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婴儿语言和情绪加工的大脑偏侧化*
Hemispheric Lateralization in Infant Language and Emotion Processing
自胎儿时期起，大脑左右半球不对称和偏侧化就已开始出现，这一过程对语言和情绪等核心认知功能的特异性发展至关重要。研究婴儿大脑偏侧化不仅能为理解该现象的早期发展提供重要证据，揭示人类复杂认知功能的发展神经机制，也对自闭症等神经发育性疾病的早期筛查具有重要意义。现有研究表明，婴儿语言加工表现出明显的左半球优势，而情绪加工则主要表现为右偏侧化。然而，与语言加工领域已确立的左半球优势效应相比，婴儿情绪加工的右半球偏侧化模式尚未获得学界共识，现有证据体系尚不完善。婴儿大脑偏侧化的发现与成人类似，但部分研究结果和结论具有发展的独特性。
The developing human brain exhibits remarkable functional specialization, with hemispheric lateralization emerging as a fundamental organizational principle that begins during fetal development. This review synthesizes current knowledge about the neural underpinnings of language and emotion processing in infants (ages 0~12 months) and toddlers (ages 1~3 years), focusing on the establishment of hemispheric asymmetry and its implications for both typical and atypical neurodevelopment.
Structural and functional hemispheric asymmetries manifest early in ontogeny, preceding the contralateral organization of sensorimotor systems. Unlike the strict contralaterality observed in primary sensory and motor pathways, cognitive lateralization represents a relative dominance where one hemisphere assumes primary responsibility while maintaining bilateral involvement. This specialized organization enhances neural efficiency by reducing redundant processing and enabling the parallel computation of complex cognitive functions. Crucially, the developmental trajectory of lateralization serves as a sensitive biomarker of neurodevelopmental integrity, with atypical patterns predicting subsequent emergence of conditions including autism spectrum disorder (ASD), schizophrenia, and obsessive-compulsive disorder.
Our comprehensive analysis reveals robust evidence of left-hemisphere dominance in infant language processing at multiple neurobiological levels. Structural MRI studies demonstrate early leftward asymmetries in perisylvian regions and white matter tracts, particularly the arcuate fasciculus connecting Broca's and Wernicke's areas. Functional neuroimaging confirms this specialization, with left temporal regions showing preferential activation for speech stimuli as early as the neonatal period. Notably, this typical pattern appears disrupted in infants at high risk for ASD, who exhibit either reduced leftward lateralization or paradoxical right-hemisphere dominance - a finding with significant implications for early identification.
The neural substrates of emotion processing present a more complex picture. While the right-hemisphere hypothesis receives substantial support from studies on emotional prosody and facial expression processing, competing evidence for valence-specific lateralization (the left hemisphere for positive affect, right for negative) complicates theoretical accounts. Developmental studies suggest this dichotomy may reflect different processing stages, with initial right-hemisphere bias for rapid emotion detection followed by valence-dependent lateralization during conscious evaluation. Methodological variations in stimulus selection and experimental paradigms likely contribute to these discrepant findings.
Three critical directions emerge for advancing this field:
First, refined experimental paradigms must address the inherent confounds of current emotion research. The prevalent use of emotional speech stimuli inadvertently engages both language and emotion networks, potentially obscuring emotion-specific lateralization. We recommend developmentally appropriate alternatives: non-linguistic auditory stimuli (e.g., emotional music) for younger infants and dynamic visual stimuli (e.g., facial/bodily expressions) for older infants. These approaches would provide a clearer characterization of emotion processing networks.
Second, the field urgently requires longitudinal investigations to map the dynamic development of functional asymmetry. Existing cross-sectional designs cannot adequately capture the potentially non-linear trajectories of lateralization establishment. Prospective studies with dense sampling intervals could identify critical periods and developmental milestones in hemispheric specialization, while clarifying the relationship between early atypical patterns and subsequent neurodevelopmental outcomes.
Third, integrative research designs simultaneously assessing language and emotion processing could yield transformative insights. The known behavioral coupling of these domains suggests their neural substrates may develop interactively. Combined assessment protocols would not only reveal potential synergies in typical development but also enhance early identification of neurodevelopmental risk through multi-modal neural signatures.
The exceptional plasticity of the infant brain underscores the clinical importance of this research. By elucidating both normative and atypical patterns of functional lateralization, we move closer to developing sensitive, objective markers for early intervention. Future work should prioritize: (1) Standardized protocols for assessing lateralization across development, (2) Mechanistic studies examining genetic and environmental influences on asymmetry development, and (3) Translational applications linking neural markers to behavioral outcomes.
This synthesis highlights how the study of early hemispheric specialization bridges fundamental neuroscience with clinical applications. As neuroimaging technologies advance, refined characterization of lateralization patterns promises to transform our understanding of both typical brain development and the origins of neurodevelopmental disorders.
infants / hemispheric lateralization / language processing / emotion processing
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陈钰, 张丹丹. (2020). 新生儿语音感知的脑机制. 心理科学, 43(4), 844-849.
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李思瑾, 王庭栋, 彭芝琳, 张丹丹. (2023). 新生儿对语音的感知、辨别和学习. 心理科学进展, 31(12), 2295-2305.
新生儿自娩出起便开始利用臻于成熟的听觉系统对语音的各要素进行大脑表征和学习记忆。考察新生儿语音加工特点, 不仅能揭示语言功能在人类发展最初阶段的认知神经机制, 还能对自闭症等神经发育性疾病的早期预警和临床诊断提供有价值的线索。我们回顾并总结了新生儿对语音的感知、辨别和学习以及语言发展对自闭症的预测作用, 发现新生儿对特定语音存在感知偏好; 新生儿具备独特的音素辨别能力; 婴儿期语言加工的脑功能或结构指标对自闭症具有一定的预测价值。我们建议未来研究从三个方面开展工作。在基础研究方面：第一, 严格控制语音材料的韵律因素, 重新审查新生儿语言加工特征及大脑偏侧化问题; 第二, 揭示新生儿语音学习的认知神经机制以及睡眠的记忆巩固作用。在临床转化研究方面, 以高风险自闭症新生儿为追踪对象, 基于纵向多模态脑观测数据, 建立疾病风险评估系统, 揭示出生早期语言发展脑指标对自闭症的预测价值。
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雷震, 毕蓉, 莫李澄, 于文汶, 张丹丹. (2021). 外显和内隐情绪韵律加工的脑机制:近红外成像研究. 心理学报, 53(1), 15-25.
准确识别言语中的情绪韵律信息对社会交往非常重要。本研究采用功能近红外成像技术, 探索外显和内隐情绪加工条件下愤怒、恐惧、快乐三种情绪韵律加工过程中的大脑皮层神经活动。结果表明, 对愤怒、恐惧、快乐韵律进行特异性加工的脑区分别为左侧额极/眶额叶、右侧缘上回、左侧额下回, 其中右侧缘上回脑区同时受到情绪和任务的调控。此外, 右侧颞中回、颞下回和颞极在情绪外显任务中的激活明显强于内隐任务。本研究的结果部分支持了情绪韵律的层次模型, 也对该模型的第三层次, 即“额区对语音情绪信息的精细加工需要外显性情绪加工任务参与”提出了质疑。
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莫李澄, 李奇, 张丹丹. (2024). 婴儿对情绪信息的加工:认知发展特征及脑机制. 心理科学进展, 32(12), 2100-2108.
语音韵律和面孔表情所传达的情绪性信息是人类解读他人情绪并进行人际互动的基础。探究婴儿对这两种载体所传达情绪信息的感知、辨别及评估, 有利于加深对婴儿认知发展特征和脑机制的理解。本文系统回顾了婴儿情绪研究, 发现颞叶和额叶皮层在婴儿情绪性语音和面孔表情加工中发挥着重要作用; 尽管婴儿的情绪加工涉及大脑双侧半球, 但已初步展现出了与成人类似的右半球优势。婴儿在出生后一周内即可分辨情绪信息, 并表现出对正性情绪的加工偏向。婴儿在6月龄左右对情绪的加工偏向逐渐从正性向负性转变。12月龄时, 婴儿的负性情绪偏向基本稳定, 且能够理解情绪性语音和面孔中的情绪涵义, 并据此指导自己的行为。基于这些发现, 我们提出了“情绪偏向发展理论”。此外, 视−听跨感官模态信息对于婴儿对特定情绪的辨别和理解起到积极的作用。
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张丹丹, 陈钰, 敖翔, 孙国玉, 刘黎黎, 侯新琳, 陈玉明. (2019). 新生儿情绪性语音加工的正性偏向——来自事件相关电位的证据. 心理学报, 51(4), 462-470.
