Hitting head, seeing stars

Jan Nauta J.Nauta at uni4nn.iaf.nl
Sat Oct 19 10:10:52 EST 1996

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'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@[]>,
>>   steven at MSHRI.ON.CA (Robert Steven) wrote:
>>>I know that the neurons in the eye are capable of responding to a 
>>>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 
>>>bang your head you could just be physically stimulating the neurons in 
>>>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 
>>>brain? or retina?) will generate spots before your eyes.
>>>Sorry no references.
>>>-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 

>Diane Pritchatt

Groningen, the Netherlands

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