KPJ <kpj@sics.se> writes:
> If one goes into bright sunlight from a dark area,
> then this means that the eyes will start to water,
> as a standard biological eye protection procedure.
>
> The excess water (``tears'') moves through the tear
> channels into the inside of the nose. This occurs
> e.g. when people cry and thus have to blow their noses.
>
> Could this explain the sneezing reaction you refer to?
No, the photic sneeze appears to be due to an accidental connection in
the trigeminal nucleus in the brainstem between some axons from the
eye and the nose; the system thinks the strong light signal is an
irritation signal and activates the sneezing effect. Although the tear
factor does probably play a part too.
-- ----------------------------------------------------------------------- Anders Sandberg Towards Ascension! asa@nada.kth.se http://www.nada.kth.se/~asa/ GCS/M/S/O d++ -p+ c++++ !l u+ e++ m++ s+/+ n--- h+/* f+ g+ w++ t+ r+ !y
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