Influence of gestational age and postnatal age on speech sound processing in NICU infants

Sensitivity to vocal emotions emerges in newborns at 37 weeks gestational age

Emotional responsiveness in neonates, particularly their ability to discern vocal emotions, plays an evolutionarily adaptive role in human communication and adaptive behaviors. The developmental trajectory of emotional sensitivity in neonates is crucial for understanding the foundations of early social-emotional functioning. However, the precise onset of this sensitivity and its relationship with gestational age (GA) remain subjects of investigation. In a study involving 120 healthy neonates categorized into six groups based on their GA (ranging from 35 and 40 weeks), we explored their emotional responses to vocal stimuli. These stimuli encompassed disyllables with happy and neutral prosodies, alongside acoustically matched nonvocal control sounds. The assessments occurred during natural sleep states using the odd-ball paradigm and event-related potentials. The results reveal a distinct developmental change at 37 weeks GA, marking the point at which neonates exhibit heightened perceptual acuity for emotional vocal expressions. This newfound ability is substantiated by the presence of the mismatch response, akin to an initial form of adult mismatch negativity, elicited in response to positive emotional vocal prosody. Notably, this perceptual shift's specificity becomes evident when no such discrimination is observed in acoustically matched control sounds. Neonates born before 37 weeks GA do not display this level of discrimination ability. This developmental change has important implications for our understanding of early social-emotional development, highlighting the role of gestational age in shaping early perceptual abilities. Moreover, while these findings introduce the potential for a valuable screening tool for conditions like autism, characterized by atypical social-emotional functions, it is important to note that the current data are not yet robust enough to fully support this application. This study makes a substantial contribution to the broader field of developmental neuroscience and holds promise for future research on early intervention in neurodevelopmental disorders.

The impact of premature birth on auditory-visual processes in very preterm schoolchildren

Interactions between stimuli from different sensory modalities and their integration are central to daily life, contributing to improved perception. Being born prematurely and the subsequent hospitalization can have an impact not only on sensory processes, but also on the manner in which information from different senses is combined-i.e., multisensory processes. Very preterm (VPT) children (<32 weeks gestational age) present impaired multisensory processes in early childhood persisting at least through the age of five. However, it remains largely unknown whether and how these consequences persist into later childhood. Here, we evaluated the integrity of auditory-visual multisensory processes in VPT schoolchildren. VPT children (N = 28; aged 8-10 years) received a standardized cognitive assessment and performed a simple detection task at their routine follow-up appointment. The simple detection task involved pressing a button as quickly as possible upon presentation of an auditory, visual, or simultaneous audio-visual stimulus. Compared to full-term (FT) children (N = 23; aged 6-11 years), reaction times of VPT children were generally slower and more variable, regardless of sensory modality. Nonetheless, both groups exhibited multisensory facilitation on mean reaction times and inter-quartile ranges. There was no evidence that standardized cognitive or clinical measures correlated with multisensory gains of VPT children. However, while gains in FT children exceeded predictions based on probability summation and thus forcibly invoked integrative processes, this was not the case for VPT children. Our findings provide evidence of atypical multisensory profiles in VPT children persisting into school-age. These results could help in targeting supportive interventions for this vulnerable population.

Longstanding Auditory Sensory and Semantic Differences in Preterm Born Children

More than 10% of births are preterm, and the long-term consequences on sensory and semantic processing of non-linguistic information remain poorly understood. 17 very preterm-born children (born at < 33 weeks gestational age) and 15 full-term controls were tested at 10 years old with an auditory object recognition task, while 64-channel auditory evoked potentials (AEPs) were recorded. Sounds consisted of living (animal and human vocalizations) and manmade objects (e.g. household objects, instruments, and tools). Despite similar recognition behavior, AEPs strikingly differed between full-term and preterm children. Starting at 50ms post-stimulus onset, AEPs from preterm children differed topographically from their full-term counterparts. Over the 108-224ms post-stimulus period, full-term children showed stronger AEPs in response to living objects, whereas preterm born children showed the reverse pattern; i.e. stronger AEPs in response to manmade objects. Differential brain activity between semantic categories could reliably classify children according to their preterm status. Moreover, this opposing pattern of differential responses to semantic categories of sounds was also observed in source estimations within a network of occipital, temporal and frontal regions. This study highlights how early life experience in terms of preterm birth shapes sensory and object processing later on in life.

