Experience-dependent effects of passive auditory exposure in infants impact theta phase synchrony and predict later language

The establishment of cortical representations critical for mounting language is supported by both ongoing neural maturation and experience-expectant plasticity as infants increasingly recognize the linguistic events that occur most often in their surrounding environment. Previous research has demonstrated that enhanced efficiency of syllabic representation and discrimination is facilitated by interactive attention-driven, nonspeech auditory experience. However, experience-dependent effects on syllable processing as a function of nonspeech, passive auditory exposure (PAE), remain unclear. As theta band-specific activity has been shown to support syllabic processing, we chose theta inter-trial phase synchrony to examine the experience-dependent effects of PAE on the processing of a syllable contrast. Results demonstrated that infants receiving PAE increased syllabic processing efficiency. Specifically, compared with controls, the group receiving PAE showed more mature, efficient processing, exhibiting less theta phase synchrony for the standard syllable at 9 months, and at 18 months, for the deviant syllable. Furthermore, the PAE modulatory effect on theta phase synchrony at 7 and 9 months was associated with language scores at 12 and 18 months. These findings confirm that supporting emerging perceptual abilities during early sensitive periods impacts syllabic processing efficiency and aligns with literature demonstrating associations between infant auditory perceptual abilities and later language outcomes.

Acoustic-level and language-specific processing of native and non-native phonological sequence onsets in the low gamma and theta-frequency bands

Acoustic structures associated with native-language phonological sequences are enhanced within auditory pathways for perception, although the underlying mechanisms are not well understood. To elucidate processes that facilitate perception, time-frequency (T-F) analyses of EEGs obtained from native speakers of English and Polish were conducted. Participants listened to same and different nonword pairs within counterbalanced attend and passive conditions. Nonwords contained the onsets /pt/, /pət/, /st/, and /sət/ that occur in both the Polish and English languages with the exception of /pt/, which never occurs in the English language in word onset. Measures of spectral power and inter-trial phase locking (ITPL) in the low gamma (LG) and theta-frequency bands were analyzed from two bilateral, auditory source-level channels, created through source localization modeling. Results revealed significantly larger spectral power in LG for the English listeners to the unfamiliar /pt/ onsets from the right hemisphere at early cortical stages, during the passive condition. Further, ITPL values revealed distinctive responses in high and low-theta to acoustic characteristics of the onsets, which were modulated by language exposure. These findings, language-specific processing in LG and acoustic-level and language-specific processing in theta, support the view that multi scale temporal processing in the LG and theta-frequency bands facilitates speech perception.

Modulation of Theta Phase Synchrony during Syllable Processing as a Function of Interactive Acoustic Experience in Infancy

Plasticity, a prominent characteristic of the infant brain, supports formation of cortical representations as infants begin to interact with and adapt to environmental sensory events. Enhanced acoustic processing efficiency along with improved allocation of attentional resources at 7 months and establishment of well-defined phonemic maps at 9 months have been shown to be facilitated by early interactive acoustic experience (IAE). In this study, using an oddball paradigm and measures of theta phase synchrony at source level, we examined short- and long-term effects of nonspeech IAE on syllable processing. Results demonstrated that beyond maturation alone, IAE increased the efficiency of syllabic representation and discrimination, an effect that endured well beyond the immediate training period. As compared with naive controls, the IAE-trained group at 7, 9, and 18 months showed less theta phase synchrony for the standard syllable and at 7 and 18 months for the deviant syllable. The decreased theta phase synchrony exhibited by the trained group suggests more mature, efficient, acoustic processing, and thus, better cortical representation and discrimination of syllabic content. Further, the IAE modulatory effect observed on theta phase synchrony in left auditory cortex at 7 and 9 months was differentially associated with receptive and expressive language scores at 12 and 18 months of age.

Early Interactive Acoustic Experience with Non-speech Generalizes to Speech and Confers a Syllabic Processing Advantage at 9 Months

During early development, the infant brain is highly plastic and sensory experiences modulate emerging cortical maps, enhancing processing efficiency as infants set up key linguistic precursors. Early interactive acoustic experience (IAE) with spectrotemporally-modulated non-speech has been shown to facilitate optimal acoustic processing and generalizes to novel non-speech sounds at 7-months-of-age. Here we demonstrate that effects of non-speech IAE endure well beyond the immediate training period and robustly generalize to speech processing. Infants who received non-speech IAE differed at 9-months-of-age from both naïve controls and those with only passive acoustic exposure, demonstrating broad modulation of oscillatory dynamics. For the standard syllable, increased high-gamma (>70 Hz) power within auditory cortices indicates that IAE fosters native speech processing, facilitating establishment of phonemic representations. The higher left beta power seen may reflect increased linking of sensory information and corresponding articulatory patterns, while bilateral decreases in theta power suggest more mature automatized speech processing, as less neuronal resources were allocated to process syllabic information. For the deviant syllable, left-lateralized gamma (<70 Hz) enhancement suggests IAE promotes phonemic-related discrimination abilities. Theta power increases in right auditory cortex, known for favoring slow-rate decoding, implies IAE facilitates the more demanding processing of the sporadic deviant syllable.

Stability of neuronal avalanches and long-range temporal correlations during the first year of life in human infants

During infancy, the human brain rapidly expands in size and complexity as neural networks mature and new information is incorporated at an accelerating pace. Recently, it was shown that single-electrode EEG in preterms at birth exhibits scale-invariant intermittent bursts. Yet, it is currently not known whether the normal infant brain, in particular, the cortex, maintains a distinct dynamical state during development that is characterized by scale-invariant spatial as well as temporal aspects. Here we employ dense-array EEG recordings acquired from the same infants at 6 and 12 months of age to characterize brain activity during an auditory odd-ball task. We show that suprathreshold events organize as spatiotemporal clusters whose size and duration are power-law distributed, the hallmark of neuronal avalanches. Time series of local suprathreshold EEG events display significant long-range temporal correlations (LRTCs). No differences were found between 6 and 12 months, demonstrating stability of avalanche dynamics and LRTCs during the first year after birth. These findings demonstrate that the infant brain is characterized by distinct spatiotemporal dynamical aspects that are in line with expectations of a critical cortical state. We suggest that critical state dynamics, which theory and experiments have shown to be beneficial for numerous aspects of information processing, are maintained by the infant brain to process an increasingly complex environment during development.

