足月胎儿对声音刺激反应的探讨

通过观察声音刺激引起胎儿产生的胎动和胎心率反应,初步探讨声音刺激能否引起胎儿的感觉和相应的反射机制。选择正常足月孕妇94例,分别接受95、100、105、110、115分贝的声音刺激,观察胎儿的胎动和胎心率反应。95分贝声音能引起胎心率轻度下降且不引起胎动,而声强在100分贝以上的声音刺激能引起胎心率加速并伴有胎动,提示95分贝声音可以引起胎儿的定向反射,和胎儿的选择性的注意有关;而100~115分贝的声音能引起胎儿的防卫反应。婴儿与生俱来的无条件反射在胎儿期就已存在。     

振动声音刺激对妊娠后期胎儿呼吸及胎动的影响

自八十年代以来许多研究都证明,足月胎儿(妊娠37—42周)会对声音与振动以胎心加速及胎动的方式进行反应。然而,时至今日,对这些反应的成熟过程了解得还甚少。其中最典型的是研究者至今仍在胎儿对感觉刺激作出反应的起始年龄上争论不休。另外,由于缺乏有关人类胎儿对外部感觉刺激反应的信息,“理想的”刺激的选择是比较困难的。     

情绪、刺激呈现方式对现实性监控的影响

以往的来源记忆研究大多以词汇和图形等为实验材料,意义丰富的声音材料尚未涉及.本实验采用中国情感数据声音系统的声音为材料,分析了情绪效价、编码和测验阶段的刺激呈现方式等对区分听觉和想象两种不同来源的现实性监控的影响.实验含编码和测验两阶段,编码任务是听声音或根据提供的文字想象声音,并判断刺激的情绪效价;测验阶段则要求被试听声音或根据文字想象声音,并做出“听过”、“想象过”或“新项目”的三项选择判断.结果显示,想象刺激低于听觉形式获得刺激的提取成绩;情绪效价显著影响听过项目的提取绩效;编码与测验刺激呈现方式匹配条件的来源监控成绩较高;恐惧刺激的判断快于厌恶刺激.上述结果表明:内部来源与外部来源提取是两种不同的活动,情绪效价对区分上述两种任务的现实性监控具有调节作用,编码与提取刺激呈现方式匹配与否对提取结果的影响明显,恐惧刺激的加工相对优先.     

无关声音效应研究述评

无关声音效应是在对注意与记忆进行研究时所发现的一个现象,有益于探讨噪音等无关声音刺激对个体认知过程、工作绩效及身心健康的影响作用。在简要回顾ISE现象的界定与理论解释争论的基础上,重点从对刺激强度不同的ISE现象之理论分析、应用价值及一些相关的近期研究方面作了介绍,从对ISE现象的理论解释、无关声音刺激的选取、研究方法的综合使用、ISE现象中的个体差异等方面做了展望。     

胎教音乐对胎儿影响的实验研究

该项研究从三个方面探讨了胎教音乐对胎儿的作用。结果发现：胎教音乐可以使胎动时间延长,并证明在胎儿后期即存在条件反射;胎儿出生后能够再认胎教音乐,说明在胎儿后期已经存在听觉记忆;胎儿的性别及神经活动类型是影响其对音乐反应的重要因素。该研究的意义在于：证明了胎儿期心理现象的存在。把对“胎儿期有无心理现象”的历史争论引入了心理学的实验过程。     

驾驶疲劳对听觉注意影响的ERP研究

目的:探讨驾驶疲劳对于听觉注意的影响.方法:采用组间对照,对照组为12名充分休息的出租车司机,实验组为15名连续驾驶10h的司机.采用听觉Oddball范式,标准刺激:800Hz,概率80%;靶刺激:1000Hz,概率10%;新异刺激:计算机产生的噪声或其他声音,概牢10%.声音强度均为85dBL,刺激间隔(SOA)1000ms,刺激呈现时间100ms.要求被试对靶刺激按鼠标反应.结果:P3a分布以额中央区为主,驾驶疲劳后新异刺激引起的P3a潜伏期没有显著变化,幅值显著降低;P3b以中央顶区为主,驾驶疲劳后靶刺激引起的P3b潜伏期没有显著变化,幅值显著降低.结论:驾驶疲劳后听觉非随意注意能力、注意加工能力下降.     

偏差声音干扰刺激对视觉注意网络系统的影响

结合注意网络测量工具和听视ODDBALL干扰范式,考察偏差声音干扰刺激的出现对注意网络系统不同功能的影响。结果发现,声音刺激序列下,视觉线索唤醒效应均消失; 标准声音刺激下,不存在线索的脱离和转移效应; 偏差声音刺激下,出现线索脱离和转移效应。研究表明,注意网络中的警觉功能具有超通道加工机制,偏差刺激下视觉注意系统中注意定向和线索转移效应的出现表明偏差干扰效应主要由偏差刺激引起的注意脱离和注意转移损耗部分引起。     

本土化情绪声音库的编制和评定

为情绪研究提供一套本土量化的声音刺激材料,在大量收集各种声音刺激的基础上精选出453个声音,并征集50名大学生对声音的愉悦度、唤醒度和优势度进行了自我报告的9点量表评分。结果表明男女生对部分声音的情绪感受有所不同;聚类分析可将声音聚为6类,大致可引发愉快、悲伤、恐惧、厌恶等情绪,提示可以同时从情绪维度和情绪类型两种途径研究情绪问题,两者结果也有相互比较的可能性;本情绪声音库还有待进一步完善。     

