Just thinking of pain, happiness etc. as things going on in your brain misses a lot of rather interesting things to do with these which more than likely will not be explained well at the neural level for a long long time to come. A well known example is phantom-limb syndrome, where people experience pain from limbs that don’t exist. Acupuncture and hypnosis, where the experience of pain can be massively moderated in some people are two other good examples. What these things suggest is that there is not necessarily a particularly direct connection between pain and our conscious experience of it. Thus, treating pain like “a mere signal to her brain” is like treating any other thought you have as a mere signal to the brain (of course, everything ends up there in the end). Simply because pain appears direct and, say, posturing about dualism or Rudds bail-out package doesn’t, doesn’t mean that that both arn’t rather complicated in terms of actually how they relate to the human experience of them.

I think that your son’s comments reflect what has happened since a lot of modern folk have stopped believing in the old Cartesian “ghost in the machine”. Too much of an awareness or belief that your mental state is simply a derivative of the fleeting alignment of molecules in your brain can lead to existential doubt as to the value of your own consciousness. It is, to my mind, de-humanising.

But on the other hand, it can help in some situations, such as your daughter’s. But also, for those suffering some forms of mental illness, being aware that you’re the victim of a series of neurochemical events beyond your control is surely better than believing that (eg) you are being controlled by secret radio waves being beamed into your head. (Or, if you are depressed, from blaming yourself somehow for your depression.)

Still, I guess you can believe that the sensible “real” you is just being overcome by the illness, which is what those of us who still ascribe to some kind of dualism still believe.