Maternal voice reduces procedural pain in neonates: A meta-analysis of randomized controlled trials

BACKGROUND

Procedural pain management is a very important part in the clinical care of neonates. We aimed to conduct a meta-analysis to evaluate the effects of maternal voice on neonatal procedural pain, to provide insights to the clinical pain care of neonates.

METHODS

Two researchers independently searched PubMed, EMBASE, The Cochrane Library, CINAHL, Web of Science, China Biomedical Literature Database, China National Knowledge Infrastructure, Wanfang and Weipu Database for randomized controlled trials (RCTs) involving the effects of maternal voice on the procedural pain of neonates up to October 25, 2022. Two investigators screened the literature based on the inclusion and exclusion criteria and evaluated the methodological quality of the inclusion study. RevMan 5.3 software was used for the meta-analysis.

RESULTS

A total of 8 RCTs with a total of 584 neonates were included. Our meta-analysis indicated that maternal voice reduces the pain score (SMD = -0.60, 95% CI: -0.81 to -0.39) and heart rate (SMD = -0.81, 95% CI: -1.44 to -0.18) and increases the comfort level (SMD = -0.47, 95% CI: -0.83 to -0.11) and blood oxygen saturation (SMD = 0.70, 95% CI: 0.03-1.38) during procedure (all P < .05). Moreover, maternal voice reduces the pain score (SMD = -0.58, 95% CI: -0.88 to -0.28) and heart rate (SMD = -0.44, 95% CI: -0.75 to -0.12) and increases the blood oxygen saturation (SMD = 0.41, 95% CI: 0.00 to -0.82) after procedure (all P < .05). No publication biases were detected by the funnel plots and Egger tests (all P > .05).

CONCLUSION

Maternal voice is beneficial to reduce procedural pain and improve the physiological indicators in neonates. It is still necessary to conduct high-quality, large sample studies in the future to further elucidate the effect of maternal voice on neonatal pain care.

A Comparison of the Clinical Presentation of Preterm Birth and Autism Spectrum Disorder: Commonalities and Distinctions in Children Under 3

Premature infants and infants later diagnosed with autism spectrum disorder (ASD) share many commonalities in clinical presentations. However, prematurity and ASD also have differences in clinical presentation. These overlapping phenotypes can lead to misdiagnoses of ASD or missing a diagnosis of ASD in preterm infants. We document these commonalities and differences in various developmental domains with the hope of aiding in the accurate early detection of ASD and timely intervention implementation in children born premature. Given the degree of similarities in presentation, evidence-based interventions designed specifically for preterm toddlers or toddlers with ASD may ultimately aid both populations.

Early Development of Neural Speech Encoding Depends on Age but Not Native Language Status: Evidence From Lexical Tone

We investigated the development of early-latency and long-latency brain responses to native and non-native speech to shed light on the neurophysiological underpinnings of perceptual narrowing and early language development. Specifically, we postulated a two-level process to explain the decrease in sensitivity to non-native phonemes toward the end of infancy. Neurons at the earlier stages of the ascending auditory pathway mature rapidly during infancy facilitating the encoding of both native and non-native sounds. This growth enables neurons at the later stages of the auditory pathway to assign phonological status to speech according to the infant's native language environment. To test this hypothesis, we collected early-latency and long-latency neural responses to native and non-native lexical tones from 85 Cantonese-learning children aged between 23 days and 24 months, 16 days. As expected, a broad range of presumably subcortical early-latency neural encoding measures grew rapidly and substantially during the first two years for both native and non-native tones. By contrast, long-latency cortical electrophysiological changes occurred on a much slower scale and showed sensitivity to nativeness at around six months. Our study provided a comprehensive understanding of early language development by revealing the complementary roles of earlier and later stages of speech processing in the developing brain.

Randomized Trial to Increase Speech Sound Differentiation in Infants Born Preterm

OBJECTIVE

To test whether infant-directed foreign language active learning would specifically increase speech sound differentiation to the intervention language while not decreasing differentiation in response to English.

