Speaker For The Diodes - April 8th, 2008

05:33 am - QotD

"The ways of being human are bounded but infinite." -- Larry Niven

[edited to add: ]

"...and hence, fractal!" -- metahacker, 2008-04-08

08:01 am - Trans-Bingo

http://arionhunter.insanejournal.com/6918.html

02:45 pm - Reverse-Enginering My Cat

I was unable to fall asleep last night. So y'all get a post like this'n.

The more I learn about feline vision, the more I want to know about feline neurology and what learned and hardwired techniques are used to compensate for the limitations of their eyes (including the extent to which cats augment vision with sonolocation when leaping, pouncing, and swatting at moving targets).

According to what I've found on the web, feline visual acuity is in the 20/200 range, they can't focus as close as humans can, and the feline retina lacks the hi-def center region that the human retina has. (I'm not sure whether distortions caused by the vertical-slit pupil matter, because when I see a cat about to pounce, the pupils are usually open wide enough to be round -- but I welcome confirmation or contradiction of that from other observers.) But they're successful predators, and sometimes execute some impressive moves in pursuit of thrown or dangled toys (and, in some cases, fingers and toes). I wanna know how they do it, what kind of filters are implemented in the retina and optic nerve, what preprocessing is done in the brain, and what learned techniques cats employ to compensate for apparently having relatively low-res eyes (a price of their very useful low-light capabilities). Based on behaviour, I would have thought they see about as well as we do, other than that nifty bit about only needing one seventh as much light, anyhow, so they don't appear to be handicapped by the trade-offs in the eyes they wound up with.[*]

(Then again, there are still some things I'd like to understand better about how we see, as well. I could've sworn I'd posted recently about the business of human vision being able to resolve misalignments of line segments where the offset in the image is well below the 'pixel size' of the retina, and about my brain doing a 'software zoom' thing that feels like it's in my eyes even though I'm sure it's in my brain -- but at the moment I can't find those entries. Did I start writing them and never finish/post them? I suspect the answers there are related to my cat-vision questions. And maybe that "batters can't see the ball any more by the time they swing" business as well.)

Unfortunately, two of the things I want are a super spiffy remote functional-MRI setup -- so that it can map brain activity while the subject is leaping and pouncing and swatting at things -- and a boatload of neurology larnin' so I'd have a prayer of making sense of the fMRI data. And neither of those is going to be very easy to acquire. ( realinterrobang suggested I invent remote-MRI ... I'm wondering whether the experiments could just be conducted inside the MRI machine with the cat un-restrained, and write a program to key in on a distinctive skull feature or something to re-algn the images afterward to compensate for the cat's movement around the chamber.)

So for now I'm trying to reverse-engineer my cat by taking note of exactly what kinds of mistakes she makes in the catching-small-missiles department, and hoping that there'll be patterns in the data obvious enough for even me to figure out. Not that the results will be likely to be unambiguous anyhow (did they ever figure out which of the competing hypotheses about how humans catch fly balls was correct?), but it's a start, and a lot cheaper than an MRI setup.[**]

In the meantime, of course, if there are any professional or amateur veterinary neurologists reading this ( anusara, do you still check in here ever?), drop me some clues, eh? Useful search terms at least? Experiments to suggest (that don't involve surgery, of course)?

[*] This brings to mind another question that I didn't think of until I started typing this up: how far back did the feline eye features evolve, and what was the eye they evolved from like? (And yes, I'm aware that I'm probably horribly oversimplifying the very question, but you can translate to what I meant to ask, right?)

[**] I mean cheaper than renting time on one, of course; I don't think the machine would fit through my doorways, and I bet it draws more current than my house wiring can supply.