Saturday, December 15, 2007

Immune system may target some brain synapses

A baby's brain has a lot of work to do, growing more neurons and connections. Later, a growing child's brain begins to pare down these connections until it develops into the streamlined brain of an adult.

Now researchers at the Stanford University School of Medicine have discovered the sculptor behind that paring process: the immune system.

The value of this discovery goes beyond understanding how connections are weeded out in a normal, developing brain. The finding could also help explain some neurodegenerative disorders - such as glaucoma, Alzheimer's disease and multiple sclerosis - that result from the loss of too many neuronal connections, which are known as synapses.

But according to an unknown model of the brain (see
an algorithm such as Gaussian adaptation may - according to its theory - simultaneously maximize the mean fitness and disorder (entropy, average information) of signal patterns, thus climbing a mental landscape efficiently obeying the Hebbian rule of associative learning. This disorder and average information may be of crucial importance to the success of the process.

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