Hitting head, seeing stars
jonesmat at ohsu.edu
Fri Oct 18 12:17:00 EST 1996
In article <Pine.SGI.3.94.961017082443.17491H-100000 at proteus> Joseph
Strout, jstrout at ucsd.edu writes:
>many other stimuli.) The cells are not activated in any coherent
>so the result appears as random points of light.
I've "seen stars" on occassion just by standing up too quickly, with no
physical jolt to my head at all. I think the two explanations above about
firing of cells in visual cortex (and maybe other cells in the pathway
between retina and cortex) are probably right on. The phenomenon can be
caused by any unusual state change of the system: a blow to the head,
transient anoxia (from standing up without taking a deep breath), from
taking drugs like LSD, or whatever.
What I find really interesting is that it's not just random points of
"light", It's randomly *moving* points of light. The stars sort of swim
around in little wavy arcs. They appear to be generated at random
locations in the visual field, then swim a little way, then fade out
quickly, but not instantaneously. It's really pretty cool. So my theory
about this is that we're not just "seeing" some neurons firing, but
actually watching the propagation of activity in waves across fields of
neurons through the tissue. As a thumbnail estimate, I'd say that each
little star occupies maybe one tenth of one percent of my entire visual
field, or less. They don't seem to change much in size as they swim
around, suggesting that the propagating wave of activity involves an
approximately constant number of neurons as it travels (maybe this is too
So does anyone know how many neurons, or what fraction of the area of
visual cortex, accounts for one tenth of one percent of the visual field?
Is it just one tenth of one percent of visual cortex area? And how many
neurons (principal, glutamatergic neurons) is that?
Interesting subject, seeing stars...
P.S. - Does anybody else notice this movement, or is it just me? Also,
has anybody noticed what happens when two stars cross paths? Do they
annihilate each other (as many disturbances in excitable media do), or do
they each just keep on going?
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