W. Horsley Gantt

Conditional reflex electrocardiogram of bulbocapnine: Conditioning of the T wave

Abstract We studied conditioning to a drug, bulbocapnine, which produces marked motor effects (catalepsy) as well as profound changes in the electrocardiogram. The latter consist mainly in changes in the amplitude of the T wave in standard limb leads and greatly exaggerated T waves which are equal in height to the R wave in bipolar precordial leads. Separating the dog from the interference of the presence of a person, and using injection of the drug from outside a sound-shielded room, we were able to demonstrate a conditional electrocardiographic change after 20 repetitions. The conditional reflex was formed to the signals of the intravenous injection (without the presence of the person), namely, to the injection of saline or to auditory signals. The effects of bulbocapnine (catalepsy and ECG pattern) are mediated through the central nervous system in contrast to certain effects of atropine and of acetylcholine on cardiac functions. The fact that cardiac changes due to bulbocapnine (centrally acting) are conditionable, whereas those due to atropine and other peripherally acting substances are not conditionable is further evidence that the criterion for conditioning is not the type of response but whether it is mediated peripherally or centrally .

The effect of Person on cardiac and motor responsivity to shock in dogs

Interaction between effect of social stimulus (Person) and a faradic shock on heart rate and motor response (leg flexion) in four dogs was observed and recorded. The trials during which the shock and petting were presented simultaneously showed a significant suppression of heart rate increase to shock when compared to the shock alone trials. The lack of this suppression effect in the motor response to the shock is discussed in relation to the concept of schizokinesis. The importance of controlling prior experience of subjects is also discussed.

The heart rate component of the social reflex in dogs: the conditional effects of petting and person.

Five dogs were given a 480-cps tone followed by shock for more than 200 trials. A 200-cps tone was then introduced followed by a person petting the dog at the end of the conditional signal (CS) for 50 trials. Finally, the 480-cps tone-shock (T-S) sequence was reintroduced for five trials, after which the person entered the experimental room and stood beside the dog during one additional T-S sequence.It was observed that both the heart rate (HR) increase to shock, and the HR decrease to petting could be conditioned rapidly (1–5 trials). These findings are discussed in terms of the theory of stimulus substitution in classical HR conditioning.After the person had been made part of a CS for petting, and the T-S sequence reintroduced, the HR increase during the CS was reduced. The HR response to the shock, however, was greater than the response to this US when the dog was alone. A control group, given the same T-S sequence with a person present who had not been a CS for petting, did not show any significant HR changes from the usual response given to the T-S sequence.It is emphasized that these findings, in conjunction with earlier reports, indicate that the cardiovascular system may be a valuable index in studying the psychophysiology of socialization processes.

Failure to develop a conditional reflex by stimulation of the cephalad portion of the severed vagosympathetic trunk: Its significance in terms of the central connections of the vagus

Stimulation of the central stump of either vagosympathetic trunk in the dog, the contralateral nerve remaining intact, regularly provoked deep respiratory movements with forceful expiration, followed by a period of apnea, and a fall in blood pressure, systolic and diastolic, of 20–60 mm/Hg. Stimulation of the cephalad portion of the left nerve provoked brief acceleration of heart rate during the period of hyperventilation, followed by bradycardia; when the stimulus was applied to the central stump of the right nerve heart rate remained relatively unchanged. When a 12-second tone as a conditional stimulus (CS) was reinforced during its last six seconds with such stimulation of the vagosympathetic trunk as an unconditional stimulus (US), despite the striking visceromotor responses elicited by the US, no conditional reflex was established even after more than 3,400 trials in 16 dogs (34–781 trials per animal).

An attempt to condition extrasystoles using direct myocardial electrical stimulation as an unconditional stimulus

Conditioning of extrasystoles which were induced by direct electrical stimulation of the ventricular myocardium was attempted. It was found that this type of cardiac irregularity which is entirely peripheral in origin could not be conditioned. Other studies have shown that extrasystoles which are produced by stimulation of the central nervous system can be conditioned. The study supports the theory that the effect of stimuli which produce physiological changes at the periphery without intermediate involvement of the central nervous system cannot be conditioned.