准确解码语音中的情绪信息能让个体更好地适应社会环境, 此能力对新生儿和婴儿尤其重要, 因为人类刚出生时听觉系统远比视觉系统发育得完善。虽然已有研究表明5~7月龄的婴儿能分辨不同情绪种类的语音, 但目前对新生儿的研究还非常少。人类是否在出生时即具有分辨不同种类情绪性语音的能力?新生儿对情绪的加工是否存在正性或负性偏向?本文选用odd-ball范式考察高兴、恐惧、愤怒三种韵律性语音在1~6天龄新生儿大脑中诱发的事件相关电位。实验1直接对比三种情绪性条件, 发现新生儿大脑的额区(F3和F4电极点)可以区分情绪性语音的正负性, 正性(高兴)语音诱发的“失匹配反应”幅度明显大于负性(愤怒和恐惧)语音。实验2采用偏差和标准刺激反转的odd-ball范式, 证实了实验1的结果并非源于三种情绪语音物理属性的差异。本文的结果提示, 新生儿大脑可自动辨别正性与负性情绪语音, 但尚不能将愤怒和恐惧两种负性语音区分开来。更重要的是, 高兴语音比两种负性语音诱发了更大的失匹配反应, 这一结果首次从神经学层面(电生理指标)为新生儿情绪性语音加工的正性偏向提供了证据。
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张丹丹, 李宜伟, 于文汶, 莫李澄, 彭程, 刘黎黎. (2023). 0-1岁婴儿情绪偏向的发展:近红外成像研究. 心理学报, 55(6), 920-929.
“负性偏向”指人们往往优先感知、注意和记忆负性(而非正性)信息, 负性偏向是情绪领域能观察到的最稳定的情绪加工现象, 普遍存在于幼儿、儿童、青少年和成人之中。但是在婴儿中如何呢?本研究采用近红外成像技术, 考察了45名0岁新生儿(日龄5.2 ± 1.7天, 23名男孩)和45名1周岁婴儿(月龄12.7 ± 1.4月, 21名男孩)对快乐和愤怒语音韵律的大脑反应。结果表明, 在大脑右半球的额叶、颞叶和顶叶的脑功能连接中出现了情绪和组别的交互作用：在新生儿组, 快乐语音条件下的脑功能连接强度高于愤怒语音条件; 在婴儿组, 愤怒语音条件下的脑功能连接强于快乐语音条件。此结果证实了我们的假设：人类刚出生时情绪加工偏向是正性的, 之后才转变成为负性。因此, “负性偏向”不是与生俱来的, 情绪加工偏向在个体发展的早期阶段会发生转变。本研究首次从发展的角度揭示了情绪偏向的变化, 该发展规律不但有利于及早发现自闭症等情绪和认知发育障碍, 还能指导家长运用恰当的交流和抚养方式科学育儿。
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In the first year of life, infants' speech perception attunes to their native language. While the behavioral changes associated with native language attunement are fairly well mapped, the underlying mechanisms and neural processes are still only poorly understood. Using fNIRS and eye tracking, the current study investigated 6-month-old infants' processing of audiovisual speech that contained matching or mismatching auditory and visual speech cues. Our results revealed that infants' speech-sensitive brain responses in inferior frontal brain regions were lateralized to the left hemisphere. Critically, our results further revealed that speech-sensitive left inferior frontal regions showed enhanced responses to matching when compared to mismatching audiovisual speech, and that infants with a preference to look at the speaker's mouth showed an enhanced left inferior frontal response to speech compared to infants with a preference to look at the speaker's eyes. These results suggest that left inferior frontal regions play a crucial role in associating information from different modalities during native language attunement, fostering the formation of multimodal phonological categories.Copyright © 2016 Elsevier Inc. All rights reserved.
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This study focuses on the early cerebral base of speech perception by exam ning functional lateralization in neonates for processing segmental and suprasegmental features of speech. For this purpose, auditory evoked responses of full-term neonates to phonemic and prosodic contrasts were measured in their temporal area and part of the frontal and parietal areas using near infrared spectroscopy (NIRS). Stimuli used here were phonemic contrast /lila/ and /the/ and prosodic contrast of declarative and interrogative forms /itta/ and /itta?/. The results showed clear hemodynamic responses to both phonemic and prosodic changes in the temporal areas and part of the parietal and frontal regions. In particular, significantly higher hemoglobin (Hb) changes were observed for the prosodic change in the right temporal area than for that in the left one, whereas Hb responses to the vowel change were similarly elicited in bilateral temporal areas. However, Hb responses to the vowel contrast were asymmetrical in the parietal area (around supra marginal gyrus), with stronger activation in the left. These results suggest a specialized function of the right hemisphere in prosody processing, which is already present in neonates. The parietal activities during phonemic processing were discussed in relation to verbal-auditory short-term memory. On the basis of this study and previous studies on older infants, the developmental process of functional lateralization from birth to 2 years of age for vowel and prosody was summarized.
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Adults diagnosed with autism spectrum disorder (ASD) show a reduced sensitivity (degree of selective response) to social stimuli such as human voices. In order to determine whether this reduced sensitivity is a consequence of years of poor social interaction and communication or is present prior to significant experience, we used functional MRI to examine cortical sensitivity to auditory stimuli in infants at high familial risk for later emerging ASD (HR group, N = 15), and compared this to infants with no family history of ASD (LR group, N = 18). The infants (aged between 4 and 7 months) were presented with voice and environmental sounds while asleep in the scanner and their behaviour was also examined in the context of observed parent-infant interaction. Whereas LR infants showed early specialisation for human voice processing in right temporal and medial frontal regions, the HR infants did not. Similarly, LR infants showed stronger sensitivity than HR infants to sad vocalisations in the right fusiform gyrus and left hippocampus. Also, in the HR group only, there was an association between each infant's degree of engagement during social interaction and the degree of voice sensitivity in key cortical regions. These results suggest that at least some infants at high-risk for ASD have atypical neural responses to human voice with and without emotional valence. Further exploration of the relationship between behaviour during social interaction and voice processing may help better understand the mechanisms that lead to different outcomes in at risk populations. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.
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Human voices play a fundamental role in social communication, and areas of the adult "social brain" show specialization for processing voices and their emotional content (superior temporal sulcus, inferior prefrontal cortex, premotor cortical regions, amygdala, and insula). However, it is unclear when this specialization develops. Functional magnetic resonance (fMRI) studies suggest that the infant temporal cortex does not differentiate speech from music or backward speech, but a prior study with functional near-infrared spectroscopy revealed preferential activation for human voices in 7-month-olds, in a more posterior location of the temporal cortex than in adults. However, the brain networks involved in processing nonspeech human vocalizations in early development are still unknown. To address this issue, in the present fMRI study, 3- to 7-month-olds were presented with adult nonspeech vocalizations (emotionally neutral, emotionally positive, and emotionally negative) and nonvocal environmental sounds. Infants displayed significant differential activation in the anterior portion of the temporal cortex, similarly to adults. Moreover, sad vocalizations modulated the activity of brain regions involved in processing affective stimuli such as the orbitofrontal cortex and insula. These results suggest remarkably early functional specialization for processing human voice and negative emotions.Copyright © 2011 Elsevier Ltd. All rights reserved.
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Two goals guided this study: (a) describe changes in infant fear and anger reactivity from 4 to 16 months and (b) examine the degree to which infant temperament, attentional regulation, and maternal sensitivity predict reactivity trajectories. Participants included 143 mothers and infants (57% male) who visited the laboratory at 4, 8, 12, and 16 months. Infant reactivity, regulation, and maternal sensitivity were assessed from laboratory situations; infant temperament was rated by mothers on the Infant Behavior Questionnaire (Rothbart, 1981). Hierarchical linear modeling indicated that overall, fear and anger reactivity increased with age, but the rate of increase for fear slowed over time. Maternal ratings of temperamental fear and anger each predicted laboratory ratings of fear and anger reactivity, respectively. Moreover, infants who showed less regulation showed greater fear reactivity and steeper increases in anger reactivity over time. Infants whose mothers were more sensitive showed slower increases in fear reactivity. Findings from this study suggest that it is important to consider both intrinsic and extrinsic factors to gain a better understanding of the processes that may be involved in the development of emotional reactivity systems.
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Asymmetry in cortical activity was tested for short- and long-term stability during the first year of life. Infants (N = 129) completed a total of four laboratory visits: two visits occurred about 1 week apart when infants were 6 months old, and two visits occurred about 1 week apart when infants were 12 months of age. At each laboratory visit, EEG readings were taken during five 1-min, neutral baselines as well as during a negative and a positive emotion-eliciting task. The stability of hemispheric asymmetry was assessed at midfrontal (F3/4, F7/8) and parietal (P3/4) electrode sites. Asymmetry in baseline and fear-eliciting episodes showed moderate short-term stability. Long-term stability was apparent when assessments were composited at 6 months and 12 months. Frontal asymmetry was greater than parietal asymmetry for baseline recordings. There was minimal evidence for stability in asymmetry during positive emotion tasks. Results are discussed with regard to the collection and interpretation of alpha asymmetry measures during infancy.© 2017 Society for Psychophysiological Research.
