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visual detail

daan daanBACHvdb at wins.uva.nl
Mon Nov 8 17:03:53 EST 1999


WHOOO! No shit! So a single photon activating a single receptor actually
(poosibly) reaches the inner part of the brain? I thought that because
of these 'convergent pathways' I read about such activation would get
snown under by other inputs!

Daan

Matt Jones schreef:
> 
> In article <38260B37.C0491951 at wins.uva.nl> daan, daanBACHvdb at wins.uva.nl
> writes:
> >Now my question is - because I cannot find anything about it - does
> >anyone know wether something like that also exists for detail (ie
> >microscopic features)? In other words: how is detail preserved in the
> >afferent visual pathway?
> 
> This is a great question. I don't know the answer, but here's a cute
> little factoid about the extent to which detail is actually preserved:
> 
> Photoreceptors in the eye can respond to a single photon. It turns out
> that in psychophysical experiments on humans,  subjects can make
> behavioural decisions based on whether or not a single photon was
> detected. Thus, however it happens, detail is at least partially
> represented at the highest levels of brain function with a resolution
> that -can- approach detection of a single photon.  That also implies that
> all the processing steps downstream of photon detection don't necessarily
> add any extra noise, which is practically an engineering miracle.
> 
> Cheers,
> 
> Matt

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