The influence of experimental neurosis on the conditional reflexes and the content of blood catecholamines and acetylcholine in dogs

Using experimental neurosis as a model, we investigated the mode of adaptive behavior, conditional reflexes and the blood level of neuromediators in four dogs placed in certain versus uncertain conditions in a Pavlovian laboratory. The research consisted of a two year training program with predictable (ordered partial reinforcement) followed by unpredictable (probabilistic reinforcement) situations. As a result, there was a decline in the acetylcholine as compared to a rise of catecholamine levels of the peripheral blood of some of these dogs. There were varied autonomic responses indicating a possible individual response specificity. In one dog, there was a disappearance of motor defense reflexes. The results support the hypothesis that probabilistic reinforcement following ordered partial reinforcement contributed to the dogs’ neurotic disintegration,i.e., uncertainty is a cause of neurotic development.     

The“response” in behavior theory

The term“response” is a basic one in behavior theory, particularly reflex theory, but its definition is not clear. The origin of the term in the common vocabulary has affected its later extensions in the analysis of behavior. Some contemporary theorists accept the existence of two“types” of response, coordinating one with the Pavlovian conditioning procedure, the other with the operant conditioning procedure of the so-called“contingent” variety. Reservations are expressed here about such distinctions between response classes and conditioning paradigms, emphasizing the difficulties that arise from certain conventions and inadequacies in current definitions and conceptions of“response.” The critical nature of the problem for behavior theory is illustrated once again by the recent laboratory finding that a familiar and accepted conditional reflex, that of the“conditioned cardiac CR,” can be fractionated into“parts” and is therefore perhaps no longer to be treated as a single unitary“response.”     

The effect of amygdala lesions on conditional and unconditional vocalizations in rats

Electrolytic lesions centered on the amygdaloid central nucleus (ACe) resulted in the inability of rats to acquire a Pavlovian conditional vocalization response. Conditioning consisted of pairing a light conditional stimulus with a tailshock unconditional stimulus (US). The thresholds of three unconditional responses (URs) to tailshock were assessed prior to conditioning. These URs are organized at spinal (spinal motor reflexes), medullary (vocalizations during shock), and forebrain (vocalization afterdischarges, VADs) levels of the neuraxis. Compared to sham-lesioned controls, rats with amygdala lesions exhibited a selective elevation in the threshold of VADs. During conditioning the amplitude and duration of VADs were selectively reduced in amygdala-lesioned rats. These findings support earlier observations of that elicitation of VADs by tailshock correlates with the capacity of this US to support fear conditioning. The ACe may be involved in both associative and non-associative aspects of fear conditioning, but for progress in our understanding it is essential to evaluate its role in the generation of conditioning relevant URs.     

Skin conductance response conditioning with CS intensities equal to and greater than UCS intensity

With .2-sec bursts of white noise as both conditioned stimulus (CS) and unconditioned stimulus (UCS), conditioning of first-interval skin conductance responses was obtained when the intensity of the CS equaled and exceeded that of the UCS. There was no evidence that second-interval response conditioning occurred. Nonspecific response frequencies were also affected by the variations in stimulus intensity, this raising some question about typical controls employed in SCR conditioning. There was some evidence that second interval responses were suppressed by the intense CS values. It was concluded that the existence of simple conditioning with a CS/UCS intensity ratio equal to or greater than unity was contrary to the Pavlovian proposition that a CS must be biologically less salient than the UCS in order for conditioning to occur. It was noted, however, that the suppression of second-interval responses might indicate that anticipatory CRs which are not confounded with orienting reflexes are prevented from exhibiting a conditioning effect when a high CS/UCS intensity ratio is employed.     

Pavlov’s position toward konorski and miller’s distinction between pavlovian and motor conditioning paradigms

Two Warsaw medical students, Jerzy Konorski and Stefan Miller, having read I. P. Pavlov’s works on conditional reflexes, informed him in a 1928 letter that they had discovered a new type of conditioning. A previously neutral stimulus preceded the passive lifting of a dog’s paw which then was followed by feeding; this stimulus then evoked the spontaneous raising of that paw. Pavlov responded informing them that their conditioning of motor responses expanded his theory of higher nervous activity, but that their conditioning paradigm—that they named CRII—did not differ fundamentally from the Pavlovian conditioning paradigm. The replication of the Warsaw experiment in Pavlov’s laboratory failed to provide unequivocal results. From 1931 to 1933, Konorski, working in Pavlov’s Leningrad laboratory, further explored the parameters of CRII. Pavlov insisted that the conditioning of motor movements differs from the conditioning of other sensory analyzers only in that, on the neural level, the motor analyzer is both afferent, that is, perceptive, and efferent, that is, responsive. Konorski was not convinced, and he subsequently maintained that the two conditioning paradigms were fundamentally different.     

