A recent analysis of brain structure in healthy individuals who carry a common 2,445-bp deletion in intron 2 of the doublecortin domain containing 2 (DCDC2) gene found that heterozygotes for the deletion showed higher grey matter volumes for several brain areas known to be involved in the processing of written and spoken language (superior, medial and inferior temporal cortex, fusiform, hippocampal / parahippocampal, inferior occipito-parietal, inferior and middle frontal gyri, especially in the left hemisphere) [doi:10.1007/s11682-007-9012-1]. The DCDC2 gene sits within a well known locus frequently found to be associated with developmental dyslexia, and associations of reading disability with DCDC2 have been confirmed in population-based studies. Further work on DCDC2 (open access) shows that the DNA that is deleted in the 2,445-bp deletion in intron 2 carries a number of repeating sequences to which developmental transcription factors bind and that inhibition of DCDC2 results in altered neuronal migration (the right-hand panel shows altered radial migration when DCDC2 is inhibited). Perhaps the greater grey matter volumes are related to this type of neuronal migration finding? Will be interesting to follow this story further!
Archive for the ‘Parahippocampal gyrus’ Category
Posted in COMT, DLPFC, Dopamine, Frontal cortex, Orbitofrontal cortex, Parahippocampal gyrus, Posterior parietal cortex, tagged 23andMe, Dopamine, Frontal lobe, Functional magnetic resonance imaging on January 1, 2008| Leave a Comment »
Holiday time is full of all things delicious and fattening. Should I have a little chocolate now, or wait till later and have a bigger dessert ? Of course, this is not a real forced choice (in my case, the answer too often seems – alas – “I’ll have both!”), but there are many times in life when we are forced to decide between ‘a little now’ or ‘more later’. Sometimes, its clear that the extra $20 in your pocket now would be better utilized later on, after a few years of compound interest. Other times, its not so clear. Consider the recent ruling by the Equal Employment Opportunity Commission, which allows employers to drop retirees’ health coverage once they turn 65 and become eligible for Medicare. Do I save my resources now to provide for my geezerdom healthcare spending, or do I enjoy (spend) my resources now while I’m young and able ? How do I make these decisions ? How does my life experience and genome interact to influence the brain systems that support these computations ? Boettiger and company provide some insight to these questions in their paper, “Immediate Reward Bias in Humans: Fronto-Parietal Networks and a Role for the Catechol-O-Methyltransferase 158Val/Val Genotype” (DOI). The authors utilize an assay that measures a subject’s preference for rewards now or later and use functional brain imaging to seek out brain regions where activity is correlated to preferences for immediate rewards. Dopamine rich brain regions such as the posterior parietal cortex, dorsal prefrontal cortex and rostral parahippocampal gyrus showed (+) correlations while the lateral orbitofrontal cortex showed a (-) correlation. Variation in the dopaminergic enzyme COMT at the rs165688 SNP also showed a correlation with preferences for immediate reward as well as with brain activation. The authors’ results suggest that improving one’s ability to weigh long-term outcomes is a likely therapeutic avenue for helping impulsive folks (like me) optimize our resource allocation. I have not yet had my genome deCODEd or Google-ed, but strongly suspect I am a valine/valine homozygote.
Indeed it seems I am a GG (Valine/Valine) at this site according to 23andMe !