Stability of neuronal avalanches and long-range temporal correlations during the first year of life in human infant

During infancy, the human brain rapidly expands in size and complexity as neural networks mature and new information is incorporated at an accelerating pace. Recently, it was shown that single electrode EEG in preterms at birth exhibits scale-invariant intermittent bursts. Yet, it is currently not known whether the normal infant brain, in particular, the cortex maintains a distinct dynamical state during development that is characterized by scale-invariant spatial as well as temporal aspects. Here we employ dense-array EEG recordings acquired from the same infants at 6 and 12 months of age to characterize brain activity during an auditory oddball task. We show that suprathreshold events organize as spatiotemporal clusters whose size and duration are power-law distributed, the hallmark of neuronal avalanches. Time series of local suprathreshold EEG events display significant long-range temporal correlations (LRTCs). No differences were found between 6 and 12 months, demonstrating stability of avalanche dynamics and LRTCs during the first year after birth. These findings demonstrate that the infant brain is characterized by distinct spatiotemporal dynamical aspects that are in line with expectations of a critical cortical state. We suggest that critical state dynamics, which theory and experiments have shown to be beneficial for numerous aspects of information processing, are maintained by the infant brain to process an increasingly complex environment during development.

Minimally-verbal children with autism show deficits in theta and gamma oscillations during processing of semantically-related visual information

To acquire language, children must build phonemic representations of their native language, learn to associate auditory words to visual objects and assemble a lexicon. It is not clear however, whether the limited linguistic ability seen in minimally-verbal (MV) children with Autism Spectrum Disorder (ASD) relates to deficits in cortical representation of an object and/or in linking an object to its semantic information. This EEG-based study investigated neural mechanisms underlying visual processing of common objects in MV-ASD and control children. Ten MV-ASD children, 4- to 7- years-old and 15 age/gender-matched controls, were presented with a picture-word matching paradigm. Time-frequency analyses were conducted at the sources generating the event-related responses at both early and late visual processing. Permutation testing identified spectral power and phase coherence clusters that significantly differed between the groups. As compared to controls, MV-ASD children exhibited smaller amplitudes and longer source latencies; decreased gamma and theta power with less theta phase coherence in occipital regions, and reduced frontal gamma power. Our results confirm that visual processing is altered in MV-ASD children and suggest that some of the linguistic differences observed in these children arise from impaired object/label cortical representations and reduced allocation of attention, which would impact lexical acquisition.

Reduced left-lateralized pattern of event-related EEG oscillations in infants at familial risk for language and learning impairment

The ability to rapidly discriminate successive auditory stimuli within tens-of-milliseconds is crucial for speech and language development, particularly in the first year of life. This skill, called Rapid Auditory Processing (RAP), is altered in infants at familial risk for language and learning impairment (LLI) and is a robust predictor of later language outcomes. In the present study, we investigate the neural substrates of RAP, i.e., the underlying neural oscillatory patterns, in a group of Italian 6-month-old infants at risk for LLI (FH+, n = 24), compared to control infants with no known family history of LLI (FH−, n = 32). Brain responses to rapid changes in fundamental frequency and duration were recorded via high-density electroencephalogram during a non-speech double oddball paradigm. Sources of event-related potential generators were localized to right and left auditory regions in both FH+ and FH− groups. Time-frequency analyses showed variations in both theta (Ɵ) and gamma (ɣ) ranges across groups. Our results showed that overall RAP stimuli elicited a more left-lateralized pattern of oscillations in FH− infants, whereas FH+ infants demonstrated a more right-lateralized pattern, in both the theta and gamma frequency bands. Interestingly, FH+ infants showed reduced early left gamma power (starting at 50 ms after stimulus onset) during deviant discrimination. Perturbed oscillatory dynamics may well constitute a candidate neural mechanism to explain group differences in RAP. Additional group differences in source location suggest that anatomical variations may underlie differences in oscillatory activity. Regarding the predictive value of early oscillatory measures, we found that the amplitude of the source response and the magnitude of oscillatory power and phase synchrony were predictive of expressive vocabulary at 20 months of age. These results further our understanding of the interplay among neural mechanisms that support typical and atypical rapid auditory processing in infancy.

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Neural sources of RAP in infancy were identified at right/left auditory regions.

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FH− infants demonstrated a mature left-lateralized pattern of neural oscillations.

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FH+ infants demonstrated a more right-lateralized pattern of neural oscillations.

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FH+ infants showed reduced left gamma power during rapid auditory discrimination.

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Source and oscillatory measures are both associated with later language skills.

A Modulatory Effect of Brief Passive Exposure to Non-linguistic Sounds on Intrinsic Functional Connectivity: Relevance to Cognitive Performance

A growing literature on resting-state fMRI (R-fMRI) has explored the impact of preceding sensory experience on intrinsic functional connectivity (iFC). However, it remains largely unknown how passive exposure to irrelevant auditory stimuli, which is a constant in everyday life, reconfigures iFC. Here, we directly compared pre- and post-exposure R-fMRI scans to examine: 1) modulatory effects of brief passive exposure to repeating non-linguistic sounds on subsequent iFC, and 2) associations between iFC modulations and cognitive abilities. We used an exploratory regional homogeneity (ReHo) approach that indexes local iFC, and performed a linear mixed-effects modeling analysis. A modulatory effect (increase) in ReHo was observed in the right superior parietal lobule (R.SPL) within the parietal attention network. Post hoc seed-based correlation analyses provided further evidence for increased parietal iFC (e.g., R.SPL with the right inferior parietal lobule). Notably, less iFC modulation was associated with better cognitive performance (e.g., word reading). These results suggest that: 1) the parietal attention network dynamically reconfigures its iFC in response to passive (thus irrelevant) non-linguistic sounds, but also 2) minimization of iFC modulation in the same network characterizes better cognitive performance. Our findings may open up new avenues for investigating cognitive disorders that involve impaired sensory processing.

From Sensory Perception to Lexical-Semantic Processing: An ERP Study in Non-Verbal Children with Autism

This study examines electrocortical activity associated with visual and auditory sensory perception and lexical-semantic processing in nonverbal (NV) or minimally-verbal (MV) children with Autism Spectrum Disorder (ASD). Currently, there is no agreement on whether these children comprehend incoming linguistic information and whether their perception is comparable to that of typically developing children. Event-related potentials (ERPs) of 10 NV/MV children with ASD and 10 neurotypical children were recorded during a picture-word matching paradigm. Atypical ERP responses were evident at all levels of processing in children with ASD. Basic perceptual processing was delayed in both visual and auditory domains but overall was similar in amplitude to typically-developing children. However, significant differences between groups were found at the lexical-semantic level, suggesting more atypical higher-order processes. The results suggest that although basic perception is relatively preserved in NV/MV children with ASD, higher levels of processing, including lexical- semantic functions, are impaired. The use of passive ERP paradigms that do not require active participant response shows significant potential for assessment of non-compliant populations such as NV/MV children with ASD.