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Early childhood (7-8 years old) and early adolescence (11-12 years old) constitute two landmark developmental stages that comprise considerable changes in neural cognition. However, very limited information from functional neuroimaging studies exists on the functional topological configuration of the human brain during specific developmental periods. In the present study, we utilized continuous resting-state functional near-infrared spectroscopy (rs-fNIRS) imaging data to examine topological changes in network organization during development from early childhood and early adolescence to adulthood. Our results showed that the properties of small-worldness and modularity were not significantly different across development, demonstrating the developmental maturity of important functional brain organization in early childhood. Intriguingly, young children had a significantly lower global efficiency than early adolescents and adults, which revealed that the integration of the distributed networks strengthens across the developmental stages underlying cognitive development. Moreover, local efficiency of young children and adolescents was significantly lower than that of adults, while there was no difference between these two younger groups. This finding demonstrated that functional segregation remained relatively steady from early childhood to early adolescence, and the brain in these developmental periods possesses no optimal network configuration. Furthermore, we found heterogeneous developmental patterns in the regional nodal properties in various brain regions, such as linear increased nodal properties in the frontal cortex, indicating increasing cognitive capacity over development. Collectively, our results demonstrated that significant topological changes in functional network organization occurred during these two critical developmental stages, and provided a novel insight into elucidating subtle changes in brain functional networks across development.Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.
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Although the voice-sensitive neural system emerges very early in development, it has yet to be demonstrated whether the neonatal brain is sensitive to voice perception. We measured the EEG mismatch response (MMR) elicited by emotionally spoken syllables "dada" along with correspondingly synthesized nonvocal sounds, whose fundamental frequency contours were matched, in 98 full-term newborns aged 1-5 days. In Experiment 1, happy syllables relative to nonvocal sounds elicited an MMR lateralized to the right hemisphere. In Experiment 2, fearful syllables elicited stronger amplitudes than happy or neutral syllables, and this response had no sex differences. In Experiment 3, angry versus happy syllables elicited an MMR, although their corresponding nonvocal sounds did not. Here, we show that affective discrimination is selectively driven by voice processing per se rather than low-level acoustical features and that the cerebral specialization for human voice and emotion processing emerges over the right hemisphere during the first days of life.
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In the vast clade of animals known as the bilateria, cerebral and behavioral asymmetries emerge against the backdrop of bilateral symmetry, with a functional trade-off between the two. Asymmetries can lead to more efficient processing and packaging of internal structures, but at the expense of efficient adaptation to a natural world without systematic left-right bias. Asymmetries may arise through the fissioning of ancestral structures that are largely symmetrical, creating new circuits. In humans these may include asymmetrical adaptations to language and manufacture, and as one or other hemisphere gains dominance for functions that were previously represented bilaterally. This is best illustrated in the evolution of such functions as language and tool manufacture in humans, which may derive from the mirror-neuron system in primates, but similar principles probably apply to the many other asymmetries now evident in a wide range of animals. Asymmetries arise in largely independent manner with multi-genetic sources, rather than as a single over-riding principle.
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Cortical volumetric asymmetry (CVA) has been widely observed in individuals with psychosis, and is associated with etiological risk factors (e.g., genetics, neuromaturation) and treatment response. However, it is unclear whether CVA abnormalities emerge before psychotic illness onset. Understanding whether CVA manifests in clinical high-risk (CHR)-compared with healthy controls and schizophrenia patients (SCZ)-over time may inform our understanding of pathogenic factors. A total of 233 individuals: 73 CHR, 112 healthy controls, and 48 SCZ underwent an MRI and clinical interviews. Ninety-four individuals including healthy volunteers (HV) (n = 49) and CHR (n = 45), completed another scan at 12-months. CVA was compared by lobe in a repeated-measure design across groups, then nested by time in a longitudinal model. CHR and SCZ groups showed reduced global CVA compared with the healthy control groups but the CHR and SCZ group did not differ from each other. A group by lobe interaction indicated the presence of lobe specific reductions in frontal and cingulate CVA. Cingulate CVA was reduced in CHR and SCZ groups compared to HC groups but did not differ from each other. Frontal CVA was reduced in the older healthy controls compared with younger-HC and CHR, but did not differ from the similarly aged SZ group. CVA is similarly impacted in SCZ and CHR groups, potentially reflecting pathogenic processes. Longitudinal analyses provided further support for the neurodevelopmental hypothesis as CHR exhibited longitudinal changes in opposite directions from normative neuromaturation in HV, which was related to increasing risk for psychosis in the CHR.© The Author(s) 2019. Published by Oxford University Press on behalf of the Maryland Psychiatric Research Center. All rights reserved. For permissions, please email: journals.permissions@oup.com.
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Ten-month-old infants viewed videotape segments of an actress spontaneously generating a happy or sad facial expression. Brain activity was recorded from the left and right frontal and parietal scalp regions. In two studies, infants showed greater activation of the left frontal than of the right frontal area in response to the happy segments. Parietal asymmetry failed to discriminate between the conditions. Differential lateralization of the hemispheres for affective processes seems to be established by 10 months of age.
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Mimicry, the spontaneous copying of others' behaviors, plays an important role in social affiliation, with adults selectively mimicking in-group members over out-group members. Despite infants' early documented sensitivity to cues to group membership, previous work suggests that it is not until 4 years of age that spontaneous mimicry is modulated by group status. Here we demonstrate that mimicry is sensitive to cues to group membership at a much earlier age if the cues presented are more relevant to infants. 11-month-old infants observed videos of facial actions (e.g., mouth opening, eyebrow raising) performed by models who either spoke the infants' native language or an unfamiliar foreign language while we measured activation of the infants' mouth and eyebrow muscle regions using electromyography to obtain an index of mimicry. We simultaneously used functional near-infrared spectroscopy to investigate the neural mechanisms underlying differential mimicry responses. We found that infants showed greater facial mimicry of the native speaker compared to the foreign speaker and that the left temporal parietal cortex was activated more strongly during the observation of facial actions performed by the native speaker compared to the foreign speaker. Although the exact mechanisms underlying this selective mimicry response will need to be investigated in future research, these findings provide the first demonstration of the modulation of facial mimicry by cues to group status in preverbal infants and suggest that the foundations for the role that mimicry plays in facilitating social bonds seem to be present during the first year of life.Copyright © 2019 The Authors. Published by Elsevier Inc. All rights reserved.
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Human infants begin to acquire their native language in the first months of life. To determine which brain regions support language processing at this young age, we measured with functional magnetic resonance imaging the brain activity evoked by normal and reversed speech in awake and sleeping 3-month-old infants. Left-lateralized brain regions similar to those of adults, including the superior temporal and angular gyri, were already active in infants. Additional activation in right prefrontal cortex was seen only in awake infants processing normal speech. Thus, precursors of adult cortical language areas are already active in infants, well before the onset of speech production.
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| [30] |
Understanding how language emerged in our species calls for a detailed investigation of the initial specialization of the human brain for speech processing. Our earlier research demonstrated that an adult-like left-lateralized network of perisylvian areas is already active when infants listen to sentences in their native language, but did not address the issue of the specialization of this network for speech processing. Here we used fMRI to study the organization of brain activity in two-month-old infants when listening to speech or to music. We also explored how infants react to their mother's voice relative to an unknown voice. The results indicate that the well-known structural asymmetry already present in the infants' posterior temporal areas has a functional counterpart: there is a left-hemisphere advantage for speech relative to music at the level of the planum temporale. The posterior temporal regions are thus differently sensitive to the auditory environment very early on, channelling speech inputs preferentially to the left side. Furthermore, when listening to the mother's voice, activation was modulated in several areas, including areas involved in emotional processing (amygdala, orbito-frontal cortex), but also, crucially, a large extent of the left posterior temporal lobe, suggesting that the mother's voice plays a special role in the early shaping of posterior language areas. Both results underscore the joint contributions of genetic constraints and environmental inputs in the fast emergence of an efficient cortical network for language processing in humans.2009 Elsevier Inc. All rights reserved.
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| [31] |
The acquisition of literacy transforms the human brain. By reviewing studies of illiterate subjects, we propose specific hypotheses on how the functions of core brain systems are partially reoriented or 'recycled' when learning to read. Literacy acquisition improves early visual processing and reorganizes the ventral occipito-temporal pathway: responses to written characters are increased in the left occipito-temporal sulcus, whereas responses to faces shift towards the right hemisphere. Literacy also modifies phonological coding and strengthens the functional and anatomical link between phonemic and graphemic representations. Literacy acquisition therefore provides a remarkable example of how the brain reorganizes to accommodate a novel cultural skill.
