Saturday, April 27, 2013

midnight aura

Olive the Cat wakes me up every morning sometime between 2 and 5, and I go put food in her bowl. This morning, at 2:30, I'm awakened by her scratching at the baseboard, and as I wake up I think I see fortification spectrum... turns out I'm about halfway through an aura. Left visual field, about 15 minutes in (noting for reference that the pain is on the right side, supraorbital nerve). I debated turning on the computer so I could record the remainder, but I think it was too far along to be worthwhile. The spectrum extended from fovea straight left, then arced downward. I watched it for a while - I'm still impressed at how straight it is at that point, I wonder if the CSD wave somehow gets caught up in the base of the calcarine sulcus.

The scotoma seemed very small, even when the wave was well into the periphery the blind region didn't seem thicker than the scintillations. The scintillations were very clear, whereas usually I don't see them very clearly - maybe because I was dark adapted the whole time, or my brain was in a sleepytime state, or maybe it was just a random thing. I did notice that closing my eyes, even though it didn't change the apparent luminance of the scene very much, made the phosphenes completely disappear for several seconds, and they would fade back into view only weakly, slowly. I couldn't go back to sleep for ~45 minutes. Ears were almost ringing, headache started. Minor, 5/10.

Yesterday, and maybe Thursday, several times, I noticed flashes, spots, in my periphery, and thought, 'something is up'. Yesterday afternoon, I'm sitting at my computer, reading text near the lower bezel, and I feel I see a phosphene or blind spot just below fixation, where the aura usually starts - it lasts ~10 seconds and disappears. Maybe that represented a false start? The cortex is weakly susceptible, and maybe there are false starts, and then it kicks off - or doesn't. Also, after the syncope episode, I've started to wonder if the tinnitus I get now and then is, at least sometimes, an aura - I had an episode yesterday.

I was dreaming about something as I woke up, and it seemed relevant somehow, but of course I've completely forgotten it now.

Wednesday, April 24, 2013

feeling very aggravated today, not going to say why. i want a new job. i said too much already.

intermittent intense photophobia the last couple of days, and much of today a strange buzzing distant feeling - could be that aggravation, but i'm voting prodrome. see what happens in the next few days.

ugh. is this even worth posting? i wrote a poem on patriot's day about the marathon bombing, but i'm not going to show it to you. it was four stanzas, four lines each, with a loose rhyme scheme as follows: xxxA, xxxB, ccxA xxxB. that's all you're getting.

i feel like my mind is a dismantled car engine, pieces scattered across the floor. is that how it seems to other people? my mind, i mean, is that how it seems to them, when they perceive it? what am i saying, when do others have an opportunity to perceive my mind? ugh. a dismantled engine scattered across the floor in a locked room, and the lights are too bright.

Friday, April 12, 2013


quick note:

went for the mri tonight; radiologist said everything looks ok, but wait to see what the neurologist says; and i can come get a copy of the pictures next week. mri was interesting, hypnotic, staring at a blank plastic surface inches from your face, keeping absolutely still, listening and feeling these musical, super loud rhythms coming from the machine.

interesting in a different way was what happened first: the nurse tried to put a contrast agent into my blood through a vein in my arm; she failed on the first time, sticking the needle into the vein and through the other side; the second time, she hit a nerve, and i went into vasovagal syncope.

everything started to tingle, my field of view started to fade, i broke into a sweat, i felt nauseated, and then

then, everything was black, and i didn't know anything or sense anything - yet i had some sort of minimal awareness. i had a vague feeling of waking up from a deep sleep in a place i didn't know. i remember feelings that i associate in some way with sunlight, trees, and mountains. i felt confused.

then, i started to feel my body - i was in a chair, but i couldn't move. why am i in a chair? where am i?

then i started to hear a shuffling sound, loud and abrasive, felt my body being rifled back and forth - the confusion was growing.

then my vision came back - when i asked her later, the nurse said my eyes were open all along, deviated down and leftward - and only then i remembered i was in the MRI clinic. at first i thought, when did i go to sleep? i wasn't sleepy.., and then i realized that i must have passed out. everything started to come back.

the nurse was calling for the doctor and others to come, and struggling to put a blood pressure meter on my arm. the sounds were all muffled for about 30 seconds or so, as though i had earplugs in. at the same time, there was intense tinnitus.

after a few minutes i felt normal again. the shuffling noise, i think, was blood rushing back into my ears, and maybe also the agitated movements of the nurse. i was soaked with sweat. they gave me a can of juice and an oxygen tube in my nose. i didn't notice anything interesting about the oxygen. i talked with the amused radiology resident, Amad, and we decided not to do the 'GAT', the contrast, unless the scan turned up something worrying, which it didn't.

this was the first time i've ever passed out, but i often get woozy from needles, getting blood drawn etc, and i stopped giving blood in college because each time the wooziness got worse - the last time i couldn't walk out of the clinic, had to lie down for 20 minutes. point is, this wasn't important, just weird.

