Genetic contributions to human brain morphology and in...( While showing an impressive growth p...)

While showing an impressive growth prenatally, the human brain is not completed at birth. There is considerable brain growth during childhood with dynamic changes taking place in the human brain throughout life, probably for adaptation to our environments.

Evidence is accumulating that brain structure is under considerable genetic influence [Peper et al., 2007]. Puberty, the transitional phase from childhood into adulthood, involves changes in brain morphology that may be essential to optimal adult functioning. Around the onset of puberty gray matter volume starts to decrease, while white matter volume is still increasing [Giedd et al., 1999].

Recent findings have shown, that variation in total gray and white matter volume of the adult human brain is primarily (7090%) genetically determined [Baare et al, 2001] and in a recent magnetic resonance imaging (MRI) brain study with 45 monozygotic and 61 dizygotic 9-year-old twin-pairs, and their 87 full siblings also high heritabilities have been found [Peper et al, in preparation]. Thus, while environmental influences may play a role in later stages during puberty, around the onset of puberty brain volumes are already highly heritable.

Genetic influences and functional relevance

Twin studies have also shown that genetic effects vary regionally within the brain, with high heritabilities of frontal lobe volumes (9095%), moderate estimates in the hippocampus (4069%), and environmental factors influencing several medial brain areas.

However, the mechanisms by which interaction between genes and environment occur throughout life as well as dynamics of brain structure and its association with brain functioning still remain unknown. Twin and family studies and newly evolving genetic approaches start to give us a glimpse as to which genes and (interacting) environmental influences are shaping our brains.

Brain structure measured macroscopically using MRI and
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