Developmental Trajectory of the Frequency-Following Response During the First 6 Months of Life

Abstract

Purpose: The aim of the present study is to characterize the maturational changes during the first 6 months of life in the neural encoding of two speech sound features relevant for early language acquisition: the stimulus fundamental frequency ( f o ), related to stimulus pitch, and the vowel formant composition, particularly F 1 . The frequency-following response (FFR) was used as a snapshot into the neural encoding of these two stimulus attributes. Method: FFRs to a consonant–vowel stimulus /da/ were retrieved from electroencephalographic recordings in a sample of 80 healthy infants (45 at birth and 35 at the age of 1 month). Thirty-two infants (16 recorded at birth and 16 recorded at 1 month) returned for a second recording at 6 months of age. Results: Stimulus f o and F 1 encoding showed improvements from birth to 6 months of age. Most remarkably, a significant improvement in the F 1 neural encoding was observed during the first month of life. Conclusion: Our results highlight the rapid and sustained maturation of the basic neural machinery necessary for the phoneme discrimination ability during the first 6 months of age.

Longitudinal trajectories of the neural encoding mechanisms of speech-sound features during the first year of life

“…months postnatal period on the maturation of the temporal fine structure encoding of speech. These results support previous cross-sectional FFR studies reporting an enhancement of F 1 neural encoding as a function of age(Anderson et al, 2015;Van Dyke et al, 2017), as well as the longitudinal findings byRibas-Prats et al (2023b), but further extend these latter findings on the longitudinal trajectory on neural F 1 encoding through early development to the age of twelve months.…”

“…While no age-related changes were observed in the encoding of voice pitch, a significant enhancement was depicted across the first six-month postnatal period in neural transmission times and neural encoding of the stimulus temporal fine structure. Results contribute to knowledge from previous studies on the developmental trajectory of speech-sound neural encoding mechanisms (Anderson et al, 2015;Arenillas-Alcón et al, 2021, Ribas-Prats et al 2019, 2023b, by specifically filling the gap with a longitudinal sample spanning the first year of life. Results unveil an early neural maturation in the neural encoding of the speech temporal fine structure and point to a sensitive developmental window in the emergence of core neural mechanisms required for speech acquisition that occurs within the first six months after birth.…”

“…An adult-like voice pitch encoding at birth has also been reported (Arenillas-Alcón et al, 2021;Jeng et al, 2016), with a more robust neural representation with age across the first year of life (Jeng et al, 2010;Ribas-Prats et al, 2023b;Van Dyke et al, 2017).…”

“…A decrease in neural conduction times and neural phase-locking onset has been already observed at the early age of 45 days (Ferreira et al, 2021), with further shortenings until the age of ten months (Anderson et al, 2015). An adult-like voice pitch encoding at birth has also been reported (Arenillas-Alcón et al, 2021; Jeng et al, 2016), with a more robust neural representation with age across the first year of life (Jeng et al, 2010; Ribas-Prats et al, 2023b; Van Dyke et al, 2017). The maturation of neural encoding of temporal fine structure components, as assessed through neural responses to the high-frequency formants and harmonics, begins as early as the first month of life (Ribas-Prats et al, 2023b) and continuous to develop until the age of ten months (Anderson et al, 2015).…”

“…The maturation of neural encoding of temporal fine structure components, as assessed through neural responses to the high-frequency formants and harmonics, begins as early as the first month of life (Ribas-Prats et al, 2023b) and continuous to develop until the age of ten months (Anderson et al, 2015).…”