Neural and Physiological Correlates of Prosocial Behavior: Temporoparietal Junction Activity in 3-Year-Old Children.

Although the development of prosocial behavior has been widely studied from the behavioral aspect, the neural mechanisms underlying prosocial behavior in the early stages of development remain unclear. Therefore, this study investigated the neural mechanisms underlying the emergence of prosocial behavior in 3-year-old children. Brain activity in the medial pFC and right TPJ (rTPJ) and facial expression activity, which are related to the ability to infer others' mental states (mentalizing), during the observation of prosocial and antisocial scenes were measured using functional near-infrared spectroscopy and electromyography, respectively. Subsequently, the children's helping and comforting behaviors toward an experimenter were assessed to examine prosocial behavioral tendencies. A correlation analysis revealed that the children who showed stronger activity levels in the rTPJ while observing prosocial scenes had more immediate helping behaviors toward others than those who did not show stronger response levels. Moreover, the amount of facial expression activity correlated with prosocial behavior, including both helping and comforting behaviors. These results suggest that the development of mentalizing ability and the social evaluation of others' actions, mediated by the rTPJ, contributes to the emergence of prosocial behavior.

Interactive live fNIRS reveals engagement of the temporoparietal junction in response to social contingency in infants.

Live social interaction is the dominant form of human social activity, but it remains unclear if brain processing of live interactive social stimuli differs substantially from processing of non-interactive social stimuli, mainly because of technical difficulties measuring brain activity during natural social interactions. This distinction is particularly important during infancy considering the importance of real-life interactions for various forms of learning. To assess the impact of live social interaction accompanied by ostensive social signals on infant cortical processing, the present study measured the cortical activities of 6-8-month-old and 10-12-month-old infants using functional near-infrared spectroscopy under contingent and non-contingent conditions (appropriately timed versus delayed responsiveness). We found greater activation over the right temporoparietal junction region in response to contingent interactions relative to non-contingent interactions in 6-8-month-old and 10-12-month-old infants. Our study indicates a critical role of contingent responsiveness for differential processing of live interactive social stimuli.

Recommendations for motion correction of infant fNIRS data applicable to multiple data sets and acquisition systems.

Despite motion artifacts are a major source of noise in fNIRS infant data, how to approach motion correction in this population has only recently started to be investigated. Homer2 offers a wide range of motion correction methods and previous work on simulated and adult data suggested the use of Spline interpolation and Wavelet filtering as optimal methods for the recovery of trials affected by motion. However, motion artifacts in infant data differ from those in adults' both in amplitude and frequency of occurrence. Therefore, artifact correction recommendations derived from adult data might not be optimal for infant data. We hypothesized that the combined use of Spline and Wavelet would outperform their individual use on data with complex profiles of motion artifacts. To demonstrate this, we first compared, on infant semi-simulated data, the performance of several motion correction techniques on their own and of the novel combined approach; then, we investigated the performance of Spline and Wavelet alone and in combination on real cognitive data from three datasets collected with infants of different ages (5, 7 and 10 months), with different tasks (auditory, visual and tactile) and with different NIRS systems. To quantitatively estimate and compare the efficacy of these techniques, we adopted four metrics: hemodynamic response recovery error, within-subject standard deviation, between-subjects standard deviation and number of trials that survived each correction method. Our results demonstrated that (i) it is always better correcting for motion artifacts than rejecting the corrupted trials; (ii) Wavelet filtering on its own and in combination with Spline interpolation seems to be the most effective approach in reducing the between- and the within-subject standard deviations. Importantly, the combination of Spline and Wavelet was the approach providing the best performance in semi-simulation both at low and high levels of noise, also recovering most of the trials affected by motion artifacts across all datasets, a crucial result when working with infant data.

"Mom called me!" Behavioral and prefrontal responses of infants to self-names spoken by their mothers.

Development of a sense of self is a fundamental process needed for human social interaction. Although functional neuroimaging studies have revealed the importance of medial prefrontal cortex (mPFC) in self-referencing, how this function develops in infancy remains poorly understood. To determine the cerebral basis underlying processing of self-related stimuli, we used behavioral measures and functional multi-channel near-infrared spectroscopy (fNIRS) to measure prefrontal cortical responses in 6-month-old infants hearing their own names. We also investigated the influence of a mother's voice on name perception in infants - an ability that plays a crucial role in the recognition of social signals. Experiment 1 measured the behavioral preferences of infants for their own names and for other names, spoken either by their mothers or by strangers. Results showed that infants significantly preferred their own name to other names, regardless of speaker type. Experiment 2 examined hemodynamic responses to the same four conditions in the prefrontal cortex. Compared with other names, hearing their own names, especially when spoken by their mother, elicited greater activity in the infant's dorsal mPFC. Furthermore, the magnitude of the cerebral response correlated with the degree of behavioral preference only when involving their mother's voice. These findings suggest that, particularly in the context of their mothers' voice, the dorsal mPFC of infants is already sensitive to social signals related to self at 6 months. At the same time, familiarity and affection related processing are also discussed as possible factors modulating dorsal mPFC activation at this age.

