Genetic contributions to regional variability in human brain structure: methods and preliminary results

Area of Science:

• Neuroscience
• Behavioral Genetics
• Human Genetics

Background:

• Twin studies are crucial for dissecting genetic and environmental influences on human brain structure.
• Previous research indicated heritability for various brain metrics, including volume and cortical patterns.

Purpose of the Study:

• To investigate genetic and environmental contributions to global and regional human brain structure variability.
• To map regional brain heritability and test specific hypotheses regarding genetic control.

Main Methods:

• Utilized magnetic resonance imaging (MRI) data from monozygotic and dizygotic twin pairs.
• Employed automated image segmentation, standard space transformation, and digital atlas parcellation for regional gray matter volume estimation.
• Applied path analysis for heritability estimation and principal component analysis for identifying shared genetic effects.

Main Results:

• Overall brain volume exhibited high heritability (0.66), while lateral ventricular volume was primarily influenced by environmental factors.
• A regional brain heritability map revealed significant genetic effects in paralimbic structures and temporal-parietal neocortex.
• Results supported the hypothesis that random asymmetry in bilateral structures is not heritable, but did not support hypotheses related to gyral ontogenesis or hemispheric asymmetry.

Conclusions:

• Genetic influences on human brain structure are regionally variable and predominantly symmetric in paralimbic and lateral temporal regions.
• Larger sample sizes are necessary for robust genetic investigations using twin imaging data.
• Preliminary findings highlight the complex interplay of genetic and environmental factors in shaping brain anatomy.