New Perspectives on Spontaneous Brain Activity: Dynamic Networks and Energy Matter

Spontaneous brain activity has received increasing attention as demonstrated by the exponential rise in the number of published article on this topic over the last 30 years. Such “intrinsic” brain activity, generated in the absence of an explicit task, is frequently associated with resting-state or default-mode networks (DMN)s. The focus on characterizing spontaneous brain activity promises to shed new light on questions concerning the structural and functional architecture of the brain and how they are related to “mind”. However, many critical questions have yet to be addressed. In this review, we focus on a scarcely explored area, specifically the energetic requirements and constraints of spontaneous activity, taking into account both thermodynamical and informational perspectives. We argue that the “classical” definitions of spontaneous activity do not take into account an important feature, that is, the critical thermodynamic energetic differences between spontaneous and evoked brain activity. Spontaneous brain activity is associated with slower oscillations compared with evoked, task-related activity, hence it exhibits lower levels of enthalpy and “free-energy” (i.e., the energy that can be converted to do work), thus supporting noteworthy thermodynamic energetic differences between spontaneous and evoked brain activity. Increased spike frequency during evoked activity has a significant metabolic cost, consequently, brain functions traditionally associated with spontaneous activity, such as mind wandering, require less energy that other nervous activities. We also review recent empirical observations in neuroscience, in order to capture how spontaneous brain dynamics and mental function can be embedded in a non-linear dynamical framework, which considers nervous activity in terms of phase spaces, particle trajectories, random walks, attractors and/or paths at the edge of the chaos. This takes us from the thermodynamic free-energy, to the realm of “variational free-energy”, a theoretical construct pertaining to probability and information theory which allows explanation of unexplored features of spontaneous brain activity.

ICA-derived cortical responses indexing rapid multi-feature auditory processing in six-month-old infants

The abilities of infants to perceive basic acoustic differences, essential for language development, can be studied using auditory event-related potentials (ERPs). However, scalp-channel averaged ERPs sum volume-conducted contributions from many cortical areas, reducing the functional specificity and interpretability of channel-based ERP measures. This study represents the first attempt to investigate rapid auditory processing in infancy using independent component analysis (ICA), allowing exploration of source-resolved ERP dynamics and identification of ERP cortical generators. Here, we recorded 60-channel EEG data in 34 typically developing 6-month-old infants during a passive acoustic oddball paradigm presenting 'standard' tones interspersed with frequency- or duration-deviant tones. ICA decomposition was applied to single-subject EEG data. The best-fitting equivalent dipole or bilaterally symmetric dipole pair was then estimated for each resulting independent component (IC) process using a four-layer infant head model. Similar brain-source ICs were clustered across subjects. Results showed ERP contributions from auditory cortex and multiple extra-auditory cortical areas (often, bilaterally paired). Different cortical source combinations contributed to the frequency- and duration-deviant ERP peak sequences. For ICs in an ERP-dominant source cluster located in or near the mid-cingulate cortex, source-resolved frequency-deviant response N2 latency and P3 amplitude at 6 months-of-age predicted vocabulary size at 20 months-of-age. The same measures for scalp channel F6 (though not for other frontal channels) showed similar but weaker correlations. These results demonstrate the significant potential of ICA analyses to facilitate a deeper understanding of the neural substrates of infant sensory processing.

Effects of Presentation Rate and Attention on Auditory Discrimination: A Comparison of Long-Latency Auditory Evoked Potentials in School-Aged Children and Adults

Decoding human speech requires both perception and integration of brief, successive auditory stimuli that enter the central nervous system as well as the allocation of attention to language-relevant signals. This study assesses the role of attention on processing rapid transient stimuli in adults and children. Cortical responses (EEG/ERPs), specifically mismatch negativity (MMN) responses, to paired tones (standard 100-100 Hz; deviant 100-300 Hz) separated by a 300, 70 or 10 ms silent gap (ISI) were recorded under Ignore and Attend conditions in 21 adults and 23 children (6-11 years old). In adults, an attention-related enhancement was found for all rate conditions and laterality effects (L>R) were observed. In children, 2 auditory discrimination-related peaks were identified from the difference wave (deviant-standard): an early peak (eMMN) at about 100-300 ms indexing sensory processing, and a later peak (LDN), at about 400-600 ms, thought to reflect reorientation to the deviant stimuli or "second-look" processing. Results revealed differing patterns of activation and attention modulation for the eMMN in children as compared to the MMN in adults: The eMMN had a more frontal topography as compared to adults and attention played a significantly greater role in childrens' rate processing. The pattern of findings for the LDN was consistent with hypothesized mechanisms related to further processing of complex stimuli. The differences between eMMN and LDN observed here support the premise that separate cognitive processes and mechanisms underlie these ERP peaks. These findings are the first to show that the eMMN and LDN differ under different temporal and attentional conditions, and that a more complete understanding of children's responses to rapid successive auditory stimulation requires an examination of both peaks.

Infant Auditory Processing and Event-related Brain Oscillations

Rapid auditory processing and acoustic change detection abilities play a critical role in allowing human infants to efficiently process the fine spectral and temporal changes that are characteristic of human language. These abilities lay the foundation for effective language acquisition; allowing infants to hone in on the sounds of their native language. Invasive procedures in animals and scalp-recorded potentials from human adults suggest that simultaneous, rhythmic activity (oscillations) between and within brain regions are fundamental to sensory development; determining the resolution with which incoming stimuli are parsed. At this time, little is known about oscillatory dynamics in human infant development. However, animal neurophysiology and adult EEG data provide the basis for a strong hypothesis that rapid auditory processing in infants is mediated by oscillatory synchrony in discrete frequency bands. In order to investigate this, 128-channel, high-density EEG responses of 4-month old infants to frequency change in tone pairs, presented in two rate conditions (Rapid: 70 msec ISI and Control: 300 msec ISI) were examined. To determine the frequency band and magnitude of activity, auditory evoked response averages were first co-registered with age-appropriate brain templates. Next, the principal components of the response were identified and localized using a two-dipole model of brain activity. Single-trial analysis of oscillatory power showed a robust index of frequency change processing in bursts of Theta band (3 - 8 Hz) activity in both right and left auditory cortices, with left activation more prominent in the Rapid condition. These methods have produced data that are not only some of the first reported evoked oscillations analyses in infants, but are also, importantly, the product of a well-established method of recording and analyzing clean, meticulously collected, infant EEG and ERPs. In this article, we describe our method for infant EEG net application, recording, dynamic brain response analysis, and representative results.

