Related Experiment Video
Updated: Jul 15, 2025
Infant Auditory Processing and Event-related Brain Oscillations
Published on: July 1, 2015
Neural processing of auditory temporal modulations in awake infants
Irene Lorenzini1, Pierre Labendzki1, Clémence Basire1
1Université Paris Cité, INCC UMR 8002, CNRS, F-75006 Paris, France.
Insights
The amplitude modulation following response (AMFR) was recorded in awake infants and adults. While responses to slow amplitude modulation were present at all ages, faster modulation processing developed by adulthood, indicating maturational changes in auditory processing.
Area of Science:
- Auditory Neuroscience
- Developmental Psychology
- Electroencephalography (EEG)
Background:
- The amplitude modulation following response (AMFR) reflects auditory phase-locking to amplitude-modulated stimuli.
- Previous AMFR studies in infants were limited to sleep states and did not explore slow modulation rates crucial for speech.
- Understanding AMFR development in awake infants is essential for assessing auditory processing maturation.
Purpose of the Study:
- To investigate the development of AMFR in awake 3- and 10-month-old infants and awake adults.
- To assess AMFR to both slow (8 Hz) and faster (40 Hz) amplitude modulation rates.
- To determine if sleep state influences AMFR recordings.
Main Methods:
- Electroencephalography (EEG) was used to record the AMFR.
- Participants included awake 3-month-olds, 10-month-olds, and young adults.
- Stimuli featured amplitude modulation at 8 Hz and 40 Hz.
Main Results:
- AMFR was observable at 8 Hz in all age groups (3-month-olds, 10-month-olds, and adults).
- Reliable AMFR to 40 Hz modulation was only observed in adults, not in infants.
- The presence of AMFR in awake adults confirmed sleep does not suppress the response.
Conclusions:
- Auditory phase-locking to slow amplitude modulation is present from early infancy.
- Processing of faster amplitude modulation rates matures into adulthood.
- Developmental differences in neural processing underlie the maturation of AMFR to faster modulation rates.
Abstract:
The amplitude modulation following response (AMFR) is the steady-state auditory response signaling phase-locking to slow variations in the amplitude (AM) of auditory stimuli that provide fundamental acoustic information. From a developmental perspective, the AMFR has been recorded in sleeping infants, compared to sleeping or awake adults. The lack of AMFR recordings in awake infants limits conclusions on the development of phase-locking to AM. Moreover, previous studies assessing phase-locking to AM using non-speech carriers have not included slow AM rates (<20 Hz), which are particularly important for speech processing. This study aimed at disentangling these issues by recording the AMFR with electroencephalography: in awake infants (3- and 10-month-olds) and awake young adults and for both slow and faster modulation rates (8 and 40 Hz). The AMFR was observable at 8 Hz at all ages (40%, 60%, and 33% of significant AMFR at 3 months, 10 months, and adults, respectively), but only adults showed reliable responses at 40 Hz (6% of significant AMFR at both 3 and 10 months, 100% in adults), thus, ruling out the possibility that sleep has a suppressing effect on the response. This pattern might be explained by developmental differences in the sources of neural processing of faster AM rates.
Related Concept Videos
01:31Hearing
01:17Auditory Perception