Full Idea
When you get maps all over the brain signalling to each other by reentry you have what Edelman calls 'global mapping', and this allows the system not only to have perceptual categories and generalisation, but also to coordinate perception and action.
Clarification
'Reentry' is interchange of signals in the brain
Gist of Idea
Concepts and generalisations result from brain 'global mapping' by 'reentry'
Source
report of G Edelman / G Tononi (Consciousness: matter becomes imagination [2000]) by John Searle - The Mystery of Consciousness Ch.3
Book Reference
Searle,John R.: 'The Mystery of Consciousness' [Granta 1997], p.42
A Reaction
This is the nearest we have got to a proper scientific account of thought (as opposed to untested speculation about Turing machines). Something like this account must be right. A concept is a sustained process, not a static item.