Temporal pattern and spectral complexity as stimulus parameters for eliciting a cardiacorienting reflex inhuman fetuses

The purpose of this study was to determine whether temporal pattern and/or spectral complexity were important stimulus parameters for eliciting a cardiac orienting reflex (OR) in low-risk human fetuses. Each of 28 term fetuses was exposed to four sounds formed from the four different combinations of temporal pattern (pulsed, continuous) and spectral complexity (sine wave, IsJ). The fetal cardiac electrical signal was captured transabdominally at a rate of 1024 Hz, and fetal R-waves were extracted by using adaptive signal-processing techniques. We found that pulsed sounds elicited a significantly greater decrease in heart rate (HR) than did continuous sounds. However, the HR response was relatively unaffected by spectral complexity. For the pure tone and the phoneme used in this study, our results indicate that temporal characteristics were more effective at eliciting a cardiac OR in human fetuses than was spectral complexity.     

Near-term fetuses process temporal features of speech

The perception of speech and music requires processing of variations in spectra and amplitude over different time intervals. Near-term fetuses can discriminate acoustic features, such as frequencies and spectra, but whether they can process complex auditory streams, such as speech sequences and more specifically their temporal variations, fast or relatively slow acoustic variations, is unclear. We recorded the cardiac activity of 82 near-term fetuses (38 weeks GA) in quiet sleep during a silent control condition and four 15 s streams presented at 90 dB SPL Leq: two piano melodies with opposite contours, a natural Icelandic sentence and a chimera of the sentence--all its spectral information was replaced with broadband noise, leaving its specific temporal variations in amplitude intact without any phonological information. All stimuli elicited a heart rate deceleration. The response patterns to the melodies were the same and differed significantly from those observed with the Icelandic sentence and its chimera, which did not differ. The melodies elicited a monophasic heart rate deceleration, indicating a stimulus orienting reflex while the Icelandic and its chimera evoked a sustained lower magnitude response, indicating a sustained attentional response or more focused information processing. A conservative interpretation of the data is that near-term fetuses can perceive sound streams and the rapid temporal variations in amplitude that are specific to speech sounds with no spectral variations at all.     

The effects of sound duration on newborns' head orientation

Two experiments assessed the importance of sound duration for eliciting head orientation responses from newborn infants. In Experiment 1, thirty infants turned with equal frequency toward 20-s continuous rattle sounds and 20-s trains of rattle segments. The duration of the rattle segments--14 and 100 ms (2/s), or 500 ms (1/s)--did not influence the likelihood of turning. Response latencies and durations proved quite similar for all stimuli. In Experiment 2, twenty-four infants heard continuous rattle sounds of four different durations: 1, 5, 10, and 20 s. They turned reliably to all stimulus durations; furthermore, the magnitude and temporal characteristics of head orientation responses did not differ for the four stimulus durations. These results suggest that the newborn's head orientation response may reflect a motor program that is initiated by auditory input and then executed in a similar fashion regardless of further stimulation.     

Comparison of fetal and maternal heart rate measures using electrocardiographic and cardiotocographic methods

PurposeTo determine the reliability at term of: (1) two methods of measuring fetal heart rate (HR), electrocardiographic (ECG, the ‘gold standard’) and cardiotocographic (CTG) and (2) two ECG methods of measuring maternal HR variability over relatively brief periods of time (s–min).MethodsDuring 20 min of rest (N = 39) and during 2 min of auditory stimulation (mother's recorded voice, n = 19), fetal HR data were collected using an ECG (Monica AN24) and a Hewlett-Packard Model 1351A CTG. Simultaneously, maternal HR data (n = 37) were collected using the same ECG device (Monica AN24) and a second stand-alone cardiac monitor (Spacelab 514T cardiac monitor with a QRS detector).ResultsDuring 20 min of maternal rest, correlations of individual fetal CTG with ECG measures of HR at each second were moderate to high (r = .57–.97) for 77% of fetuses. Correlations of HR averaged over fetuses and over each of the 20 min were high (r = .93–.97); fetal HR averaged over 20 min varied between devices from 0.0 to 0.8 bpm. During 2 min of maternal voice presentation, correlations of fetal HR over each second were moderate to high (r = .54–.99) for 95% of fetuses and high (all rs = .99) when averaged across fetuses in 30 s or 2 min epochs. Average fetal HR between devices over the 2 min voice varied from 0.0 to 0.6 bpm. Correlations and/or % agreement between the two ECG methods of measuring maternal HR were high. Average maternal HR over 10 min showed 81% of pairs with a difference of ≤1 bpm; correlations for HR variability measures varied from r = .89 to .97.ConclusionsGood reliability was demonstrated between individual spontaneous and auditory induced fetal CTG and ECG with high correlations when HR data were averaged over fetuses or in 30–120 s epochs. High reliability of maternal HR measures was obtained using two ECG devices.     