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| [32] |
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| [33] |
Processing faces and understanding facial expressions are crucial skills for social communication. In adults, basic face processing and facial emotion processing rely on specific interacting brain networks. In infancy, however, little is known about when and how these networks develop. The current study uses functional near-infrared spectroscopy (fNIRS) to measure differences in 5-month-olds' brain activity in response to fearful and happy facial expressions. Our results show that the right occipital region responds to faces, indicating that the face processing network is activated at 5 months. Yet sensitivity to facial emotions appears to be still immature at this age: explorative analyses suggest that if the facial emotion processing network was active this would be mainly visible in the temporal cortex. Together these results indicate that at 5 months, occipital areas already show sensitivity to face processing, while the facial emotion processing network seems not fully developed.
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| [34] |
Both language capacity and strongly lateralized hand preference are among the most intriguing particularities of the human species. They are associated in the adult brain with functional and anatomical hemispheric asymmetries in the speech perception-production network and in the sensori-motor system. Only studies in early life can help us to understand how such asymmetries arise during brain development, and to which point structural left-right differences are the source or the consequence of functional lateralization. In this study, we aimed to provide new in vivo structural markers of hemispheric asymmetries in infants from 1 to 4 months of age, with diffusion tensor imaging. We used 3 complementary analysis methods based on local diffusion indices and spatial localizations of tracts. After a prospective approach over the whole brain, we demonstrated early leftward asymmetries in the arcuate fasciculus and in the cortico-spinal tract. These results suggest that the early macroscopic geometry, microscopic organization, and maturation of these white matter bundles are related to the development of later functional lateralization.
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| [35] |
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| [36] |
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| [37] |
Failure to develop normal language comprehension is an early warning sign of autism, but the neural mechanisms underlying this signature deficit are unknown. This is because of an almost complete absence of functional studies of the autistic brain during early development. Using functional magnetic resonance imaging, we previously observed a trend for abnormally lateralized temporal responses to language (i.e. greater activation on the right, rather than the expected left) in a small sample (n = 12) of sleeping 2-3 year olds with autism in contrast to typically developing children, a finding also reported in autistic adults and adolescents. It was unclear, however, if findings of atypical laterality would be observed in a larger sample, and at even earlier ages in autism, such as around the first birthday. Answers to these questions would provide the foundation for understanding how neurofunctional defects of autism unfold, and provide a foundation for studies using patterns of brain activation as a functional early biomarker of autism. To begin to examine these issues, a prospective, cross-sectional design was used in which brain activity was measured in a large sample of toddlers (n = 80) during the presentation of a bedtime story during natural sleep. Forty toddlers with autism spectrum disorder and 40 typically developing toddlers ranging in age between 12-48 months participated. Any toddler with autism who participated in the imaging experiment prior to final diagnosis was tracked and diagnoses confirmed at a later age. Results indicated that at-risk toddlers later diagnosed as autistic display deficient left hemisphere response to speech sounds and have abnormally right-lateralized temporal cortex response to language; this defect worsens with age, becoming most severe in autistic 3- and 4-year-olds. Typically developing children show opposite developmental trends with a tendency towards greater temporal cortex response with increasing age and maintenance of left-lateralized activation with age. We have now demonstrated lateralized abnormalities of temporal cortex processing of language in autism across two separate samples, including a large sample of young infants who later are diagnosed with autism, suggesting that this pattern may reflect a fundamental early neural developmental pathology in autism.
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| [38] |
Background: Language is a highly lateralized function, with typically developing individuals showing left hemispheric specialization. Individuals with autism spectrum disorder (ASD) often show reduced or reversed hemispheric lateralization in response to language. However, it is unclear when this difference emerges and whether or not it can serve as an early ASD biomarker. Additionally, atypical language lateralization is not specific to ASD as it is also seen more frequently in individuals with mixed-and left-handedness. Here, we examined early asymmetry patterns measured through neural responses to speech sounds at 12 months and behavioral observations of handedness at 36 months in children with and without ASD.Methods: Three different groups of children participated in the study: low-risk controls (LRC), high risk for ASD (HRA; infants with older sibling with ASD) without ASD, and HRA infants who later receive a diagnosis of ASD (ASD). Event-related potentials (ERPs) to speech sounds were recorded at 12 months. Utilizing a novel observational approach, handedness was measured by hand preference on a variety of behaviors at 36 months.Results: At 12 months, lateralization patterns of ERPs to speech stimuli differed across the groups with the ASD group showing reversed lateralization compared to the LRC group. At 36 months, factor analysis of behavioral observations of hand preferences indicated a one-factor model with medium to high factor loadings. A composite handedness score was derived; no group differences were observed. There was no association between lateralization to speech at 12 months and handedness at 36 months in the LRC and HRA groups. However, children with ASD did show an association such that infants with lateralization patterns more similar to the LRC group at 12 months were stronger right-handers at 36 months.Conclusions: These results highlight early developmental patterns that might be specific to ASD, including a potential early biomarker of reversed lateralization to speech stimuli at 12 months, and a relation between behavioral and neural asymmetries. Future investigations of early asymmetry patterns, especially atypical hemispheric specialization, may be informative in the early identification of ASD.
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| [39] |
Vocal expressions of emotions consistently activate regions in the superior temporal cortex (STC), including regions in the primary and secondary auditory cortex (AC). Studies usually report broadly extended functional activations in response to vocal expressions, with considerable variation in peak locations across several auditory subregions. This might suggest different and distributed functional roles across these subregions instead of a uniform role for the decoding of vocal emotions. We reviewed recent studies and conducted an activation likelihood estimation meta-analysis summarizing recent fMRI and PET studies dealing with the processing of vocal expressions in the STC and AC. We included two stimulus-specific factors (paraverbal/nonverbal expression, stimulus valence) and one task-specific factor (attentional focus) in the analysis. These factors considerably influenced whether functional activity was located in the AC or STC (influence of valence and attentional focus), the laterality of activations (influence of paraverbal/nonverbal expressions), and the anterior-posterior location of STC activity (influence of valence). These data suggest distributed functional roles and a differentiated network of auditory subregions in response to vocal expressions.Copyright © 2012 Elsevier Ltd. All rights reserved.
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| [40] |
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| [41] |
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| [42] |
In human adults, voices are processed in specialized brain regions in superior temporal cortices. We examined the development of this cortical organization during infancy by using near-infrared spectroscopy. In experiment 1, 7-month-olds but not 4-month-olds showed increased responses in left and right superior temporal cortex to the human voice when compared to nonvocal sounds, suggesting that voice-sensitive brain systems emerge between 4 and 7 months of age. In experiment 2, 7-month-old infants listened to words spoken with neutral, happy, or angry prosody. Hearing emotional prosody resulted in increased responses in a voice-sensitive region in the right hemisphere. Moreover, a region in right inferior frontal cortex taken to serve evaluative functions in the adult brain showed particular sensitivity to happy prosody. The pattern of findings suggests that temporal regions specialize in processing voices very early in development and that, already in infancy, emotions differentially modulate voice processing in the right hemisphere.(c) 2010 Elsevier Inc. All rights reserved.
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| [43] |
Language impairments, a hallmark feature of autism spectrum disorders (ASD), have been related to neuroanatomical and functional abnormalities. Abnormal lateralization of the functional language network, increased reliance on visual processing areas, and increased posterior brain activation have all been reported in ASD and proposed as explanatory models of language difficulties. Nevertheless, inconsistent findings across studies have prevented a comprehensive characterization of the functional language network in ASD. The aim of this study was to quantify common and consistent patterns of brain activation during language processing in ASD and typically developing control (TD) participants using a meta-analytic approach. Activation likelihood estimation (ALE) meta-analysis was used to examine 22 previously published functional Magnetic Resonance Imaging (fMRI)/positron emission tomography studies of language processing (ASD: N = 328; TD: N = 324). Tasks included in this study addressed semantic processing, sentence comprehension, processing figurative language, and speech production. Within-group analysis showed largely overlapping patterns of language-related activation in ASD and TD groups. However, the ASD participants, relative to TD participants, showed: (1) more right hemisphere activity in core language areas (i.e., superior temporal gyrus and inferior frontal gyrus), particularly in tasks where they had poorer performance accuracy; (2) bilateral MTG hypo-activation across many different paradigms; and (3) increased activation of the left lingual gyrus in tasks where they had intact performance. These findings show that the hypotheses reviewed here address the neural and cognitive aspects of language difficulties in ASD across all tasks only in a limited way. Instead, our findings suggest the nuances of language and brain in ASD in terms of its context-dependency. Autism Res 2016, 9: 1046-1057. © 2016 International Society for Autism Research, Wiley Periodicals, Inc.© 2016 International Society for Autism Research, Wiley Periodicals, Inc.
