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Developmental biology - Brain Development

Brain Grey Matter Grows Rapidly In First Years

Age is reflected as two different growth rates between grey and white matter in the brain...

Infant brain development is very poorly understood, so research on the topic is vital to developing assessments of infant brain sensitivity to environmental factors. Identifying these factors and their outcomes is the purpose of the FinnBrain imaging study conducted by the University of Turku in Finland.

Adult brain structure and division of its different brain hemispheres is already well studied. But, study of the developing brain is limited. By understanding these processes, future studies will be able to more easily detect factors like mom's prenatal health, and its impact on the infant brain.

For the study, 68 babies aged 2-5 weeks were scanned using MRI. Investigators explore normal infant brain development for the differences between hemispheric volumes and their asymmetry. Affects of age and sex on brain lobe volumes and their asymmetry are of particular interest.

• The developing brain is most sensitive to environmental factors during pregnancy, and these factors may drastically alter the course of development, according to doctoral candidate Satu Lehtola, FinnBrain Birth Cohort Study, University of Turku.

• According to Lehtola, in both sexes brain lobes were similar in their asymmetry; the right temporal lobe, left parietal, and left occipital lobes being larger than their counter side. Differences between sexes were found, but are subtle and include only locally restricted areas in the grey matter.

• In these studies carried out with very young infants, results are in line with previous findings, strengthening perceptions on early brain development.
These findings reveal infant age manifests as different rates of growth in grey and white matter.

Results align with existing research showing growth rate of grey matter is more rapid during the first years of life. Grey matter disaggregates into lobar volumes though, the lobar volumes of full-term infants did not differ in a statistically significant manner as infants' ages only varied by a few weeks.

Lehtola believes the results provide a good basis to continue research on the effects of early environmental factors on brain volumes, a key aim of the FinnBrain research project. The research is published in the journal Brain Structure and Function.

Information on normal brain structure and development facilitates the recognition of abnormal developmental trajectories and thus needs to be studied in more detail. We imaged 68 healthy infants aged 2–5 weeks with high-resolution structural MRI (magnetic resonance imaging) and investigated hemispheric asymmetry as well as the associations of various total and lobar brain volumes with infant age and sex. We found similar hemispheric asymmetry in both sexes, seen as larger volumes of the right temporal lobe, and of the left parietal and occipital lobes. The degree of asymmetry did not vary with age. Regardless of controlling for gestational age, gray and white matter had different age-related growth patterns. This is a reflection of gray matter growth being greater in the first years, while white matter growth extends into early adulthood. Sex-dependent differences were seen in gray matter as larger regional absolute volumes in males and as larger regional relative volumes in females. Our results are in line with previous studies and expand our understanding of infant brain development.

S. J. Lehtola, J. J. Tuulari, L. Karlsson, R. Parkkola, H. Merisaari, J. Saunavaara, T. Lähdesmäki, N. M. Scheinin and H. Karlsson

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Dec 3, 2018   Fetal Timeline   Maternal Timeline   News   News Archive

Study of the developing brain is limited, but by understanding its processes, science and medicine hope they will be able to more easily detect factors like mom's prenatal health as it impacts the infant brain. Image Credit: Public Domain.

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