An electrophysiological investigation of discourse coherence in healthy adults

This study used event-related potentials (ERPs) to investigate discourse-coherence processing. Because there are scant data on ERP indices of discourse coherence in typical adults, it is important to study a non-clinical population before examining clinical populations. Twelve adults listened to a story with sentences in a coherent versus incoherent order. Sequences of nonsense syllables served as a control. ERPs in the 200-400 ms time window, reflecting phonological and lexical processing, and in the 600-900 ms time window, reflecting later discourse processing for integration, were investigated. Results revealed a right anterior and posterior positivity that was greater for coherent than for incoherent discourse during the 600-900 ms time window. These findings point to an index of discourse coherence and further suggest that ERPs can be used as a clinical tool to study discourse-processing disorders in populations with brain damage, such as aphasia and traumatic brain injury.

Tracking the attentional blink profile: a cross-sectional study from childhood to adolescence

This cross-sectional study is the first to examine the developmental trajectory of temporal attention control from childhood to adolescence. We used a rapid serial visual presentation paradigm, calling for the identification of two targets (T1 and T2) embedded in a distractor stream. In adults, manipulating the lag time within the target doublet typically leads to pronounced impairment in report for T2, when it follows T1 after approximately 200 ms, with one intervening distractor (lag 2); this is referred to as the attentional blink (AB). Participants, however, tend to identify T2 more often when the targets have occurred in a row ("lag-1 sparing"), or are separated by larger lag times, resulting in a hook-shaped accuracy profile. Here, we investigated the extent to which this AB profile undergoes systematic developmental changes in 204 students aged between 6 and 16 years (grades 1-10). T1-T2 lags varied from zero up to seven intervening distractors. Behavioral accuracy in younger children (grades 1-2) was found to follow a linear path, having its minimum at the earliest lag. Lag-1 sparing, accompanied by a relative accuracy loss in the AB interval, first appeared in grade 3, and became more robust in grade 4. From grades 5-6, the hook-shaped profile remained stable, with steady increases in overall performance up through the highest grades. This suggests that younger children's performance is limited by processing speed, while from preadolescence onwards, children are increasingly able to identify rapid target sequences at the cost of an interference sensitive, higher control system.

Distraction by emotion in early adolescence: affective facilitation and interference during the attentional blink

This study examined the extent to which early adolescents (aged 10–13 years) differ from adults in their sensitivity to attention capture by affective stimuli during rapid processing. A rapid serial visual presentation paradigm (RSVP) was implemented as a dual task, requiring the report of two green target stimuli embedded in a stream of distractors. Known as the “attentional blink” (AB), task performance is typically impaired when the first and second targets (T1 and T2, respectively) are separated by at least one distractor and about 200 ms of time. Here we used written verbs of pleasant, neutral, and unpleasant content as T1 items, while affectively neutral exemplars served as T2 and distractor events. The temporal distance between T1 and T2 was manipulated to contain either one distractor (intertarget interval 232 ms) or five distractors (intertarget interval 696 ms). Students reported pleasant T1 words more accurately, compared to neutral and unpleasant words, indicating facilitation of appetitive content on performance during RSVP. Emotional relevance of T1 was at the expense of T2 accuracy: at an intertarget interval of 232 ms (i.e., during the AB period), identification of (neutral) T2 words was impaired when preceded by pleasant and unpleasant T1s. No interference across targets was observed, however, beyond the blink period, in which T1 and T2 were separated by 696 ms. Thus, emotionally relevant events capture and hold attentional resources, at the cost of attentive processing in subsequent episodes. Contrary to our findings in adults, these capture effects were most obvious when the available capacity was limited, i.e., during the critical interval of the AB. The findings are discussed in light of the use of alternative cognitive strategies as development proceeds beyond early adolescence into adulthood.

Regional infant brain development: an MRI-based morphometric analysis in 3 to 13 month olds

Elucidation of infant brain development is a critically important goal given the enduring impact of these early processes on various domains including later cognition and language. Although infants' whole-brain growth rates have long been available, regional growth rates have not been reported systematically. Accordingly, relatively less is known about the dynamics and organization of typically developing infant brains. Here we report global and regional volumetric growth of cerebrum, cerebellum, and brainstem with gender dimorphism, in 33 cross-sectional scans, over 3 to 13 months, using T1-weighted 3-dimensional spoiled gradient echo images and detailed semi-automated brain segmentation. Except for the midbrain and lateral ventricles, all absolute volumes of brain regions showed significant growth, with 6 different patterns of volumetric change. When normalized to the whole brain, the regional increase was characterized by 5 differential patterns. The putamen, cerebellar hemispheres, and total cerebellum were the only regions that showed positive growth in the normalized brain. Our results show region-specific patterns of volumetric change and contribute to the systematic understanding of infant brain development. This study greatly expands our knowledge of normal development and in future may provide a basis for identifying early deviation above and beyond normative variation that might signal higher risk for neurological disorders.

Early gamma oscillations during rapid auditory processing in children with a language-learning impairment: changes in neural mass activity after training

Children with language-learning impairment (LLI) have consistently shown difficulty with tasks requiring precise, rapid auditory processing. Remediation based on neural plasticity assumes that the temporal precision of neural coding can be improved by intensive training protocols. Here, we examined the extent to which early oscillatory responses in auditory cortex change after audio-visual training, using combined source modeling and time-frequency analysis of the human electroencephalogram (EEG). Twenty-one elementary school students diagnosed with LLI underwent the intervention for an average of 32 days. Pre- and post-training assessments included standardized language/literacy tests and EEG recordings in response to fast-rate tone doublets. Twelve children with typical language development were also tested twice, with no intervention given. Behaviorally, improvements on measures of language were observed in the LLI group following completion of training. During the first EEG assessment, we found reduced amplitude and phase-locking of early (45-75 ms) oscillations in the gamma-band range (29-52 Hz), specifically in the LLI group, for the second stimulus of the tone doublet. Amplitude reduction for the second tone was no longer evident for the LLI children post-intervention, although these children still exhibited attenuated phase-locking. Our findings suggest that specific aspects of inefficient sensory cortical processing in LLI are ameliorated after training.

Pediatric neuroimaging in early childhood and infancy: challenges and practical guidelines

Structural and functional magnetic resonance imaging (fMRI) has been used increasingly to investigate typical and atypical brain development. However, in contrast to studies in school-aged children and adults, MRI research in young pediatric age groups is less common. Practical and technical challenges occur when imaging infants and children, which presents clinicians and research teams with a unique set of problems. These include procedural difficulties (e.g., participant anxiety or movement restrictions), technical obstacles (e.g., availability of child-appropriate equipment or pediatric MR head coils), and the challenge of choosing the most appropriate analysis methods for pediatric imaging data. Here, we summarize and review pediatric imaging and analysis tools and present neuroimaging protocols for young nonsedated children and infants, including guidelines and procedures that have been successfully implemented in research protocols across several research sites.

