Monday, June 25, 2012

scintillating scotoma 3

another event is now shimmering its way out into my far left periphery. i used the dynamic perimetry program i had written; seems to work. some improvements can be made; need to include warnings or preventions for the cursor going out of screen. should implement cursor size info/adjustment. maybe cursor color or shape.

i mention the last two because definitely, there is a general sort of aftereffect. it's scotoma-like, but with no clear location of the scotoma; i.e., it feels like things are missing, e.g. if i put my hand out about 15-20 degrees left, stuff just feels kind of scrambled. actually, there is definitely a blind spot about 30 degrees left, i just found it. this is too far to measure with this screen; perimetry stops at ~20 degrees, i guess.

again, i don't know what the precursors were. been depressed all weekend (see previous post); saw some funny spots yesterday, and got preoccupied with some really visible floaters yesterday afternoon at tkd, which is probably unrelated. seems like the main indicator is just a superstitious feeling that "i wonder if it's going to happen again". maybe that's the CSD running through my frontal lobe somewhere.

note that i'm basically having a monthly period: the first of these (that i recorded here) was April 24, then May 28, and now it's June 25 (24).

i've been meaning for a while to list the other occasions that i can remember. i may be able to remember them all. before these past three, it happened twice earlier this year: once was during, uh, sex, which was weird, in China (within a few days of new years), and the second was on a sunday afternoon in late january or early february, when i was on my way to tkd, walking around cleveland circle.

before that, probably have to go back a year. it's happened several times with me just sitting here at my computer; probably half the times. i announced a few on facebook. i woke up once, early last year, with the SS starting right off. makes me wonder if it happens sometimes when i'm sleeping. it's happened after sex a couple of times. only once in the lab, i think, after j** checking my eyes. except for that morning one, i think it's almost always at night.

i would guess that, all together, this has happened 10-15 times in the last 2.5 years. until now, i don't think it had happened in summertime, only winter and spring. lots of headaches, maybe biweekly on average, without interesting symptoms.

i think these map data will be usable, and better quality than the paint drawings. not as pretty, but i can just generate post hoc pictures. i'll process them in the next couple of days, probably tomorrow. basically, it seemed very similar to the last two times, except that after the first minute or two of scotoma (again, i noticed it had started because, suddenly, i couldn't read), which i managed to record, the scotoma disappeared, or at least i couldn't find it. i thought maybe i had scared it away, but then it returned, right on track. anyways, update later when maps and stats are done.


some plots: sorry, didn't label any axes. descriptions accompany each:

This is the progression in spatial coordinates. color represents time in minutes, which you see in the colorbar. i also tied marker size to time, to help represent the thickening of the scotoma with time. 

This is progression in logpolar coordinates; x-axis is degrees from leftwards (in the last post, i was coding angle relative to 'up'), y-axis is log(degecc + 1). now it looks a lot more like a straight wave, though there is a bend to it, as if the wave has a 160° trailing angle. maybe that would be straighter with a more realistic cortical space transform? maybe not. i'll get around to finding out later this summer.

This last one is just binning the previous plot into 10° strips, plotting logecc+1 against time (like in the previous headache post). if i assume that the speed of the wave is closest to the fastest estimate that i get from these kinds of fits (it must be faster, since i'm only measuring at an angle to the wave), then i estimate that for this event, the speed of the wave was at least 0.248 logecc+1 / min. this compares with estimates of 0.250 and 0.258 for the last two events (i cited a lower number last time; that was the median, this is the max). once i learn to transform logpolar into v1 coordinates, i'll bother to do the extra geometry to measure the true transverse speed of the wave.

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