EFFECTS OF DEPTH AND RATE OF BREATHING ON HEART RATE AND HEART RATE VARIABILITY

Effects of depth and rate of breathing on heart rate (HR) and HR variability were observed in two experiments. Respiration rate (RR) affected only cardiac stability, faster breathing producing more stable cardiac rate. Respiration depth (RD) affected both HR level and variability. Deep breathing produced faster, more variable HR, while shallow breathing had the opposite effects. A third experiment, in which Ss were trained to control HR using respiration, further illustrated the dramatic effects of respiration on cardiac rate. Implications of these results for experiments utilizing HR as a dependent variable and studies of autonomic control were discussed.     

HEART RATE CONDITIONING IN THE CAT AND ITS RELATIONSHIP TO OTHER PHYSIOLOGICAL RESPONSES

Twenty cats were classically conditioned using electric shock as the unconditional stimulus (US). A 1000 cps tone served as the reinforced conditional stimulus (CS+) and a 500 cps tone as the non-reinforced conditional stimulus (CS–). The CS–US interval was 10 seconds. Data collected show a heart rate deceleration to the CS+ which is accompanied by a drop in blood pressure, respiratory apnea, a negative baseline shift of the galvanic skin potential (GSP), pupillary dilatation, a decrease of the electromyographic (EMG) activity of the muscles of the shocked foreleg, and a low voltage fast pattern of the electroencephalographic (EEG) activity of the sigmoid gyrus of the cerebral cortex and olfactory bulb. The heart rate deceleration is present after muscle paralysis with succinyl choline and it is blocked by atropine. It is presumed to be of vagal origin. Difference in CS+ and US responsivity is discussed.     

THE NEONATAL EVOKED HEART RATE RESPONSE AND THE LAW OF INITIAL VALUE

Two-second long square wave tones at frequencies of 125 and 1000 Hz and 75 db sound pressure were presented to six newborn infants. Mean heart rates were computed for the 10 sec prior to and the 10 sec following stimulus onset, i.e. the prestimulus and stimulus heart rate values respectively. LIV was shown to operate strongly only in the case of the 125 Hz stimulus. Even for this stimulus, LIV depended upon the state of the infant, showing an appropriate negative correlation between prestimulus and stimulus values in regular sleep and quiet wakefulness but a slightly positive correlation in irregular sleep. In randomly selected control periods, the first 5 sec served as prestimulus values and the second 5 sec as stimulus values. Regression coefficients for these control periods did not differ significantly from those during which the stimulus was actually present. In view of the special conditions required for its demonstration, the generality of Wilder's “law” seems to be seriously questioned.     

THE EFFECTS OF UCS TEMPORAL UNCERTAINTY ON HEART RATE AND PAIN

Every one of the 8 Ss in this experiment showed lower heart rate in anticipation of a temporally uncertain UCS than he did during anticipation of a temporally certain one. Vigilance for uncertainty removing cues during UCS uncertain trials was offered as an explanation for the reduced heart rate of this condition. Previous investigations showing acceleration in heart rate under conditions of UCS temporal uncertainty were criticized, particularly with respect to the adequacy of the cardiac baseline employed. One unexpected and unexplained finding of this study was that 7 out of 8 Ss rated shocks as more painful when the UCS was certain than when it was uncertain.     

UNIDIRECTIONAL AND LARGE MAGNITUDE HEART RATE CHANGES WITH AUGMENTED SENSORY FEEDBACK

In the first of two studies, subjects (Ss) were required to either raise or lower heart rate (HR) relative to pre-trial baseline by altering a tone which changed frequency with HR. Reliable increases but no decreases in HR were found. In a second study extended training of a single S with visual feedback resulted in consistent sustained HR increases of 15 to 35 beats per minute (bpm), but only slight decreases. Sustained elevated rate was accompanied by anxiety. No reliable changes in breathing occurred in either study.     

HEART RATE RESPONSES OF THE CURARIZED RAT

Heart rate of curarized and non-curarized rats was recorded while both groups were exposed to classical conditioning procedures with tone as the conditional stimulus (CS) and shock as the unconditional stimulus (UCS). The unconditional HR response of curarized animals to the tone was significantly greater than that of the non-curarized animals, while the HR response to shock of the curarized animals was significantly less than that of the non-curarized group. Both groups showed evidence of conditioning over 30 conditioning trials.     

HEART RATE RESPONSE HABITUATION IN HIGH-RISK PREMATURE INFANTS

The hypothesis suggested by Luria (1963) that infants with central nervous system damage fail to habituate to repeated stimulation was tested using an experimental group whose clinical course suggested a relatively high probability of CNS damage, a control group matched for age in weeks since conception, and a group of normal, fullterm infants. An auditory stimulus at 80 db SPL was presented for 3 sec at 20-sec intervals. Heart rate change averaged across time on Trials 1–5 and Trials 26–30 were compared. The hypothesis was not confirmed, since significant habituation was found on Trials 26–30 for all groups. However, latency of response was significantly longer in high-risk Ss. A developmental trend toward decreased latency of response with increasing gestational age was identified.     