Experimental psychogenic hypertension: Blood pressure changes conditioned to painful stimuli (Schizokinesis)

Summary1.During habituation in 4 dogs to a new environment and attachment of apparatus, the blood pressure was at first high but fell from about 175 systolic the first day to about 135 on the ninth day.2.In the first group of dogs used two years previously to form 3 cardiac conditional reflexes to 3 intensities of shock, the blood pressure measured after a 13-month rest was retained and specific to the 3 intensities of shock. In another group of 2 dogs the blood pressure was specific to the excitatory and to the inhibitory signals for pain.3.The conditioned hypertension was parallel to the conditioned heart rate.4.The conditioned hypertension was parallel to the motor conditional reflex with certain exceptions: the conditioned hypertension was, like the cardiac conditional reflex, quicker to form and more persistent, thus being present often in the absence of the motor conditional reflex—an evidence ofschizokinesis.5.The conditioned hypertension was retained for a 13-month rest period without intervening training, being present immediately when the dog was brought back into the environment where the stress had been given.6.Although the conditioned hypertension was retained in the long rest period,it could in one dog be reduced somewhat by repeating the conditional stimulus without the shock (non-reinforcement), a more efficient way of extinction than simple rest. In another dog the hypertension became exaggerated though there was no repetition of the stress, showing evidence of an internal development (autokinesis).7.The amplitude of the conditioned hypertension varied according to the individual dog from about 130 average control to limits of 150 to 225 (conditioned hypertension) in the separate dogs.1. n nDuring habituation in 4 dogs to a new environment and attachment of apparatus, the blood pressure was at first high but fell from about 175 systolic the first day to about 135 on the ninth day. n n n n n2. n nIn the first group of dogs used two years previously to form 3 cardiac conditional reflexes to 3 intensities of shock, the blood pressure measured after a 13-month rest was retained and specific to the 3 intensities of shock. In another group of 2 dogs the blood pressure was specific to the excitatory and to the inhibitory signals for pain. n n n n n3. n nThe conditioned hypertension was parallel to the conditioned heart rate. n n n n n4. n nThe conditioned hypertension was parallel to the motor conditional reflex with certain exceptions: the conditioned hypertension was, like the cardiac conditional reflex, quicker to form and more persistent, thus being present often in the absence of the motor conditional reflex—an evidence ofschizokinesis. n n n n n5. n nThe conditioned hypertension was retained for a 13-month rest period without intervening training, being present immediately when the dog was brought back into the environment where the stress had been given. n n n n n6. n nAlthough the conditioned hypertension was retained in the long rest period,it could in one dog be reduced somewhat by repeating the conditional stimulus without the shock (non-reinforcement), a more efficient way of extinction than simple rest. In another dog the hypertension became exaggerated though there was no repetition of the stress, showing evidence of an internal development (autokinesis). n n n n n7. n nThe amplitude of the conditioned hypertension varied according to the individual dog from about 130 average control to limits of 150 to 225 (conditioned hypertension) in the separate dogs.

Effects of pentobarbital sodium anesthesia and neurohumoral agents on the cardiac orienting reflex

Studies of the cardiac orienting reflex in 16 dogs, moderately anesthetized and awake are reported. In the anesthetized dogs prominent transient heart rate decrease was commonly noted within one or two beats after the onset of various auditory stimuli, and less often after visual stimuli. This cardiac inhibition was neither as prominent nor as frequent in occurrence in awake dogs. The respiratory cycle at stimulus onset influenced the appearance and degree of heart rate decrease, with the greatest and most frequent decreases occurring during the expiratory phase. Atropine abolished the response. There was little evidence of habituation of this orienting response under anesthesia, although “waxing” and “waning” apparently related to minute-by-minute fluctuations in degree of unconsciousness, occurred. These findings are discussed in relation to neurophysiological and neuroanatomical correlates of orienting responses, hypotheses of orienting and attention and cardiovascular neurohumoral mediators.

Learning Theories: Pavlovian Paradigm

Publisher Summary This chapter discusses the learning theories regarding Pavlovian paradigm. Russian physiologist, I. P. Pavlov, was interested in studying integrated physiology in healthy animals. One of Pavlovs interests was to understand the physiology of digestion and he was concerned that such methods were not adequate to allow a proper observation of this living system. By developing a fistula system, and by the development of the Pavlov pouch, he was able to begin observing various reflex stomach secretions involved in the ongoing digestive process. This method for studying normal physiological reflexes led Pavlov to observe a new and strange reflex physiology that had not previously been seen. His discoveries have been extended beyond the gastric secretions or salivary reflexes he studied, however, the principles remain the same. Pavlovs contribution to behavior through his work on the conditional reflex was based on precise measurement. His interest in the conditional reflex (CR) as a way of studying cortical function led him to propose a physiological theory of conditioning phenomena that involved the processes of cortical excitation and inhibition.