[rdancer]

For example echolocation (in humans, not bats) is done in visual cortex[1]. Visual cortex shows activity during dreams and imagination. Blind people do use their visual cortex.

[1] Sorry, don't have a cite, but there are a lot of results on Google talking about it: https://archive.is/iDE27

[DonaldFisk]

This doesn't surprise me. They are using their visual cortex to process sensory data (auditory images) which substitute for sight.