[Pocketfuzz (OP)]

I'm curious about this because in humans, our vision takes a while (post-birth) to straighten itself out and for the eyes to learn how to invert the image of the world properly. But after our eyes learn to invert images, they don't go back to an inverted view. However, bats not only sleep upside down, they walk around, mate, give birth, yadda yadda upside down. And yet when they fly they're right-side up like birds...so how do a bat's eyes/brain continually flip the image of the world they're in? Or are they simply really good at navigating with the world flipped in any direction? Are their eyes oriented to flip the world ground-down like humans and other mammals? Or is it predominantly ground-up and flipped while they're in flight?

I know this question may sound mad unclear, so please ask if it sounds really confusing or I've missed something. I can't find any information on it, as far as non-echolocating bats go, so any thoughts or things you've seen is cool! TIA

[chris]

Lovely question; and - excuse the pun - at first glance it looks like this would be a problem, but that's not actually how the visual system works or is wired.

In mammals, of which bats are an example, the right side of the brain decodes and presents to consciousness everything on the left hand side of the body, and vice versa. In other words, the right side of my brain is "seeing" what's on my left and my left brain is "seeing" what's on my right.

But this doesn't mean it's simply a case of connecting my left eye to my right brain and my right eye to my left brain because, if you cover up one of your own eyes, you'll literally see for yourself that each eye makes a contribution to both "sides" of the visual world.

To sort this out, each side of the brain has to mix the inputs from both eyes in the right way. At the back of a human brain, where vision is processed, is the "striate" or "stripey" cortex. If you follow the nerve connections into this area, you can see that these stripes correspond to inputs from alternate eyes; so there is a right eye stripe then a left eye stripe and so on. During early post-natal life, when the visual system is maturing, the two eyes "fight" for control of these "ocular dominance columns". To do this, they need normal visual input from each eye. It's this competing activity that drives the maturation of the system. The orientation of the animal is actually less important, because both eyes get the same inverted / right way up view of the world.

In terms of learning what is the right way up or down, this is merely a learned response. Humans that wear inverting prisms for a period of time can "normalise" to being in an apparently upside down world, and then re-normalise to seeing things the right way up again when the goggles are removed.

I suspect that bats will have the same capacity, although they also place a much greater emphasis (at least the smaller insectivorous varieties) on echo location because, being night-active, there isn't a lot of light about anyway. That said, the visual acuity of a rat is, on average, poorer than many bats, so the saying "blind as a bat" should probably be altered to "blind as a rat"...

[evan_au]

Humans spend most of their time vertical, so things like trees, houses, cars, people and writing are mostly seen in a single orientation.

However, flying creatures can approach objects from any orientation. I recall hearing about some experiments on pigeons which suggested that when they learned to recognize a pattern, they were very good at recognizing that pattern when presented in any orientation.