gist of sentence
hi there,
can you tell me gist of this sentence.i dont understand whats happen with his tonque.?

but then various things came to his aid. And in a mysterious way, he thought he
was improving, that he was gaining the normal visual ability to read
back. But he wasn’t. What was happening was that he was unconsciously
copying the shapes of letters with his tongue. And that would show
people who lose their reading are still able to write, which is a strange
thing. So in a way, he was converting what his eyes saw and writing it
with his tongue. And I would absolutely not have thought such a thing
was possible.

Question

gist of sentence
hi there,
can you tell me gist of this sentence.i dont understand whats happen with his tonque.?

but then various things came to his aid. And in a mysterious way, he thought he
was improving, that he was gaining the normal visual ability to read
back. But he wasn’t. What was happening was that he was unconsciously
copying the shapes of letters with his tongue. And that would show
people who lose their reading are still able to write, which is a strange
thing. So in a way, he was converting what his eyes saw and writing it
with his tongue. And I would absolutely not have thought such a thing
was possible.

Answer

Out of context, your story is very strange! It sounds like a psychological study on a brain injury patient? I would wager that he had a stroke...

The gist is that someone who has become unable to read is still able to see letters in detail. This means that they can understand/see the shape of the letter but not understand the meaning of the letter. Kinda like looking at Hindi letters without knowing anything about Hindi. He is tracing the letters with the movement of his tongue in a similar way that a child traces new letters of the alphabet on paper with a pencil.

Answer

The meaning isn't obvious, but it seems that this person may have had a brain injury which inhibits his ability to write.  So instead, his brain is compensating for the loss by relying on his mouth to form the shapes of the letters, essentially spelling out the words with the shape of his mouth, tongue, and lips.  For example, the mouth is in a different form when saying the letter O than it is in saying the letter A.