye ipsilateral to its US. Experiment 4 showed how the associative tendencies controlled by additional stimuli could be evaluated by presentations in compound with such discriminanda: A 30-s stimulus, presumed to acquire a conditioned emotional response but no eyeblink CR, equally potentiated the eyelid CRs elicited by both CSs; a 1,050-ms CS that evoked an eyeblink CR in isolation also increased the responding to both CSs but biased it toward its own lateralized CR.

Acoustic Stimulation↗
PubMed1991

Modulation of a discrete Pavlovian conditioned reflex by a putative emotive Pavlovian conditioned stimulus.

Three experiments showed the modulation of a rabbit eyeblink conditioned response (CR) to a Pavlovian conditioned stimulus (CS) by 30-s stimuli (A & B) that had been differentially paired with paraorbital shock. The CS (Y) was a 1,050-ms cue that had been paired with paraorbital shock outside A or B. In testing, the amplitude of CRs was greater when Y was presented within A than within B. Differential modulation occurred whether shock in A had been preceded by another 1,050-ms cue, X(AX+,BX-;Experiment 1) or not (A+B-;Experiment 2). Experiment 3 compared the technique of Experiment 1 (AX+) with that of Experiment 2 (A+) and found the latter to be advantageous for facilitation of CRs to Y by A. These data are consistent with the predictions of a model of Pavlovian conditioning (AESOP, Wagner & Brandon, 1989) that distinguishes between emotive and sensory conditioning as did Konorski (1967).

Animals↗
PubMed1991

Modulation of unconditioned defense reflexes by a putative emotive Pavlovian conditioned stimulus.

Four experiments showed differential modulation of defensive unconditioned responses (URs) in rabbits by contextual stimuli that Brandon and Wagner (1991) have shown similarly to modulate conditioned eyeblink responses. Two 30-s auditory cues, A and B, were differentially paired with shock. Tests were presentations of a response-eliciting probe stimulus within A, B, or a comparable blank interval, Experiments 1 and 2 demonstrated that A and B differentially facilitated eyeblink URs, and Experiments 3 and 4 showed that A and B similarly differentially facilitated startle responses elicited by airpuffs to the ear. These data are consistent with a characterization of Pavlovian conditioning that distinguishes between emotive and sensory conditioning and assumes that conditioned emotional responses similarly modulate specific conditioned and unconditioned defensive reflexes (Konorski, 1967; Wagner & Brandon, 1989).

Animals↗
PubMed1991

Modulation of a conditioned eyeblink response by a putative emotive stimulus conditioned with hindleg shock.

Two experiments with rabbits showed that the differential modulation of a conditioned eyeblink response (CR) by 30-s auditory stimuli previously paired with shock was independent of the locus of shock application. In Experiment 1, the modulation occurred when the CR was trained with paraorbital shock and the 30-s stimuli were trained with either hindleg or paraorbital shock. Experiment 2 replicated the observed adequacy of hindleg shock for modulation training, under 2 different conditions of eyeblink conditioning. The data, along with the findings that the same 30-s stimuli similarly facilitate the unconditioned eyeblink and the airpuff-elicited startle response (Brandon, Bombace, Falls & Wagner, 1991), were viewed as supporting the notion that the CR-modulation is dependent upon a conditioned fear response elicited by the 30-s cues (Wagner & Brandon, 1989).

Animals↗
PubMed1989

Modulation of behavioral and insulin responses by contextual stimuli paired with food.

A context-like conditioned stimulus (CS) previously paired with a food unconditioned stimulus (US) enhanced both food-related activity and insulin secretion in rats. Experiment 1 documented the effectiveness of an appetitive conditioning procedure in which a 10 sec visual CS ("x") was followed by food when embedded within one 35 sec auditory CS ("A"), but not another ("B"). Approach to a food magazine during x was enhanced (facilitated) when x was within A, as compared to within B or alone. Experiment 2 documented the adequacy of blood sampling and insulin assay procedures that could be accommodated to the conditioning procedure. Plasma insulin was observably different after unconditioned deliveries of glucose solutions of different intensities. In Experiment 3, training as in Experiment 1 was followed by testing for food magazine approach and changes in insulin levels following x alone or in the presence of A or B. It was demonstrated that the A cue enhanced both responses. The results support the view [e.g., (18,19)] that insulin secretion is in part under the control of environmental cues, and findings (22) that show that conditioned context-like cues can modulate consummatory responding to punctate CSs.

Animals↗
PubMed1986

Development of context-specific tolerance to morphine: support for a dual-process interpretation.

