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Biomedical subjects

C X Poulos

Publications and source records attributed to C X Poulos.

44 records · Page 3Linked to original sources
PubMed1979

An associative analysis of pretreatment effects in gustatory conditioning by amphetamine.

Various attempts have been made to account for the fact that pertreatment with some pharmacological agents reduces the ability of such agents to induce conditioned aversion to a flavor. One explanation, based on the concept of tolerance, suggests that pretreatment is effective because it renders the animal less sensitive to direct effects of a given dose of the agent. A second explanation emphasizes the possibility that procedural consequences of pretreatment interfere with associability of flavor and drug effect during conditioning. The second explanation was tested in two experiments. In experiment I nonreinforced presentations of drug administration cues completely reversed the attenuating effects of amphetamine pretreatment on gustatory conditioning by amphetamine. This finding was replicated and extended in the second experiment which was also designed to eliminate an alternative nonassociative explanation for the results. The principle of associative blocking may explain the effect of pretreatment on subsequent gustatory conditioning by drugs.

Animals↗
PubMed1979

Associative factors in drug pretreatment effects on gustatory conditioning: cross-drug effects.

The pretreatment effect (PE) in gustatory avoidance conditioning refers to the fact that pretreatment with a variety of pharmacological agents subsequently reduces the ability of the same agents to induce gustatory aversion. Explanations of this phenomenon emphasize either tolerance or associative interference. Any explanation of the phenomenon must also account for the present findings which demonstrate the PE when agents of pretreatment and conditioning were pharmacologically dissimilar. Rats were pretreated with d-amphetamine and tested for acquisition of an aversion to saccharin conditioned by amphetamine or morphine. The PE was obtained regardless of the drug used in conditioning. An associative manipulation involving nonreinforced presentation of the drug administration cues (i.e., injections followed by saline instead of drug), that attenuated the PE when pretreatment and conditioning were with amphetamine, was also effective when the pretreatment agent was amphetamine and the conditioning agent was morphine. The findings were interpreted within a framework of compensatory conditioning of a general physiological mechanism common to all gustatory avoidance.

Animals↗
PubMed1976

Heart-rate decelerative Pavlovian conditioning with tilt as UCS: towards behavioural control of cardiac dysfunction.

As part of a programme the ultimate goal of which is to teach behavioural control of stress-induced maladaptive cardiac accelerations through Pavlovian decelerative conditioning, this study was directed at examining the feasibility of using tilting of the body from a head-up to a head-down position as the unconditional stimulus (UCS) to elicit phasic cardiac deceleration as the unconditional response (UCR). Experiment I assessed the reflexive features of the cardiac response to 32 tilt UCS trials delivered at mean intervals of 75 sec. The results yielded a large-magnitude (over 30 BsPM) cardiac decelerative UCR with fast recruitment and complete resistance to habituation. Experiment II examined the feasibility of using the tilt UCS to demonstrate associative control over decelerative responding to a tone as the conditional stimulus (CS). Relative to a control 'backward' UCS-CS group with an interstimulus interval (ISI) of 14.5 sec, a 0.5 sec ISI CS-UCS experimental group demonstrated both orderly acquisition and extinction performance. The magnitude of the conditional deceleration of some 4 BsPM is greater than the extent of control generally achieved with biofeedback, but still constitutes a problem for theoretical accounts of classical conditioning framed in terms of stimulus substitution, and is still only of borderline clinical significance.

Acoustic Stimulation↗
PubMed1975

Human Pavlovian decelerative cardiac conditioning based on a respiratory-induced cardiac deceleration as an unconditional reflex.

This study was directed at examining the feasibility of using a respiratory-induced cardiac decelerative reflex as an unconditioned response (UCR) in a Pavlovian conditioning paradigm. Experiment I assessed the reflexive features of the cardiac response under a respiratory procedure which involved 3 sec of exhalation, 4 sec of inhalation, and then 30 sec of breath-holding (BH). The results indicated that the BH onset aspect of this respiratory cycle involved a phasic, large-magnitude cardiac deceleration (27 beats/min) with short latency, fast recruitment, and no indication of habituation over trials. Experiment II examined the feasibility of using BH onset as an unconditioned stimulus (UCS) in a Pavlovian paradigm by presenting an auditory conditional stimulus (CS) 1 sec prior to the instructed BH aspect of the respiratory cycle. A separate control condition involved presenting the CS 10 sec after BH onset which constituted a 'backward' conditioning control. The results indicated that the conditioning group displayed a significant cardiac deceleration on CS-alone test trials (under normal breathing) in contrast to the absence of such an effect for the control group. In brief, the study suggested that a decelerative conditioned response (CR) could be established by using a respiratory-induced cardiac deceleration as a Pavlovian UCS. Potential clinical applications of such a decelerative CR were noted.

Acoustic Stimulation↗
PubMedDate not supplied

Appetitive differential conditioning of the rabbit's jaw movement response. Effects of cue similarity and US magnitude.

Two experiments examined appetitive differential conditioning of the rabbit's jaw movement response (JMR) in a two-phase procedure. The first phase entailed reinforced training with one conditioned stimulus (CS+), and the second phase involved intermixed presentations of CS+ and an unreinforced stimulus (CS-). In Experiment 1, CS+ was a 600-Hz tone, and CS- was either a 660-, 1,000-, or 2,100-Hz tone. In Experiment 2, the magnitude of the water unconditioned stimulus (US) paired with CS+ was either 1, 3, or 9 ml. The experiments revealed that 1) the level of responding to CS- rose for several days and then declined over the remainder of training; 2) the physical similarity between CS+ and CS- directly affected the level of responding to CS- but had no discernable effect on the level of responding to CS+; and 3) US magnitude positively affected the level of responding to CS+ and, to a lesser extent, CS-. The results are discussed in terms of their implications for Spence's gradient interaction theory and Pavlov's external inhibition hypothesis.

Animals↗