Question

Lacking any exposure to language before adolescence, a person will never master any language due to the ________ of unused neural connections.

Answer 1

I believe the answer is: pruning

In psychological term, pruning is the process of eliminating a certain information from our brain in order to be replaced with the information that are deemed more necessary for our everyday use.
In language learning, pruning could happen when after we acquire the knowledge of new language but left them unused.