Aversive and appetitive electrodermal classical conditioning using pictures as stimuli

The principal goal of this study was to verify whether it was possible to obtain both aversive and appetitive electrodermal classical conditioning, using pictures as conditioned stimuli (CS), and unconditioned stimuli (US). Additionally, we tried to verify whether, as a consequence of such conditioning, diminution of the unconditioned response (UR) was observed. With this aim, IAPS (?International Affective Picture System?) pictures were selected as stimuli. A picture showing a burnt face was used as the aversive US (USav), and a picture showing a scene with erotic content was used as the appetitive US (USap). As the aversive CS (CSav), and appetitive CS (CSap), two images with intermediate values of valence and arousal showing male faces were selected. In the experimental group, 10 CSav/USav and 10 CSap/USap trials were presented. In the control group 10 CSav, CSap, USav, and USap trials were presented in pseudorandom order. Skin conductance response (SCR) elicited by both the CSs and the USs was scored. Results showed aversive conditioning, but neither appetitive conditioning nor UR diminution. Problems to obtain conditioning using pictures as stimuli and possible options to overcome them in future research are discussed.     

Cardiovascular dynamics during classical appetitive and aversive conditioning in laboratory primates

This report describes changes in the rate of rise of left and right intraventricular pressures during aversive and appetitive conditioning procedures in chair-restrained rhesus monkeys. The conditioning paradigm consisted of a one-minute tone followed, in the one case, by an electric shock, and in the other, by the delivery of Purina monkey pellets. The conditional cardiovascular response was characterized by short latency, highly significant elevations in the derivatives of both ventricular pressures as well as a marked arterial pressor response and tachycardia. The magnitude of the conditional response to the classical aversive procedure was somewhat larger than that to appetitive conditioning. These alterations in the rate of development of intraventricular pressure can be attributed largely to augmentation in the sympathetic neural input to the heart and contribute to an analysis of selective aspects of the nervous regulation of the heart in intact, behaviorally conditioned animals.     

The relationship between motor and secretory behaviors in classical appetitive conditioning

Three hungry dogs received pairings of food with an accessible, illuminated panel. This resulted in the dogs’ approaching the lighted panel and salivating. Despite the similarity of these conditioning procedures to those used in a large body of research primarily with avians, however, the dogs did not physically contact the lighted stimulus panel. These results bear on several issues concerning the form and direction of classically conditioned behaviors.     

Extinction instead of incubation following classical aversive conditioning in dogs

Two dogs received a single paired classical conditioning trial, with tone CS and 12 mA shock US. Both dogs then showed a conditioned blood pressure increase in response to the nonreinforced CS, which extinguished with additional nonreinforced presentations. The CR showed spontaneous recovery four days later, but reextinguished with additional nonreinforced presentations. The results were interpreted as not supporting Eysenck’s theory of “incubation” following one-trial aversive conditioning. Partial support for this study was provided by Grant 28462 from the National Heart, Lung, and Blood Institute.     

Total peripheral resistance changes in dogs during aversive classical conditioning

The arterial pressure, heart rate, stroke volume, cardiac output and total peripheral resistance of laboratory dogs were monitored continuously before and during a 30 min period in which aversive classical conditioning procedures were applied. The experimental stimulation generated inhibition of behavioral activity (“freezing”) together with sustained increases in arterial pressure averaging 30%, and increases in heart rate and cardiac output of 60–70%. The calculated total peripheral resistance decreased by an average of 20%. The behavioral and cardiovascular responses were sustained during the aversive conditioning period. The results suggest that significant peripheral vasodilation occurred under these conditions which was probably not due to metabolic byproducts of behavioral activity, but probably reflected sympathetic cholinergic effects upon blood vessels in the skeletal muscles. These data document the significance of the skeletal muscle circulation in the total peripheral resistance to blood flow in unanesthetized animals.     

Personality and conditioning: Some personality,cognitive and psychophysiological parameters of classical appetitive (sexual) GSR conditioning

A number of personality, cognitive and psychophysiological measures taken from a sample of 25 male volunteers were correlated with, classical (sexual) GSR acquisition and extinction rates, and the data factor analyzed. The acquisition and extinction factors identified were indexed by the psychophysiological (CS and US) variables. Cognitive and personality dimensions accounted for a negligible amount of variance.     

