> > So the EM fields account for the experiences that accompany the brain processes. A kind of epiphenomena. > > So why don't my experiences change when I'm in an MRI? >
I haven't been through the detail - I hope to verify this in my simulations to come.... but... As far as I am aware MRI magnets are DC and the technique uses nuclear spin alignment and measures re-radiated RF as the spins respond to incident RF. The RF is very high frequency and wont have any net effect on the neural processes, which are comparatively large scale and very slow. Although it might heat up the material a bit and affect things that way. Depends on power levels. But the effects of superimposed magnetic fields I think could have multiple effects. There's a possible effect on (a) action potential propogation and (b) a possible effect on the field expressions responsible for the subjective qualities. (a) My initial feeling is that the static fields won't have any net effect because the geometries of the field expression are symmetrical, so propogation may be affected on either side of the axon, but the wave still travels via the unaffected portions. But it could be more subtle in that you could, depending on field orientation, effect localised arrestation which might stop processing...and you'd find you couldn't do something as well or could do something better than before. If you varied the field strength over time and localised its affects.... as in TMS you can get effects like this I think. (b) Qualia generation... this is a relationship of the fields with space. To alter them I think you'd have to have a very fast change in a specific direction, - a magnetic gradient significant over the thickness of the cortex or less. Not sure how you'd do this. The effects could be very subtle - cognitive functions altered - learning better/worse...remembering better worse... short term, long term.... But I'm pretty sure that in large scale static fields the net effect is 'common mode', and the processes are 'differential', so nothing will happen. I spent a lot of time in an aluminium potline where the fields stopped my watch and killed floppy discs. Although computer hard disks were OK. Electron gun CRTs were affected but LCD screens weren't. Very complex situation. >> Did you read the painting metaphor? I can't say it any clearer. > > I read it - makes no sense to me. > > Brent Meeker > Shame. Cheers colin --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Everything List" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/everything-list?hl=en -~----------~----~----~----~------~----~------~--~---
