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Electrophysiological maturation predicts neural speech processing in infancy
Poster Session D, Thursday, October 1, 4:30 - 6:30 pm, Wangari Maathai
Katharina Menn1, Melis Cetincelik2, Anika van der Klis3, Caroline Junge3, Tineke Snijders1; 1Tilburg University, NL, 2Maastricht University, NL, 3Utrecht University, NL
The infant brain is not fully matured at birth. During the first years of life, the brain undergoes rapid electrophysiological development, shifting from dominant low-frequency activity to greater high-frequency activity (Schaworonkow & Voytek, 2021; Le Van Quyen et al., 2006). Crucially, these electrophysiological properties of the infant brain shape information processing, such as speech perception. It has therefore been hypothesized that neural maturation directly influences early language development (Menn et al., 2023). However, direct empirical evidence for this relationship remains scarce. Here, we test this hypothesis by examining whether individual differences in neural maturation associate with neural speech processing in infancy. We analyzed EEG data from a sample of 79 Dutch-learning 10-month-old infants, each tested twice on the same protocol within approximately one week, yielding n = 141 artifact-free datasets. During each session, EEG was recorded during two tasks: (1) a visual task during which infants watched toys on a screen, used to assess neural maturation, and (2) a speech task during which they listened to Dutch nursery rhymes, used to measure speech processing. Neural maturation was quantified using frequency analyses of EEG. We measured the individual’s peak frequency in the infant alpha range from 4–9 Hz (Corcoran, et al., 2018), and the aperiodic (1/f) slope of the EEG power spectrum, which captures the relative balance between high- and low-frequency activity (Donoghue et al., 2020). A steeper slope reflects more low-frequency activity while a flatter slope reflects increased high-frequency activity, indicative of neural maturation. Speech processing was assessed using speech-brain coherence, which captures the synchronization between neural activity and the speech envelope—a proposed mechanism underlying speech processing (Meyer, 2018; Giraud & Poeppel, 2018). Coherence was measured at three linguistically relevant rates: prosodic (1–3 Hz), syllabic (3–5 Hz), and phonemic (5–15 Hz). Higher coherence indicates stronger speech tracking and thus more robust speech processing. Analyses revealed a significant relationship between aperiodic slope and neural tracking, specifically at the phoneme-rate. Infants with a flatter aperiodic slope, indicative of a more mature brain (greater high-frequency activity), showed stronger neural tracking at the phonemic rate (t = -2.28, p = .024). In contrast, individual alpha frequency was not significantly related to speech-brain coherence at any rate (all p > .8). These findings suggest that individual differences in electrophysiological maturation already associate with early speech processing, supporting a direct link of EEG maturation in shaping infants’ speech processing, and potentially language acquisition.
Topic Areas: Language Development/Acquisition, Speech Perception