STUDY DESIGN

Pilot randomized controlled trial of stable infants born preterm in the newborn intensive care unit with normal auditory brainstem responses, whose parents spoke only English and had no musical training or familial hearing abnormality. Assignment was to 1 of 3 groups: passive exposure to English infant-directed lullabies and readings (English-enrichment, control group) and contingent exposure by active sucking on a sensor-equipped pacifier to either infant-directed French lullabies and readings (English environment, French-contingent learning group) or infant-directed Mandarin lullabies and readings (English environment, Chinese-contingent learning group). The main outcome measures were preintervention and postintervention event-related potentials (ERPs) in response to standardized speech syllables in each language.

RESULTS

Forty-one subjects completed the study, including 15 in the English-enrichment control group and 13 each in the French-contingent and Chinese-contingent groups. The median gestational age at birth was 34 weeks (IQR, 8.75 weeks); postmenstrual age at intervention ranged from 36 to 46 weeks and was similar across the 3 groups. Postintervention mean ERP amplitude to pairs of English speech sounds did not differ across the 3 groups; however, ERP amplitude in French sound differentiation was greater in the French-contingent group than in the Chinese-contingent or English-enrichment groups, and ERP amplitude greater in Chinese sound differentiation was greater in the Chinese-contingent group compared with the other 2 groups.

CONCLUSION

Contingent infant-directed foreign language exposure increased speech sound differentiation specific to the intervention language and did not decrease differentiation in response to English.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT03232931.

Mismatch response in preterm and asphyxic neonates: a functional electrophysiological investigation of attention and habituation

BACKGROUND AND AIM

There is a lack of diagnostic tools for early risk stratification of cognitive outcome in infants born preterm and infants with asphyxia. Using auditory event-related potentials and mismatch response, we aimed to assess possible differences in early attention and learning, as a marker for brain maturation to subsequently improve the allocation of early neurodevelopmental support.

STUDY DESIGN AND METHODS

This cross-sectional study included 22 very preterm infants (gestational age (GA) < 32 weeks), eight term infants with asphyxia and 35 healthy term infants. An auditory oddball-paradigm with three consecutive stimulation blocks, separated by a two-minute break, was used as a cognitive discrimination task to assess attention and habituation.

RESULTS

The peak-to-peak analysis in the group comparisons showed no significant differences for the first stimulation block. In term healthy infants and term infants after asphyxia, no significant differences were found in amplitudes between block one and three. Preterm infants showed significantly (p = .007) lower amplitudes in the third block for F7 congruent to a positive habituation. The amplitude of the grouped electrodes correlated positively with GA for frontal (R = .271, p= .029) and parietal electrodes (R =.275, p = .027).

CONCLUSION

We found no differences in the auditory attention paradigm between preterm or term asphyxic and control infants when they were evaluated at term corrected age. Most infants did not show any electrophysiologically measurable learning effect indicating habituation or dishabituation. The small sample size of this study is a clear limitation. Therefore, the results must be evaluated with caution, especially regarding their potential predictive value for future cognitive development of infants with a developmental risk. However, our study underlines the possibility of an electrophysiological evaluation as a feasible tool to assess very early cognition in infants.

Perspectives from the Society for Pediatric Research. Neonatal encephalopathy clinical trials: developing the future

The next phase of clinical trials in neonatal encephalopathy (NE) focuses on hypothermia adjuvant therapies targeting alternative recovery mechanisms during the process of hypoxic brain injury. Identifying infants eligible for neuroprotective therapies begins with the clinical detection of brain injury and classification of severity. Combining a variety of biomarkers (serum, clinical exam, EEG, movement patterns) with innovative clinical trial design and analyses will help target infants with the most appropriate and timely treatments. The timing of magnetic resonance imaging (MRI) and MR spectroscopy after NE both assists in identifying the acute perinatal nature of the injury (days 3-7) and evaluates the full extent and evolution of the injury (days 10-21). Early, intermediate outcome of neuroprotective interventions may be best defined by the 21-day neuroimaging, with recognition that the full neurodevelopmental trajectory is not yet defined. An initial evaluation of each new therapy at this time point may allow higher-throughput selection of promising therapies for more extensive investigation. Functional recovery can be assessed using a trajectory of neurodevelopmental evaluations targeted to a prespecified and mechanistically derived hypothesis of drug action. As precision medicine revolutionizes healthcare, it should also include the redesign of NE clinical trials to allow safe, efficient, and targeted therapeutics. IMPACT: As precision medicine revolutionizes healthcare, it should also include the redesign of NE clinical trials to allow faster development of safe, effective, and targeted therapeutics. This article provides a multidisciplinary perspective on the future of clinical trials in NE; novel trial design; study management and oversight; biostatistical methods; and a combination of serum, imaging, and neurodevelopmental biomarkers can advance the field and improve outcomes for infants affected by NE. Innovative clinical trial designs, new intermediate trial end points, and a trajectory of neurodevelopmental evaluations targeted to a prespecified and mechanistically derived hypothesis of drug action can help address common challenges in NE clinical trials and allow for faster selection and validation of promising therapies for more extensive investigation.

