Naseem Choudhury

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.

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.

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.

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.

Resting frontal gamma power at 16, 24 and 36 months predicts individual differences in language and cognition at 4 and 5 years

Gamma activity has been linked to a variety of different cognitive processes and exists in both transient and persistent forms. Across studies, different brain regions have been suggested to contribute to gamma activity. Multiple studies have shown that the function of gamma oscillations may be related to temporal binding of early sensory information to relevant top-down processes. Given this hypothesis, we expected gamma oscillations to subserve general brain mechanisms that contribute to the development of cognitive and linguistic systems. The present study aims to examine the predictive relations between resting-state cortical gamma power density at a critical point in language and cognitive acquisition (i.e. 16, 24 and 36 months), and cognitive and language output at ages 4 and 5 years. Our findings show that both 24- and 36-month gamma power are significantly correlated with later language scores, notably Non-Word Repetition. Further, 16-, 24- and 36-month gamma were all significantly correlated with 4-year PLS-3 and CELF-P sentence structure scores. Although associations reported here do not reflect a direct cause and effect of early resting gamma power on later language outcomes, capacity to generate higher power in the gamma range at crucial developmental periods may index better modulation of attention and allow easier access to working memory, thus providing an advantage for overall development, particularly in the linguistic domain. Moreover, measuring abilities at times when these abilities are still emergent may allow better prediction of later outcomes.

The relationship between sustained attention and cognitive performance in 17–24-month old toddlers

The purpose of this study was to investigate individual differences in sustained attention and task performance with toddlers. Participants were 61 17–24-month old toddlers. Indices of sustained attention (duration of attention and frequency of off-task glances) were assessed during two 4 min problem solving tasks, and then related to problem solving and the mental scale of the Bayley scales of infant development-II (BSID-II). As expected, toddlers who attended to tasks for longer periods of time were more successful at problem solving, and had higher scores on the BSID-II than toddlers who attended for shorter periods of time. In addition, older toddlers had longer attention spans, more frequent off-task glances, and were more successful at problem solving than younger toddlers. Interestingly, toddlers with more frequent off-task glances had longer attention spans, were more successful at problem solving, and had higher BSID-II scores than peers with fewer off-task glances. These findings suggest that although behavioural indices can be used to identify sustained attention, the relationship between behaviours thought to capture distractibility and attention is more complex than had been previously assumed. Results are discussed in the context of current theories of infant attention and cognitive performance. Copyright

Using Early Standardized Language Measures to Predict Later Language and Early Reading Outcomes in Children at High Risk for Language-Learning Impairments

The aim of the study was to examine the profiles of children with a family history (FH+) of language-learning impairments (LLI) and a control group of children with no reported family history of LLI (FH—) and identify which language constructs (receptive or expressive) and which ages (2 or 3 years) are related to expressive and receptive language abilities, phonological awareness, and reading abilities at ages 5 and 7 years. Participants included 99 children (40 FH+ and 59 FH—) who received a standardized neuropsychological battery at 2, 3, 5, and 7 years of age. As a group, the FH+ children had significantly lower scores on all language measures at 2 and 3 years, on selected language and phonological awareness measures at 5 years, and on phonological awareness and nonword reading at 7 years. Language comprehension at 3 years was the best predictor of later language and early reading for both groups. These results support past work suggesting that children with a positive family history of LLI are at greater risk for future language and reading problems through their preschool and early school-age years. Furthermore, language comprehension in the early years is a strong predictor of future language-learning status.

Plasticity in developing brain: active auditory exposure impacts prelinguistic acoustic mapping.

A major task across infancy is the creation and tuning of the acoustic maps that allow efficient native language processing. This process crucially depends on ongoing neural plasticity and keen sensitivity to environmental cues. Development of sensory mapping has been widely studied in animal models, demonstrating that cortical representations of the sensory environment are continuously modified by experience. One critical period for optimizing human language mapping is early in the first year; however, the neural processes involved and the influence of passive compared with active experience are as yet incompletely understood. Here we demonstrate that, while both active and passive acoustic experience from 4 to 7 months of age, using temporally modulated nonspeech stimuli, impacts acoustic mapping, active experience confers a significant advantage. Using event-related potentials (ERPs), we show that active experience increases perceptual vigilance/attention to environmental acoustic stimuli (e.g., larger and faster P2 peaks) when compared with passive experience or maturation alone. Faster latencies are also seen for the change discrimination peak (N2*) that has been shown to be a robust infant predictor of later language through age 4 years. Sharpening is evident for both trained and untrained stimuli over and above that seen for maturation alone. Effects were also seen on ERP morphology for the active experience group with development of more complex waveforms more often seen in typically developing 12- to 24-month-old children. The promise of selectively “fine-tuning” acoustic mapping as it emerges has far-reaching implications for the amelioration and/or prevention of developmental language disorders.

Differential patterns of development: the interaction of birth weight, temperament, and maternal behavior.

A short-term longitudinal study of 83 families compared patterns of development between full-term small for gestational age (SGA) and normal birth weight (NBW) infants. Data were collected on infant temperament and maternal interaction at 3 and 6 months, and infant developmental outcomes at 6 months in order to investigate relationships between infant and maternal behavior, and developmental outcomes as a function of birth weight. Findings revealed few differences between SGA and NBW groups. However, the relations between infant temperament and maternal behavior varied as a function of birth weight and home environment. Specifically, more positive home environments were associated with higher ratings of maternal behavior and lower levels of infant negative reactivity for SGA but not for NBW infants. In addition, higher negative reactivity was related to lower performance on both the mental and psychomotor scales of the Bayley Scales of Infant Development (BSID), with stronger associations reported for SGA infants than for NBW infants.

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.