Effects of external cathodal polarization on classical motor conditioning in dogs

The present study was designed to determine the effects of cathodal polarization on the establishment of motor conditional reflexes (CR's), with faradic shock as reinforcement. Ten dogs were used as controls and another seven as experimental subjects (ES's). In the ES's, stainless-steel electrodes were implanted on the face, infraorbitally, for chronic polarization. Four days later the ES's were trained in a soundproof room with classical conditioning procedures while they were co9nstantly polarized with direct current (1 to 2 ma). Control dogs showed strong (+3 and +4) motor CR's within the first 50reinforced trials, with differentiation after 50 trials. In contrast, the ES's showed poor motor conditioning: six ES's showed poor motor CR's in the first 50 reinforced trials. Only one ES showed prompt, good motor CR's. The fact that cathodal polarization interferes with theestablishment of motor CR's suggests an inhibitory effect on the acquisition of musculoskeletal CR's. It is possible that the inhibitory effects observed are related to the depression produced by cathodal polarization in humans.     

Extinction instead of incubation following classical aversive conditioning in dogs.

Two dogs received a single paired classical conditioning trial, with tone CS and 12 mA shock US. Both dogs then showed a conditioned blood pressure increase in response to the nonreinforced CS, which extinguished with additional nonreinforced presentations. The CR showed spontaneous recovery four days later, but reextinguished with additional nonreinforced presentations. The results were interpreted as not supporting Eysenck's theory of "incubation" following one-trial aversive conditioning.     

The effects of lesions in the central nucleus of the amygdala on appetitive classical conditioning in rats

Abstract: Lesions in the central nucleus of the amygdala (cAMY) have been known to interfere with the acquisition of fear classical conditioning when footshock is used as an unconditioned stimulus (US). The present study examined whether or not a similar interference would occur with an appetitive US. Five rats with lesions in the cAMY (the cAMY group), and eight unoperated control rats were trained in an appetitive classical conditioning paradigm, which did not include elements of operant learning, using a visual conditioned stimulus (CS) (5 W of light for 10 s duration) paired with a food pellet US (45 mg, cheese flavor). The behavioral index of appetitive conditioning was an increase in rearing approach behavior to the CS after CS and US pairings. During CS and US pairings, the movement of the rat was limited so that this approach behavior could not occur. As a result, all control rats showed an increase in rearing, but the cAMY group did not. These results suggest that the cAMY is critical for appetitive as well as fear classical conditioning.     

Analysis of us-preexposure effects in appetitive conditioning

In two experiments, rats received preexposure to one type of food followed by autoshaping in which presentation of one lever was associated with the preexposed food, and presentation of another lever with a novel type of food pellet. In both it was found that acquisition of the leverpress response occurred more readily on the lever associated with the novel food. This example of the US (unconditioned stimulus) preexposure effect is not to be explained in terms of the development of competing responses during preexposure. Explanations in terms of blocking by contextual cues and of habituation to the US are considered.     

The control of appetitive instrumental responding does not depend on classical conditioning to the discriminative stimulus

In Experiment I, rats were exposed to a classical relationship between a clicker-light compound and response-independent food. Conditioning to the light was blocked if the clicker had previously served as a classical signal for food, but not if it had been established as a discriminative stimulus for food-reinforced lever pressing. In Experiment II, a tone-light compound served as a discriminative stimulus for lever pressing. Control by the light was blocked if the tone was independently trained as a discriminative stimulus, but not if it was trained as a classical signal for response-independent food. These results suggest that discriminative stimuli do not come to control appetitive instrumental responding by virtue of their implicit classical relationship to the instrumental reinforcer.     

Overtraining in classical conditioning: A comparison of motor and cardiac systems in dogs

Data from the analysis of the Overlearning Reversal Effect (ORE) noted in a simultaneous, visual discrimination task, and the lack of this effect in a position habit discrimination, led to the prediction that the ORE would not be noted in classical conditioning. It was further noted that very little work on discrimination learning had been reported in Pavlovian conditioning. The idea of schizokinesis, as observed by Gantt and others in classical conditioning, has been elaborated using the simple conditioning paradigm, and no data were available to test whether this same split would occur on a more complex level of conditioning, such as a discrimination task. To test these ideas, nine dogs were trained to a criterion of minimum discrimination, and then divided into three groups and given varying amounts of overtraining (OT). The discrimination task given the animal was to flex its paw during the CS+ signalling the onset of a brief shock. After the varying amounts of OT all groups were placed in extinction, followed by reversal training until each dog reached a criterion of minimum reversal. The results indicated 1) that the cardiac discrimination did not form before the motor discrimination; 2) extinction of differentiation was not significantly affected by the amount of OT given; 3) the mean level of responding in the motor system during extinction was highly correlated with the mean level of responding during the initial discrimination training; 4) OT had no effect on the speed of reversal of either the motor or the cardiac systems; 5) the speed of reversal learning in the motor system was highly correlated with the speed of initial discrimination.     