Neonatal Multisensory Processing in Preterm and Term Infants Predicts Sensory Reactivity and Internalizing Tendencies in Early Childhood

Multisensory processes include the capacity to combine information from the different senses, often improving stimulus representations and behavior. The extent to which multisensory processes are an innate capacity or instead require experience with environmental stimuli remains debated. We addressed this knowledge gap by studying multisensory processes in prematurely born and full-term infants. We recorded 128-channel event-related potentials (ERPs) from a cohort of 55 full-term and 61 preterm neonates (at an equivalent gestational age) in response to auditory, somatosensory, and combined auditory-somatosensory multisensory stimuli. Data were analyzed within an electrical neuroimaging framework, involving unsupervised topographic clustering of the ERP data. Multisensory processing in full-term infants was characterized by a simple linear summation of responses to auditory and somatosensory stimuli alone, which furthermore shared common ERP topographic features. We refer to the ERP topography observed in full-term infants as "typical infantile processing" (TIP). In stark contrast, preterm infants exhibited non-linear responses and topographies less-often characterized by TIP; there were distinct patterns of ERP topographies to multisensory and summed unisensory conditions. We further observed that the better TIP characterized an infant's ERPs, independently of prematurity, the more typical was the score on the Infant/Toddler Sensory Profile (ITSP) at 12 months of age and the less likely was the child to the show internalizing tendencies at 24 months of age. Collectively, these results highlight striking differences in the brain's responses to multisensory stimuli in children born prematurely; differences that relate to later sensory and internalizing functions.

Early vocal contact and music in the NICU: new insights into preventive interventions

It is now clearly established that the environment and the sensory stimuli, particularly during the perinatal period, have an impact on infant's development. During the last trimester of gestation, activity-dependent plasticity shapes the fetal brain, and prematurity has been shown to alter the typical developmental trajectories. In this delicate period, preventive interventions aiming at modulating these developmental trajectories through activity-inducing interventions are currently underway to be tested. The purpose of this review paper is to describe the potentialities of early vocal contact and music on the preterm infant's brain development, and their potential beneficial effect on early development. Scientific evidence supports a behavioral orientation of the newborn to organized sounds, such as those of voice and music, and recent neuroimaging studies further confirm full cerebral processing of music as multisensory stimuli. However, the impact of long-term effects of music exposure and early vocal contact on preterm infants' long-term neurodevelopment needs be further investigated. To conclude, it is necessary to establish the neuroscientific bases of the early perception and the long-term effects of music and early vocal contact on the premature newborns' development. Scientific projects are currently on the way to fill this gap in knowledge.

A randomised controlled trial of protocolised music therapy demonstrates developmental milestone acquisition in hospitalised infants

AIM

To compare the effectiveness of an intensive-intermittent vs. standard spaced protocolised music therapy intervention on supporting developmental milestone acquisition of infants >44 weeks postmenstrual age (PMA) hospitalised in a Neonatal Intensive Care Unit (NICU).

METHOD

This was a comparative effectiveness study of infants 44-66 weeks PMA with a projected NICU stay of at least one month from recruitment. Infants were randomised to one of two treatment groups: traditional therapy (2x/week) and intermittent-intensive (4x/week, off, 4x/week, off). Both groups received the same number of sessions over a 4-week period. Sessions at the start and end of the treatment period were video recorded. Two masked researchers reviewed and coded videos. Milestones used for video recording were adapted from the Developmental Assessment of Young Children.

RESULTS

Twenty-four infants participated, with groups matched for birth age, PMA at start of study, race, IVH severity, and respiratory support. Total and motor composite scores were higher post-intervention (Cohen's d = 0.71 and 0.97, both p < 0.01), with the same degree of skill acquisition found for both intervention groups.

