Shortening of the QT interval of the EKG is associated primarily with increased ventricular contractility rather than heart rate

The objective of this study was to gather direct evidence on whether the duration of the QT interval relates primarily to heart rate or to ventricular contractility. The electrocardiographic and cardiodynamic consequences of electrical stimulation (15 V, 5 ms, 10Hz) of various intrathoracic sympathetic efferent neuronal structures were studied in 10 anesthetized mongrel dogs. Stimulation of efferent sympathetic axons in the right intraganglionic nerve, which innervates the sinoatrial node, induced tachycardia (110±5 - 133±6 bpm; p<0.01) without significantly altering right or left ventricular intramyocardial ventricular chamber pressures. The QT interval, as determined by leads I, II and III of the EKG and a transthoracic lead, was not affected by this intervention (310±8 - 302±ms). Increasing heart rate to a similar degree (111±3 - 131±3 bpm) by right atrial pacing did not induce changes in the QT interval. When right (23±3 - 49±8 mm Hg; p<0.01) and left (81±10 - 127±19 mm Hg; p<0.01) ventricular forces were augmented without concomitant increases in heart rate by stimulating efferent sympathetic axons in the left caudal pole cardiopulmonary nerve the QT interval shortened (322±11 - 290±12 ms; p<0.01). Only when an efferent sympathetic nerve, that contains fibers destined for both the sinoatrial node and the ventricles was stimulated did both heart rate and ventricular contractility augment and QT shorten (318±10 - 290±11 ms; p<0.01). These results indicate that QT interval shortening induced by efferent sympathetic neurons is primarily associated with augmentation of ventricular contractility rather than heart rate.     

Home-based reinforcement and the modification of pre-delinquents' classroom behavior

In Exp. I, five pre-delinquents from Achievement Place attended a special summer school math class where study behavior and rule violations were measured daily for each boy. The boys were required to take a "report card" for the teacher to mark. The teacher simply marked yes or no whether a boy had "studied the whole period" and "obeyed the class rules." All yeses earned privileges in the home that day but a no lost all the privileges. Using a reversal design, it was shown that privileges dispensed remotely could significantly improve classroom performance. In Exp. II and III, home-based reinforcement was also shown to be effective in improving the study behavior of two youths in public school classrooms. In addition, data from Exp. III suggest that the daily feedback and reinforcement may be faded without much loss in study behavior. Home-based reinforcement was demonstrated to be a very effective and practical classroom behavior modification technique.     

The smoke reflex in rabbits an example of autonomic control of cardiorespiratory function

This study was undertaken to elucidate aspects of autonomic behavior as reflected in the “smoke reflex” in rabbits. Allowing smoke to envelop the nostrils of a rabbit resulted in prompt apnea, bradycardia, diminution of peripheral pulse and elevation of systemic blood pressure. Atropine and vagotomy, or both, mitigated the bradycardia, but the combined effect of propranolol and vagotomy was required to abolish bradycardia. Phenoxybenzamine (dibenzyline) alone blocked only the peripheral vasoconstriction and pressor response. The combination of vagotomy, propranolol and phenoxybenzamine blocked all manifestations of the reflex with the exception of apnea. A classical concept holds that responses of the autonomie nervous system must be either distinctly adrenergic (sympathetic) or cholinergic (parasympathetic), and that visceral regulation is achieved by an antagonism between the two. This study introduces contrary evidence and demonstrates that in certain adaptive behavior there is a patterned response that includes activation of discrete elements of both cholinergic and adrenergic divisions, as well as inhibition of one component of the latter.     

The bradycardia of the dive reflex—A possible mechanism of sudden death

Slowing of the heart rate as part of an oxygen-conserving reflex has been observed in man when breath-holding with the face under water. Emotionally significant situations were found capable of either inhibiting or facilitating the reflex, thus placing the mechanism under the control of the cerebral hemispheres. Indeed, features of the reflex have been induced in human subjects during attempts to penetrate the brachial artery with a hypodermic needle and in association with a mild startle reaction. The latter was observed to a striking degree in four subjects who subsequently died of recurrent myocardial infarction. It is suggested that a protective response designed to conserve oxygen may be inappropriately involved under a variety of circumstances and may be lethal if excessive or if unbalanced by opposing forces.     

Reinforcement variables in the control of unit reading responses

The present study was concerned with the effects of schedules of reinforcement upon the rate of verbal responding to written material in children. Four multiple schedules were used; multiple CRF-EXT, multiple CRF-VR, multiple CRF-VI, and multiple VR-VI, one subject being run on each schedule. Rates under CRF were lower than under VR, and somewhat higher than under VI, and much higher than under extinction. The subject run on multiple VR-VI showed little rate difference in the two components.     

Some effects of combined SDs

When the individual S^D components of a multiple schedule were combined, their control over a response summated, thus increasing the response probability to a point over that controlled by either of the S^Ds independently. Summation was concluded to be a phenomenon relevant for operant as well as respondent stimulus control (Pavlov, in Kimble, 1960; Hull, 1943). The results of the present study appear to be a special case of the general S^D enhancement effect demonstrated by Hanson (1959) and by Pierrel and Sherman (1960).     

Self-presentation: Social skills and inconsistency as independent facets of self-monitoring

Using a German adaption of Snyder's (1974) Self-Monitoring scale, we show that the scale has two independent facets, which encompass different aspects that are central to the original theoretical concept. Replicated factor analyses of the SM item pool suggest two uncorrelated subscales of equal length. Compared to the total scale, these two subscales are not only more economical and more reliable, but also provide more conceptual clarity, as demonstrated in three validity studies. In particular, the Social Skills subscale taps various self-perceived social and acting skills and is related to uninhibited and spontaneous self-expressions in interpersonal situations. The Inconsistency subscale measures discrepancies between the overt expression of one's feelings, attitudes, and beliefs and the way the person actually experiences them. This scale relates to social anxiety, sensitivity to situational cues, and self-reported situational inconsistency. The two subscales are similar to factors recently identified for the original American scale. Based on this cross-cultural convergence the validity of the current Self-Monitoring research is discussed.     

Effects of transient coronary artery occlusion on canine intrinsic cardiac neuronal activity

In order to further elucidate the regulatory function of canine epicardial neurons, the effects of transient coronary artery occlusion on their spontaneous activity was studied. Fifty-eight individual, spontaneously active units were identified by means of their action potential configurations in specific loci of atrial and ventricular epicardial fat of 10 anesthetized dogs. The activity of 49 of the units was modified by one minute of coronary artery occlusion. Twenty-four of the 49 responding units exhibited increased activity and 37 decreased activity during coronary artery occlusions. Activity changes were sometimes, but not always, associated with decreased left ventricular intramyocardial systolic pressure. During reperfusion, the activity of 6 units was increased compared to control levels, even though ventricular pressures remained the same. Following acute decentralization, 48% of previously active units generated spontaneous activity; the activity of 89% of these was altered during coronary artery occlusion despite the fact that overall cardiodynamics were unchanged. Following hexamethonium administration, the activity generated by 9 of 10 spontaneously active units was modified by coronary artery occlusion. It is concluded that transient coronary artery occlusion can modify the activity generated by intrinsic cardiac neurons, such modification involving central and peripheral neuronal interactions.