[abeppu]

I think the distinction you're drawing between "the central nervous system" and "the brain" is mistaken here -- the brain is part of the CNS. This kind of reflex basically has to involve the brain b/c it involves both the visual system and the motor system i.e. there's not a fast path from the retina to moving your appendages etc that doesn't include the brain.

The "fully process" part is part of the story though -- e.g. perhaps some reactions use the dorsal stream based on peripheral vision while ventral stream is still waiting on a saccade and focus to get higher resolution foveal signals. But though these different pathways in the brain operate at different speeds, they're both still very much in the brain.

[ljsprague]

Some touch-based reflexes might avoid the higher parts of the brain though no?

[abeppu]

Yeah I think there are multiple documented cases of this, where especially well-practiced motor-plans seem to be 'pushed down', and if they're interrupted, correction can start faster than a round trip to the brain.

[trhway]

In this article you can see a typical and a "broken" "visual to amygdala fear shortcuts" (the "broken" is MRI of the famous climber Honnold)

https://assets.nautil.us/10086_6412121cbb2dc2cb9e460cfee7046...

https://nautil.us/the-strange-brain-of-the-worlds-greatest-s...

(the path is from the back of the head (V5?) where the visual nerve comes into brain)