As the community — and thought — about imaging genetics grows, new studies are emerging. These studies focus on the way that genes are found to play a role in different cognitive functions. In a recent special issue of Behavior Genetics, the focus is on the progress in the linkage between the genetic map and behavioural traits. There are a lot of interesting articles in this special issue, altough I find a few especially intriguing.
In a nice review, Steven Buyske reviews different findings that map cognitive functions and the gene map. Here's the abstract:
Human cognition in normal and disease states is both environmentally and genetically mediated. Except for measures of language-specific abilities, however, few cognitive measures have been associated with specific genes or chromosomal regions. We performed genome-wide linkage analysis of five neuropsychological tests in the Collaborative Study on Genetics of Alcoholism sample. The sample included 1579 individuals (53% female, 76% White Non-Hispanic) in 217 families. There were 390 markers with mean intermarker distance of 9.6 cM. Performance on the Digit Symbol Substitution Test, a component of the Wechsler Adult Intelligence Scale-R, showed significant linkage to 14q11.2 and suggestive linkage to 14q24.2. This test of sustained visual attention also involves visual-motor coordination and executive functions. Performance on the WAIS-R Digit Span Test of immediate memory and mental flexibility showed suggestive linkage to 11q25. Although the validity of these results beyond populations with a susceptibility for alcohol dependence is unclear, these results are among the first linkage results for non-language components of cognition.
But hey, there's more. There are studies on the association of genes and anxiety and neuroticism; gene association of feelings of loneliness; gene association to age at first cigarette; genes on academic skills; and genes on IQ (of course).
The question is: where will it end? Of course, genes are abundantly represented in the body. They are, after all, the receipt to every cell and how they should work. But what level of description and explanation should we apply in this gene-to-cognition mapping? I fear that at least in some studies, old "folk-psychological" concepts about cognitive traits are compared to high-detailed analysis and knowledge about the genes. In order to understand how genes get expressed in a way that they shape behaviour, we need to work out the intermediate stages. We need to know how genes influence neurons, transmitters, plasticity on one level; how they shape interacting neurons and neural assemblies; and finally how this cumulates into one or the other kinds of behaviour. The leap from gene to behaviour is, IMHO, too wide. The solution is in the nitty-gritty details.
Way to go CIMBI!