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Visual processing in infants and children studied using functional MRI
E Martin1, P Joeri, T Loenneker
1Department of Magnetic Resonance, University Children's Hospital Zurich, Zürich, Switzerland.
Insights
Functional magnetic resonance imaging (fMRI) reveals that the primary visual cortex in children matures functionally around 1.5 years of age. This study tracked visual processing development in children using fMRI, noting age-related changes in brain activity.
Area of Science:
- Neuroscience
- Developmental Neuroscience
- Pediatric Imaging
Background:
- Visual processing development is crucial for cognitive growth.
- Understanding age-related changes in brain activity using neuroimaging is essential.
Purpose of the Study:
- To investigate the developmental trajectory of visual processing in children using functional magnetic resonance imaging (fMRI).
- To determine the age at which the primary visual cortex in children exhibits adult-like functional responses.
Main Methods:
- Functional magnetic resonance imaging (fMRI) was employed to study visual processing in 58 children aged 1 day to 12 years.
- Participants were either sedated or under general anesthesia during the fMRI scans.
- A visual stimulation paradigm was used to elicit brain responses, measuring blood oxygenation level-dependent (BOLD) contrast signals.
Main Results:
- The percentage of children showing a positive BOLD signal increased with age, with 71% of those 6 years and older responding.
- A significant proportion of children exhibited a negative BOLD signal, particularly in younger age groups (up to 47% in 1-6 year olds).
- Negative BOLD signals were localized to secondary visual cortical areas, distinct from positive BOLD signal locations.
Conclusions:
- The primary visual cortex in children does not achieve adult-like functional responses until approximately 1.5 years of age.
- These findings suggest distinct postnatal cortical mechanisms contribute to visual perception development.
- fMRI is a valuable tool for studying pediatric brain development, though anesthesia/sedation effects require consideration.
Abstract:
We studied the development of visual processing in 58 children, ranging from 1 d to 12 y of age (median age 29 mo), using functional magnetic resonance imaging. All but nine children had either been sedated using chloral hydrate (n = 12) or pentobarbital (n = 28). Nine children were studied under a full halothane/ N2O:O2 anesthesia. In the first postnatal month, 30% of the neonates showed a positive blood oxygenation level-dependent (BOLD) contrast signal, whereas, for infants between the ages of 1 mo and 1 y, 27% did so. Thirty-one percent of children between 1 and 6 y of age and 71% of children aged 6 y and above showed a positive BOLD contrast signal change to our visual stimulation paradigm. Besides the usual positive BOLD contrast signal change, we also noted that a large portion of the children measured displayed a negative BOLD contrast signal change. This negative BOLD contrast signal change was observed in 30% of children up to 1 mo of age, in 27% between 1 mo and 1 y of age, in 47% between 1 and 6 y of age, and in 14% of children 6 y and older. In the children in which we observed a negative correlating BOLD contrast signal change, the locus was more anterior and more lateral than the positive BOLD contrast signal, placing it in the secondary visual cortical area. The results indicate that when using functional magnetic resonance imaging on children, the primary visual cortical area does not respond functionally in the same manner as that of the adult until 1.5 y of age. This supports earlier clinical and electrophysiologic findings that different cortical mechanisms seem to contribute to visual perception at different times postnatally.