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EEG alpha rhythm in infants
T A Stroganova1, E V Orekhova, I N Posikera
1Brain Research Institute, Russian Academy of Medical Sciences, Moscow. strogano@rinet.ru
Insights
Infant alpha rhythm and sensorimotor mu rhythm development were studied using EEG in 154 twins. Alpha rhythm frequency increased with visual experience, while mu rhythm frequency depended on both prenatal and postnatal development.
Area of Science:
- Neuroscience
- Developmental Neuroscience
- Infant EEG
Background:
- The development of brain rhythms like alpha and mu rhythms in infants is crucial for understanding cognitive and sensorimotor maturation.
- Previous research has primarily focused on older children and adults, leaving a gap in understanding early brain activity patterns.
Purpose of the Study:
- To investigate the 'functional topography' of alpha rhythms in infants during the second half of their first year of life.
- To explore the relationship between early visual and somatosensory experiences and the development of specific brain rhythms.
Main Methods:
- Electroencephalography (EEG) was recorded from 154 healthy infants (32-41 weeks gestational age) aged 7.4 to 12.4 months.
- EEG data were collected during two conditions: sustained visual attention and a dark homogenous visual field.
- Spectral analysis was used to identify and quantify rhythmic activity in specific frequency bands.
Main Results:
- Alpha rhythm (5.2-9.6 Hz) showed increased spectral amplitudes over the occipital-parietal cortex during darkness compared to visual attention.
- A distinct rhythmic component (6.0-8.8 Hz) was observed at precentral sites during visual attention, suppressed in darkness, suggesting a link to sensorimotor mu rhythm.
- Infant alpha rhythm frequency increased with postnatal age, correlating with visual experience, while mu rhythm frequency depended on both prenatal and postnatal development.
Conclusions:
- Early visual experience critically influences the development of infant alpha rhythm.
- The development of sensorimotor mu rhythm appears to be influenced by somatosensory input, present even prenatally.
Abstract:
The 'functional topography' approach has been applied to study alpha rhythms in infant twins during the second half-year of life. The experimental sample included 154 normal infants born at 32-41 weeks of gestational age. Their chronological age varied from 7.4 to 12.4 months. EEG was registered during wakefulness under two experimental conditions: sustained visual attention and dark homogenous visual field. During darkness as compared with visual attention the sharp increase of spectral amplitudes within 5.2-9.6 Hz band was observed over the occipital-parietal cortex. The properties of the 5.2-9.6 Hz occipital rhythmic activity comply with the classical properties of alpha rhythm. The distinct spectral peak in 6.0-8.8 Hz band at precentral recording sites was observed during sustained visual attention. This rhythmic component was suppressed under the condition of total darkness. Arguments in favour of homology between the infant central rhythm and adult sensorimotor mu rhythm are advanced. The group mean of alpha peak frequency increased from 6.24 +/- 0.45 Hz at 8 months to 6.78 +/- 0.38 Hz at 11 months of chronological age. The frequency of infant alpha rhythm depended only on the period of extrauterine experience, regardless of gestational age at birth. This result points to the critical role of early visual experience in alpha rhythm development. The group mean of the peak frequency of mu rhythm also increased during the second half-year of life, from 7.03 +/- 0.47 Hz at 8 months to 7.42 +/- 0.46 Hz at 11 months. Unlike alpha rhythm, the peak frequency of mu rhythm depended on duration of both intra- and extrauterine development. We speculate that the development of sensorimotor mu rhythm is influenced by somatosensory stimulation, which, in sharp contrast to the visual input, is present in the uterus.