One-trial appetitive conditioning in the sexual behavior system

One-trial Pavlovian conditioning has been demonstrated with aversive reinforcers such as electric shock and lithium chloride. The present experiments using male Japanese quail were conducted to determine if an appetitive unconditioned stimulus (US), the opportunity to copulate with a female quail, can also generate one-trial learning. In Experiment 1, subjects were exposed to a contextual conditioned stimulus (CS) for 35 sec and then given copulatory opportunity. In Experiment 2, male birds were given 0, 2, or 4 min of exposure to the contextual CS before presentation of a female. In both cases, control groups received comparable exposure to both the contextual CS and the sexual US, but in an unpaired fashion. Subjects were tested for sexual learning by reintroducing them to the experimental context in the presence of a test object that incorporated the taxidermically prepared head of a female quail. In both Experiments 1 and 2, subjects for whom the contextual CS and sexual US had been paired displayed significantly more approach to the test object than did unpaired subjects.     

Automated discrete-trials techniques of appetitive conditioning in honey bees

Automated techniques of appetitive conditioning in honey bees are described. The subject is pretrained to come to the laboratory, where it is confined while the training trials are programmed and then is free to return to the hive. The responses recorded are approach to and entering a tube into which sucrose solution is pumped. Illustrative experiments on classical conditioning, simple instrumental conditioning, and choice are reported.     

Human classical conditioning

Recent reports of failure to obtain blocking in human galvanic skin response (GSR) conditioning, together with our own equivocal results with eyelid conditioning, have motivated us to re-examine the status of the conditioned stimulus (CS) in human conditioning studies. The issues raised by compound stimuli, by contextual cues and occasion setting stimuli, and by cross-modal transfer are considered in the light of data from our laboratories. These data include observations on the interchangeability of stimulus modalities during acquisition, the use of varying information loads embedded in occasion setting displays, the comparison of alternative blocking designs and the analysis of response topography in relation to stimulus variability. They suggested that an adequate account of the CS in human conditioning studies must recognize that it is dynamically processed and reprocessed both during and after acquisition.     

Effects of contextual conditioning and unconditional stimulus presentation on performance in appetitive conditioning

Four experiments with rat subjects examined the effects of contextual conditioning on conditioned appetitive performance. Experiment 1 compared the effects of contextual conditioning on performance to conditioned stimuli (CSs) with different conditioning histories. Contextual conditioning enhanced performance to the CS if the CS had first been conditioned and then extinguished, but had no effect on performance when the CS had been merely paired or unpaired with food. Experiments 2 and 3 then asked whether the effect on the extinguished CS was due to contextual conditioning acting as a cue for conditioning. In Experiment 2, extinction procedures in which extra unconditioned stimuli (USs) were presented during the intertrial intervals were found to reduce the CS's sensitivity to enhancement by contextual conditioning, but had no effect on spontaneous recovery. In Experiment 3, USs added to conditioning or extinction acquired the ability to cue the corresponding performance. Under some conditions, USs added to conditioning could suppress performance (Experiment 4). The results suggest that contextual conditioning has complex effects that can be better understood by recognizing that contextual conditioning, as well as the USs that create it,Mayacquire discriminative control over conditioned responding.     

Reinforcement in an in vitro analog of appetitive classical conditioning of feeding behavior in Aplysia: blockade by a dopamine antagonist

In a recently developed in vitro analog of appetitive classical conditioning of feeding in Aplysia, the unconditioned stimulus (US) was electrical stimulation of the esophageal nerve (En). This nerve is rich in dopamine (DA)-containing processes, which suggests that DA mediates reinforcement during appetitive conditioning. To test this possibility, methylergonovine was used to antagonize DA receptors. Methylergonovine (1 nM) blocked the pairing-specific increase in fictive feeding that is usually induced by in vitro classical conditioning. The present results and previous observation that methylergonovine also blocks the effects of contingent reinforcement in an in vitro analog of appetitive operant conditioning suggest that DA mediates reinforcement for appetitive associative conditioning of feeding in Aplysia.     

Central localization of plasticity involved in appetitive conditioning in Lymnaea

Learning to associate a conditioned (CS) and unconditioned stimulus (US) results in changes in the processing of CS information. Here, we address directly the question whether chemical appetitive conditioning of Lymnaea feeding behavior involves changes in the peripheral and/or central processing of the CS by using extracellular recording techniques to monitor neuronal activity at two stages of the sensory processing pathway. Our data show that appetitive conditioning does not affect significantly the overall CS response of afferent nerves connecting chemosensory structures in the lips and tentacles to the central nervous system (CNS). In contrast, neuronal output from the cerebral ganglia, which represent the first central processing stage for chemosensory information, is enhanced significantly in response to the CS after appetitive conditioning. This demonstrates that chemical appetitive conditioning in Lymnaea affects the central, but not the peripheral processing of chemosensory information. It also identifies the cerebral ganglia of Lymnaea as an important site for neuronal plasticity and forms the basis for detailed cellular studies of neuronal plasticity.