so, the quick note is: order of losing consciousness - all at once. order of regaining consciousness - awareness of self, body, hearing, and vision. glad i've been reading those tononi papers - i would estimate my phi went something like this:

Thursday, April 11, 2013

physics and psychophysics

reading papers on "information integration theory" lately. up to this most recent one - barrett and seth, PLoS-CB 2011 - i had an okay grasp on the math, but now i'm considering skimming. the first author of this paper is a theoretical physicist by training, so i don't feel too bad that i can't quite take it. feeling a little bad led me to this train of thought:

in my field of psychophysics we use mathematics to describe human behaviors, with those behaviors driven by simple physical stimuli. some psychophysical models can be rather complicated, but the more complicated they get, the less realistic they get, because so to speak they inevitably start biting off more than they can chew. for example, channel theory is a bunch of mathematical objects, but they have to be fit to particular contexts. even a simple psychophysical rule or law involves constants that vary from person to person, from apparatus to apparatus.

no one in psychophysics should fool themselves into thinking that they can someday come down to a simultaneously correct and meaningful mathematical theory of whatever phenomenon they are studying, because every phenomenon is an artificially isolated part of a much more complicated whole, and the ways that the circumstances of the phenomenon can be varied are nearly infinite. but thankfully, no one in psychophysics does, i think, fool themselves this far; we recognize that mathematics is a good tool for getting a handle on what we are studying, at the same time that what we are studying is clearly variable in ways that we can only hope not to approximate too poorly. for us, mathematics is an operational description of what we're studying.

in physics, on the other hand, they have things down to the level where you will hear physicists talk about mathematical objects and physical phenomena as more-or-less the same thing. quarks and bosons, gravity and magnetic fields, are things that are only really understood through mathematics. my knowledge of physics mostly comes from reading feynman and hawking, and watching random lectures (and once having been a physics undergrad, briefly), so it's not like i have anything like an up-close viewpoint of the physicist's perspective, but i think this viewpoint is plainly very popular. john wheeler talked about the root of all reality being information, which is only a mathematical construction as far as the human mind is concerned - obviously he felt the isomorphism was close enough to make this sort of claim.

apparently, for physicists to achieve this nearly perfect mathematical description of physical reality, the mathematics had to get pretty complicated. so, when you read a paper by a physicist on a topic that you feel like you should have a good handle on - you're a psychologist, the topic is consciousness - you have quite a bit of difficulty in parsing his descriptions, even though you realize that he's not talking about anything approaching the sophistication of string theory or QED.

so.. i'll go back and give it another 20 minutes, maybe make it another half-page. also, tomorrow night i'm having an MRI of my neck, to check for dissections in my carotid arteries. fun fun fun.

(only now did i realize that this topic would have been perfect for a new dialogue.. maybe i will recast it?)

Tuesday, April 09, 2013

visual cortex is weird

Migraine weirdness:
1. The weekend after the AF, neck was constantly sore in a weird way. No sign of headache. Soreness disappeared yesterday (Monday).
2. Monday saw waves of photophobia, but it never lasted more than twenty minutes or so, or it was low-level enough that I could adapt to it, and wouldn't notice until the ambient light changed.
3. Today, a bit of photophobia and a faint headache, slightly nauseated. Am I just hyper-sensitive? Also, this morning when I awoke, saw the m-scaled lattice that I've mentioned before; it flashes on for just a few hundred milliseconds, and fades as the morning-light bedroom scene comes into view. I would say it looks most like Form Constant III as described by Bressloff et al (no I am not on any drugs, though Bressloff prefers to refer to drug-induced hallucinations):

(This image is from Bressloff et al's 2002 Neural Computation paper. Note the coincidental opposite symmetry between this kind of m-scaled 'spiral' pattern and the ancestor map in the previous post, which can be seen as another kind of spiral lattice - something like what you'd get if you plotted a flat lattice in the visual field and looked it it in cortical space.)

Also, to reiterate an observation I made in the AF post, in light of reading all this stuff about integrated information and consciousness over the past few days: migraine scotoma are invisible, unlike the disturbingly visible grayness I saw when my left retina stopped working. The normal explanation for the invisibility of cortical scotoma is that it is "filled in", which I've always felt was fishy.. I know it's well-studied, and now I'll have to read about it.

My feeling is that there is no filling in, at least not in the way it's usually talked about, but rather that the scotoma is a scotoma in visual space period - if you don't see the space, you don't see any blankness, and you see the scene continue directly from one side to the other, not knowing any better. Maybe it's hard to justify this intuition, but I think it's similar to noting (as hemianopia patients do) that beyond the edges of the visual field, there's not an expanse of nothingness, but rather no expanse at all. If there is no expanse, there is no edge, so you get the strange condition of not being able to see the boundaries of your own visual field, because the boundary would have to be defined as between two expanses. With a proper mapping between visual direction and field location, you can be properly aware of the geometry of the visible field, without any need for it to be bounded. (Put another way, topologically, the space behind my head is equivalent to a hole in the visual field - if I can't perceive that space as being bounded by the same boundary as the visible field, why should I be able to see the boundaries, and the invisible expanse, of a cortical scotoma?)