Comparison of the Sensory Profile Among Autistic Individuals and Individuals with Williams Syndrome.

PURPOSE: With the current study, we aimed to reveal the similarities and differences in sensory profiles between Williams syndrome (WS) and autism spectrum disorder. METHODS: Using the sensory profile questionnaire completed by the caregivers, we analyzed the WS (n = 60, 3.4-19.8 years) and autistic (n = 39, 4.2-14.0 years) groups. RESULTS: The Severity Analysis revealed a significant group difference in Sensory Sensitivity but not in Low Registration, Sensation Seeking, and Sensation Avoiding subscales. Age can modulate the subscale scores differently across groups. For Sensation Seeking, the scores of both groups decreased with development. However, the scores of Sensory Sensitivity decreased with age in the autistic group but not in the WS group. Sensation Avoiding scores increased with development in the WS group but not in the autistic group. No significant developmental changes were observed in Low Registration. CONCLUSION: This study highlights the cross-syndrome similarities and differences in sensory profiles and developmental changes in autistic individuals and individuals with WS.

Development of emotion comprehension in children with autism spectrum disorder and Williams syndrome.

Although research has shed light on the development of emotion comprehension in typically developing children, little is known about emotion comprehension in children who are developing atypically. Thus, this study examined the developmental trajectory of emotion understanding in non-clinical (NC) children and children with autism spectrum disorder (ASD) and Williams syndrome (WS) using a Test of Emotion Comprehension. In the test, we measured children's understanding of (I) recognition of emotions based on facial expressions, (II) external causes of emotions, (III) desire-based emotions, (IV) belief-based emotions, (V) the influence of a reminder on a present emotional state, (VI) regulating an experienced emotion, (VII) hiding an emotional state, (VIII) mixed emotions, and (IX) moral emotions. A Bayesian modeling approach was applied to compare the developmental trajectories of emotion understanding across the syndrome groups. The results revealed that NC children and children with WS followed significantly different developmental trajectories in specific aspects of emotion understanding, while children with ASD followed a very similar path to NC children. Children with ASD and NC children gradually developed an understanding of each component of emotion comprehension as they matured. However, the understanding of some components, such as desire-based emotions, hiding an emotional state, and moral emotions, in children with WS was affected by their Autism Spectrum Quotient scores. This is one of the first cross-syndrome studies to assess the development of emotion comprehension in children with ASD and WS, providing important insights for understanding the nature of disability and advancing the development of intervention programs.

Electrophysiological evidence of global structure-from-motion processing of biological motion in 6-month-old infants.

Understanding the actions of others is a fundamental and important skill for navigating our social world. A striking example of how our visual system is sensitive to others' actions is the phenomenon of biological motion (BM), in which the visual system encodes socially relevant information regarding action from as few as a dozen point-lights of motion. Previous studies have demonstrated that infants can discriminate between BM and other types of actions. However, there is a lack of electrophysiological evidence outlining the exact point of time within the first year of life when global structure-from-motion processing of BM emerges. We herein show a clear event-related potential (ERP) response related to the global structure-from-motion processing of a coherent human point-light walker in 6-month-old infants. We introduced a novel experimental paradigm composed of two stimuli phases to extract a single ERP component related to the global structure-from-motion processing of a coherent human point-light walker. Furthermore, we demonstrated that an enhanced single ERP component observed at approximately 482-586 ms following the onset of the stimulus of a coherent human point-light walker was larger than that of a spatially scrambled point-light walker in 6-month-old infants. These findings suggest that 6-month-old infants can process the global structure-from-motion information of a coherent human point-light walker, which may involve the posterior part of the superior temporal sulcus region. The current findings further refine the recently outlined developmental theory of BM processing.

Comparison of the Social Responsiveness Scale-2 among Individuals with Autism Spectrum Disorder and Williams Syndrome in Japan.

This study examined the similarities/differences between the social phenotypes of Williams syndrome (WS) and autism spectrum disorder (ASD). As cultural norms may affect symptom evaluation, this study administered the Social Responsiveness Scale-2 to Japanese individuals with WS (n = 78, 4.4-44.0 years) and ASD (n = 75, 4.7-55.4 years). The scores for Social Motivation and Social Communication were significantly more severe in the ASD than WS group. Overall, the similarities and differences between the social phenotypes of the syndromes were consistent with the findings of a recent study conducted in the UK, except for the social awareness subscale score. This highlights the importance of cross-cultural investigations of WS and ASD.

Optical imaging during toddlerhood: brain responses during naturalistic social interactions.

