Classical conditioning of blood pressure inMacaca mulatta with cardiac rate controlled

The interaction of heart rate and blood pressure responses was studied in four male rhesus monkeys (M. mulatta) during classical delay conditioning and extinction. During initial conditioning sessions, heart rate was held constant by means of an external cardiac pacemaker; in follow-up conditioning sessions, the heart was free of constraint. Observations were made after these conditioning sessions, (a) during several sessions given over to continued training while different pacing rates were in effect; (b) during a series of extinction sessions in which the heart was paced and unpaced; and, (c) when a heart rate CR was simulated by manipulation of the pacer with no conditioned or unconditioned stimuli present. Throughout all sessions, systolic and diastolic pressures were measured at each heart beat. It was found that blood pressure conditioning was largely unaffected when heart rate changes were prevented during acquisition. Extinction of blood pressure responses was also seen to proceed relatively unimpeded when the heart was paced at a fixed frequency. During the postacquisition conditioning sessions, the several different pacing rates that were tested did not produce any significant differential effects in the blood pressure CRs. Simulated heart rate CRs were accompanied by small changes in pressures, sometimes opposite in direction from the pressure CRs observed during unpaced conditioning trials.     

Conditioning the cardiorespiratory dynamics of locomotion in dogs

In 17 dogs blood pressure in the carotid artery, heart rate, pneumogram and actogram of the hind leg were recorded during rest and during locomotion on a treadmill. The increases in cardiorespiratory dynamics which occurred during locomotion were then conditioned. The conditional stimulus was represented by the noise and vibration of the treadmill. It was determined that conditional changes in cardiorespiratory dynamics can be formed quickly on the basis of locomotion. Qualitatively the changes were the same as the unconditional changes, and their magnitude was 60 to 70 per cent that of the unconditional changes. Conditional increase in cardiorespiratory dynamics was most intensive in the first 30 seconds from the onset of the conditional stimulus. In acute extinction of these conditional changes, movements of the extremities were inhibited first, followed by inhibition of increased blood pressure, then inhibition of increased heart rate, and last, inhibition of increased respiratory rate. In another series of experiments on five dogs cardiorespiratory responses were conditioned to a sudden change from moderate locomotion (50 m per min) to rapid locomotion (200 m per min). Increased cardiorespiratory dynamics could be conditioned easily. Increased circulation of blood and increased respiratory rate on exposure to conditional stimuli signalling muscular exertion can be considered an important preparation of the organism for actual muscular activity. This preparation also takes place in natural life conditions.     

Effect of movement on the cardiac conditional reflex

The cardiac component of the motor conditional reflex to a faradic stimulus to the hind leg in three dogs was measured. The leg was paralyzed by crushing 4 to 5 anterior roots of the lumbar nerves (second to sixth). The cardiac experiments were repeated beginning four days after operation and measurements were taken of the cardiac conditional reflex. A comparison of the increase in cardiac rate to the conditional stimulus before and after operating showed no significant difference in spite of the fact that the dog was unable to lift his leg to the stimulus. From this we conclude that the execution of the movement is not necessary for the increase of heart rate in the cardiac conditional reflex.     

Use of the conditional reflex to assess the temporal characteristics of curarization effects on heart rate responding

A Pavlovian methodological counterpart to the use of druginduced changes in operant rates of responding was used to assess the temporal characteristics of d-tubocurarine chloride effects on the heart rate conditional reflex in rats. After a stable conditional reflex had been established, the base heart rate, as well as the unconditional and conditional reflex, was monitored during administration of the drug. A sizable behavioral effect was reflected in all three measures, including a temporary abolition of the conditional and unconditional reflexes. An interpretation of these results was discussed, and further development and application of this specific methodology was explored.     

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.     

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.     

Dentist phobia

This study analyzes so-called hopeless gaggers,i.e., patients in whom dental treatment and wearing of a prosthesis produced a retching or vomiting reaction, in order to investigate the sources and properties of this pathologic reaction. In 35 patients, an anamnestic inquiry, a determination of the reflexogenic zone, a recording of the peripheral pattern of the pathologic reflex, and extinction training were performed. A group of six normal persons served as a comparison group. It was shown that patients, in comparison with normals, had an enlarged receptive field, were sensitive to a broader population of stimuli, and showed precursors and aftereffects of the retching-vomiting not found in normals. This pathologic reaction was the symptom of different Psychopathologie processes, such as specific fear, repugnance-fear-based disturbances, diffuse anxiety, goal-directed behavior, depressive states and, at least in one case, visceral pathology. The various patients differed with respect to properties of the reaction as well as in the sensitivity to the extinction procedure. It is discussed that different integrative nervous processes play a role in the origin and development of the syndrome: activation of unconditional reflexes, activation of classic and instrumental conditional reflexes, activation of such reflexes by an increase of the reactivity level of specific and unspecific structures of the brain, generalization of stimuli,etc.     

