I don't know if quantum effects are an "important part of brain function".

But it's plausible there could be interference or stimulation of the function of the brain.

Strong magnetic fields can already affect the brain.

And in space, astronauts have been able to "see" cosmic rays, which are direct stimulation of neurons, that happen to be associated with vision:

https://en.wikipedia.org/wiki/Cosmic_ray_visual_phenomena

(on the other hand, guess what part of me is actually thinking up this comment)