Event-Related Brain Potentials and Frequency-Following Response to Syllables in Newborns and Adults

Area of Science:

• Neuroscience
• Developmental Psychology
• Speech Science

Background:

• Auditory event-related brain potentials (ERPs), including mismatch negativity (MMN) and frequency-following response (FFR), are crucial for understanding speech sound encoding in the auditory pathway.
• Assessing these neural responses in newborns and adults provides insights into developmental trajectories of speech perception.

Purpose of the Study:

• To investigate and compare the neural encoding of speech sounds, specifically syllables, in 3-day-old newborns and adults using electroencephalography (EEG).
• To examine the maturation of auditory processing for speech features like vowel pitch and place of articulation from birth through adulthood.

Main Methods:

• Collected EEG data from 17 newborns (3 days old) and 21 adults (22.7 years old) during passive auditory stimulation with synthetic and natural speech syllables.
• Utilized alternating blocks of fast and slow stimulation rates, including standard and deviant syllables differing in place of articulation.
• Analyzed frequency-following responses (FFR) for pitch and formant encoding and event-related potentials (ERPs), specifically mismatch negativity (MMN), for articulatory feature detection.

Main Results:

• Newborns demonstrated functional encoding of vowel pitch via FFR but showed immature encoding of vowel formant structure.
• Both newborns and adults exhibited mismatch negativity (MMN) in response to deviant syllables, indicating developing sensitivity to place of articulation, though with differing topographies.
• The findings suggest that experience-dependent developmental factors differentially influence the maturation of FFR and ERPs for speech sound features.

Conclusions:

• Early auditory experience plays a significant role in shaping the neural processing of speech sounds from birth.
• The study confirms the feasibility of using ERPs and FFRs in short experimental sessions to assess the hierarchy of neural speech sound encoding in infants.
• These findings contribute to understanding the developmental timeline of speech perception and auditory pathway maturation.