I remember over 13 years ago, this was a topic on brain talk. The conclusion was that our olfactory bulb of neurons was being "recruited" by some signalling process whereby the cells that were normally devoted to the task of molecular recognition of odour molecules via the nasal passage, were somehow " converted into dopamine producing and or enhancing function, by an unknown mechanism. Peg, I don't have any idea why your particulate case of " anosmia"is specific to the perception of "phantom smells" , all I can say is that what was once a very intense sense for myself has diminished to the point of being muted to almost nothing..