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Excitation-inhibition balance in infancy: implications for speech processing and language development
Poster Session D, Thursday, October 1, 4:30 - 6:30 pm, Wangari Maathai
This poster is part of the Sandbox Series.
Maaike Nieuwenhuizen1, Sergio Miguel Pereira Soares2,3, Caroline Rowland2,3, Katharina Menn1, Tineke Snijders1,2; 1Tilburg University, The Netherlands, 2Max Planck Institute for Psycholinguistics, 3Donders Institute for Brain, Cognition and Behaviour
Infants learn language from linguistic input, but they do not all learn from that input in the same way or at the same pace. This variability may partly reflect individual differences in the maturational state of the neural systems through which language input is processed. In spoken language acquisition, such differences have been suggested to constrain which aspects of the speech signal infants can process most efficiently at different points in development (Snijders & Menn, 2026). A neurobiological mechanism that may contribute to these maturational constraints is the balance between cortical excitation and inhibition (E/I balance). During infancy, inhibitory systems gradually mature, altering how E/I is balanced in the developing brain. These changes are thought to support the transition from heightened plasticity towards increasingly refined and specialised processing, and to regulate sensitive periods during which neural circuits are particularly receptive to experience-driven refinement (Dorrn et al., 2010; Werker & Hensch, 2015). Studying E/I balance may therefore help connect individual differences in early brain maturation with infants’ emerging ability to process speech and learn language. Work in older children and adolescents suggests that developmental differences in functional E/I balance are related to language abilities (Plueckebaum et al., 2023), but it remains unclear whether such links are already present during infancy. This study therefore asks whether individual differences in E/I balance, and in its developmental trajectory across the first year of life, are associated with neural responses to speech and later language and cognitive outcomes. Longitudinal EEG data were collected from 129 infants at 6, 9, and 12 months in three conditions (resting state, nursery-rhyme listening, and an auditory oddball paradigm with native and non-native phoneme contrasts). All data have been collected and will be analysed before the conference. From resting-state EEG, we will derive two functional markers of E/I balance: (1) an index using amplitude fluctuations and temporal autocorrelation of alpha oscillations (Bruining et al., 2023), and (2) the aperiodic slope of the power spectrum (Gao et al., 2017). Based on prior research, we hypothesise both measures to indicate increased inhibitory activity with age. We will test whether E/I balance is associated with two neural speech-processing measures: neural tracking of continuous speech, estimated from the nursery-rhyme listening using temporal response function models, and phoneme discrimination, indexed by mismatch responses in the oddball paradigm. Finally, we examine whether infant E/I balance is associated with later language skills (measured with the MacArthur-Bates Communicative Development Inventories at 12, 18, and 24 months) and cognitive development (measured with the Bayley Scales of Infant and Toddler Development III at 24 months). We hypothesise that more mature E/I profiles relate to stronger speech tracking, more perceptually tuned phoneme discrimination, and more advanced later language and cognitive outcomes. By examining how intrinsic brain dynamics relate to speech processing and later developmental outcomes, this study contributes to a developmental account of language acquisition in which infants’ learning trajectories are shaped not only by input, but also by the maturational state of the brain through which that input is processed.
Topic Areas: Language Development/Acquisition, Speech Perception