身体攻击行为学生自主神经活动的情绪唤醒特点

运用情绪生理学的方法,以31名具有身体攻击行为的初中工读学生和30名普通初中生为研究对象,研究了身体攻击行为学生与普通学生在基线生理唤醒和情绪生理唤醒的方面不同特点。结果发现,在生理唤醒的基线水平上,身体攻击行为学生与普通学生在指温、R-R间期、心率、指脉率方面差异显著,身体攻击行为学生的指温、心率、指脉率比普通学生低,身体攻击行为学生的R-R间期比普通学生R-R间期长。在愤怒刺激条件下,身体攻击行为学生报告的愤怒体验水平比普通学生高;愤怒诱发刺激引起身体攻击行为学生R-R间期、心率变化显著,而普通学生R-R间期、心率变化不显著。厌恶与恐惧、悲伤、愉快诱发刺激引起普通学生皮肤电变化显著,而身体攻击行为学生皮肤电变化不显著     

Intracerebral scopolamine administration attenuates Pavlovian heart rate conditioning in the rabbit

Scopolamine hydrobromide was injected into the a) septum, b) dorsal hippocampus, or c) lateral ventricles of conscious rabbits via bilateral chronic indwelling cannulas. The cardiac orienting reflex (OR) and heart rate (HR) classical conditioning were assessed. A fourth group of animals received injections of the vehicle solution into these same brain areas and were otherwise similarly trained. Scopolamine had no effect on the cardiac OR produced by unreinforced tone stimuli. The OR consisted of pronounced bradycardia that habituated over successive trials in all groups. The HR change during classical conditioning also consisted of bradycardia. However, these conditional HR changes were attenuated by scopolamine injected into the septum and lateral ventricles, but were not affected by injections into the dorsal hippocampus. These results suggest that centrally applied scopolamine may affect a central nervous system associative process, and not a mechanism directly involved in primary bradycardia.     

Developmental change in fetal response to repeated low-intensity sound

The aim of this study was to investigate developmental changes in heart rate response to repeated low-intensity (85 dB) sound stimulation in fetuses between 32 and 37 weeks of gestation. We measured amplitude changes in heart rate as our index of fetal response. At 35 to 37 weeks of gestation, the majority of fetuses showed a deceleratory response at the first trial. Amplitude decreased with further trials using the same stimulus before recovering when exposed to another type of stimulation. In contrast, responses in fetuses at 32 to 34 weeks of gestation were variable across trials and there was no recovery with exposure to another type of stimulation. Our results suggest that fetal habituation of cardiac response changes with developmental age.     

Differential maturation of fetal responses to vibroacoustic stimulation in a high risk population

Maturation of human fetal response to vibroacoustic stimulation was examined in 163 high risk fetuses from 23 to 36 weeks gestational age (GA). Each fetus received three vibroacoustic trials and three no-stimulus control trials (randomly assigned) while fetal heart rate (FHR) was recorded and body movement was observed on ultrasound scan. For data analyses, fetuses were categorized into preterm compromised (n = 57), preterm healthy (n = 42) and term healthy (n = 64) based on evidence of compromise at birth. Differential maturation was observed among the outcome groups. The term healthy group exhibited a body movement and, on the first stimulus trial, an FHR deceleration response at 27 weeks GA with a shift to an FHR acceleration response at 30 weeks GA. By 33 weeks GA, responding was indistinguishable from that reported for low risk fetuses with response rates of 92% for both movements and FHR accelerations. The preterm healthy outcome group showed a body movement and an FHR acceleration response at 27 weeks GA. Over gestation, there was no maturation of either response. The preterm compromised outcome group showed a body movement response at 24 weeks GA which did not mature. An FHR acceleration response was elicited at 27 weeks GA with the magnitude of the acceleration increasing over gestation; at 33 weeks GA the magnitude was below that observed in the term healthy group. With advancing gestation, the rate of cardiac–movement coupling increased only in the two healthy outcome groups. It was concluded that differential fetal behaviour as a function of fetal/newborn outcome may reflect differential functional development of the fetal nervous system.     