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| [44] |
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| [45] |
In this article, we integrate two constructionist approaches-the theory of constructed emotion and rational constructivism-to introduce several novel hypotheses for understanding emotional development. We first discuss the hypothesis that emotion categories are abstract and conceptual, whose instances share a goal-based function in a particular context but are highly variable in their affective, physical, and perceptual features. Next, we discuss the possibility that emotional development is the process of developing emotion concepts, and that emotion words may be a critical part of this process. We hypothesize that infants and children learn emotion categories the way they learn other abstract conceptual categories-by observing others use the same emotion word to label highly variable events. Finally, we hypothesize that emotional development can be understood as a concept construction problem: a child becomes capable of experiencing and perceiving emotion only when her brain develops the capacity to assemble ad hoc, situated emotion concepts for the purposes of guiding behavior and giving meaning to sensory inputs. Specifically, we offer a predictive processing account of emotional development. (PsycINFO Database Record (c) 2019 APA, all rights reserved).
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| [46] |
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| [47] |
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| [48] |
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| [49] |
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| [50] |
Background: Autism spectrum disorder (ASD) has been called a developmental disconnection syndrome, however the majority of the research examining connectivity in ASD has been conducted exclusively with older children and adults. Yet, prior ASD research suggests that perturbations in neurodevelopmental trajectories begin as early as the first year of life. Prospective longitudinal studies of infants at risk for ASD may provide a window into the emergence of these aberrant patterns of connectivity. The current study employed functional connectivity near-infrared spectroscopy (NIRS) in order to examine the development of intra- and inter-hemispheric functional connectivity in high- and low-risk infants across the first year of life.;Methods: NIRS data were collected from 27 infants at high risk for autism (HRA) and 37 low-risk comparison (LRC) infants who contributed a total of 116 data sets at 3-, 6-, 9-, and 12-months. At each time point, HRA and LRC groups were matched on age, sex, head circumference, and Mullen Scales of Early Learning scores. Regions of interest (ROI) were selected from anterior and posterior locations of each hemisphere. The average time course for each ROI was calculated and correlations for each ROI pair were computed. Differences in functional connectivity were examined in a cross-sectional manner.;Results: At 3-months, HRA infants showed increased overall functional connectivity compared to LRC infants. This was the result of increased connectivity for intra- and inter-hemispheric ROI pairs. No significant differences were found between HRA and LRC infants at 6- and 9-months. However, by 12-months, HRA infants showed decreased connectivity relative to LRC infants.;Conclusions: Our preliminary results suggest that atypical functional connectivity may exist within the first year of life in HRA infants, providing support to the growing body of evidence that aberrant patterns of connectivity may be a potential endophenotype for ASD.
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| [51] |
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| [52] |
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| [53] |
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| [54] |
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| [55] |
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| [56] |
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| [57] |
Cerebral asymmetry is a cardinal feature of functional organization in the human brain and an important biomarker of successful brain development. Studies have demonstrated that functional network asymmetries across hemispheres undergo significant development through childhood and adulthood. However, it remains unknown when such asymmetries of functional networks emerge and how they develop across the early months of infancy. To address this issue, we used multiple-channel functional near-infrared spectroscopy (fNIRS) imaging to record spontaneous brain activity in 66 healthy infants aged 3-9 months. We then adopted a graph-theory analysis approach to quantify the topological characteristics of hemispheric networks in each participant. Our results showed that infants aged 3 to 6 months old exhibited leftward asymmetries in local network efficiency, while infants aged 6 to 9 months old exhibited leftward asymmetries in global network efficiency. Importantly, the degree of leftward asymmetry in global network efficiency was increased over development from 3 to 9 months old, with a faster increase in the left hemisphere than in the right hemisphere. At the regional level, 3- to 6-month-old infants exhibited leftward asymmetries in functional connectivity strength (FCS) in the temporal cortex, whereas the FCS asymmetries were located in the temporal, frontal, and occipital cortexes for 6- to 9-month-old infants. Furthermore, the 6- to 9-month-old infants also exhibited leftward asymmetries in nodal efficiency around the frontal cortex. These combined findings demonstrate that functional asymmetric organization has emerged in early infancy, which could lay a critical foundation for the development of brain functions (e.g., language and social cognition functions) later in life.Copyright © 2022 Elsevier Ltd. All rights reserved.
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| [58] |
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| [59] |
Two separate lines of research have examined the influence of song and infant-directed speech (IDS—a speech register that includes some melodic features) on language learning, suggesting that the use of musical attributes in speech input can enhance language learning. However, the benefits of these two types of stimuli have never been directly compared. In this investigation, we compared the effects of song and IDS for immediate word learning and long-term memory of the learned words. This study examines whether the highly musical stimuli (i.e., song) would facilitate language learning more than the less musical stimuli (i.e., IDS). English-speaking adults were administered a word learning task, with Mandarin Chinese words presented in adult-directed speech (ADS), IDS, or song. Participants’ word learning performance was assessed immediately after the word learning task (immediate word learning) and then 1 day later (long-term memory). Results showed that both song and IDS facilitated immediate word learning and long-term memory of the words; however, this facilitative effect did not differ between IDS and song, suggesting that the relationship between the degree of musicality and language learning performance is not linear. In addition, song and IDS were found to facilitate the word association process (mapping a label to its referent) rather than the word recognition process. Finally, participants’ confidence in their answers might not differ among ADS, IDS, and sung words.
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| [60] |
Neurodevelopmental delays in intensive care neonates are common but difficult to predict. In children, hemisphere differences in cortical processing of speech are predictive of cognitive performance. We hypothesized that hemisphere differences in auditory event-related potentials in intensive care neonates are predictive of neurodevelopment in infancy, even in those born preterm. Event-related potentials to speech sounds were prospectively recorded in 57 infants (gestational age 24-40 weeks) prior to discharge. The Developmental Assessment of Young Children was performed at 6 and 12 months. Hemisphere differences in mean amplitudes increased with postnatal age (P <.01) but not with gestational age. Greater hemisphere differences were associated with improved communication and cognitive scores at 6 and 12 months, but decreased in significance at 12 months after adjusting for socioeconomic and clinical factors. Auditory cortical responses can be used in intensive care neonates to help identify infants at higher risk for delays in infancy. © The Author(s) 2013.
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| [61] |
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| [62] |
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| [63] |
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| [64] |
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| [65] |
The importance of infant social-emotional development for outcomes across the lifecourse has been amply demonstrated. Despite this, most screening measures of social-emotional development are designed for children 18 months of age and over, with a clear gap in earlier infancy. No systematic review has yet harvested the evidence for candidate indicators in the perinatal window. This paper examines modifiable risk and protective factors for two seminal early markers of social-emotional development: attachment security and behavioral regulation mid-infancy. We searched meta-analytic and longitudinal studies of developmental relationships between modifiable exposures in the perinatal window (pregnancy to 10 months postpartum) and attachment and behavioral regulation status measured between 12 and 18 months. Six electronic databases were used: ERIC, PsycINFO, Medline Complete, Informit, Embase, and Scopus. Twelve meta-analytic reviews and 38 original studies found replicated evidence for 12 indicators across infant, caregiving, and contextual domains predictive of infant behavioral regulation and attachment status between 12 and 18 months. Key among these were caregiving responsiveness, maternal mental health, couple relationship, and SES as a contextual factor. Perinatal factors most proximal to the infant had the strongest associations with social-emotional status. Beyond very low birthweight and medical risk, evidence for infant-specific factors was weaker. Risk and protective relationships were related but not always inverse. Findings from this review have the potential to inform the development of reliable tools for early screening of infant social-emotional development for application in primary care and population health contexts.
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| [66] |
The present review covers the latest findings on the lateralization of the dorsal and ventral attention systems, their functional specialization, and their clinical relevance for stroke-induced attentional dysfunction. First, the original assumption of a bilateral dorsal system for top-down attention and a right-lateralized ventral system for stimulus-driven attention is critically reviewed. The evidence for the involvement of the left parietal cortex in attentional functions is discussed and findings on putative pathways linking the dorsal and ventral network are presented. In the second part of the review, we focus on the different attentional subsystems and their lateralization, discussing the differences between spatial, feature- and object-based attention, and motor attention. We also review studies based on predictive coding frameworks of attentional functions. Finally, in the third section, we provide an overview of the consequences of specific disruption within the attention networks after stroke. The role of the interhemispheric (im)balance is discussed, and the results of new promising therapeutic approaches employing brain stimulation techniques such as transcranial magnetic stimulation (TMS) or transcranial direct current stimulation (tDCS) are presented.Copyright © 2020 Elsevier Ltd. All rights reserved.
