Hitting head, seeing stars

Robert Steven steven at MSHRI.ON.CA
Thu Oct 17 01:38:47 EST 1996


>I write for Popular Science magazine, and for a column called FYI, I'm
>trying to answer a reader's question:
>
>      When you hit your head and see "stars," what are you really seeing?
>
>Can anyone point me to an answer for that? I've tried a couple
>neurologists/head injury experts, but haven't come up with much of an
>explanation.
>
>Many thanks.
>
>PJ Skerrett
>skerrett at world.std.com

I know that the neurons in the eye are capable of responding to a physical
stimulus. If you poke your eye in the right place, for example, the neurons are
stimulated and you will see a spot in your visual field. So I guess if you
bang your head you could just be physically stimulating the neurons in your
eyes. Or
maybe the neurons in the visual cortex are physically stimulated by a hit to the
head resulting in the perception of spots or stars in the visual field.

Could also involve blood flow. Transient restrictions in blood flow (to the
brain? or retina?) will generate spots before your eyes.

Sorry no references.

Back to eye poking. You can confirm for yourself that what you see is inverted
upside down and left to right as it passes through the lens of the eye to the
back of the retina. If you press (gently - and be careful!) on the top
right of one of your eyes (while looking down, so you can get close to the
back of your
eye where the retina is) you'll see a spot in the bottom left of your visual
field.

-Rob Steven





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