Onset and maturation of fetal heart rate response to the mother’s voice over late gestation

Background: Term fetuses discriminate their mother’s voice from a female stranger’s, suggesting recognition/learning of some property of her voice. Identification of the onset and maturation of the response would increase our understanding of the influence of environmental sounds on the development of sensory abilities and identify the period when speech and language might influence auditory processing. Aim: To characterize the onset and maturation of fetal heart rate response to the mother’s voice. Methods: 143 fetuses from 29 to 40 weeks gestational age (GA) received a standardized protocol: no‐sound pre‐voice baseline (2 min), audio recording of their mother reading a story (2 min), no‐sound post‐voice (2 min). The voice was delivered 10 cm above the maternal abdomen at an average of 95 dB A; heart rate was recorded continuously. Results: For data analyses, fetuses were categorized into four age groups: 29–31, 32–34, 35–37, and > 37 weeks GA. Onset of response to the mother’s voice occurred at 32–34 weeks GA. From 32 to 37 weeks GA, there was an initial heart rate decrease followed by an increase. At term, there was a response shift to an initial heart rate increase. The percentage of fetuses responding increased over gestation from 46% at 32–34 weeks GA to 83% at term. Conclusion: A relatively long latency and sustained duration of the heart rate response suggest auditory processing, the formation of neural networks, above the level of the brainstem.     

Maturation of fetal responses to music

Maturation of fetal response to music was characterized over the last trimester of pregnancy using a 5-minute piano recording of Brahms' Lullaby, played at an average of 95, 100, 105 or 110 dB (A). Within 30 seconds of the onset of the music, the youngest fetuses (28-32 weeks GA) showed a heart rate increase limited to the two highest dB levels; over gestation, the threshold level decreased and a response shift from acceleration to deceleration was observed for the lower dB levels, indicating attention to the stimulus. Over 5 minutes of music, fetuses older than 33 weeks GA showed a sustained increase in heart rate; body movement changes occurred at 35 weeks GA. These findings suggest a change in processing of complex sounds at around 33 weeks GA, with responding limited to the acoustic properties of the signal in younger fetuses but attention playing a role in older fetuses.     

The temporal weighting of loudness: effects of the level profile

In four experiments, we studied the influence of the level profile of time-varying sounds on temporal perceptual weights for loudness. The sounds consisted of contiguous wideband noise segments on which independent random-level perturbations were imposed. Experiment 1 showed that in sounds with a flat level profile, the first segment receives the highest weight (primacy effect). If, however, a gradual increase in level (fade-in) was imposed on the first few segments, the temporal weights showed a delayed primacy effect: The first unattenuated segment received the highest weight, while the fade-in segments were virtually ignored. This pattern argues against a capture of attention to the onset as the origin of the primacy effect. Experiment 2 demonstrated that listeners adjust their temporal weights to the level profile on a trial-by-trial basis. Experiment 3 ruled out potentially inferior intensity resolution at lower levels as the cause of the delayed primacy effect. Experiment 4 showed that the weighting patterns cannot be explained by perceptual segmentation of the sounds into a variable and a stable part. The results are interpreted in terms of memory and attention processes. We demonstrate that the prediction of loudness can be improved significantly by allowing for nonuniform temporal weights.     

