Language learning differs in brains at autism risk
Babies who are later diagnosed with autism often show delays in learning to speak. But when exactly does that difference begin in the brain? New research followed babies over time and found measurable differences in speech processing within the first two years of life. The findings matter for early diagnosis and for what they reveal about brain development more broadly.
Researchers followed 44 babies from 2.5 to 22.6 months of age. Some had a higher likelihood of autism (due to having an older sibling with autism); the others did not. Using brainwave measurements (EEG), they examined two mechanisms: how well the brain tracks the rhythm of speech sounds (neural entrainment) and whether babies unconsciously pick up on regularities in language (statistical speech processing).
Less sensitive to the beat of speech
The study, published in eLife, shows that babies at higher likelihood for autism were less able to track the rhythmic structure of syllables. That sensitivity to speech rhythm was linked to language ability at twenty months. These babies also showed less curiosity towards new words during a recognition test. Notably, statistical speech processing itself was not impaired. But in the lower-likelihood group, hearing multiple different speakers temporarily disrupted word segmentation around twelve months, which did not occur in the higher-likelihood group. This suggests reduced sensitivity to variability in human voices in that group.
From infant brains to brain ageing
What does this have to do with ageing? The brain mechanisms established early in life partly determine how resilient the brain is later on. Differences in neural entrainment and statistical learning in infancy have been linked to cognitive vulnerability in later life. Understanding how these early patterns form is a building block for research into how to slow or prevent cognitive decline with ageing.
Search terms to explore further: neural entrainment speech development, statistical language processing early brain development, EEG longitudinal language acquisition