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

Abstract

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 (fo), related to stimulus pitch, and the vowel formant composition, particularly F1. The frequency-following response (FFR) was used as a snapshot into the neural encoding of these two stimulus attributes. 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. Stimulus fo and F1 encoding showed improvements from birth to 6 months of age. Most remarkably, a significant improvement in the F1 neural encoding was observed during the first month of life. 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.