Decelerative cardiac responsiveness to acoustical stimulation in the near term fetus

Human fetal cardiac responses (36-39 weeks gestational age) to brief, repeated vocal stimuli (male or female voice uttering the same sentence), given at 90-95 dB SPL ex utero (around 20-30 dB less in utero) during a state of low fetal heart rate (FHR) variability, were examined using highly conservative statistical criteria taking into account each subject's prestimulus FHR variability. Subjects exposed to either of the two stimuli displayed significantly more decelerative heart rate (HR) changes compared to control subjects receiving no stimulation. The decelerative changes started during the first seconds following the onset of stimulation and reached their amplitude peak within 10 or 20 sec, depending on the subject. The directions—HR acceleration or deceleration—and the amplitude of the response depended on prestimulus HR variability only, not on prestimulus level. No major difference was found between the effects of the two voices. The data are compared to previous studies demonstrating fetal decelerative changes to acoustic stimuli of less than 105 dB SPL. The choice of an objective criterion to define an HR response and the possible orienting response nature of the decelerative change are discussed.     

Impression of smoothness of a sound stream in relation to legato in musical performance

Physically continuous sounds do not always produce the subjective impression of legato. In the present study, the effect of temporal factors on the impression of smoothness of a sound stream was systematically investigated in relation to the dynamic characteristics of hearing. The results showed that decaying sounds, successively presented, were perceived as being marginally connected when the sounds physically overlapped, while steady-state sounds were perceived as being marginally connected when they were physically separated. It was also shown that judgments by the subjects agreed quite well with the effect intended by the pianist when the passage was given in different temporal interpretations.     

Level of Muscular Tension as an Aspect of Personality

The purpose of this study was to compare two methods of analyzing the effects of exteroceptive feedback training on the voluntary bidirectional control of human cardiac rate with the use of a within-subject control design. In this design heart rate (HR) during an experimental period (increase or decrease) is compared with that recorded during some other control period, generally a baseline “rest” period. Ten male undergraduates were instructed to control HR and given visual feedback of heart activity. Trials on which Ss were to raise and to lower HR were both given in a single training session. The data were analyzed in two ways: (a) cardiac rate during HR control periods was compared to an initial pre-experiment baseline; (b) cardiac rate during HR control periods was compared to a running pretrial baseline. The results support the argument that the former procedure fails to take account of habituating levels of cardiac rate and favors finding large magnitude decreases in HR but small increases, whereas the latter procedure favors finding large magnitude increases but small decreases. It is suggested that magnitude of directional control will be artifactual when initial values are used to assess change. Contaminating influences on the running pretrial baseline were also discussed.     

Effects of sound frequency on behavioral and cardiac orienting in newborn and five-month-old infants

Alert newborn and 5-month-old infants' responsivity to variations in spectral composition of a rattle sound was examined. Each child received four stimulus conditions: low-, mid-, and high-frequency bandpass-filtered rattles and an unfiltered broadband rattle. Stimuli were played through a single loudspeaker laterally positioned, and head orientation and cardiac responses to sound were recorded. Compared to other stimuli, the low-frequency sound elicted less head turning in both age groups, with this effect exaggerated in younger infants. Head orientation toward the mid-frequency, high-frequency, and broadband stimuli did not differ with age. For all conditions, latency and duration of newborns' head turning was longer than that of 5-month-olds. Newborns responded with cardiac deceleration only on trials when they failed to turn. When head turns occurred, an acceleratory cardiac response was obtained. Five-month-olds responded with reliable cardiac deceleration irrespective of head turning toward the sound. Heart rate change did not vary as a function of frequency at either age, suggesting that all stimuli were equally effective in eliciting the infant's attention.     

Infant vocal development during the first 6 months: speech quality and melodic complexity

The early development of infant non‐distress vocalizations was investigated in this study. Thirteen infants, from 4 to 24 weeks of age, and their mothers were observed weekly in a face‐to‐face interaction situation. The speech quality (syllabic versus vocalic) and melodic complexity (simple versus complex) of infant vocalizations were coded independently. Based on speech quality and melodic complexity, four types of infant non‐distress vocalizations were categorized: simple and complex syllabic (speech‐like) vocalizations as well as simple and complex vocalic (non‐speech‐like) vocalizations. Results showed that complex syllabic sounds were of longer duration and complex vocalic sounds were less frequent than the other types of vocalizations. Curvilinear developmental trends were found in the rate of simple vocalic sounds and in the mean duration of complex syllabic sounds. Furthermore, before 4 months of age, vocalic sounds were more likely to be associated with simple melodic contours, after which syllabic sounds were more likely to be associated with complex melodic contours. A dynamic systems perspective on the early development of infant vocalization is discussed. Copyright © 2000 John Wiley & Sons, Ltd.     