Time course of ERP generators to syllables in infants: a source localization study using age-appropriate brain templates

Event-related potentials (ERPs) have become an important tool in the quest to understand how infants process perceptual information. Identification of the activation loci of the ERP generators is a technique that provides an opportunity to explore the neural substrates that underlie auditory processing. Nevertheless, as infant brain templates from healthy, non-clinical samples have not been available, the majority of source localization studies in infants have used non-realistic head models, or brain templates derived from older children or adults. Given the dramatic structural changes seen across infancy, all of which profoundly affect the electrical fields measured with EEG, it is important to use individual MRIs or age-appropriate brain templates and parameters to explore the localization and time course of auditory ERP sources. In this study 6-month-old infants were presented with a passive oddball paradigm using consonant-vowel (CV) syllables that differed in voice onset time. Dense-array EEG/ERPs were collected while the infants were awake and alert. In addition, MRIs were acquired during natural non-sedated sleep for a subset of the sample. Discrete dipole and distributed source models were mapped onto individual and averaged infant MRIs. The CV syllables elicited a positive deflection at about 200 ms followed by a negative deflection that peaked around 400 ms. The source models generated placed the dipoles at temporal areas close to auditory cortex for both positive and negative responses. Notably, an additional dipole for the positive peak was localized at the frontal area, at the anterior cingulate cortex (ACC) level. ACC activation has been reported in adults, but has not, to date, been reported in infants during processing of speech-related signals. The frontal ACC activation was earlier but smaller in amplitude than the left and right auditory temporal activations. These results demonstrate that in infancy the ERP generators to CV syllables are localized in cortical areas similar to that reported in adults, but exhibit a notably different temporal course. Specifically, ACC activation in infants significantly precedes auditory temporal activation, whereas in adults ACC activation follows that of temporal cortex. We suggest that these timing differences could be related to current maturational changes, to the ongoing construction of language-specific phonetic maps, and/or to more sensitive attentional switching as a response to speech signals in infancy.

Reduced Sensory Oscillatory Activity during Rapid Auditory Processing as a Correlate of Language-Learning Impairment

Successful language acquisition has been hypothesized to involve the ability to integrate rapidly presented, brief acoustic cues in sensory cortex. A body of work has suggested that this ability is compromised in language-learning impairment (LLI). The present research aimed to examine sensory integration during rapid auditory processing by means of electrophysiological measures of oscillatory brain activity using data from a larger longitudinal study. Twenty-nine children with LLI and control participants with typical language development (n=18) listened to tone doublets presented at a temporal interval that is essential for accurate speech processing (70-ms interstimulus interval). The children performed a deviant (pitch change of second tone) detection task, or listened passively. The electroencephalogram was recorded from 64 electrodes. Data were source-projected to the auditory cortices and submitted to wavelet analysis, resulting in time-frequency representations of electrocortical activity. Results show significantly reduced amplitude and phase-locking of early (45-75 ms) oscillations in the gamma-band range (29-52 Hz), specifically in the LLI group, for the second stimulus of the tone doublet. This suggests altered temporal organization of sensory oscillatory activity in LLI when processing rapid sequences.

Maturation of auditory evoked potentials from 6 to 48 months: prediction to 3 and 4 year language and cognitive abilities

OBJECTIVE

To investigate the maturation of long-latency auditory evoked potentials (LLAEP) from 6 to 48 months in infants with a family history of language impairment (FH+) and control infants (FH-).

METHODS

LLAEPs of seventeen FH+ infants were compared to 28 FH- infants at 6, 9, 12, 16, 24, 36 and 48 months. Participants received a passive oddball paradigm using fast- and slow-rate non-linguistic auditory stimuli and at 36 and 48 months completed a battery of standardized language and cognitive tests.

RESULTS

Overall, the morphology of LLAEP responses differed for fast- versus slow-rate stimuli. Significant age-related changes in latency and amplitude were observed. Group differences, favoring FH- infants, in the rate of maturation of LLAEPs were found. Responses to fast-rate stimuli predicted language abilities at 36 and 48 months of age.

CONCLUSIONS

The development of LLAEP in FH+ children is modulated by differences in the rate of maturation as well as variations in temporal processing abilities.

SIGNIFICANCE

These findings provide evidence for the role of non-linguistic auditory processes in early language development and illustrate the utility of using a perceptual-processing skills model to further our understanding of the precursors of language development and impairment.

Source localization of event-related potentials to pitch change mapped onto age-appropriate MRIs at 6 months of age

Auditory event-related potentials (ERPs) have been used to understand how the brain processes auditory input, and to track developmental change in sensory systems. Localizing ERP generators can provide invaluable insights into how and where auditory information is processed. However, age-appropriate infant brain templates have not been available to aid such developmental mapping. In this study, auditory change detection responses of brain ERPs were examined in 6-month-old infants using discrete and distributed source localization methods mapped onto age-appropriate magnetic resonance images. Infants received a passive oddball paradigm using fast-rate non-linguistic auditory stimuli (tone doublets) with the deviant incorporating a pitch change for the second tone. Data was processed using two different high-pass filters. When a 0.5 Hz filter was used, the response to the pitch change was a large frontocentral positive component. When a 3 Hz filter was applied, two temporally consecutive components associated with change detection were seen: one with negative voltage, and another with positive voltage over frontocentral areas. Both components were localized close to the auditory cortex with an additional source near to the anterior cingulate cortex. The sources for the negative response had a more tangential orientation relative to the supratemporal plane compared to the positive response, which showed a more lateral, oblique orientation. The results described here suggest that at 6 months of age infants generate similar response patterns and use analogous cortical areas to that of adults to detect changes in the auditory environment. Moreover, the source locations and orientations, together with waveform topography and morphology provide evidence in infants for feature-specific change detection followed by involuntary switching of attention.

Early cognitive and language skills are linked to resting frontal gamma power across the first 3 years

High-frequency cortical activity in humans and animals has been linked to a wide variety of higher cognitive processes. This research suggests that specific changes in neuronal synchrony occur during cognitive processing, distinguished by emergence of fast oscillations in the gamma frequency range. To determine whether the development of high-frequency brain oscillations can be related to the development of cognitive abilities, we studied the power spectra of resting EEG in children 16, 24 and 36 months of age. Individual differences in the distribution of frontal gamma power during rest were highly correlated with concurrent language and cognitive skills at all ages. Gamma power was also associated with attention measures; children who were observed as having better inhibitory control and more mature attention shifting abilities had higher gamma power density functions. We included a group of children with a family history of language impairment (FH+) and thus at higher risk for language disorders. FH+ children, as a group, showed consistently lower gamma over frontal regions than the well-matched FH- controls with no such family history (FH-). We suggest that the emergence of high-frequency neural synchrony may be critical for cognitive and linguistic development, and that children at risk for language impairments may lag in this process.

