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Updated: Oct 2, 2025
Infant Auditory Processing and Event-related Brain Oscillations
Published on: July 1, 2015
EEG effective connectivity during the first year of life mirrors brain synaptogenesis, myelination, and early right
Jorge Bosch-Bayard1, Rolando J Biscay2, Thalia Fernandez3
1McGill Center for Integrative Neuroscience (MCIN), Ludmer Center for Neuroinformatics and Mental Health, Montreal Neurological Institute (MNI), McGill University, Montreal H3A2B4, Canada.
Insights
This study describes infant brain connectivity development using electroencephalogram (EEG) in the first year. Findings show brain networks mature, mirroring myelination and cognitive growth, with right hemisphere dominance early on.
Area of Science:
- Neuroscience
- Developmental Neuroscience
- Computational Neuroscience
Background:
- Infant brain development involves complex changes in neural networks.
- Understanding electroencephalogram (EEG) effective connectivity provides insights into brain maturation.
- Early brain development is influenced by synaptogenesis and myelination.
Purpose of the Study:
- To describe the maturation of EEG effective connectivity in healthy infants during their first year of life.
- To correlate early brain connectivity patterns with known developmental processes like myelination and synaptogenesis.
- To investigate age-related changes in brain network organization and hemispheric dominance.
Main Methods:
- A cross-sectional sample of 125 healthy infants (0-12 months) underwent EEG during quiet sleep.
- Source-level EEG data were analyzed using the sLoreta method.
- Isolated effective coherence was calculated to measure directed information flow, minimizing signal leakage.
Main Results:
- Connectivity initially concentrated in subcortical and parietal regions, expanding to temporal, occipital, and frontal areas, consistent with myelination.
- Age-related changes were predominantly long-range and bilateral, with increased connectivity in the right hemisphere and decreased connectivity in the left.
- Theta and alpha frequency bands showed significant age-related changes, with strong parietal-temporal-occipital to frontal connections observed.
Conclusions:
- EEG effective connectivity maturation in infants aligns with synaptogenesis, myelination, and functional development.
- The findings support a model of early brain development characterized by progressive network maturation and right hemisphere specialization.
- Bidirectional information exchange between the thalamus and cortical regions across frequency bands is crucial for early brain function.
Introduction:
The maturation of electroencephalogram (EEG) effective connectivity in healthy infants during the first year of life is described.
Methods:
Participants: A cross-sectional sample of 125 healthy at-term infants, from 0 to 12 months of age, underwent EEG in a state of quiet sleep.
Procedures:
The EEG primary currents at the source were described with the sLoreta method. An unmixing algorithm was applied to reduce the leakage, and the isolated effective coherence, a direct and directed measurement of information flow, was calculated.
Results And Discussion:
Initially, the highest indices of connectivity are at the subcortical nuclei, continuing to the parietal lobe, predominantly the right hemisphere, then expanding to temporal, occipital, and finally the frontal areas, which is consistent with the myelination process. Age-related connectivity changes were mostly long-range and bilateral. Connections increased with age, mainly in the right hemisphere, while they mainly decreased in the left hemisphere. Increased connectivity from 20 to 30 Hz, mostly at the right hemisphere. These findings were consistent with right hemisphere predominance during the first three years of life. Theta and alpha connections showed the greatest changes with age. Strong connectivity was found between the parietal, temporal, and occipital regions to the frontal lobes, responsible for executive functions and consistent with behavioral development during the first year. The thalamus exchanges information bidirectionally with all cortical regions and frequency bands.
Conclusions:
The maturation of EEG connectivity during the first year in healthy infants is very consistent with synaptogenesis, reductions in synaptogenesis, myelination, and functional and behavioral development.
