Diane Pritchatt <diane at bnclib.demon.co.uk> wrote:
>Some of our staff were doing some research into making a visual cortex
>stimulator for the blind at one stage. It was explained to me that the
>'stars' or spots were caused by chemicals called phosphenes. Perhaps
>you could look into that further?
>Diane
Diane's 'stars' or spots are phosphenes. Phosphenes have nothing to do with
chemicals. A phosphene is a visual experience resulting from artificiial (e.g.
electrical or mechanic) stimulation of the eye or brain.
>In article <544tfg$7fk at highway.leidenuniv.nl>, Jeroen Schaap <Schaap at rul>lf2.medfac.leidenuniv.nl> writes
>>In article <v01540b00ae8b75cfde51@[192.197.250.46]>,
>>steven at MSHRI.ON.CA (Robert Steven) wrote:
>>[snip]
>>>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.
>>>>>[snip]
>>>-Rob Steven
>>>>>>>>>>Another idea, Oliver Sack researched aurea's during migraine attacks. So
>>it is possible that with a head bang you temporarilly deprive your
>>visual cortex of input after which this areas go and generate
>>chaotic-like patterns.
>>>>I have no refs for Sacks; I've only seen some tv-interview (extensive)
>>on dutch television and I have the dutch text of these interviews. 'Een
>>schiterend ongeluk' from 'uitgeverij Contact'.
>>>>Daniel Dennet has a certain point of view, that is 'vision-demons' just
>>go on with making 'pictures' and as a result you see stars; it's not
>>exactly what he is saying, but you may extract this from his story.
>>Sorry, it's a time ago I've read it. But the title is: 'Consiousness
>>explained'.
>>>>Jeroen
>--
>Diane Pritchatt
Groningen, the Netherlands