Functional connectivity of the sensorimotor area in naturally sleeping infants

Patterns of cortical functional connectivity in normal infants were examined during natural sleep by observing the time course of very low frequency oscillations. Such oscillations represent fluctuations in blood oxygenation level and cortical blood flow thus allowing computation of neurophysiologic connectivity. Structural and resting-state information were acquired for 11 infants, with a mean age of 12.8 months, using a GE 1.5 T MR scanner. Resting-state data were processed and significant functional connectivity within the sensorimotor area was identified using independent component analysis. Unilateral functional connectivity in the developing sensory-motor cortices was observed. Power spectral analysis showed that slow frequency oscillations dominated the hemodynamic signal at this age, with, on average, a peak frequency for all subjects of 0.02 Hz. Our data suggest that there is more intrahemispheric than interhemispheric connectivity in the sensorimotor area of naturally sleeping infants. This non-invasive imaging technique, developed to allow reliable scanning of normal infants without sedation, enabled computation of neurophysiologic connectivity for the first time in naturally sleeping infants. Such techniques permit elucidation of the role of slow cortical oscillations during early brain development and may reveal critical information regarding the normative development and lateralization of brain networks across time.

Understanding language and cognitive deficits in very low birth weight children

Very-low-birth-weight infants are at much higher risk for cognitive and language delays but the nature of such deficits is not clearly understood. Given increasing rates of prematurity and infants born very-low-birth-weight, examination of mechanisms that underlie poorer developmental outcome is essential. We investigated language and cognitive abilities in very-low and normal birth-weight infants to determine whether performance differences were due to poorer global cognitive performance or to deficits in specific processing abilities. Thirty-two very-low and 32 normal birth-weight infants received visual and auditory-visual habituation recognition-memory tasks, and standardized language and cognitive assessments. Very-low-birth-weight infants performed more poorly on visual and auditory-visual habituation tasks and scored lower than controls on cognitive and language measures. These findings suggest that differences in language abilities in very-low-birth-weight children may be part of a global deficit that impacts many areas of cognitive functioning rather than a specific impairment in rapid auditory processing.

Infant information processing and family history of specific language impairment: converging evidence for RAP deficits from two paradigms

An infant's ability to process auditory signals presented in rapid succession (i.e. rapid auditory processing abilities [RAP]) has been shown to predict differences in language outcomes in toddlers and preschool children. Early deficits in RAP abilities may serve as a behavioral marker for language-based learning disabilities. The purpose of this study is to determine if performance on infant information processing measures designed to tap RAP and global processing skills differ as a function of family history of specific language impairment (SLI) and/or the particular demand characteristics of the paradigm used. Seventeen 6- to 9-month-old infants from families with a history of specific language impairment (FH+) and 29 control infants (FH-) participated in this study. Infants' performance on two different RAP paradigms (head-turn procedure [HT] and auditory-visual habituation/recognition memory [AVH/RM]) and on a global processing task (visual habituation/recognition memory [VH/RM]) was assessed at 6 and 9 months. Toddler language and cognitive skills were evaluated at 12 and 16 months. A number of significant group differences were seen: FH+ infants showed significantly poorer discrimination of fast rate stimuli on both RAP tasks, took longer to habituate on both habituation/recognition memory measures, and had lower novelty preference scores on the visual habituation/recognition memory task. Infants' performance on the two RAP measures provided independent but converging contributions to outcome. Thus, different mechanisms appear to underlie performance on operantly conditioned tasks as compared to habituation/recognition memory paradigms. Further, infant RAP processing abilities predicted to 12- and 16-month language scores above and beyond family history of SLI. The results of this study provide additional support for the validity of infant RAP abilities as a behavioral marker for later language outcome. Finally, this is the first study to use a battery of infant tasks to demonstrate multi-modal processing deficits in infants at risk for SLI.

Links between abnormal brain structure and cognition in holoprosencephaly

Converging information on medical issues, motor ability, and cognitive outcomes is essential when addressing long-term clinical management in children with holoprosencephaly. This study considered whether adding more informative structural indices to classic holoprosencephaly categories would increase prediction of cognitive outcomes. Forty-two children with holoprosencephaly were examined to determine the association of deep gray nuclei abnormalities with cognitive abilities and the effect of motor skill deficits on cognitive performance. Additionally, a cognitive profile was described using the Carter Neurocognitive Assessment, an experimental diagnostic instrument designed specifically for young children with severe neurodevelopmental dysfunction. Findings indicated that nonseparation of the deep gray nuclei was significantly associated with the cognitive construct of vocal communication, but not with the cognitive constructs of social awareness, visual attention, or auditory comprehension. Importantly, motor skill deficits did not significantly affect performance on the Carter Neurocognitive Assessment. This study is the first investigation to provide a descriptive overview of specific cognitive skills in this group of children. The results also strongly suggest that this feature of the brain's structure does not predict all aspects of neurodevelopmental function. These findings contribute a critical component to the growing body of knowledge regarding the medical and clinical outcomes of children with holoprosencephaly.

Development of structure and function in the infant brain: implications for cognition, language and social behaviour

Recent advances in cognitive neuroscience have allowed us to begin investigating the development of both structure and function in the infant brain. However, despite the rapid evolution of technology, surprisingly few studies have examined the intersection between brain and behaviour over the first years of life. Even fewer have done so in the context of a particular research question. This paper aims to provide an overview of four domains that have been studied using techniques amenable to elucidating the brain/behaviour interface: language, face processing, object permanence, and joint attention, with particular emphasis on studies focusing on early development. The importance of the unique role of development and the interplay between structure and function is stressed throughout. It is hoped that this review will serve as a catalyst for further thinking about the substantial gaps in our understanding of the relationship between brain and behaviour across development. Further, our aim is to provide ideas about candidate brain areas that are likely to be implicated in particular behaviours or cognitive domains.

