Episode 133 (Assistant Professor Giovanni Di Liberto)

The ResearchWorks Podcast

EMERGENCE OF THE CORTICAL ENCODING OF PHONETIC FEATURES IN THE FIRST YEAR OF LIFE

Giovanni M. Di Liberto, Adam Attaheri, Giorgia Cantisani, Richard B. Reilly, Áine Ní Choisdealbha, Sinead Rocha, Perrine Brusini & Usha Goswami

Nature Communications volume 14, Article number: 7789 (2023)

Abstract

Even prior to producing their first words, infants are developing a sophisticated speech processing system, with robust word recognition present by 4–6 months of age.
These emergent linguistic skills, observed with behavioural investigations, are likely to rely on increasingly sophisticated neural underpinnings. The infant brain is known to robustly track the speech envelope, however previous cortical tracking studies were unable to demonstrate the presence of phonetic feature encoding.
Here we utilise temporal response functions computed from electrophysiological responses to nursery rhymes to investigate the cortical encoding of phonetic features in a longitudinal cohort of infants when aged 4, 7 and 11 months, as well as adults.
The analyses reveal an increasingly detailed and acoustically invariant phonetic encoding emerging over the first year of life, providing neurophysiological evidence that the pre-verbal human cortex learns phonetic categories. By contrast, we found no credible evidence for age-related increases in cortical tracking of the acoustic spectrogram.