Gene-hyped as we are here at BrainEthics, I'm mentioning a few articles that are highlighting the relationship between genes, brain and mind. As neuroscience deals with the wet matter of the mind – the fatty, information-processing and massively energy consuming body part we call the brain – we must also realize that the basic building block of the brain is the genome.
This is not as simple as it may sound. Genes simply do not merely encode how a cell is to look like or function. Genes only react to the environment in which they are situated. The development of, say, a hippocampal cell is not encoded in the genome per se; it stems from the influence of the local environment of that part of the brain, and how the brain cell (at the developmental stage actually more like a stem cell) migrates and connects to the network that will develop into the hippocampus. Neuroscience is certainly sorting out the nitty-gritty details on this, with the fantastic work by people such as Pasco Rakic. IMHO, even neuroimaging cannot escape this turn: we must move from the "blobology" of fMRI, PET and all other neuroimaging methods (this even applies to the clever diffusion fMRI, as described recently), and towards a better understanding of what goes on within these blobs. Just as I briefly mentioned in my post about Nikos Logothetis.
So here's a few additions in the story about imaging genetics, the study where neuroimaging is informed by genetic variations:
What is the hidden structure of the genome? The human genome is much more diverse and dynamic than what one could get the impression of through normal genotyping studies. Variations abound, and in a number beyond what we normally think. These are not just curiosities; they play important roles in the way that the body (and brain) develops and functions. In a news article in Nature, Andrew Sharp briefly presents two ways to study the genome, and how the new insight about variability influences current research. From the article: "The genetics community is only just beginning to appreciate the extent of structural variation present in the human genome and its role in human disease. Although we now have a finished human genome sequence in hand, geneticists have begun to appreciate that this is in fact a highly dynamic structure. The realization that the long-awaited reference sequence represents only one version of the human genome, which has significant large-scale variation between any two individuals, means that techniques such as these for investigating genome structure will be in high demand."
What is a gene? In another Nature news article, Helen Pearson discusses how RNA is becoming the new field of studying how genetic information is implemented in the organism. From the article: "In classical genetics, a gene was an abstract concept – a unit of inheritance that ferried a characteristic from parent to child. As biochemistry came into its own, those characteristics were associated with enzymes or proteins, one for each gene. And with the advent of molecular biology, genes became real, physical things – sequences of DNA which when converted into strands of so-called messenger RNA could be used as the basis for building their associated protein piece by piece. The great coiled DNA molecules of the chromosomes were seen as long strings on which gene sequences sat like discrete beads. This picture is still the working model for many scientists. But those at the forefront of genetic research see it as increasingly old-fashioned – a crude approximation that, at best, hides fascinating new complexities and, at worst, blinds its users to useful new paths of enquiry."
How heritable is Alzheimer's Disease? According to a study by Margaret Gatz and colleagues, the influence of genetics is very high, and higher than often thought. For a best-fit model estimation, genes are though to be responsible for 79%. Environmental risk factors do indeed play a role, but not as high as we might think from previous reports.
How to read the genome and its functional implications? Simon Fisher and Clyde Francks have a nice review in Trends in Cognitive Science on the genetic influence of dyslexia. Dyslexia is being used here as a model to explain how to use genotyping in a meaningful way to study the genetic influence on cognitive function and dysfunction.
These are just to mention a few important articles from this burgeoning scientific field. More are bound to follow, and we'll cover them the best we can here at BrainEthics.
(BTW, the image used here is from the Rakic Lab, illustrating the migration of brain cells during development. At the Human Brain Mapping conference in Toronto last year, Rakic held a superb talk showing movies of migrating cells. It was a true eye-opener to those of us who had not realized how much actually goes on during development. I can see that they are setting up a page for a media gallery, hopefully that will cover some of these excellent movies. I'll be watching that page closely.)
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