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| [67] |
This study uses near-infrared spectroscopy in young infants in order to elucidate the nature of functional cerebral processing for speech. Previous imaging studies of infants' speech perception revealed left-lateralized responses to native language. However, it is unclear if these activations were due to language per se rather than to some low-level acoustic correlate of spoken language. Here we compare native (L1) and non-native (L2) languages with 3 different nonspeech conditions including emotional voices, monkey calls, and phase scrambled sounds that provide more stringent controls. Hemodynamic responses to these stimuli were measured in the temporal areas of Japanese 4 month-olds. The results show clear left-lateralized responses to speech, prominently to L1, as opposed to various activation patterns in the nonspeech conditions. Furthermore, implementing a new analysis method designed for infants, we discovered a slower hemodynamic time course in awake infants. Our results are largely explained by signal-driven auditory processing. However, stronger activations to L1 than to L2 indicate a language-specific neural factor that modulates these responses. This study is the first to discover a significantly higher sensitivity to L1 in 4 month-olds and reveals a neural precursor of the functional specialization for the higher cognitive network.
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| [68] |
Sensitive responding to others' emotional body expressions is an essential social skill in humans. Using event-related brain potentials, it has recently been shown that the ability to discriminate between emotional body expressions develops between 4 and 8 months of age. However, it is not clear whether the perception of emotional body expressions in others evokes sensitive brain responses linked to motivational processes in infants. We therefore examined frontal EEG alpha asymmetry in response to dynamic happy and fearful body expressions presented to 4- and 8-month-old infants in 2 orientations (upright and inverted). Our results revealed that only 8-month-olds but not 4-month-olds showed significant differences in their frontal asymmetry responses between emotional expressions when presented in an upright orientation. Specifically, 8-month-old infants showed a greater lateralization to the left hemisphere in response to happy expression, indexing a greater tendency to approach, whereas they showed a greater lateralization to the right hemisphere in response to fearful expressions, indexing a greater tendency to withdraw. These findings provide further support for the notion that infants' perception of emotion undergoes a developmental tuning during this period in development. Critically, the results suggest that the infant brain becomes sensitive to the motivational significance conveyed by the emotional body expressions.PsycINFO Database Record (c) 2015 APA, all rights reserved.
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| [69] |
Recognition of other people's facial expressions of emotion plays an important role in social communication in infants as well as adults. Evidence from behavioral studies has demonstrated that the ability to recognize facial expressions develops by 6 to 7 months of age. Although the regions of the infant brain involved in processing facial expressions have not been investigated, neuroimaging studies in adults have revealed that several areas including the superior temporal sulcus (STS) participate in the processing of facial expressions. To examine whether the temporal area overlying the STS is responsible for the processing of facial expressions in infants, near-infrared spectroscopy (NIRS) was used to measure the neural activity in the temporal area overlying the STS as infants looked at happy and angry faces. NIRS provides a non-invasive means of estimating cerebral blood flow in the human brain and does not require severe constraints of head-movement. According to the International 10-20 system for EEG electrode placement, the measurement area was located in the bilateral temporal area centered at positions T5 and T6, which correspond to the STS. The time-course of the average change in total-Hb concentration revealed a clear difference in the pattern of hemodynamic responses to happy and angry faces. The hemodynamic response increased gradually when infants looked at happy faces and was activated continuously even after the disappearance of the face. In contrast, the hemodynamic responses for angry faces increased during the presentation of angry faces, then decreased rapidly after the face disappeared. Moreover, the left temporal area was significantly activated relative to the baseline when infants looked at happy faces, while the right temporal area was significantly activated for angry faces. These findings suggest hemispheric differences in temporal areas during the processing of positive and negative facial expressions in infants.Copyright © 2010 Elsevier Inc. All rights reserved.
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| [70] |
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| [71] |
Emotions are valenced mental responses and associated physiological reactions that occur spontaneously and automatically in response to internal or external stimuli, and can influence our behavior, and can themselves be modulated to a certain degree voluntarily or by external stimuli. They are subserved by large-scale integrated neuronal networks with epicenters in the amygdala and the hippocampus, and which overlap in the anterior cingulate cortex. Although emotion processing is accepted as being lateralized, the specific role of each hemisphere remains an issue of controversy, and two major hypotheses have been proposed. In the right-hemispheric dominance hypothesis, all emotions are thought to be processed in the right hemisphere, independent of their valence or of the emotional feeling being processed. In the valence lateralization hypothesis, the left is thought to be dominant for the processing of positively valenced stimuli, or of stimuli inducing approach behaviors, whereas negatively valenced stimuli, or stimuli inducing withdrawal behaviors, would be processed in the right hemisphere. More recent research points at the existence of multiple interrelated networks, each associated with the processing of a specific component of emotion generation, i.e., its generation, perception, and regulation. It has thus been proposed to move from hypotheses supporting an overall hemispheric specialization for emotion processing toward dynamic models incorporating multiple interrelated networks which do not necessarily share the same lateralization patterns.
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| [72] |
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| [73] |
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| [74] |
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| [75] |
For the hemispheric laterality of emotion processing in the brain, two competing hypotheses are currently still debated. The first hypothesis suggests a greater involvement of the right hemisphere in emotion perception whereas the second hypothesis suggests different involvements of each hemisphere as a function of the valence of the emotion. These hypotheses are based on findings for facial and prosodic emotion perception. Investigating emotion perception for other stimuli, such as music, should provide further insight and potentially help to disentangle between these two hypotheses. The present study investigated musical emotion perception in patients with unilateral right brain damage (RBD, n = 16) or left brain damage (LBD, n = 16), as well as in matched healthy comparison participants (n = 28). The experimental task required explicit recognition of musical emotions as well as ratings on the perceived intensity of the emotion. Compared to matched comparison participants, musical emotion recognition was impaired only in LBD participants, suggesting a potential specificity of the left hemisphere for explicit emotion recognition in musical material. In contrast, intensity ratings of musical emotions revealed that RBD patients underestimated the intensity of negative emotions compared to positive emotions, while LBD patients and comparisons did not show this pattern. To control for a potential generalized emotion deficit for other types of stimuli, we also tested facial emotion recognition in the same patients and their matched healthy comparisons. This revealed that emotion recognition after brain damage might depend on the stimulus category or modality used. These results are in line with the hypothesis of a deficit of emotion perception depending on lesion laterality and valence in brain-damaged participants. The present findings provide critical information to disentangle the currently debated competing hypotheses and thus allow for a better characterization of the involvement of each hemisphere for explicit emotion recognition and their perceived intensity.Copyright © 2020 Elsevier Ltd. All rights reserved.
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| [76] |
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| [77] |
Research investigating the early development of emotional processing has focused mainly on infants' perception of static facial emotional expressions, likely restricting the amount and type of information available to infants. In particular, the question of whether dynamic information in emotional facial expressions modulates infants' neural responses has been rarely investigated. The present study aimed to fill this gap by recording 7-month-olds' event-related potentials to static (Study 1) and dynamic (Study 2) happy, angry, and neutral faces. In Study 1, happy faces evoked a faster right-lateralized negative central (Nc) component compared to angry faces. In Study 2, both happy and angry faces elicited a larger right-lateralized Nc compared to neutral faces. Irrespective of stimulus dynamicity, a larger P400 to angry faces was associated with higher scores on the Negative Affect temperamental dimension. Overall, results suggest that 7-month-olds are sensitive to facial dynamics, which might play a role in shaping the neural processing of facial emotional expressions. Results also suggest that the amount of attentional resources infants allocate to angry expressions is associated to their temperamental traits. These findings represent a promising avenue for future studies exploring the neurobiological processes involved in perceiving emotional expressions using dynamic stimuli.© 2019 Wiley Periodicals, Inc.
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| [78] |
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| [79] |
Humans, but no other animal, make meaningful use of spoken language. What is unclear, however, is whether this capacity depends on a unique constellation of perceptual and neurobiological mechanisms or whether a subset of such mechanisms is shared with other organisms. To explore this problem, parallel experiments were conducted on human newborns and cotton-top tamarin monkeys to assess their ability to discriminate unfamiliar languages. A habituation-dishabituation procedure was used to show that human newborns and tamarins can discriminate sentences from Dutch and Japanese but not if the sentences are played backward. Moreover, the cues for discrimination are not present in backward speech. This suggests that the human newborns' tuning to certain properties of speech relies on general processes of the primate auditory system.