Psychopharmacology and conditional reflexes

Drugs may be used in several ways to investigate their role in behavior. (1) The placebo effect is usually connected with the relation of the person to the drug. (2) Using the drug as an unconditional stimulus, its action may help to analyze the role of peripheral vs. central stimuli in the formation of conditional reflexes; our work has shown that the effect of drugs which act solely at the peripheral nerve endings without the involvement of the central nervous system cannot become conditioned. (3) The action of drugs on the conditional reflex (CR) compared with their action on the unconditional reflex (UR) explains some of their behavioral effects. (4) Schizokinesis is often prominent in the action of drugs. Although a drug may increase the level of the heart rate, for example, it can, on the other hand, diminish the reactivity shown in the CR. Meprobamate and mescaline affect differently the cardiac and the motor components of the CR, illustrating a schizokinesis. (5) The type of individual is an important factor in the action of drugs; the same drug may have opposite effects on different individuals. This leads to the conclusion that a drug should fit the individual as well as the disease. (6) Autokinesis is often seen in drug action. Therefore a single dose of some drugs, such as acetylcholine, epinephrine or LSD, may permanently change the relationships between excitation and inhibition, in the direction of improvement or deterioration (positive or negative autokinesis).     

An attempt to condition components of urine formation in dogs

Previous research on the renal conditional reflex (CR) has resulted in contradictory data. The work of Bykov with dogs and of Hoferet al. with humans indicated that a renal CR is possible, but the experiments of Corsonet al. and Watt and Gantt with dogs having normal or transplanted cervical kidneys showed no clear-cut renal CR’s. The present work supports the latter finding. Three female mongrel dogs were used. One dog (normal) had an externalized ureter; the other two (experimental) had denervated cervical kidneys (autografts). In 155 days of experiments, the investigators found diuresis to occur only on unconditional stimulus,i.e., only when a dog drank diluted milk (one part milk to four parts water)ad lib.; the dogs drank an average of between 500 and 1,100 ml. No diuresis occurred when 30 ml. of the mixture were given (conditional stimulus). Urinalysis indicated a lack of renal conditioning with respect to the excretion rates and the concentrations of creatinine and electrolytes, except for the sodium concentration in the normal dog’s urine, which decreased on bothad lib and test (30 ml) days; the volume was not affected. Conclusion: Drinking a small quantity of diluted milk as a conditional stimulus did not produce a conditional diuretic response either in the normal dog or in the two dogs with transplanted kidneys.     

Achilles Tendon Reflexes and Surface EMG Activity during Anticipation of a Significant Event and Preparation for a Voluntary Movement

Achilles tendon reflexes were evoked bilaterally during and shortly after an interstimulus-interval (ISI) of 4 s and expressed as percentages of an averaged control reflex. Surface EMG of the soleus muscles was recorded continuously during the ISI, and expressed as percentages of a control EMG level. Three types of tasks were introduced, according to a between subjects design. Condition I consisted of a guessing task, involving anticipation of the second stimulus (S2) and not requiring a motor response. Conditions II and III were a warned choice and simple RT task respectively, the motor response to S2 being a plantar flexion of either the left or right foot in Condition II, and a plantar flexion of the right foot in Condition III. The results can be stated as follows: 1. Anticipation of a stimulus is not sufficient for a reflex increase to occur during an ISI. Preparation for a movement seems to be a necessary condition.

2. The reflex increase during preparation is rather independent of the amount of selectivity in the preparatory process; simple and choice RT tasks yield similar results, although the mean RTs do differ.

3. A difference between the involved and non-involved legs in the simple RT task is not found in the present experiment, as opposed to other studies. The particular instruction given to the subjects could be of importance in producing this difference.

4. Reflex changes cannot simply be accounted for by changes in background EMG of the agonist, as the EMG time course shows no changes over time in either condition.