情绪干扰听觉反应冲突的ERP研究

采用ERP技术研究13例正常青年人在声音诱发的不同情绪条件下,对反应抑制加工过程的影响,并试图阐明其潜在脑机制。实验中选择正、中、负三种声音各50种,作为诱发情绪的刺激材料。结果发现Go条件下的反应时在负性、中性、正性条件下依次减短;Go与Nogo刺激均诱发出显著的N1成分,中性条件下波幅显著大于正负性情绪条件。此外,三种情绪背景下, Nogo刺激诱发出显著的N2与P3成分。Nogo-N2主要分布在头皮前中部,在Fz点波幅最大。Nogo-P3主要分布在头皮中部,Pz点波幅最大。中性条件下Nogo-N2波幅显著大于负性与正性条件,而正性和负性之间差异不显著。行为结果表明,听觉负性情绪诱发对反应执行有干扰作用;ERP结果表明声音诱发的情绪对早期听觉选择性注意具有调节作用。听觉情绪诱发对反应抑制加工过程有显著影响,且该影响在早期反应冲突监控阶段最为明显。     

复合运动刺激视觉追踪的初步研究

本实验采用多目标追踪和复合刺激研究范式,将注意追踪和知觉的整体优先性两个研究领域中存在的知觉组织规律相结合,对单一和多个复合刺激进行注意追踪研究.结果表明:在单一或多个复合刺激追踪过程中,同样遵循静态知觉组织原则;不同知觉组织形式对知觉加工有不同的影响,突出的颜色变化可以促进知觉组织加工.     

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.     

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.     

Fetal habituation performance: Gestational age and sex effects

Habituation is the decrement in response to repeated stimulation. Fetal habituation performance may reflect the functioning of the central nervous system (CNS) prenatally. However, basic characteristics of the prenatal habituation phenomena remain unclear, such as the relationship with gestational age (GA) and fetal sex. The current study investigated the relationship between habituation performance and both fetal sex and advancing gestational age, by comparing habituation performance at 31 and 35 weeks GA within a sample of 74 singleton pregnancies, all with normal neonatal outcomes. A vibroacoustic stimulus was used to habituate the fetus and motor responses were monitored via ultrasound. The criterion for habituation was defined as no response to five consecutive stimulus presentations. Prenatal habituation performance was found to demonstrate a developmental trend, with an increased proportion of fetuses habituating with advancing gestational age and requiring fewer stimulus presentations to satisfy the habituation criterion. Fetal sex also appears to have a moderating influence on gestational changes in habituation performance. Hence, the ongoing maturation of the fetal CNS does appear to be reflected in fetal habituation performance, indicating the need to consider the composition of fetal samples in terms of both gestational age and sex. Variability in interfetal performance was found to be high and clinical applications remain speculative.     

Sex moderates associations between prenatal glucocorticoid exposure and human fetal neurological development

Maternal cortisol levels (at 15, 19, 25, 31 and 37 weeks’ gestation) and fetal movement response to vibroacoustic stimulation (VAS; at 25, 31 and 37 weeks) were assessed in 190 mother‐fetus pairs. Fetuses showed a response to the VAS at 25 weeks and there was evidence of increasing maturation in the response at 31 and 37 weeks. Early elevations in cortisol predicted a failure to respond to the VAS at 25 weeks and later elevations in cortisol were associated with a larger response among fetuses when assessed near term. The associations between cortisol and VAS emerged earlier and were more apparent among female fetuses than among the males. The findings provide support for the role of prenatal glucocorticoids in shaping human fetal CNS development.     

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.     

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.     

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.     

Auditory habituation in the fetus and neonate: an fMEG study

Habituation – the most basic form of learning – is used to evaluate central nervous system (CNS) maturation and to detect abnormalities in fetal brain development. In the current study, habituation, stimulus specificity and dishabituation of auditory evoked responses were measured in fetuses and newborns using fetal magnetoencephalography (fMEG). An auditory habituation paradigm consisting of 100 trains of five 500 Hz tones, one 750 Hz tone (dishabituator) and two more 500 Hz tones, respectively, were presented to 41 fetuses (gestational age 30–39 weeks) and 22 newborns or babies (age 6–89 days). A response decrement between the first and fifth tones (habituation), an increment between the fifth tone and the dishabituator (stimulus specificity) and an increment between the fifth (last tone before the dishabituator) and seventh tones (first tone after the dishabituator) (dishabituation) were expected. Fetuses showed weak responses to the first tone. However, a significant response decrement between the second and fifth tones (habituation) and a significant increment between the fifth tone and the dishabituator (stimulus specificity) were found. No significant difference was found for dishabituation nor was a developmental trend found at the group level. From the neonatal data, significant values for stimulus specificity were found. Sensory fatigue or adaptation was ruled out as a reason for the response decrement due to the strong reactions to the dishabituator. Taken together, the current study used fMEG to directly show fetal habituation and provides evidence of fetal learning in the last trimester of pregnancy.     

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.