CONCLUSION

A developmental music therapy protocol supports developmental skills acquisition of post-term infants in a NICU. Similar outcomes for both groups provide therapists with varying treatment dosing options to best support their patients.

Neuroprocessing Mechanisms of Music during Fetal and Neonatal Development: A Role in Neuroplasticity and Neurodevelopment

The primary aim of this viewpoint article is to examine recent literature on fetal and neonatal processing of music. In particular, we examine the behavioral, neurophysiological, and neuroimaging literature describing fetal and neonatal music perception and processing to the first days of term equivalent life. Secondly, in light of the recent systematic reviews published on this topic, we discuss the impact of music interventions on the potential neuroplasticity pathways through which the early exposure to music, live or recorded, may impact the fetal, preterm, and full-term infant brain. We conclude with recommendations for music stimuli selection and its role within the framework of early socioemotional development and environmental enrichment.

Randomized controlled trial protocol to improve multisensory neural processing, language and motor outcomes in preterm infants

BACKGROUND

Premature infants are at risk for abnormal sensory development due to brain immaturity at birth and atypical early sensory experiences in the Neonatal Intensive Care Unit. This altered sensory development can have downstream effects on other more complex developmental processes. There are currently no interventions that address rehabilitation of sensory function in the neonatal period.

METHODS

This study is a randomized controlled trial of preterm infants enrolled at 32-36 weeks postmenstrual age to either standard care or standard care plus multisensory intervention in order to study the effect of multisensory intervention as compared to standard care alone. The study population will consist of 100 preterm infants in each group (total n = 200). Both groups will receive standard care, consisting of non-contingent recorded parent's voice and skin-to-skin by parent. The multisensory group will also receive contemporaneous holding and light pressure containment for tactile stimulation, playing of the mother's voice contingent on the infant's pacifier sucking for auditory stimulation, exposure to a parent-scented cloth for olfactory stimulation, and exposure to carefully regulated therapist breathing that is mindful and responsive to the child's condition for vestibular stimulation. The primary outcome is a brain-based measure of multisensory processing, measured using time locked-EEG. Secondary outcomes include sensory adaptation, tactile processing, speech sound differentiation, motor and language function, measured at one and two years corrected gestational age.

DISCUSSION

This is the first randomized controlled trial of a multisensory intervention using brain-based measurements in order to explain the causal effects of the multisensory intervention on neural processing changes to mediate neurodevelopmental outcomes in former preterm infants. In addition to contributing a critical link in our understanding of these processes, the protocolized multisensory intervention in this study is therapist administered, parent supported and leverages simple technology. Thus, this multisensory intervention has the potential to be widely implemented in various NICU settings, with the opportunity to potentially improve neurodevelopment of premature infants.

TRIAL REGISTRATION

NIH Clinical Trials ( clinicaltrials.gov ): NCT03232931 . Registered July 2017.

Feasibility of event-related potential (ERP) biomarker use to study effects of mother's voice exposure on speech sound differentiation of preterm infants

Atypical maturation of auditory neural processing contributes to preterm-born infants' language delays. Event-related potential (ERP) measurement of speech-sound differentiation might fill a gap in treatment-response biomarkers to auditory interventions. We evaluated whether these markers could measure treatment effects in a quasi-randomized prospective study. Hospitalized preterm infants in passive or active, suck-contingent mother's voice exposure groups were not different at baseline. Post-intervention, the active group had greater increases in/du/-/gu/differentiation in left frontal and temporal regions. Infants with brain injury had lower baseline/ba/-/ga/and/du/-/gu/differentiation than those without. ERP provides valid discriminative, responsive, and predictive biomarkers of infant speech-sound differentiation.

Music exposure and maturation of late preterm sleep-wake cycles: a randomised crossover trial

AIM

To determine the effect of music on sleep-wake cycle (SWC) patterns in late preterm neonates.

METHODS

In a masked crossover study, infants between 32 and 36 6/7 weeks gestation were randomised to music exposure either during the first six or last six hours of a 12-hour observation period. SWC characteristics were determined by continuous amplitude-integrated electroencephalography (aEEG) read by two coders masked to exposure sequence. Analysis was performed in paired comparisons. ANOVA was used to assess the effects of music exposure, period and crossover on SWC outcomes: (i) Burdjalov Scores (BS) during active sleep (AS) (ii) per cent and duration of quiet sleep (QS).

