Wednesday, July 04, 2012

scintillating scotoma 3.b

I just can't let this go. Maybe this is as far as I can get with it for the time being. I wasn't satisfied with the straight-line model of the CSD wave that I had been playing with, because there was just no straightforward way of figuring out direction, origin, speed, etc. But I had a great idea: say the wave is like a surface wave, with a point origin, spreading out in every direction at a the same speed. Maybe this isn't true; it may be that the phenomenon is limited to V1; it may be that the origin is, e.g., the interface between cortical areas; it may be that the speed or direction varies. The first isn't a problem, but if we assume the second two (point origin, constant velocity) are true, or close to true, then we can come up with the simple model you see in the gif above: according to my June 24 data (fit with a lazy grid search), the CSD is a surface wave, traveling at (exactly!) 3mm/min, arising within about 3mm of the V1/V2 border, near the foveal confluence.

I'm not going to go into detail here about the spatial properties of the wave. It's simple, that's enough for you.

Anyways, nothing crazy here; this is all consistent so far with what I understand of the published research so far. It's a lot of fun figuring out how to create and convert all these maps, and it's amazing just how solid those parameter estimates are given the data. Sometime soon I'll look deeper into it, hopefully I can put it off for a while.

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