Cardiovascular generalization and differentiation: The relationship between heart rate and blood pressure

The present study was designed to study generalization and differentiation and to check the relation between heart rate and blood pressure in cardiovascular conditioning. Five naive mongrel dogs were presented with 10 sec 1000 cps tone regularly reinforced with 0.5-sec shock to a left foreleg. Four other 10-sec tones (600, 800, 1200, 1400 cps), never reinforced, were administered in a randomized and counterbalanced fashion using a differential reinforcing technique. The response measures were heart rate and three indices of blood pressure,i.e., systolic, diastolic, and pulse pressures.“Initial response” of heart rate showed rapid tachycardia to all tones, with no generalization and differentiation among five tones.“Terminal response” clearly indicated generalization gradients that tachycardia to 800 and 1200 cps tones were higher than those to 600 and 1400 cps tones, respectively. Some differences were noted among systolic, diastolic, and pulse pressures, with pulse pressure showing a trend of generalization and differentiation in the“initial response.” No statistical difference, however, was obtained in blood pressure scores. Beat-by-beat analyses of correlations between heart rate and diastolic blood pressure showed that the correlations successively decreased during the“terminal response.” Overall correlations between heart rate and three indices of blood pressure were obtained, with the highest correlation between heart rate and pulse pressure. Considering the above results in relation to the classical conditioning theory, it was tentatively concluded that“initial response” includes non-conditional factors, while“terminal response” reflects mainly a true conditional response, particularly, at a long CS-US interval. This interpretation leads to the hypothesis that conditional response with a short CS-US interval may attain better conditioning scores in terms of the summation effect between a non-conditional factor and a true conditional factor.     

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.     

Cardiac conditioning and extinction inMacaca mulatta during block of the CR by cardiac pacing

Previous work has shown that behavior acquisition within the Pavlovian paradigm occurs in the absence of responding,i.e., when conditional and unconditional responses are blocked during training. The parallel question of extinction under response blocking has received less attention. The experiments reported here find that a cardiac CR can be conditioned and extinguished even when rate changes are prevented by cardiac pacing during acquisition and extinction procedures. This finding suggests that the cardiac CR is established independently of peripheral innervations, and that “feedback” from the changing response is not necessary for Pavlovian learning of this sort to occur.     

One-trial cardiac conditioning in dogs

Our interest in cardiovascular conditioning, particularly the fact that conditional tachycardia has been observed in many dogs after only one or two combinations of conditional and unconditional stimuli, led us to investigate conditioning using a single application of an unconditional stimulus. Initially we studied the effect of orienting stimuli (soft tones) on the heart rate in 9 dogs. After 30–100 presentations of the tones alone, each dog received on one occasion a 25-volt shock (sufficient to cause yelping and struggling) to a leg as unconditional stimulus immediately following a tone. Thereafter 30–100 additional tones were presented with no further shock. Little or no heart rate change occurred during the orienting tones (before shock). Three types of cardiac changes occurred during experimental sessions after the shock: 1) Increased heart rate during the tones in 5 dogs; 2) Generalized lowering of heart rate during all experimental sessions after shock in 4 dogs; 3) Electrocardiographic changes during tones in 3 of the dogs also showing the generalized decrease in heart rate. No motor flexion conditional reflexes developed. Tones an octave different in pitch from the one associated with the shock also caused approximately the same heart rate changes, indicating lack of differentiation. This one-trial cardiac conditioning persisted after the single conditioning trial for more than a month in 2 dogs and for at least 3 to 5 sessions in the other dogs.     