RESULTS

Thirty infants were studied. A total of 222 QS cycles (median seven per patient; range five to 12) were analysed. Music exposure was associated with higher BS (F = 10.60, p = 0.0019) in AS and decreased interruptions during QS. The advanced postconceptual age (PCA) SWC pattern during AS was equivalent to a one-week mean. Number, duration and ratio of QS cycles did not change with music exposure.

CONCLUSION

Music exposure elicits an increasing PCA pattern in AS and fewer interruptions in QS. Music may benefit sleep in late preterm infants.

Investigating skin-to-skin care patterns with extremely preterm infants in the NICU and their effect on early cognitive and communication performance: a retrospective cohort study

OBJECTIVES

The primary objective of the study was to investigate how patterns of skin-to-skin care might impact infant early cognitive and communication performance.

DESIGN

This was a retrospective cohort study.

SETTING

This study took place in a level-IV all-referral neonatal intensive care unit in the Midwest USA specialising in the care of extremely preterm infants.

PARTICIPANTS

Data were collected from the electronic medical records of all extremely preterm infants (gestational age <27 weeks) admitted to the unit during 2010-2011 and who completed 6-month and 12-month developmental assessments in the follow-up clinic (n=97).

OUTCOME MEASURES

Outcome measures included the cognitive and communication subscales of the Bayley Scales of Infant Development, Third Edition (Bayley-III); and skin-to-skin patterns including: total hours of maternal and paternal participation throughout hospitalisation, total duration in weeks and frequency (hours per week).

ANALYSIS

Extracted data were analysed through a multistep process of logistic regressions, t-tests, χ2 tests and Fisher's exact tests followed with exploratory network analysis using novel visual analytic software.

RESULTS

Infants who received above the sample median in total hours, weekly frequency and total hours from mothers and fathers of skin-to-skin care were more likely to score ≥80 on the cognitive and communication scales of the Bayley-III. However, the results were not statistically significant (p>0.05). Mothers provided the majority of skin-to-skin care with a sharp decline at 30 weeks corrected age, regardless of when extremely preterm infants were admitted. Additional exploratory network analysis suggests that medical and skin-to-skin factors play a parallel, non-synergistic role in contributing to early cognitive and communication performance as assessed through the Bayley-III.

CONCLUSIONS

This study suggests an association between early and frequent skin-to-skin care with extremely preterm infants and early cognitive and communication performance.

Effects of caffeine treatment for apnea of prematurity on cortical speech-sound differentiation in preterm infants

Caffeine, standard treatment for apnea of prematurity, improves brainstem auditory processing. We hypothesized that caffeine also improves cortical differentiation of complex speech sounds. We used event-related potential methodology to measure responses to speech-sound contrasts in 45 intensive care neonates, stratified by cumulative exposure as no-, low-, and high-caffeine groups. Sound differentiation in the low-caffeine group and near-term no-caffeine infants was similar with repeated measures analysis of variance controlling for gestational and postnatal age. However, a generalized estimating equation approach demonstrated that, at equivalent postnatal age, differentiation was reduced in the high-caffeine (gestational age 25 weeks) compared to the low-caffeine group (gestational age 28 weeks), reflecting the importance of maturity at birth (Z = 2.77, P < .006). We conclude that caffeine improves measures of auditory processing associated with improved neurodevelopmental outcomes in preterm infants. However, current usage of caffeine for apnea of prematurity cannot fully compensate for the effects of brain immaturity on speech sound processing.

Critical periods in speech perception: new directions

A continuing debate in language acquisition research is whether there are critical periods (CPs) in development during which the system is most responsive to environmental input. Recent advances in neurobiology provide a mechanistic explanation of CPs, with the balance between excitatory and inhibitory processes establishing the onset and molecular brakes establishing the offset of windows of plasticity. In this article, we review the literature on human speech perception development within the context of this CP model, highlighting research that reveals the interplay of maturational and experiential influences at key junctures in development and presenting paradigmatic examples testing CP models in human subjects. We conclude with a discussion of how a mechanistic understanding of CP processes changes the nature of the debate: The question no longer is, "Are there CPs?" but rather what processes open them, keep them open, close them, and allow them to be reopened.