HEART RATE RESPONSES TO AUDITORY CLICKS IN NEONATES

The neonatal heart rate (HR) response to brief stimuli has generally been reported to be a monophasic acceleration. In this study brief auditory clicks to 6 neonates elicited, to a significantly greater degree than in non-stimulus conditions: 1) deceleration alone, 2) acceleration alone, and 3) a biphasic response consisting of an initial deceleration and a subsequent acceleration. The data are not yet available which would permit selection among the orienting reflex (OR), defense reflex, startle reflex, and Moro reflex models of these HR responses. With regard to peripheral mechanism, the early decelerative response was probably mediated by increased vagal inhibitory tone. The later accelerative response may have been mediated by one or more of the following mechanisms: decreased vagal inhibitory tone, activation of vagal accelerator fibers, and/or activation of sympathetic accelerator fibers.     

MEAN HEART RATE PREDICTED BY TASK DEMAND CHARACTERISTICS

Mean HRs recorded during sequences of perceptual-motor and cognitive tasks were predicted from ratings of task characteristics such as complexity and frequency of stimuli, transformations, and responses. In three separate groups of Ss and tasks the correlations between mean HRs and task demand ratings were ≥.91.     

心率信号非线性动力结构的确定

在Silvio等提出的压力反射控制心脏活动的短期压力模型的基础上,推导出关于心率信号的一种四参量的非线性结构,通过实际的心率信号降维分析,表明心率信号存在非线性动力结构,为心率信号是确定性低维混沌的诊断提供了依据。     

心率与黄金数的联系

健康成年人的静息平均心率，总是在最高心率的黄金分割数附近的数。（１）在年青时的心率几乎等于黄金数。（２）随年龄的增加，心率跟黄金数的接近程度逐步从靠近到远离的方向变化。（３）从心率的比值和黄金数的偏差程度准确地划分人生的发育期、成熟期、衰老前期及衰老期。     

THE EFFECT OF EXOGENOUS CHANGES IN HEART RATE AND RHYTHM UPON REACTION TIME PERFORMANCE

The influence of different heart rates and rhythm on reaction time performance was examined in two groups of experimental subjects, heart rate in one group being varied by atrial pacing and in the other group by ventricular pacing. A mixed preparatory interval series of visual reaction time trials was employed, with preparatory interval durations of 3, 4, and 5 sec. Study 1 subjects, exposed to atrial pacing in a cardiac catheterization laboratory immediately before coronary artery cineangiography, demonstrated no change in reaction time response with the pacing situation when heart rate was 115 beats per minute (bpm). Response speed was most rapid with the 5 sec preparatory interval, slowest with the exposure to an exogenously-induced tachycardia. Presentation first of a variable paced tachycardia following a regular tachycardia was associated with slightly prolonged times in both situations, as compared to reaction time produced with the reverse order of pacing presentation. These differences were not statistically significant. Presence or absence of cineangiographic evidence or coronary arteriosclerosis within Study 1 exerted no effect on reaction time performance. Study 2 individuals, paced with an external (Chardack) pacemaker in a quiet laboratory environment, confirmed the results obtained from Study 1. These data would suggest that the level of background heart rate is unimportant as a determinant of reaction time response.     

INFANT HEART RATE RESPONSE AS A FUNCTION OF STIMULUS AND STATE

Heart rate (HR) response to simple stimuli apparently changes from an accelerative to decelerative response in the first few months of life. The present study of 4 month old infants showed that response depends on state and on the intensity and rise time of stimuli. The response was solely decelerative in alert infants but in less alert states of increasing agitation or increasing somnolence, deceleration lessened and acceleration appeared. Rapid rise time had an acceleratory effect which was more pronounced during sleep than during the waking state. Results were compared with those obtained to the same stimuli in parallel studies of newborns and adults. It appears that the decelerative response in awake Ss, presumably an orienting response, has a curvilinear relationship to age which cannot be ascribed to differences in initial HR level, state, stimulus intensity, or stimulus rise time.     

HEART RATE ELUCTUATIONS AND FIXED FOREPERIOD REACTION TIME

Visual reaction times were recorded in a fixed foreperiod situation, to study the relation between sensorimotor performance and heart rate measures. With 42 male college students as Ss, both resting and performance levels of heart rate and heart rate fluctuations were obtained. Reaction time data were collected from blocks of trials at given foreperiods which ranged from 1 to 9 sec. Three groups of subjects, formed on the basis of high, medium, and low levels of peak-trough differences in heart rate during the reaction-time trials, showed different foreperiod functions. The hypothesis that fluctuations in heart rate are related to fixed foreperiod reaction time performance was supported.     