Behavior systems,associationism, and Pavlovian conditioning

Associative and behavior systems accounts of Pavlovian conditioning have different emphases. The traditional associative account has focused on the role of the unconditional stimulus (US) in strengthening stimulus associations according to a set of general laws. The behavior systems account has focused on the relation of conditional responding to the preorganized perceptual, motor, and motivational organization engaged by the US. Knowledge of a behavior system enables successful prediction of the form and ease of conditioning as a function of the type of conditional stimulus (CS), US, and the CS-US relation. At the same time, Pavlovian manipulations act as a window on how a behavior system works. Both associative and behavior systems accounts can be criticized as incomplete and idiosyncratic. A comprehensive account of Pavlovian conditioning could profit from their integration.     

The hippocampus and stress induced 17-OHCS elevations

The physiologic contribution of the limbic brain to emotionally induced stress is still poorly understood. The present study is designed to more specifically evaluate the role of the hippocampus in stress induced plasma 17-OHCS elevations. The conditional reflex to a sequential presentation of tone and shock was used as the stress agent in adult mongrel dogs. Plasma 17-OHCS levels were determined by the Porter-Silber method. Control and stress levels of 17-OHCS were determined before and after unilateral (left) hippocampectomy, and subsequent contralateral (right) hippocampectomy. A unilateral posterior hippocampal lesion partially attenuated (20%) the normal 17-OHCS stress response. In contrast to unilateral lesions, equivalent bilateral posterior hippocampal lesions abolished the normal 17-OHCS stress response. These observations support the thesis that the elevated 17-OHCS levels in response to the conditioning paradigm is dependent on the hippocampus. Furthermore, it is dependent upon the continuity of the hippocampal circuit and not upon the volumetric steroid binding capacity of the hippocampus. These studies also suggest that a unilaterally functioning hippocampus may be adequate to meet the physiologic needs of stress, as reflected by the 17-OHCS response. Presented at the 1978 meeting of the Pavlovian Society, St. Petersburg, Florida.     

Application of pavlovian concepts to anxiety and forearm blood flow

Forearm blood flow is presented as an objective index of anxiety. The mechanism by which increase in muscle blood flow occurs as part of a co-ordinated response to “fight or flight” in animals and in man is discussed. An increased forearm blood flow may indicate a considerable degree of internal agitation, although a patient may appear outwardly calm, and this is thought to be evidence of schizokinesis. Patients with anxiety often experience panic attacks with considerable physiological arousal and this may lead to one-trial conditioning. Autokinesis may result in the development of further symptoms, and the Effect of Person on the cardiovascular system in animals and man is considered. Conditionability of anxious patients was investigated and the acquisition and extinction rates of conditional eyelid responses were found to be similar in a group of patients with anxiety, a variety of psychoneurotic disorders, and normal controls. The use of forearm blood flow to monitor reduction in anxiety brought about by medication, desensitization and psychotherapy has been found to be a valuable addition to the objective methods of assessment in psychiatry.     

Complex form of instrumental behavior of dogs

A complex form of higher nervous activity, conditional reflex transswitching or switching, was elaborated in four dogs under conditions of unrestrained movements, freedom of reinforcement choice (food or water), place of reinforcement determined by situation factors as well as independent switching on of conditional stimuli. It was shown that motivated goal-directed behavior of the animals was determined by activation of forward and backward connections. The chains of instrumental conditioned reflexes forming in the final analysis the complex behavior are developed according to the “trialand-error” principle. In the instrumental conditioned reflexes there are two constantly coexisting types of mutually complementing conditioned connections of the signal with reinforcement—direct and indirect. In experiments with unrestrained conditions of animals and independent regulation of the experiment, one of the frequently encountered physiological mechanisms of generalization appears to be efferent and afferent generalization.     

Orbeli’s experimental work on color discrimination in dogs

In the 1900’s, L. A. Orbeli, on I. P. Pavlov’s request, attempted to establish color discrimination in dogs. Previous experiments used the motor discrimination method and gave inconsistent results. In contrast, Orbeli used the salivary conditional reflex method, which he considered to be more precise than the method that relied on erratic movements of a dog. After experimentation that lasted about one and a half years, Orbeli failed to establish color discrimination. When subsequent experiments by Russians and Germans yielded positive results with the motor discrimination method, Orbeli switched to this method and also obtained positive results. These findings were confirmed by most subsequent experiments on color discrimination in dogs. The utility of Pavlovian conditioning in sensory experimentation was not universally justified and its importance was greater in the study of learning.     