Autonomic nervous system activity of preschool-age children who stutter

PURPOSE

The purpose of this study was to investigate potential differences in autonomic nervous system (ANS) activity to emotional stimuli between preschool-age children who do (CWS) and do not stutter (CWNS).

METHODS

Participants were 20 preschool-age CWS (15 male) and 21 preschool-age CWNS (11 male). Participants were exposed to two emotion-inducing video clips (negative and positive) with neutral clips used to establish pre-and post-arousal baselines, and followed by age-appropriate speaking tasks. Respiratory sinus arrhythmia (RSA)-often used as an index of parasympathetic activity-and skin conductance level (SCL)-often used as an index of sympathetic activity-were measured while participants listened to/watched the audio-video clip presentation and performed a speaking task.

RESULTS

CWS, compared to CWNS, displayed lower amplitude RSA at baseline and higher SCL during a speaking task following the positive, compared to the negative, condition. During speaking, only CWS had a significant positive relation between RSA and SCL.

CONCLUSION

Present findings suggest that preschool-age CWS, when compared to their normally fluent peers, have a physiological state that is characterized by a greater vulnerability to emotional reactivity (i.e., lower RSA indexing less parasympathetic tone) and a greater mobilization of resources in support of emotional reactivity (i.e., higher SCL indexing more sympathetic activity) during positive conditions. Thus, while reducing stuttering to a pure physiological process is unwarranted, the present findings suggest that the autonomic nervous system is involved.

EDUCATIONAL OBJECTIVES

The reader will be able to: (a) summarize current empirical evidence on the role of emotion in childhood stuttering; (b) describe physiological indexes of sympathetic and parasympathetic activity; (c) summarize how preschool-age children who stutter differ from preschool-age children who do not stutter in autonomic activity; (d) discuss possible implications of current findings in relation to the development of childhood stuttering.

Hemisphere differences in speech-sound event-related potentials in intensive care neonates: associations and predictive value for development in infancy

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 effect of postnatal age on the early tactile manual abilities of preterm infants

BACKGROUND

Although preterm infants possess early tactile manual abilities, the influence of the postnatal experience has not yet been systematically examined.

AIMS

To investigate whether early tactile manual habituation, discrimination and recognition (following interference) of shape in preterm infants are modified by postnatal age.

STUDY DESIGN

Prospective study.

SUBJECTS

Forty preterm infants were assessed from the post-conceptional age (PCA) of 34 weeks. Two groups were made up according to postnatal age (PNA): low PNA (PNA≤10 days of life) and high PNA (PNA≥12 days of life).

OUTCOME MEASURES

An object (prism or cylinder) was presented repeatedly in the left hand, and holding times of the object were recorded during each trial.

RESULTS

Holding time was shorter for all preterm infants following successive presentation of the same object irrespective of postnatal age range. In the discrimination phase, the mean holding time for the novel object was longer than holding times in the last two habituation trials, in both PNA groups. Finally, the mean holding time of the familiar object presented in the recognition phase was shorter than the holding time of the novel object presented previously, but only in the low PNA group.

CONCLUSIONS

Tactile manual habituation and discrimination of shape information is present in preterm infants at a post-conceptional age of 34 weeks, independently of postnatal age. However, tactile manual recognition of familiar shapes following interference is affected by length of postnatal experience. The significance of this last result is discussed in detail.

Effect of maturation on suprasegmental speech processing in full- and preterm infants: a mismatch negativity study

Infants born prematurely are at higher risk for later linguistic deficits present in delayed or atypical processing of phonetic and prosodic information. In order to be able to specify the nature of this atypical development, it is important to investigate the role of early experience in language perception. According to the concept of Gonzalez-Gomez and Nazzi (2012) there is a special intrauterine sensitivity to the prosodic features of languages that should have a special role in language acquisition. Therefore, we may also assume that pre- and full-term infants having months difference in intrauterine experience show different maturation patterns of processing prosodic and phonetic information present at word level. The aim of our study was to investigate the effect of these differences on word stress pattern vs. phoneme information processing. Two age groups of infants (6 and 10 month-olds) were included in our study. 21 of 46 of the total of infants investigated were prematurely born with low birth weight. We used the mismatch negativity (MMN) event related brain potential (ERP) component, a widely used electrophysiological correlate of acoustic change detection, for testing the assumed developmental changes of phoneme and word stress discrimination. In a passive oddball paradigm we used a word as standard, a pseudo-word as phoneme deviant, and an illegally uttered word as stress deviant. Our results showed no differences in MMN responses in the phoneme deviant condition between the groups, meaning a relatively intact maturation of phoneme processing of preterm infants as compared to their contemporaries. However, the mismatch responses measured in the stress condition revealed significant between-group differences. These results strengthen the view that the total length of intrauterine experience influences the time of emergence of prosodic processing.

