Articles like this are always useful when trying to make up one’s mind in the ever interesting ‘nature vs. nurture’ debate
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UCLA Team Maps How Genes Affect Brain Structure, Intelligence
Source: Science Daily
Published: 11/5/2001 Author: University Of California – Los Angeles
UCLA brain mapping researchers have created the first
images to show how an individuals genes influence their
brain structure and intelligence.
The findings, published in the Nov. 5 issue of the journal
Nature Neuroscience, offer exciting new insight about how parents
pass on personality traits and cognitive abilities,
and how brain diseases run in families.
The team found that the amount of gray matter in the
frontal parts of the brain is determined by the genetic
make-up of an individuals parents, and strongly correlates
with that individuals cognitive ability, as measured by
intelligence test scores.
More importantly, these are the first images to uncover how
normal genetic differences influence brain structure and
intelligence.
Brain regions controlling language and reading skills were
virtually identical in identical twins, who share exactly
the same genes, while siblings showed only 60 percent of
the normal brain differences.
This tight structural similarity in the brains of family
members helps explain why brain diseases, including
schizophrenia and some types of dementia, run in families.
We were stunned to see that the amount of gray matter in
frontal brain regions was strongly inherited, and also
predicted an individuals IQ score, said Paul Thompson,
the studys chief investigator and an assistant professor
of neurology at the UCLA Laboratory of Neuro Imaging.
The brains language areas were also extremely similar in
family members. Brain regions that were found to be most
similar in family members may be especially vulnerable to
diseases that run in families, including some forms of
psychosis and dementia.
The scientists employed magnetic resonance imaging
technology to scan a group of 20 identical twins, whose
genes are identical, and 20 same-sex fraternal twins, who
share half their genes.
Using a high-speed supercomputer, they created color-coded
images showing which parts of the brain are determined by
our genetic make-up, and which are more adaptable to
environmental factors, such as learning and stress.
To create the maps of genetic influences on the brain, the
UCLA scientists teamed up with the National Public Health
Institute of Finland, and the Finnish Universities of
Helsinki and Oulu.
In a national initiative, the Finnish team tracked all the
same-sex twins born in Finland between 1940 and 1957
9,500 pairs of twins many of whom received brain scans
and cognitive tests.
Their genetic similarity was confirmed by analyzing 78
different genetic markers. These individual pieces of DNA
match exactly in identical twins, and half of them match in
siblings.
Recent research has shown that many cognitive skills are
surprisingly heritable, with strong genetic influences on
verbal and spatial abilities, reaction times, and even some
personality qualities, including emotional reactions to
stress.
These genetic relationships persist even after statistical
adjustments are made for shared family environments, which
tend to make members of the same family more similar. Until
this study, little was known about how much individual
genotype accounts for the wide variations among individual
brains, as well as individuals cognitive ability.
The UCLA researchers are also applying this new genetic
brain mapping approach to relatives of schizophrenic
patients, and individuals at genetic risk for Alzheimers
disease, to screen them for early brain changes, and help
understand familial risk for inherited brain disorders
where specific risk genes are unknown.
Other UCLA researchers involved in the project are Tyrone
Cannon, a professor of psychiatry and biobehavioral and
human genetics, and Arthur Toga, professor of neurology and
director of the UCLA Laboratory of Neuro Imaging.
Images from the study are available online for viewing or
downloading from here
