Hitting head, seeing stars

Jeroen Schaap Schaap at rullf2.medfac.leidenuniv.nl
Mon Oct 21 08:24:45 EST 1996


In article <2096.6867T967T1389 at cabin.llcc.cc.il.us>,
   bkemler at cabin.llcc.cc.il.us (Bill Kemler) wrote:
[snip]
>Hitting your head is an example of mechanical stimulation triggering
>these visual sensations (as is rubbing your eyes hard). What kind of
>visual experience you will have will depend on which cells in cortex 
are
>most effected by the stimulation. The visual cortex contains 
specialized cells called "feature detectors".
>Each type of feature detector normally reacts most strongly to a
[snip
>Bill Kemler   2.31¹
>
FROM: "Jason Fox" <jwfox at winternet.com>
[snip]
>So you're saying that if done to a child, the visual cortex would 
>interpret
>sound waves and the auditory light waves? Sounds interesting... If you
>asked the subject what lighning sounded like, what would they discribe? 
>Or
>if you did it to an adult? The question comes up though if those brain
>functions are determined genetically or through environment. If the 
>second,
>then you're right, but if the first, "sounds" like you are "seeing" 
>things
>wrong. :)
Why make it so binair? Some could be genetically, some learned. Anyhow, 
I think you make a giant 'Cartesian' argument here. Visual information 
=== visual experience, there can't exist such a place in the brain where 
some pathways are 'recognized' and labelled "Hey, this is visual". At 
least if one adopts the same line Denett has. Read 'Consiousness 
explained'. 
>- Jason Fox   -   jwox at winternet.com          


I would like to turn it a little bit around. Why would banging your head 
etc actually trigger (excite) neuronal events? It is not neccesary and 
in contradiction to absence of simular and/or parallel events for other 
sensory systems. Why would those bangs or those chemicals only trigger 
receptors in the eye? 
	In what extent is rubbing your eye equivalent to banging your 
head? Eye-rubbing is more site-specific, I would say, but also a 
complete different event. Higher pressure at the site of the 
photoreceptors maybe with other physical parameters of importance. But 
what happens after a head bang? A lot of things, but as far as I can 
imagine, no increase of local pressure on the retina. In conclusion, two 
completely unrelated (at first glance) events cause the same subjective 
experience. (Is it the same at all? Maybe, maybe not.)
	Another conclusion, it is not the actual information coming from 
the photoreceptors that eventually gives rise to the stars, because 
directly after them a lot of downstream processing occurs. Even signals 
'surfing' the optic tract are not likely to be specifically excited by 
headbanging. So somewhere in the head a bang has the same effect as 
doing something like rubbing your eye. I would like to think this 'site' 
as being those area's that interpret visual information at some higher 
level. (with very diffuse borders). 
	At least I can imagine depriving those areas from cohorent 
information can be accomplished by both eye rubbing and head banging and 
chemicals etc. Psychedelics are known to exert mostly inhibitory 
effects, could be consistent with a headbang deminishing all neuronal 
activity. All this eventually leading to pattern generating mechanisms 
to be triggered at will, experienced like stars. Again, if you think in 
Dennett's way. In this, Lee's (FROM: lkh at mail.cei.net (Lee Kent 
Hempfling)) balancing mechanism can explain why those mechanisms are 
triggered at all.

Maybe a headbang isn't a headbang after all. A deterministic catalog 
could be: Bangs on visual cortex, on midbrain (unconsiousness), on 
auditory cortex, sensory cortex. Has anybody experience with which kind 
of headbang you would create a visual hallicunation? 

:-)

Jeroen



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