Four experiments were concerned with the development in rats of context-specific tolerance to the sedating and analgesic effects of morphine. Experiment 1 was conducted to assess the temporal course of activity changes and analgesia consequent to acute morphine administration. Experiments 2, 3, and 4 were conducted to assess the development of context-specific morphine tolerance in the two measures under different conditions of pairing of morphine with a distinctive environment. In support of a dual-process model (postulating both a general tendency for conditioned diminution of unconditioned responding and a more restricted influence of the development of specific conditioned compensatory responses), tolerance was observed in both measures, but evidence of conditioned compensatory response was found only in the activity measure. The differential evidence of conditioned compensatory response in the two measures was interpreted as consistent with the fact that the activity measure showed a biphasic unconditioned response in Experiment 1 whereas the analgesic measure did not.

Animals↗
PubMed1980

One-trial overshadowing: evidence of distributive processing.

Evidence of "overshadowing" following a single training trial was obtained in each of five experiments measuring stimulus-evoked suppression of licking in rats. In three conditioned emotional response experiments, less conditioned suppression was observed to either a light or a tone when the stimuli had been paired with shock in compound that when either had been paired with shock in isolation. This difference occurred when the stimuli were diffuse and produced differential orienting behaviors on the training trial (Experiment 1). But, it was as demonstrable when the stimuli were designed to be localizable from the same source and produce apparently compatible orienting behaviors (Experiments 2A and 3A). The difference was also as substantial when the stimulus compound was composed of successive, nonoverlapping stimulus elements as when composed of simultaneous elements (Experiment 3A). In two companion habituation studies (Experiments 2B and 3B) using the same stimulus arrangements but no pairing with shock, there was consistently less habituation of the unconditioned suppression to the visual and tonal stimuli when exposed in compound rather than in isolation. One-trial "overshadowing" is at odds with those theories that approach overshadowing only as a multiple-trial phenomenon. The apparent generality of the effect provides impetus for a theoretical account that supposes some manner of distributive processing.

Animals↗
PubMed1980

Evaluation of blocking and conditioned inhibition to a CS signaling a decrease in US intensity.

Two experiments employing a conditioned emotional response procedure with rats evaluated the associative tendencies acquired by a target CS when a compound of that stimulus and another CS was reinforced by a low-intensity US whereas the latter CS alone was reinforced by a higher intensity US. Experiment 1 involved a blocking sequence in which the element and compound trials occurred in successive phases, followed by eventual testing of the responding to the target CS alone. Less evidence of excitatory conditioning was observed than in a comparison group which had the element and compound paired with the same low-intensity US. Experiment 2 included contemporaneous differential reinforcement of the element and compound CSs and periodic summation tests in which the target CS was compounded with another independently trained CS. Clear evidence was obtained of the development of inhibitory tendencies by the target CS. The results are consistent with the predictions of the Rescorla-Wagner model and are discussed in relation to the several determining assumptions of the model.

Animals↗
PubMed1977

Posttrial reinstatement of the CS in Pavlovian conditioning: facilitation or impairment of acquisition as a function of individual differences in responsiveness to the CS.

Gray and Appignanesi reported that conditioning to an element of a compound conditioned stimulus (CS) was facilitated when the compound not only preceded the unconditioned stimulus (US) but was briefly reinstated shortly after US termination. The manipulation was embedded in a "blocking" design, and the effect was interpreted as being peculiar to such a situation. The present study reports five experiments, using rats in a conditioned emotional response (CER) paradigm, aimed at further evaluating the effects of CS reinstatement. In a blocking experiment patterned after that of Gray and Appignanesi, reinstatement was observed to have a decremental rather than an incremental effect on conditioned responding. In four experiments involving simple conditioning with unitary CSs, reinstatement was observed to have either an incremental or decremental effect, depending upon the subject's preconditioning responsiveness to the CSs involved. Possible mechanisms for such variable effects are discussed without obvious resolution.

Acoustic Stimulation↗
PubMed1975

Short-term memory for "surprising" versus "expected" unconditioned stimuli in Pavlovian conditioning.

Rabbits were trained via a Pavlovian eyelid-conditioning regime to respond differentially to a conditioned stimulus (CSR) depending on whether or not that stimulus was preceded several seconds earlier by a preparatory stimulus consisting of an electric shock otherwise employed as an unconditioned stimulus (UCS). Following training, differential responding to CSR varied systematically with the interval between the preparatory stimulus and CSR, consistent with assumptions concerning decay of information in short-term memory. The major finding, however, involved the test effects of announcing the preparatory stimulus by either a conditioned stimulus with which it had otherwise been paired (CS+) or a conditioned stimulus with which it had otherwise been systematically unpaired (CS-). The greater differential responding to the following CSR in the latter case is taken to support the notion that a "surprising" UCS is more likely to be retained (rehearsed) in short-term memory than is an "expected" UCS.

Acoustic Stimulation↗