Wednesday, April 08, 2009

Schizophrenia and autism: the connectopathies?

For the past few years we've been thinking about developmental disorders of cognition, such as "schizophrenia" and "autism", as being fundamentally wiring disorders.

So very different conditions, but both arising from disordered development of neuronal connectivity.

It's not exactly a new idea. I recall the insult "wired wrong" from 40 years ago. It may turn out to be quite wrong, and it's unlikely to have clinical implications for years, but it's still worth tracking (emphases mine) ...
Finding out how the brain is wired | Wired | The Economist

.... Dr Lichtman’s work is the most famous example of the emerging science of connectomics. But it is not the only one. For, just as every organism has a genome (the complete set of its genes, as encoded in its DNA), every organism with a nervous system has a connectome (the complete set of its nerve cells and the connections between them). In practice, of course, a connectome will change over the course of time as new connections form and old ones die. But that does not stop people like Dr Lichtman dreaming of a Human Connectome Project inspired by the success of the Human Genome Project....

...The cerebral cortex—the part of a mammal’s brain that thinks—is composed of 2mm-long units called cortical columns. Winfried Denk of the Max Planck Institute for Medical Research in Heidelberg, Germany, estimates that it would take a graduate student (the workhorse of all academic laboratories) about 130,000 years to reconstruct the circuitry of such a column. But efforts to automate the process are gaining ground.

... The result of all this effort, it is hoped, will be precise circuit-diagrams of brains. The first brains to be mapped will probably have belonged to mice. Besides being cheap and disposable, a mouse brain weighs half a gram and packs a mere 16m neurons. Human brains (1.4kg and 100 billion neurons) will come later, when all the wrinkles have been ironed out in rodents, and proper methods devised to analyse the results. But come they will. And when they do, the most complicated object in the known universe will begin to give up the secrets of how it really works.

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