Professor Seth Grant, an expert in the molecular mechanism of learning and memory at Edinburgh University, told BBC News Online that PKM was a particular version of an enzyme called protein kinase C (PKC) that had long been implicated in learning.

BBC: Scientists boost memory power

Short-term memory, he discovered, relies on the phosphorylation mechanism described by Dr Greengard.

ECONOMIST: The Nobel prizes

Schwartz believed memory maintenance could be boiled down to a simple molecular mechanism, but it was no easy matter to find the important one.

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