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That is so interesting!  I guess if someone's "switchboard" is organized in such a way that an input signal gets transmitted to more than one major box (i.e. visual and olfactory) at the same time, it would be capable of producing outputs similar to the sensations experienced by those individuals who are synesthetic (like "tasting" a particular color). 

One thing about your answer really stood out to me:  you describe an "errant" axon that somehow picks up a signal from the "normal" pathway, and allows it to continue along two separate cables.  It struck me that, at least in synesthetic individuals, these "errant" pathways are fixed-a particular input always leads to THE SAME abnormal output (for example, the individual will always experience the same taste sensation upon seeing a particular color).  This makes sense in terms of the switchboard model, because the "circuits" have been connected in a particular way in that individual since the nervous system developed. 

That said, some further questions: how then do we explain nervous disorders that seem to indicate, for lack of a better term, "random firing", so that it is impossible to predict the pattern of output that a person will experience?  Also, in class, we touched on the possibility that neuron connections are capable of changing, and that such a change would cause a change in behavior.  Are "random firing" types of disorders caused by changes in neuron connections?  Why is it that some pathways seem to be more prone to change than others (ex: thought pathways are constantly modified, whereas a synesthetic person who sees the letter "A" as red is very unlikely to all of a sudden perceive it as blue)?  I would like to discuss these ideas more in class.