Electricity from cells to brains

Communication and computation within cells relies, as we have seen, largely on chemical reactions between biomolecules and on the diffusive motion of these molecules. However, as multicellular organisms evolved, and the distribution of tasks between separate parts of the organism required rapid communication over much longer distances, a new kind of carrier had to be used. 

Hence the general stategy employed by multicellular organisms for long-range communication seems to be a hybridization between electrical and molecular informa- 

In higher organisms, neurons form brains, which can perform a lot of tasks beyond the capability of today s computers, such as rapid access associative memory. Just how brains compute and remember is nowadays, in the decade of the brain a matter of much research and even more debate. However, one hypothesis, which was once fashionable a few decades ago has been ruled out. The brain does not store information in the sequence of molecules. Although, of course, it uses molecular interactions for computation, it does not use biomolecules to encode or process datasets. Hence, a brain working on the basis of molecular computation remains still to be invented, although quite a few interesting components are provided by nature. 

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