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

Abstract

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.

Infant event-related potentials to speech are associated with prelinguistic development

“…Our results are in line with previous studies showing that large P1 responses ( Cantiani et al, 2016 ; Fellman et al, 2004 ; Leppänen et al, 2010 ) and large MMRs or other change-related responses to frequency changes ( Cantiani et al, 2019 , 2016 ; Choudhury and Benasich, 2011 ; Leppänen et al, 2010 ) are associated with good language-related skills. In infants and young children, the P1 has been proposed to reflect the detection of and orienting to a sound ( Čeponiene et al, 2008 ; Čeponiené et al, 2005 ; Ortiz-Mantilla et al, 2012 ).…”

“…Longitudinal associations between language skills and change-related neural measures other than the MMR/discriminatory N2 (e.g. neural oscillations and vocabulary, Cantiani et al, 2019 ; source-resolved P3 and vocabulary, Piazza et al, 2016 ; complex tone stimuli in both) have also been reported.…”

Is atypical rhythm a risk factor for developmental speech and language disorders?

“…We are aware of only one study investigating oscillatory brain activity in infants and its relationship to later speech/language development ( Cantiani et al, 2019 ). In this study, oscillatory activity was measured in 6-month-old infants with or without a family history of language or reading impairment in a rapid auditory processing paradigm.…”

EEG Effective Source Projections Are More Bilaterally Symmetric in Infants Than in Adults

“…EEG results of Musacchia et al (2013) suggested an overall greater involvement of the right hemisphere in processing of tones in 4-month-old infants, but a left-lateralized response to rapid pitch changes. This latter result has been recently confirmed in 6-month-old typically developing infants, whereas infants at high risk for language impairment demonstrated a more right-lateralized pattern (Cantiani et al, 2019). Homae (2014), in his review of literature on the development of interhemispheric organization using fNIRS measures, summarized studies showing both bilateral and unilateral activation patterns in infant populations.…”