CONTINGENCY SPACES AND MEASURES IN CLASSICAL AND INSTRUMENTAL CONDITIONING1

The contingency between conditional and unconditional stimuli in classical conditioning paradigms, and between responses and consequences in instrumental conditioning paradigms, is analyzed. The results are represented in two- and three-dimensional spaces in which points correspond to procedures, or procedures and outcomes. Traditional statistical and psychological measures of association are applied to data in classical conditioning. Root mean square contingency, ø, is proposed as a measure of contingency characterizing classical conditioning effects at asymptote. In instrumental training procedures, traditional measures of association are inappropriate, since one degree of freedom—response probability—is yielded to the subject. Further analysis of instrumental contingencies yields a surprising result. The well established “Matching Law” in free-operant concurrent schedules subsumes the “Probability Matching” finding of mathematical learning theory, and both are equivalent to zero contingency between responses and consequences.     

Synchronization and coupling of phases in periodic processes of conditioning

Locomotor avoidance conditioning and locomotor food conditioning in male albino rats demonstrated that locking of temporary connections is accomplished by coupling of phases of different synchronized periodic neural processes. Phase coupling was verified by the formation of parallel periodic courses of reaction times and motor reaction times in the process of elaboration of conditional avoidance reflexes, and by the curve of the corresponding correlation coefficients, which were calculated from the reaction times and motor reaction times in food conditioning measured every day during the period of stabilization. The authors hold the view that a locking mechanism based on the synchronization of periodic processes in conditioning is most compatible with efficient formation of conditional reflexes and can promote adaptation. Furthermore, it is assumed that information storage, too, occurs periodically, according to the principle of rotary storage.     

Pavlovian conditioning in human skilled motor behavior

The role of Pavlovian contingencies in human skilled motor behavior was investigated in three experiments by means of a new conditioning preparation. In Experiment 1 the present method was shown to be appropriate for the study of associative learning. Subjects who experienced a standard delay configuration performed significantly more conditioned responses than subjects who received either backward conditioning or random pairings. Stimulus generalization was shown to be slight in two additional groups. Subsequent experiments examined conditioning with multiple conditioned stimuli (CSs). In particular, in Experiment 2 some reciprocal overshadowing was demonstrated when two conditional stimuli (tone and vibration) were compounded. Experiment 3 investigated blocking. Blocking was less than expected, however. Subjects’ perceptions of the stimuli and reaction time data suggest that a certain proportion had shifted their attention to the added element of the CS compound. Results are discussed in relation to other studies on Pavlovian learning in humans and animals, which are concerned with “stimulus selection.”     

Differential effects of forward or simultaneous conditioned stimulus-unconditioned stimulus intervals on the defensive behavior system of the Norway rat (Rattus norvegicus)

To test several predictions derived from a behavior-systems approach, the authors assessed Pavlovian fear conditioning in rats after 30 trials of forward, simultaneous, or unpaired training. Direct evidence of conditioned fear was collected through observation of flight and freezing reactions during presentations of the conditioned stimulus (CS) alone. The authors also tested the CS's potential to reinforce an instrumental escape response in an escape-from-fear paradigm. On the one hand, rats that received forward training showed conditioned freezing, but no conditioned flight was observed. On the other hand, rats that received simultaneous training showed conditioned flight, but no conditioned freezing was observed. Rats that received either forward or simultaneous pairings showed instrumental learning of the escape-from-fear response. Implications for several theories of Pavlovian conditioning are discussed.     

Psychogenic vagotonia in a family of beagle dogs

Eight inbred beagle dogs, litter mates of two generations, exhibited psychogenic vagotonia (long sinus pauses and transient atrioventricular block of the heart) during orienting to tones. This was intensified during tones following “one-trial conditioning” to a single painful leg-shock. It was potentiated during conditional stimuli (CS+) regularly reinforced by leg-shock; whereas unreinforced tones (CS?) elicited less vagotonia. Additional evidence of differentiation was observed in one dog when the differential magnitudes of the responses were reversed following reversal of the significance of the conditional stimuli. The possible mechanisms of these changes and correlations with clinical material are discussed. Results of this study illustrate the interplay between constitutional predisposition and psychological factors in prominent cardiovascular changes.