Auditory event-related responses in children with semi-lobar holoprosencephaly

The purpose of this study was to evaluate auditory sensory and discrimination responses in children with semi-lobar holoprosencephaly (HPE). Event-related potential (ERP) signals were recorded to tone pair stimuli at 62 electrode sites from the scalp using an oddball paradigm (a two-block design, inter-stimulus interval=70 or 300 ms; frequency of tone pair=100 vs. 100 Hz for the frequent and 100 vs. 300 Hz for the infrequent). Latencies and amplitudes of P150, N250, and mismatch negativity (MMN)-like components were compared between children with HPE and controls. Our results revealed less organized ERP waveforms to both stimuli in children with HPE, with diminished P150 and N250 components across brain area. Robust and delayed MMN-like responses were elicited from the children with HPE, with decreased MMN amplitudes in the central, parietal, occipital, and posterior temporal areas. Our results suggest that while brain sensory responses to auditory tones may be impaired in children with semi-lobar HPE, subcomponents of auditory discrimination processes remain functional.

Brain responses to tonal changes in the first two years of life

Maturation of auditory perceptual and discrimination process within the first two years of life is investigated in healthy infants by examining event-related potentials (ERPs). High-density EEG signals were recorded from the scalp monthly between 3 and 24 months of age. Two types of stimuli (100 vs. 100 Hz for standard stimuli; 100 vs. 300 Hz for deviant stimuli; occurrence rate: 85:15%) were presented using an oddball paradigm. Latencies and amplitudes were compared across development. The results showed that latencies of P150, N250, P350, and N450 components gradually decreased with increasing age. Amplitudes of the N250 and P350 components gradually increased and reached the maximum at 9 months, and then gradually decreased with the increase of age. Mismatch negativity was not obvious at 3 months of age, but was seen at 4-5 months and became robust after 6 months. Robust late positivity was recorded at all ages. These mismatch responses were noticeable in the frontal, central, and parietal areas, and the maximal MMN amplitude distribution gradually moved from the parietal area to the frontal area across the age range. Two important periods--one around 6 months and the other around 9 months are suggested in the maturation of auditory central system. Dynamical changes in the underlying source strengths and orientations may be principal contributors to ERP morphological changes in infants within the first 24 months.

The infant as a prelinguistic model for language learning impairments: predicting from event-related potentials to behavior

Associations between efficient processing of brief, rapidly presented, successive stimuli and language learning impairments (LLI) in older children and adults have been well documented. In this paper we examine the role that impaired rapid auditory processing (RAP) might play during early language acquisition. Using behavioral measures we have demonstrated that RAP abilities in infancy are critically linked to later language abilities for both non-speech and speech stimuli. Variance in infant RAP thresholds reliably predict language outcome at 3 years-of-age for infants at risk for LLI and control infants. We present data here describing patterns of electrocortical (EEG/ERP) activation at 6 month-of-age to the same non-verbal stimuli used in our behavioral studies. Well-defined differences were seen between infants from families with a history of LLI (FH+) and FH- controls in the amplitude of the mismatch response (MMR) as well as the latency of the N250 component in the 70 ms ISI condition only. Smaller mismatch responses and delayed onsets of the N250 component were seen in the FH+ group. The latency differences in the N250 component, but not the MMR amplitude variation, were significantly related to 24-month language outcome. Such converging tasks provide the opportunity to examine early precursors of LLI and allow the opportunity for earlier identification and intervention.

The Carter Neurocognitive Assessment for children with severely compromised expressive language and motor skills

In this paper, different means of assessing cognitive development in children with severe impairments in both their expressive language and their motor skills are reviewed. A range of techniques are considered, including traditional cognitive tests and behavioral and physiological measures, but these techniques are generally impractical and minimally informative when it comes to assessing children with both motor and speech impairments. Electrophysiological measures show some promise for the future, but are currently inadequate for wide-ranging cognitive assessment. Development of the Carter Neurocognitive Assessment (CNA) is described. The CNA is appropriate for use in clinical and research settings and was designed to minimalize the impact of severely impaired motor skills and expressive language on performance. The CNA is intended to itemize and quantify a range of skills reflecting a cognitive level up to approximately 18 to 24 months in four areas: Social Awareness, Visual Attention, Auditory Comprehension and Vocal Communication. The use of the CNA to assess the performance and developmental growth of eight children with Holoprosencephaly (HPE), a midline developmental brain malformation, is described. The CNA is a useful tool for the assessment of children with severely compromised motor and verbal skills and has provided a more positive view of the cognitive potential of children with severe handicaps, such as the sample of children with HPE, than that presented in the past.

Timing errors in auditory event-related potentials

Electronic problems of electroencephalographic (EEG) system may occur in even the best-managed laboratories. Timing error may happen in the coupling of computers from various manufactures, resulting in the misalignment of event markers that signal the onset of stimuli. In one system, an impedance check desynchronized a computer and thus caused misalignment of events in EEG signals. Thus, the aim of this study was to develop a method to identify and correct such timing errors that contaminated 114 raw data of EEG/auditory event-related potentials (ERPs) recorded in one of our longitudinal studies. A two-step procedure was introduced in the correction of timing errors. First, the time delay was roughly estimated by identifying a P150 component in two ERP blocks. Second, a small phase-locked positive wave was identified for fine estimation. Reliability within and among evaluators was examined using ERP data with simulated timing errors. Concordant results were obtained in 104 (91.2%) of the 114 raw EEG/ERP data sets. Our results showed that the method presented here is reliable and can be used for correcting timing errors without introduction of experimenter bias.

Age and experience-related improvements in gap detection in the rat

The ability to accurately process brief, successive acoustic signals rapidly presented to the central nervous system is believed to underlie successful language development. The limits of temporal resolution of the auditory system, often assessed using gap detection tasks, has been widely studied in relation to developing and decoding speech. In the present study, a reflex modification paradigm was used to investigate potential shifts in gap detection thresholds in rats across development, with test sessions beginning on postnatal day (P) 15, P35 and P64. We found that thresholds decreased over the course of development. These thresholds were determined to lie between 10 and 20 ms for the P15 and P35 groups, and between 5 and 10 ms for the P64 group. Moreover, we observed improvements in gap detection thresholds in all age groups over 5 days of testing, including the youngest age group (P15). These later results suggest that experience-dependent plasticity mechanisms at the level of sensory processing are operational and observable both very early in development, and also in adult animals. The present findings also demonstrate maturational improvements in silent gap detection using a pre-pulse inhibition paradigm.

Developmental language learning impairments

Developmental language learning impairments (LLI) are one of the most prevalent of all developmental disabilities, can occur in children for a wide variety of reasons, and have been shown to co-occur frequently with other developmental social, emotional and behavioral disorders, as well as with academic achievement problems. Research pertaining to developmental LLI of unknown origin, with an emphasis on the continuum between oral and written language impairment, is the focus of this review. Given the complexity of language learning, research has focused on multiple levels of analysis, including linguistic, neuropsychological, genetic, neurobiological, and remediation studies. To date, the vast majority of data on LLI derive from studies focused on a single level of analysis. Although attempts have been made to integrate data across studies and multiple levels of analysis, this has proven to be problematic, given the heterogeneity of the subject populations used to study LLI, as well as the differences in ages, degree of impairment, and types of impairment included in each study. Given that LLI is a complex developmental disability, it is suggested that future research would benefit from taking a multiple levels of analysis approach with the same individuals, incorporating mathematical models designed to analyze dynamically changing complex systems, and studying individual differences in language learning, prospectively and longitudinally, throughout the most dynamic stages of the process.