Friday, April 05, 2013

ancestral geography

I've not been working on this too much, but I took a couple of hours yesterday to fill in another space in my records, and then I got the idea to make the figure you see here. The tree plot is a map of all my known ancestors, with their distances from the center scaled to their birth years, relative to my birth year of 1979. Red lines are women, blue lines are men. The rings are labeled as to year.

The colored backgrounds indicate - by correspondence with the geographical map on the right - where these people were born, or at least where they spent their early lives. Where they combined to produce the next generation tells you, more or less, where they wound up.

The dominant region is clearly West Tennessee, whence hailed my mother's mother's people and my father's father's people, going back to before the Civil War (the double ring). My mother and many of her father's people came from Southeast Tennessee, part of the crimson. My father's mother's father came from Michigan, just across the border from the source of most of his family in northern Indiana, indicated by the magenta.

There's a lot of northern South Carolina, in the region of Spartanburg and, just across the border in southern North Carolina in Mecklenburg county, indicated by the yellow. A branch of my mother's mother's family had come through Kentucky, the light green.

Middle Tennessee, the olive green, has generated a number of us, including a part of my mother's father's family (the ill-fated Lewis Morgan and his mother Nancy Sewell, who must have been in the first generation born in Nashville), and my father and myself at the center.

If you follow this further out (I stopped 6 generations back, at the four-greats grandparents level), everyone that I know of is in Virginia (you can see those touches of orange in the periphery), South Carolina, Pennsylvania, Massachusetts, or Ireland. It is amazing what you can learn from the internet!

Thursday, April 04, 2013

amaurosis fugax

Yesterday, about 5 o'clock, sitting at my desk. Go to stretch, arms behind me, pulling on my shoulder, started to greyout (I don't know a better term for this - whatever you call the visual consequence of ocular hypotension) just a bit - which is normal for me when I stretch after having sat still for too long - and instead of resolving the greyout continues. My field of view starts to fade in blotches, but I can still see - I realize that it's just in one eye. I close one, then the other, and now I know that the view from my left eye is fading.

I jump up and run to Eli's office, and by this time, my left eye view is almost completely blank, except for a space around the fovea, maybe 5° wide and 2° high. This makes sense - the foveal blood supply comes from the choroid, not the apparently blocked ophthalmic artery. The blankness is plainly visible as a flat gray. This is different from the scotoma of the migraine aura, which is as visible as the space behind my head. The boundary between the visible center and the blankness is shimmering, flickering, like the smoldering edge of slowly burning paper. Eli gets his ophthalmoscope to try and see what's happening, and the superior field starts to fade back into view.

It's then stable for about a minute, the inferior field is blank gray, and there's a smoldering horizontal boundary between the superior and inferior fields. I see some strange parafoveal phosphenes, like super-high contrast arcs. Eli is shining a light in my eye, and I'm shocked to realize that this bright light is totally failing to punch through the grayness. I wave my hand in the scotoma and though I can't see it, I feel like I can sense the motion.

The inferior nasal field returns, very subtly, so that I just realize it's back without noticing much about how it returns. It's patchy but quick - then the inferior temporal field returns. After this point, I can't find any other blind areas; everything has returned. In fact, I can't find any obvious differences between the two eyes, though at this time Eli is urging me to go to the ER to get examined. My heart is pounding and my head is starting to hurt. For the next 10-15 minutes, as I'm on my way to the hospital, I can see my pulse with the left eye, but then no more, and everything is back to normal.

Eli gets me in to see someone at MEEI, and I'm examined by an ophthalmology resident. The doctor pronounces this a case of ocular migraine, which as far as I understand means "we don't know, but everything looks ok".

Typical Wednesday afternoon. Hey, April is here!

**edit @ 16:21**

While I don't like the 'migraine' label, I guess I can't deny that there might be something to it. It is unknown what the proximal cause of a migraine is, though it's definitely associated with cortical spreading depression in the brain, the physiological correlate of a migraine aura; the current consensus seems to be that the CSD produces substances that inflame tissues in the brain, which then is perceived as pain, and which fits with the experience of headache beginning partway through the aura.

But what causes the CSD? One sure way to cause it is to deprive an area of cortex of blood - stroke causes CSD even in areas of cortex that still have blood supply but happen to be nearby the ischemic areas. So it could be that the aura/CSD is caused by a very local, transient ischemia. The ischemia can't be very large or long-lived because there don't tend to be other symptoms accompanying the well-described auras.

I would be happy if I could confirm that this episode is somehow related to the migraines, i.e. that I experienced a spasm of the ophthalmic artery of the same sort that I usually experience on a much smaller scale, and deeper in my brain, immediately preceding a migraine aura. I also do not feel much affection for this experience, in contrast to the fascinating auras - I hope this does not happen repeatedly, because I don't think it can be good for the retina to periodically starve it of oxygen.