     

Functioning of peripheral Ia pathways in leg muscles of newly walking toddlers

Monosynaptic and polysynaptic spinal level reflexes in the leg muscles of infants show significant dispersion across muscles, high variability, and no change in response patterns over the first 10 months. Here we tested the hypothesized relation between early walking experience and the tuning of these responses in three primary gait muscles of participants in four subgroups: cruisers (n = 7) and toddlers with one (n = 5), two (n = 5), or three (n = 5) months of walking experience. Reflex responses in multiple Ia pathways – tendon reflex (T-reflex), vibration-induced inhibition of the T-reflex (VIM-T-reflex), and tonic vibration-induced reflex (VIR), were elicited by mechanical stimuli applied to the distal tendons of the quadriceps, gastrocnemius-soleus, and tibialis anterior of both legs. Walking skill was assessed via a GAITRite mat. Generally, walking experience seemed to be related to slowly emerging improvements and, depending on muscle tested and pathway, progress was quite varied. Amplitude and latency of reflex responses were more clearly impacted by age or leg length while the ratio or distribution pattern of reflex response among antagonist pairs of muscles was impacted by walking experience and skill. As walking experience increased, the ratio of reflex responses tended to increase for the stimulated and decrease for the antagonist reflex loops with distribution of the pattern shifting gradually toward a single type of reflex response in all tested muscles. The very slow tuning of these reflexes may underlie the many missteps and falls reported to occur during early walking and suggest that subsequent studies should continue to follow the developmental trajectory through the first year of walking experience.     

Blocking of inhibitory conditioning within a serial conditioned stimulus-conditioned inhibitor compound: Maintenance of acquired behavior without an unconditioned stimulus

Well-trained classically conditioned stimuli, presented unreinforced, were protected from extinction when they were followed by a signal of the omission of the reinforcer (conditioned inhibitor Konorskian type) in eight cats. An aversive classical conditioning paradigm with shock as the reinforcer was used. Of several behavioral (leg flexion, vocalization) and organismic arousal (heart rate, respiration rate, respiration amplitude) measures of conditioned responses, the respiration amplitude changes were found to be most informative for the continuous assessment of elicited arousal of low and medium intensity. In all subjects conditioned stimuli presented during extinction in serial compound with the conditioned inhibitor elicited larger responses than did conditioned stimuli presented alone during extinction. The mechanism of protection from extinction in a paradigm in which the elicitor of learned behavior occurs prior to the conditioned inhibitor provides the organism with the mechanism for the maintenance of learned behavior in the absence of a reinforcer.     

Acquisition and discrimination of appetitively and aversively conditioned heart rate responses in rhesus monkeys

This report describes the acquisition of a conditional heart rate response to both classical aversive and appetitive conditioning in eight rhesus monkeys(Macaca mulatta). The behavioral paradigm consisted of two discrete one minute tones followed by the corresponding unconditional stimuli,i.e., electric shock or Purina monkey chow. A third tone followed by neither food nor shock served as a discriminative stimulus (DS). The conditional heart rate responses developed in two phases. The first phase was characterized by similar responses to both conditional stimuli and the DS. Control heart rate rose during this period. During the second phase, control heart rate decreased (five animals), the DS response disappeared, and different conditional heart rate patterns to food and shock emerged. The existence of distinct conditional response patterns indicates probable differences in the autonomic nervous regulation of the heart during aversive and appetitive conditioning.     

Sensitization and aversive conditioning: Effects on the startle reflex and electrodermal responding

Animal data suggest that shock sensitization as well as aversive learning potentiates the acoustic startle reflex. The present experiment tested, whether this shock sensitization also occurs in human subjects and whether it precedes aversive conditioning. Sixty subjects viewed—prior to conditioning—a series of slides of different emotional contents including the to be conditioned stimuli (CSs). Afterwards, the experimenter attached the shock electrodes and initiated shock exposure. Then, subjects were randomly assigned to view a series of two slides, each for eight acquisition trials in which one slide was followed by a shock. Subsequently, extinction trials (12 for each slide) were administered. During preconditioning, acquisition, and extinction, startle probes occurred unpredictably during and between slide viewing. Preconditioning data replicated previous results by Lang and his associates, showing that the startle response magnitude is directly related to the affective valence induced by the slides. Shock exposure strongly facilitated the startle reflex magnitude. This shock sensitization was absent for the skin conductance response. Course of learning also varied for both response systems. The data suggest that startle reflex potentiation indexes the acquisition of an avoidance disposition, which is preceded by a general sensitization of the protective reflexes. Skin conductance learning follows arousal changes and is modulated by cognitive processes.     

The discovery of the principles of reinforcement,extinction, generalization,and differentiation of conditional reflexes in Pavlov’s laboratories

The discovery of reinforcement, extinction, generalization, and differentiation with the conditional reflex method in Pavlov’s laboratories is described. Modern American introductory texts show that contemporary understanding of the experimental work on conditioning in Pavlov’s laboratories is derived from a 1927 English translation of Pavlov’s lectures on the conditional reflexes. The lectures present the discoveries topically, not chronologically. In contrast, this article presents a chronological account of the contributions of S. G. Vul’fson, I. F. Tolochinov, and B. P. Babkin, which led to the conceptualization of reinforcement and extinction, and the work of V. N. Boldyrev and N. A. Kashereninova, which led to the formulation of the concepts of generalization and differentiation. This historical approach avoids giving the impression that the development of the Pavlovian paradigm was a highly systematic pursuit.     