Spectral versus temporal features in dichotic listening

Ear advantage for the processing of dichotic speech sounds can be separated into two components. One of these components is an ear advantage for those phonetic features that are based on spectral acoustic cues. This ear advantage follows the direction of a given individual's ear dominance for the processing of spectral information in dichotic sounds, whether speech or nonspeech. The other factor represents a right-ear advantage for the processing of temporal information in dichotic sounds, whether speech or nonspeech. The present experiments were successful in dissociating these two factors. Since the results clearly show that ear advantage for speech is influenced by ear dominance for spectral information, a full understanding of the asymmetry in the perceptual salience of speech sounds in any individual will not be possible without knowing his ear dominance.     

Decelerative cardiac responsiveness to acoustical stimulation in the near term fetus.

Human fetal cardiac responses (36-39 weeks gestational age) to brief, repeated vocal stimuli (male or female voice uttering the same sentence), given at 90-95 dB SPL ex utero (around 20-30 dB less in utero) during a state of low fetal heart rate (FHR) variability, were examined using highly conservative statistical criteria taking into account each subject's prestimulus FHR variability. Subjects exposed to either of the two stimuli displayed significantly more decelerative heart rate (HR) changes compared to control subjects receiving no stimulation. The decelerative changes started during the first seconds following the onset of stimulation and reached their amplitude peak within 10 or 20 sec, depending on the subject. The direction--HR acceleration or deceleration--and the amplitude of the response depended on prestimulus HR variability only, not on prestimulus level. No major difference was found between the effects of the two voices. The data are compared to previous studies demonstrating fetal decelerative changes to acoustic stimuli of less than 105 dB SPL. The choice of an objective criterion to define an HR response and the possible orienting response nature of the decelerative change are discussed.     

Near-term fetal response to maternal spoken voice

Knowledge about prenatal learning has been largely predicated on the observation that newborns appear to recognize the maternal voice. Few studies have examined the process underlying this phenomenon; that is, whether and how the fetus responds to maternal voice in situ. Fetal heart rate and motor activity were recorded at 36 weeks gestation (n = 69) while pregnant women read aloud from a neutral passage. Compared to a baseline period, fetuses responded with a decrease in motor activity in the 10 s following onset of maternal speech and a trend level decelerative heart rate response, consistent with an orienting response. Subsequent analyses revealed that the fetal response was modified by both maternal and fetal factors. Fetuses of women who were previously awake and talking (n = 40) showed an orienting response to onset of maternal reading aloud, while fetuses of mothers who had previously been resting and silent (n = 29) responded with elevated heart rate and increased movement. The magnitude of the fetal response was further dependent on baseline fetal heart rate variability such that largest response was demonstrated by fetuses with low variability of mothers who were previously resting and silent. Results indicate that fetal responsivity is affected by both maternal and fetal state and have implications for understanding fetal learning of the maternal voice under naturalistic conditions.     

Cardiac autonomic reactivity and recovery in predicting carotid atherosclerosis: the cardiovascular risk in young Finns study.

The present study examined the association of cardiac autonomic task-induced reactivity and recovery to preclinical atherosclerosis. Thirty-three men and 33 women aged 24-39 years participated in the ongoing epidemiological Cardiovascular Risk in Young Finns study. The authors measured heart rate (HR), respiratory sinus arrhythmia (RSA), and preejection period (PEP) during the mental arithmetic and speech tasks in 1999. Carotid atherosclerosis was assessed by measuring the thickness of the common carotid artery intima-media complex (IMT) with ultrasound in 2001. Higher HR, RSA, and PEP reactivity were associated with lower IMT values even after adjusting for cardiovascular risk factors (lipid levels, obesity, and blood pressure). In addition, better HR recovery after the mental arithmetic task was associated with lower IMT values, and this association persisted after all adjustments. Thus, higher task-induced cardiac autonomic reactivity and better HR recovery were related to less preclinical atherosclerosis. The authors concluded that cardiac pattern of reactivity and quick recovery may be associated with better cardiovascular health, and therefore all reactivity occurring in challenging situations should not automatically be considered as potentially pathological.