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| [80] |
Asymmetry of the neonatal brain is not yet understood at the level of structural connectivity. We utilized DTI deterministic tractography and structural network analysis based on graph theory to determine the pattern of structural connectivity asymmetry in 124 normal neonates. We tracted white matter axonal pathways characterizing interregional connections among brain regions and inferred asymmetry in left and right anatomical network properties. Our findings revealed that in neonates, small-world characteristics were exhibited, but did not differ between the two hemispheres, suggesting that neighboring brain regions connect tightly with each other, and that one region is only a few paths away from any other region within each hemisphere. Moreover, the neonatal brain showed greater structural efficiency in the left hemisphere than that in the right. In neonates, brain regions involved in motor, language, and memory functions play crucial roles in efficient communication in the left hemisphere, while brain regions involved in emotional processes play crucial roles in efficient communication in the right hemisphere. These findings suggest that even at birth, the topology of each cerebral hemisphere is organized in an efficient and compact manner that maps onto asymmetric functional specializations seen in adults, implying lateralized brain functions in infancy.Copyright © 2013 Elsevier Inc. All rights reserved.
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| [81] |
A failure to develop normal language is one of the most common first signs that a toddler might be at risk for autism. Currently the neural bases underlying this failure to develop language are unknown.In this study, functional magnetic resonance imaging (fMRI) was used to identify the brain regions involved in speech perception in 12 2-3-year-old children with autism spectrum disorder (ASD) during natural sleep. We also recorded fMRI data from two typically developing control groups: a mental age-matched (MA) (n = 11) and a chronological age-matched (CA) (n = 12) group. During fMRI data acquisition, forward and backward speech stimuli were presented with intervening periods of no sound presentation.Direct statistical comparison between groups revealed significant differences in regions recruited to process speech. In comparison with their MA-matched control subjects, the ASD group showed reduced activity in an extended network of brain regions, which are recruited in typical early language acquisition. In comparison with their CA-matched control subjects, ASD participants showed greater activation primarily within right and medial frontal regions. Laterality analyses revealed a trend toward greater recruitment of right hemisphere regions in the ASD group and left hemisphere regions in the CA group during the forward speech condition. Furthermore, correlation analyses revealed a significant positive relationship between right hemisphere frontal and temporal activity to forward speech and receptive language skill.These findings suggest that at 2-3 years, children with ASD might be on a deviant developmental trajectory characterized by a greater recruitment of right hemisphere regions during speech perception.
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| [82] |
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| [83] |
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| [84] |
Dynamic facial expressions of emotions constitute natural and powerful means of social communication in daily life. A number of previous neuroimaging studies have explored the neural mechanisms underlying the processing of dynamic facial expressions, and indicated the activation of certain social brain regions (e.g., the amygdala) during such tasks. However, the activated brain regions were inconsistent across studies, and their laterality was rarely evaluated. To investigate these issues, we measured brain activity using functional magnetic resonance imaging in a relatively large sample (n = 51) during the observation of dynamic facial expressions of anger and happiness and their corresponding dynamic mosaic images. The observation of dynamic facial expressions, compared with dynamic mosaics, elicited stronger activity in the bilateral posterior cortices, including the inferior occipital gyri, fusiform gyri, and superior temporal sulci. The dynamic facial expressions also activated bilateral limbic regions, including the amygdalae and ventromedial prefrontal cortices, more strongly versus mosaics. In the same manner, activation was found in the right inferior frontal gyrus (IFG) and left cerebellum. Laterality analyses comparing original and flipped images revealed right hemispheric dominance in the superior temporal sulcus and IFG and left hemispheric dominance in the cerebellum. These results indicated that the neural mechanisms underlying processing of dynamic facial expressions include widespread social brain regions associated with perceptual, emotional, and motor functions, and include a clearly lateralized (right cortical and left cerebellar) network like that involved in language processing.© 2019 Wiley Periodicals, Inc.
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| [85] |
Language impairment is common in autism spectrum disorders (ASD) and is often accompanied by atypical neural lateralization. However, it is unclear when in development language impairment or atypical lateralization first emerges. To address these questions, we recorded event-related-potentials (ERPs) to native and non-native speech contrasts longitudinally in infants at risk for ASD (HRA) over the first year of life to determine whether atypical lateralization is present as an endophenotype early in development and whether these infants show delay in a very basic precursor of language acquisition: phonemic perceptual narrowing. ERP response for the HRA group to a non-native speech contrast revealed a trajectory of perceptual narrowing similar to a group of low-risk controls (LRC), suggesting that phonemic perceptual narrowing does not appear to be delayed in these high-risk infants. In contrast there were significant group differences in the development of lateralized ERP response to speech: between 6 and 12 months the LRC group displayed a lateralized response to the speech sounds, while the HRA group failed to display this pattern. We suggest the possibility that atypical lateralization to speech may be an ASD endophenotype over the first year of life.Copyright © 2012 Elsevier Ltd. All rights reserved.
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| [86] |
Ruba and Repacholi (2020) review an important debate in the emotion development literature: whether infants can perceive and understand facial configurations as instances of discrete emotion categories. Consistent with a psychological constructionist account (Lindquist & Gendron, 2013; Shablack & Lindquist, 2019), they conclude that infants can perceive valence on faces, but argue the evidence is far from clear that infants perceive and understand discrete emotions. Ruba and Repacholi outline a novel developmental trajectory of emotion perception and understanding in which early emotion concept learning may be language-independent. In this comment, we argue that language may play a role in emotion concept acquisition even prior to children’s ability to produce emotion labels. We look forward to future research addressing this hypothesis.
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| [87] |
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| [88] |
While neonates have no sophisticated language skills, the neural basis for acquiring this function is assumed to already be present at birth. Receptive language is measurable by 6 months of age and meaningful speech production by 10-18 months of age. Fiber tracts supporting language processing include the corpus callosum (CC), which plays a key role in the hemispheric lateralization of language; the left arcuate fasciculus (AF), which is associated with syntactic processing; and the right AF, which plays a role in prosody and semantics. We examined if neonatal maturation of these fiber tracts is associated with receptive language development at 12 months of age.Diffusion-weighted imaging (DWI) was performed in 86 infants at 26.6 ± 12.2 days post-birth. Receptive language was assessed the MacArthur-Bates Communicative Development Inventory at 12 months of age. Tract-based fractional anisotropy (FA) was determined using the NA-MIC atlas-based fiber analysis toolkit. Associations between neonatal regional FA, adjusted for gestational age at birth and age at scan, and language development at 12 months of age were tested using ANOVA models.After multiple comparisons correction, higher neonatal FA was positively associated with receptive language at 12 months of age within the genu (< 0.001), rostrum (< 0.001), and tapetum (< 0.001) of the CC and the left fronto-parietal AF ( = 0.008). No significant clusters were found in the right AF.Microstructural development of the CC and the AF in the newborn is associated with receptive language at 12 months of age, demonstrating that interindividual variation in white matter microstructure is relevant for later language development, and indicating that the neural foundation for language processing is laid well ahead of the majority of language acquisition. This suggests that some origins of impaired language development may lie in the intrauterine and potentially neonatal period of life. Understanding how interindividual differences in neonatal brain maturity relate to the acquisition of function, particularly during early development when the brain is in an unparalleled window of plasticity, is key to identifying opportunities for harnessing neuroplasticity in health and disease.Copyright © 2019 Sket, Overfeld, Styner, Gilmore, Entringer, Wadhwa, Rasmussen and Buss.
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| [89] |
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| [90] |
Pre-diagnostic intervention for autism spectrum disorder (ASD) allows symptoms to be addressed as they emerge, often between six to 18 months, rather than after the full onset of the disorder. A systematic literature review, spanning the previous six years was conducted in order to provide an updated review looking at the earliest behavior symptoms of ASD. All included studies used a prospective experimental design, reported on symptoms that emerged before 18-months of age, exclusively in children who would later receive a diagnosis, and were assessed for quality. This review is the first to address this research question through the use of a systematic research design and extends the literature by following up on recommendations for future research from previous findings.
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| [91] |
Understanding the rapidly developing building blocks of speech perception in infancy requires a close look at the auditory prerequisites for speech sound processing. Pioneering studies have demonstrated that hemispheric specializations for language processing are already present in early infancy. However, whether these computational asymmetries can be considered a function of linguistic attributes or a consequence of basic temporal signal properties is under debate. Several studies in adults link hemispheric specialization for certain aspects of speech perception to an asymmetry in cortical tuning and reveal that the auditory cortices are differentially sensitive to spectrotemporal features of speech. Applying concurrent electrophysiological (EEG) and hemodynamic (near-infrared spectroscopy) recording to newborn infants listening to temporally structured nonspeech signals, we provide evidence that newborns process nonlinguistic acoustic stimuli that share critical temporal features with language in a differential manner. The newborn brain preferentially processes temporal modulations especially relevant for phoneme perception. In line with multi-time-resolution conceptions, modulations on the time scale of phonemes elicit strong bilateral cortical responses. Our data furthermore suggest that responses to slow acoustic modulations are lateralized to the right hemisphere. That is, the newborn auditory cortex is sensitive to the temporal structure of the auditory input and shows an emerging tendency for functional asymmetry. Hence, our findings support the hypothesis that development of speech perception is linked to basic capacities in auditory processing. From birth, the brain is tuned to critical temporal properties of linguistic signals to facilitate one of the major needs of humans: to communicate.