Infant discrimination of rapid auditory cues predicts later language impairment

The etiology and mechanisms of specific language impairment (SLI) in children are unknown. Differences in basic auditory processing abilities have been suggested to underlie their language deficits. Studies suggest that the neuropathology, such as atypical patterns of cerebral lateralization and cortical cellular anomalies, implicated in such impairments likely occur early in life. Such anomalies may play a part in the rapid processing deficits seen in this disorder. However, prospective, longitudinal studies in infant populations that are critical to examining these hypotheses have not been done. In the study described, performance on brief, rapidly-presented, successive auditory processing and perceptual-cognitive tasks were assessed in two groups of infants: normal control infants with no family history of language disorders and infants from families with a positive family history for language impairment. Initial assessments were obtained when infants were 6-9 months of age (M=7.5 months) and the sample was then followed through age 36 months. At the first visit, infants' processing of rapid auditory cues as well as global processing speed and memory were assessed. Significant differences in mean thresholds were seen in infants born into families with a history of SLI as compared with controls. Examination of relations between infant processing abilities and emerging language through 24 months-of-age revealed that threshold for rapid auditory processing at 7.5 months was the single best predictor of language outcome. At age 3, rapid auditory processing threshold and being male, together predicted 39-41% of the variance in language outcome. Thus, early deficits in rapid auditory processing abilities both precede and predict subsequent language delays. These findings support an essential role for basic nonlinguistic, central auditory processes, particularly rapid spectrotemporal processing, in early language development. Further, these findings provide a temporal diagnostic window during which future language impairments may be addressed.

The importance of rapid auditory processing abilities to early language development: evidence from converging methodologies

The ability to process two or more rapidly presented, successive, auditory stimuli is believed to underlie successful language acquisition. Likewise, deficits in rapid auditory processing of both verbal and nonverbal stimuli are characteristic of individuals with developmental language disorders such as Specific Language Impairment. Auditory processing abilities are well developed in infancy, and thus such deficits should be detectable in infants. In the studies presented here, converging methodologies are used to examine such abilities in infants with and without a family history of language disorder. Behavioral measures, including assessments of infant information processing, and an EEG/event-related potential (ERP) paradigm are used concurrently. Results suggest that rapid auditory processing skills differ as a function of family history and are predictive of later language outcome. Further, these paradigms may prove to be sensitive tools for identifying children with poor processing skills in infancy and thus at a higher risk for developing a language disorder.

Look who's talking: a prospective study of familial transmission of language impairments

Language impairments have been hypothesized to have a genetic component. Previous studies of the familial aggregation of language impairments have relied on a retrospective approach based on parental/self-reported history of language development. This study examined familial aggregation prospectively, by investigating language acquisition and cognitive development in the younger siblings and offspring of individuals with well-defined language impairments. It was predicted that children with a positive family history for language impairments would be more likely to show delays in language acquisition than would age- and gender-matched controls. Similar delays were not expected in nonlinguistic domains, such as conceptual, gestural, or general cognitive development. Ten children with a positive family history and 10 age- and gender-matched controls were tested. Analyses of linguistic and cognitive assessments at 16 to 26 months confirmed the predictions. Children with a family history of language impairments had lower receptive and expressive language scores than controls, with 50% of them scoring at least 1.5 SD below the mean for their age. At the same time, performance on a number of tasks that did not rely on language abilities did not differ as a function of family history. These results indicate that children with a positive family history for language impairments are at risk for language delay; the results also support a familial component to language impairments.

Maternal attitudes and knowledge of child-rearing: associations with family and child outcomes

A prospective, longitudinal study of a low birthweight, preterm cohort examined the effects of maternal knowledge of child development and concepts of child rearing on the quality of home environment and on child cognitive and behavioral outcomes. Measures of maternal knowledge at 12 months were found to be significantly associated with the quality of the home environment, the number of child behavior problems, and to a small but significant extent child Stanford-Binet IQ at 36 months. Maternal characteristics were associated with both maternal knowledge and maternal behavior. Child characteristics, including birthweight, were not associated with maternal knowledge or concepts of development for most of the cohort. Subgroup analyses by race/ethnicity revealed a similar pattern of results. However, a measure of neonatal health status was shown to be significantly associated with cognitive outcome in the African-American subgroup at 24 and 36 months.

Language, learning, and behavioral disturbances in childhood: a longitudinal perspective

OBJECTIVE

Investigate longitudinally the course of development of preschool learning impaired (LI) children to better understand the interaction between neurodevelopmental delay, behavioral/emotional disorders, and language development and disorders.

METHOD

Relationships between developmental language disorders and emotional problems were investigated in 99 8-year-old specifically language impaired and control children originally assessed at age 4 years using the Achenbach Child Behavior Checklist and the Conners' Parents Questionnaire.

RESULTS

LI children received higher behavior problem scores and were more likely to score in the clinical range than were control children. Neither degree of early language impairment nor amount of language improvement predicted 8-year behavioral/emotional status. LI children with the largest drop in IQ between ages 4 and 8 received the highest behavior problem scores. No significant comorbid relationship was seen between LI and attention-deficit hyperactivity disorder.

CONCLUSIONS

The enhanced incidence of behavior problems reported heretofore may be related more to lower IQ than to linguistic deficit per se. Care must be taken to differentiate the symptoms of neurodevelopmental delay and emotional disturbance, however, preschool children with scores in the clinical range on such measures should be referred for additional evaluation.

Health care use among young children in day care. Results in a randomized trial of early intervention

Exposure of young children to group day-care settings increases the risk of illness and may result in higher use of medical care. These observations raise concerns that the use of such settings for early intervention programs for low-birth-weight infants may increase the already high burden of medical care costs incurred by these children and their families. To address the question of medical care use associated with center-based care, we examined the hospital-based and ambulatory care reported for participants of the Infant Health and Development Program. This project is a multisite randomized trial of an early intervention program for preterm low-birth-weight infants with an intervention including 2 years of center-based care. The Intervention group did not differ in hospital-based care and averaged only two more physicians' visits over the 3-year observation period than the comparison group. We conclude that early intervention programs involving high-quality group care are not accompanied by substantial increases in health care use.