Using naturalistic utterances to investigate vocal communication processing and development in human and non-human primates

Humans and several non-human primates possess cortical regions that are most sensitive to vocalizations produced by their own kind (conspecifics). However, the use of speech and other broadly defined categories of behaviorally relevant natural sounds has led to many discrepancies regarding where voice-sensitivity occurs, and more generally the identification of cortical networks, "proto-networks" or protolanguage networks, and pathways that may be sensitive or selective for certain aspects of vocalization processing. In this prospective review we examine different approaches for exploring vocal communication processing, including pathways that may be, or become, specialized for conspecific utterances. In particular, we address the use of naturally produced non-stereotypical vocalizations (mimicry of other animal calls) as another category of vocalization for use with human and non-human primate auditory systems. We focus this review on two main themes, including progress and future ideas for studying vocalization processing in great apes (chimpanzees) and in very early stages of human development, including infants and fetuses. Advancing our understanding of the fundamental principles that govern the evolution and early development of cortical pathways for processing non-verbal communication utterances is expected to lead to better diagnoses and early intervention strategies in children with communication disorders, improve rehabilitation of communication disorders resulting from brain injury, and develop new strategies for intelligent hearing aid and implant design that can better enhance speech signals in noisy environments. This article is part of a Special Issue entitled "Communication Sounds and the Brain: New Directions and Perspectives".

Cortical speech sound differentiation in the neonatal intensive care unit predicts cognitive and language development in the first 2 years of life

AIM

Neurodevelopmental delay in childhood is common in infants born preterm, but is difficult to predict before infants leave the neonatal intensive care unit (NICU). We hypothesized that event-related potential (ERP) methodology characterizing the cortical differentiation of speech sounds in hospitalized infants would predict cognitive and language outcomes during early childhood.

METHODS

We conducted a prospective study of 57 infants in NICU (34 male, gestational age at birth 24-40wks), quantifying the amplitude of ERP responses to speech sounds before discharge (median gestational age 37.1wks), followed by standardized neurodevelopmental assessments at 12 months and 24 months. Analyses were performed using ordinary least squares linear regression.

RESULTS

Overall validity of constructs using all ERP variables, as well as sex, maternal education, gestational age, and age at ERP, was good and allowed significant prediction of cognitive and communication outcomes at 12 months and 24 months (R(2) =22-42%; p<0.05). Quantitative models incorporating specific ERPs, gestational age, and age at ERP explained a large proportion of the variance in cognition and receptive language on the Bayley Scales of Infant Development at 24 months (R(2) >50%; p<0.05).

INTERPRETATION

This study establishes ERP methodology as a valuable research tool to quantitatively assess cortical function in the NICU and to predict meaningful outcomes in early childhood.

Decreased right temporal activation and increased interhemispheric connectivity in response to speech in preterm infants at term-equivalent age

Preterm infants are at increased risk of language-related problems later in life; however, few studies have examined the effects of preterm birth on cerebral responses to speech at very early developmental stages. This study examined cerebral activation and functional connectivity in response to infant-directed speech (IDS) and adult-directed speech (ADS) in full-term neonates and preterm infants at term-equivalent age using 94-channel near-infrared spectroscopy. The results showed that compared with ADS, IDS increased activity in larger brain areas such as the bilateral frontotemporal, temporal, and temporoparietal regions, both in full-term and preterm infants. Preterm infants exhibited decreased activity in response to speech stimuli in the right temporal region compared with full-term infants, although the significance was low. Moreover, preterm infants exhibited increased interhemispheric connectivity compared with full-term controls, especially in the temporal and temporoparietal regions. These differences suggest that preterm infants may follow different developmental trajectories from those born at term owing to differences in intrauterine and extrauterine development.