Connectome


There is a new project (like the human genome project) called the human connectome project to which the NIH has given $30 million. The hope is to map the connections in the whole human nervous system. Some new experimental procedures seem to make this possible although it will take an enormous amount of work. It also needs the sort of powerful computer systems that now exist to build the map and make it usable – the amount of data with be enormous.

Only some corners have been mapped so far. The indications from these starts are that the brain is organized more like a flat network and less like a hierarchy. This is in line with recent thinking and moving away from top-down/bottom-up thinking. There seems to be no top and no bottom. Also being confirmed is the notions of loops and circuits, structures involved in feedback.

When I was young, the brain is envisaged as a telephone exchange, then as a computer, but now the analogy is with the internet. The idea is that there are a large number of ways to get from any one neuron to another and back again. We are now seeing the first experimental evidence for this new way of seeing the brain.

The basic connections are made during the development of the nervous system. There is a complicated dance of migrating cells forming layers, sheets, grids and knots. Mistakes in this process cause some very serious conditions. Then, with the person born into and living in the real world, this structure of connections is tailored in each individual. Connections are lost and gained to fit a particular person’s age, history, surroundings, culture, language and so on. The original basic architecture is not lost in this tailoring and learning process. Useful links are strengthened and useless ones weakened or lost, but the structure remains.

We can assume that there will be surprises along the way to this map just as there were with the human genome project. Perhaps we will be able to see the architecture of consciousness in a few years.

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