Despite the importance of our ability to interact and communicate with others, the early development of the social brain network remains poorly understood. We examined brain activity in 12- to 14-month-old infants while they were interacting live with an adult in two different naturalistic social scenarios (i.e., reading a picture book versus singing nursery rhymes with gestures), as compared to baseline (i.e., showing infants a toy without eye contact or speech). We used functional near-infrared spectroscopy (fNIRS) recorded over the right temporal lobe of infants to assess the role of the superior temporal sulcus-temporoparietal junction (STS-TPJ) region during naturalistic social interactions. We observed increased cortical activation in the STS-TPJ region to live social stimuli in both socially engaging conditions compared to baseline during real life interaction, with greater activation evident for the joint attention (reading book) condition relative to the social nursery rhymes. These results supported the view that the STS-TPJ region, engaged in the cortical social brain network, is already specialized in infants for processing social signals and is sensitive to communicative situations. This study also highlighted the potential of fNIRS for studying brain function in infants entering toddlerhood during live social interaction.

Social interaction facilitates word learning in preverbal infants: Word-object mapping and word segmentation.

In natural settings, infants learn spoken language with the aid of a caregiver who explicitly provides social signals. Although previous studies have demonstrated that young infants are sensitive to these signals that facilitate language development, the impact of real-life interactions on early word segmentation and word-object mapping remains elusive. We tested whether infants aged 5-6 months and 9-10 months could segment a word from continuous speech and acquire a word-object relation in an ecologically valid setting. In Experiment 1, infants were exposed to a live tutor, while in Experiment 2, another group of infants were exposed to a televised tutor. Results indicate that both younger and older infants were capable of segmenting a word and learning a word-object association only when the stimuli were derived from a live tutor in a natural manner, suggesting that real-life interaction enhances the learning of spoken words in preverbal infants.

Infant word segmentation recruits the cerebral network of phonological short-term memory.

Segmenting word units from running speech is a fundamental skill infants must develop in order to acquire language. Despite ample behavioral evidence of this skill, its neurocognitive basis remains unclear. Using behavioral testing and functional near-infrared spectroscopy, we aimed to uncover the neurocognitive substrates of word segmentation and its development. Of three age-groups of Japanese infants (5-6, 7-8, and 9-10months of age), the two older age-groups showed significantly larger temporo-parietal (particularly supramarginal gyrus) responses to target words repeatedly presented for training, than to control words. After the training, they also exhibited stronger inferior frontal responses to target words embedded in sentences. These findings suggest that word segmentation largely involves a cerebral circuit of phonological (phonetic) short-term memory. The dorsal pathway involved in encoding and decoding phonological representation may start to function stably at around 7months of age to facilitate the growth of the infant's vocabulary.

Insights on NIRS Sensitivity from a Cross-Linguistic Study on the Emergence of Phonological Grammar.

Each language has a unique set of phonemic categories and phonotactic rules which determine permissible sound sequences in that language. Behavioral research demonstrates that one's native language shapes the perception of both sound categories and sound sequences in adults, and neuroimaging results further indicate that the processing of native phonemes and phonotactics involves a left-dominant perisylvian brain network. Recent work using a novel technique, functional Near InfraRed Spectroscopy (NIRS), has suggested that a left-dominant network becomes evident toward the end of the first year of life as infants process phonemic contrasts. The present research project attempted to assess whether the same pattern would be seen for native phonotactics. We measured brain responses in Japanese- and French-learning infants to two contrasts: Abuna vs. Abna (a phonotactic contrast that is native in French, but not in Japanese) and Abuna vs. Abuuna (a vowel length contrast that is native in Japanese, but not in French). Results did not show a significant response to either contrast in either group, unlike both previous behavioral research on phonotactic processing and NIRS work on phonemic processing. To understand these null results, we performed similar NIRS experiments with Japanese adult participants. These data suggest that the infant null results arise from an interaction of multiple factors, involving the suitability of the experimental paradigm for NIRS measurements and stimulus perceptibility. We discuss the challenges facing this novel technique, particularly focusing on the optimal stimulus presentation which could yield strong enough hemodynamic responses when using the change detection paradigm.

An online database of infant functional near infrared spectroscopy studies: a community-augmented systematic review.

Until recently, imaging the infant brain was very challenging. Functional Near InfraRed Spectroscopy (fNIRS) is a promising, relatively novel technique, whose use is rapidly expanding. As an emergent field, it is particularly important to share methodological knowledge to ensure replicable and robust results. In this paper, we present a community-augmented database which will facilitate precisely this exchange. We tabulated articles and theses reporting empirical fNIRS research carried out on infants below three years of age along several methodological variables. The resulting spreadsheet has been uploaded in a format allowing individuals to continue adding new results, and download the most recent version of the table. Thus, this database is ideal to carry out systematic reviews. We illustrate its academic utility by focusing on the factors affecting three key variables: infant attrition, the reliability of oxygenated and deoxygenated responses, and signal-to-noise ratios. We then discuss strengths and weaknesses of the DBIfNIRS, and conclude by suggesting a set of simple guidelines aimed to facilitate methodological convergence through the standardization of reports.