Differential preparatory cardiovascular responses to aversive and appetitive behavioral conditioning

Dogs were required to press a response panel either to avoid shock or obtain food. During a one-hour interval immediatelypreceding performance on the avoidance task, blood pressure increased while heart rate decreased. In contrast, both blood pressure and heart rate increased during the one-hour interval immediatelypreceding performance on the food task. During both the shock-avoidance and food performancesper se, however, elevations in heart rate and blood pressure were observed, though the avoidance task produced less consistent heart rate changes. These effects were observed (1) with different individual dogs on each of the two training procedures, and (2) with the same dogs exposed successively to both aversive and appetitive behavioral conditioning.     

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

Summary  

Effect of dopamine on diuresis and its role in forming a renal CR

Four female mongrel dogs were used. Three had both ureters transplanted to the surface of the abdomen and one had a unilateral nephrectomy on the left and the right ureter transplanted to the abdomen. In dogs with externalized ureters our results with dopamine show changes in cardiac rate and renal secretion. The method used was 1) injection of dopamine, 2) measurement of subsequent changes in renal secretions (unconditional reflex), 3) and heart rate (HR). After 40 daily injections im of 2.5 mg/kg in normal saline the possible production of a diuretic CR was tested by injecting normal saline im and a tone was used as a signal. The control for normal saline showed no change in HR nor any of the constituents measured. The dopamine injection resulted in an increase of epinephrine in the urine of 300–600 per cent for 45 minutes; of norepinephrine of 200–500 per cent for 45 minutes; of an increase of 50 per cent in urine volume for 45 or more minutes; of absolute Na secretion of 49 per cent, of K, 20 per cent; of creatinine, 39 per cent (average in 3 dogs for 45 minutes diuresis). When the conditional stimulus (normal saline and tone) was given after several months training with the conditional signal and the injection of dopamine, there was no significant CR change to the HR nor any of the above components of urine. The conclusion is that in spite of the great increase of urine volume and composition of above substances there was no significant increase to the signals for the im injection of dopamine,i.e., no conditioning to dopamine.     

Achilles tendon reflexes and surface EMG activity during anticipation of a significant event and preparation for a voluntary movement

Achilles tendon reflexes were evoked bilaterally during and shortly after an interstimulus-interval (ISI) of 4 s and expressed as percentages of an averaged control reflex. Surface EMG of the soleus muscles were recorded continuously during the ISI, and expressed as percentages of a control EMG level. Three types of tasks were introduced, according to a between subjects design. Condition I consisted of a guessing task, involving anticipation of the second stimulus (S2) and not requiring a motor response. Conditions II and III were a warned choice and simple RT task respectively, the motor response to S2 being a plantar flexion of either the left or right foot in Condition II, and a plantar flexion of the right foot in Condition III. The results can be stated as follows: 1. Anticipation of a stimulus is not sufficient for a reflex increase to occur during an ISI. Preparation for a movement seems to be a necessary condition. 2. The reflex increase during preparation is rather independent of the amount of selectivity in the preparatory process; simple and choice RT tasks yield similar results, although the mean RTs do differ. 3. A difference between the involved and non-involved legs in the simple RT task is not found in the present experiment, as opposed to other studies. The particular instruction given to the subjects could be of importance in producing this difference. 4. Reflex changes cannot simply be accounted for by changes in background EMG of the agonist, as the EMG time course shows no changes over time in either condition.     

Phase-dependent reflex modulation in tibialis anterior during passive viewing of walking

It is well established that reflexes are highly adaptive, as they depend both on our intention and on the active state of the muscles. Reflex gains change dynamically during actions such as walking and running, with the gain of cutaneous reflexes being increased at the end of the stance phase but decreased at the end of the swing phase in the tibialis anterior (TA) muscle. Reflex gains can even change during the mere observation of an action. The mechanisms and functions of such modulations are unclear. It has been suggested that the changed reflex gains prevent the actual performance of actions that we see. However, the modulation of reflexes in response to seeing an action has never been reproduced for the active execution of such actions. In the present study, medium-latency cutaneous reflexes from the TA muscle, of which the activity and reflexes during walking are well known, were measured in human subjects. The results show that the gain changes of the medium-latency responses of the TA are the same as during active walking. We conclude that reflexes do not represent an inhibitory mechanism that prevents motor output during action observation. Instead, our findings provide evidence that even the peripheral spinal motor system is actively involved in the motor resonance processes, without evoking any measurable motor responses.