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| [92] |
Hemispheric specialization for the comprehension and expression of linguistic and emotional prosody is typically attributed to the right hemisphere. This study used techniques adapted from meta-analysis to critically examine the strength of existing evidence for hemispheric lateralization of prosody following brain damage.
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| [93] |
This study assessed whether the neonatal brain recruits different neural networks for native and non-native languages at birth. Twenty-seven one-day-old full-term infants underwent functional near-infrared spectroscopy (fNIRS) recording during linguistic and non-linguistic stimulation. Fourteen newborns listened to linguistic stimuli (native and non-native language stories) and 13 newborns were exposed to non-linguistic conditions (native and non-native stimuli played in reverse). Comparisons between left and right hemisphere oxyhemoglobin (HbO2) concentration changes over the temporal areas revealed clear left hemisphere dominance for native language, whereas non-native stimuli were associated with right hemisphere lateralization. In addition, bilateral cerebral activation was found for non-linguistic stimulus processing. Overall, our findings indicate that from the first day after birth, native language and prosodic features are processed in parallel by distinct neural networks. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.
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| [94] |
Although it is well-established that human language functions are mostly lateralized to the left hemisphere of the brain, little is known about the functional mechanisms underlying such hemispheric dominance. The present study investigated intrinsic organization of the whole brain at rest, by means of functional connectivity and graph theoretical analysis, with the aim to characterize brain functional organization underlying typical and atypical language dominance. We included healthy left-handers, both those with typical left-lateralized language and those with atypical right-lateralized language. Results show that 1) differences between typical and atypical language lateralization are associated with functional connectivity within the language system, particularly with weakened connectivity between left inferior frontal gyrus and several other language-related areas; and 2) for participants with atypical language dominance, the degree of lateralization is linked with multiple functional connectivities and graph theoretical metrics of whole brain organization, including local efficiency and small-worldness. This is the first study, to our knowledge, that linked the degree of language lateralization to global topology of brain networks. These results reveal that typical and atypical language dominance mainly differ in functional connectivity within the language system, and that atypical language dominance is associated with whole-brain organization.
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| [95] |
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| [96] |
This is the first longitudinal study to evaluate the relations between hemispheric laterality for emotion processing and the development of facial emotion recognition (FER) skills, both of which show similar developmental trajectories. Five to 12-year-old children (N = 160) completed an emotion discrimination task, emotion matching task, identity matching task, and behavioral lateralization for emotion processing task at baseline and 1 year later. Lateralization at baseline predicted later emotion discrimination, whereas change in strength of lateralization across the year predicted emotion matching ability. Lateralization was not a significant predictor of identity matching. These findings provide evidence that it is changes in laterality for emotion processing that contribute to improvements in FER skills between 5 and 12 years of age.© 2018 Society for Research in Child Development.
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| [97] |
Features of brain asymmetry have been implicated in a broad range of cognitive processes; however, their origins are still poorly understood. Here we investigated cortical asymmetries in 442 healthy term-born neonates using structural and functional magnetic resonance images from the Developing Human Connectome Project. Our results demonstrate that the neonatal cortex is markedly asymmetric in both structure and function. Cortical asymmetries observed in the term cohort were contextualized in two ways: by comparing them against cortical asymmetries observed in 103 preterm neonates scanned at term-equivalent age, and by comparing structural asymmetries against those observed in 1,110 healthy young adults from the Human Connectome Project. While associations with preterm birth and biological sex were minimal, significant differences exist between birth and adulthood.© 2023. The Author(s), under exclusive licence to Springer Nature Limited.
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| [98] |
Human neonates can discriminate phonemes, but the neural mechanism underlying this ability is poorly understood. Here we show that the neonatal brain can learn to discriminate natural vowels from backward vowels, a contrast unlikely to have been learnt in the womb. Using functional near-infrared spectroscopy, we examined the neuroplastic changes caused by 5 h of postnatal exposure to random sequences of natural and reversed (backward) vowels (T1), and again 2 h later (T2). Neonates in the experimental group were trained with the same stimuli as those used at T1 and T2. Compared with controls, infants in the experimental group showed shorter haemodynamic response latencies for forward vs backward vowels at T1, maximally over the inferior frontal region. At T2, neural activity differentially increased, maximally over superior temporal regions and the left inferior parietal region. Neonates thus exhibit ultra-fast tuning to natural phonemes in the first hours after birth.© 2022. The Author(s).
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| [99] |
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| [100] |
Prevalence estimates of autism are essential for informing public policy, raising awareness, and developing research priorities. Using a systematic review, we synthesized estimates of the prevalence of autism worldwide. We examined factors accounting for variability in estimates and critically reviewed evidence relevant for hypotheses about biological or social determinants (viz., biological sex, sociodemographic status, ethnicity/race, and nativity) potentially modifying prevalence estimates of autism. We performed the search in November 2021 within Medline for studies estimating autism prevalence, published since our last systematic review in 2012. Data were extracted by two independent researchers. Since 2012, 99 estimates from 71 studies were published indicating a global autism prevalence that ranges within and across regions, with a median prevalence of 100/10,000 (range: 1.09/10,000 to 436.0/10,000). The median male-to-female ratio was 4.2. The median percentage of autism cases with co-occurring intellectual disability was 33.0%. Estimates varied, likely reflecting complex and dynamic interactions between patterns of community awareness, service capacity, help seeking, and sociodemographic factors. A limitation of this review is that synthesizing methodological features precludes a quality appraisal of studies. Our findings reveal an increase in measured autism prevalence globally, reflecting the combined effects of multiple factors including the increase in community awareness and public health response globally, progress in case identification and definition, and an increase in community capacity. Hypotheses linking factors that increase the likelihood of developing autism with variations in prevalence will require research with large, representative samples and comparable autism diagnostic criteria and case-finding methods in diverse world regions over time. LAY SUMMARY: We reviewed studies of the prevalence of autism worldwide, considering the impact of geographic, ethnic, and socioeconomic factors on prevalence estimates. Approximately 1/100 children are diagnosed with autism spectrum disorder around the world. Prevalence estimates increased over time and varied greatly within and across sociodemographic groups. These findings reflect changes in the definition of autism and differences in the methodology and contexts of prevalence studies.© 2022 The Authors. Autism Research published by International Society for Autism Research and Wiley Periodicals LLC.
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| [101] |
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| [102] |
Very early in development, vocal emotional cues are more critical than facial expressions in guiding infants' behavior. However, the processing of emotional prosody in the very early days of life is still far from clearly understood. To address the issue, this study used functional near-infrared spectroscopy to examine brain response of neonates when they passively listened to fearful, angry, happy and neutral prosodies. It was found that while the right temporal cortex (mainly located in the middle temporal gyrus and superior temporal gyrus) exhibited enhanced response to emotional, relative to neutral, prosody, a right parietal area (approximately located in the supramarginal gyrus) showed a heightened sensitivity to fearful, relative to happy and neutral, prosody. These findings highlight the crucial importance of the right hemisphere in the perception of emotional prosody in neonates. Furthermore, the result is consistent with the notion of a negativity bias, supporting the evolutionary importance of threatening information that could be processed at birth.Copyright © 2017 Elsevier B.V. All rights reserved.
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| [103] |
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| [104] |
Face-selective regions (FSRs) are among the most widely studied functional regions in the human brain. However, individual variability of the FSRs has not been well quantified. Here we use functional magnetic resonance imaging (fMRI) to localize the FSRs and quantify their spatial and functional variabilities in 202 healthy adults. The occipital face area (OFA), posterior and anterior fusiform face areas (pFFA and aFFA), posterior continuation of the superior temporal sulcus (pcSTS), and posterior and anterior STS (pSTS and aSTS) were delineated for each individual with a semi-automated procedure. A probabilistic atlas was constructed to characterize their interindividual variability, revealing that the FSRs were highly variable in location and extent across subjects. The variability of FSRs was further quantified on both functional (i.e., face selectivity) and spatial (i.e., volume, location of peak activation, and anatomical location) features. Considerable interindividual variability and rightward asymmetry were found in all FSRs on these features. Taken together, our work presents the first effort to characterize comprehensively the variability of FSRs in a large sample of healthy subjects, and invites future work on the origin of the variability and its relation to individual differences in behavioral performance. Moreover, the probabilistic functional atlas will provide an adequate spatial reference for mapping the face network.Copyright © 2015 Elsevier Inc. All rights reserved.
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