PACED RESPIRATION AND HEART RATE CONTROL

Five human subjects were presented with a high frequency tone on each short inter-heartbeat interval (IBI) and a low frequency tone on each long IBI. They were instructed to produce high tones in the presence of one visual stimulus and low tones in the presence of another under conditions of paced and unpaced respiration. The results indicated that control of heart rate is not dependent upon respiratory mediation.     

PSYCHOPHYSIOLOGICAL AND COGNITIVE DEVELOPMENT IN CHILDREN: THE RELATIONSHIP OF SKIN CONDUCTANCE AND HEART RATE TO WORD ASSOCIATIONS AND TASK REQUIREMENTS

Heart rate and skin resistance were recorded from male and female children five to seven years of age during the following conditions: low arousal (rest), high arousal (auditory and visual stimulation), and administration of a Word Association Test (WAT) and the Peabody Picture Vocabulary Test (PPVT). Children who gave a mature response pattern (paradigmatic) on the WAT tended to have lower conductance levels than immature responders. Heart rate decreased during environmental intake (high arousal), increased during environmental rejection (WAT), and was unchanged during a combined intake and rejection situation (PPVT). The skin conductance data were interpreted as being consistent with recent theories concerning the development of mature cognitive behaviors in children and the psychophysiological correlates of complex and simple behaviors.     

SOME PARAMETERS OF HEART RATE CHANGE: PERCEPTUAL VERSUS MOTOR TASK REQUIREMENTS, NOXIOUSNESS, AND UNCERTAINTY

Sensory-motor integration and physiological patterns were investigated in a modified reaction time task. Following a READY signal, one of 2 DISCRIMINATIVE signals indicated that a right or left reaction was to be made to a GO signal. For one group, the DISCRIMINATIVE and GO signals occurred simultaneously; for another group, the GO signal was delayed 10 sec. In different sessions, shock occurred with the DISCRIMINATIVE signal on 0%, 33%, or 100% of the trials. The basic pattern of heart rate response was the same in all conditions, namely, acceleration followed by deceleration immediately prior to the DISCRIMINATIVE and GO signals. All experimental manipulations appeared to contribute to cardiac deceleration; for example, the greatest decrease occurred prior to the simultaneous DISCRIMINATIVE-GO signal with 33% shock probability. The least deceleration (and fastest reaction times) occurred to the delayed GO signal. Anticipation of a motor response and or shock also accentuated the accelerative limb of the heart rate curve, as well as producing increased skin conductance. Muscle action potentials from the chin showed an equivocal relationship to cardiac acceleration (or less deceleration) and to faster reaction times. Results are discussed in terms of an attentional hypothesis, and their relevance to speculations by Lacey and Obrist is examined.     

血压负荷,血压昼夜节律及心率变异性与左室肥厚的关系

目的：观察高血压左心室肥厚患者血压负荷，血压昼节律和心率变异性及其相关性。方法：选择伴有左室肥厚的高血压患者31例（I组），不伴左心室肥厚的高血压患者33例（Ⅱ组），选择年龄与患者可比的健康人30例作为对照组（Ⅲ组），进行动态血压与动态心电图同步监测，分析24小时血压负荷，血压昼夜节律及24小时心率变异性时域指标。结果：（1）血压负荷，血压昼节律：I、Ⅱ组24小时血压负荷，日间血压及夜间血压显著高于Ⅲ组，I组与Ⅱ组间血压负荷有显著差异；I与Ⅱ组非构型血压显著高于Ⅲ组，I与Ⅱ组二者间的非构型高血压出现率有显著差异。（2）心率变异性：I、Ⅱ组心率变异性各参数显著低于Ⅲ组，I与Ⅱ组间心率变异性也有显著差异。（3）四个指标的相关性：I组HRV与24小时血压负荷，非构型出现率及左室肥厚呈负相关。结论：高血压左室肥厚患者昼夜节律消失，血压负荷增加，心率变异性降低。副交感神经调节功能减弱可能与上述变化有关。高血压治疗中应注意改变心率变异性，恢复血压昼夜节律，减少血压负荷。     

HEART RATE, SKIN CONDUCTANCE, AND INTENSITY RATINGS DURING EXPERIMENTALLY INDUCED ANXIETY: HABITUATION WITHIN AND AMONG DAYS

Twenty Ss were divided into two groups according to whether they received as a noxious stimulus in a count-up a mild shock or a punishing sound. Trials were varied over as well as within days. Among the findings: (1) There was considerable evidence of response fractionation among and within measures of heart rate, skin conductance, and rated stimulus intensity. (2) Trials over days exhibited an incubation effect for shock in the skin conductance data, a displacement of maximum heart rate reactivity toward the beginning of the time dimension, and a greater degree of habituation of the rated intensity of the shock stimulus than of the sound stimulus. It was concluded that habituation and incubation reflect cognitive processes, that the forward displacement of heart rate is the result of a centrally mediated inhibitory process, and that the gradient of such inhibition is steeper than the gradient of anxiety.