I'm curious about this too.
In my own perspective, I feel like it's not that the mind-stream gets cut off, but we can direct it to whatever we want without subconsciously clinging onto it or being hindered by addictions, neuroses and compulsions. Currently my mind doesn't seem to have that background noise of never-ending thoughts, just breath if I want to, or kasina if I want to, or the task at hand if I want to. Though it can still run off a little because it's connected to the donkey body...
We continue to hear, see, taste, feel and smell, and according to the pali texts, they are the individual consciousnesses that come together to form the illusion of a self... I feel like it is an illusion, like finding out a mirage was never there in the desert. Realizing there's nothing but shifting sand, light plays, smoke and mirrors. But knowing that the illusion is there doesn't mean the illusion doesn't actually exist... The mirage is still there, but the insight itself seems to cut away the fear of losing a self. Dependent origination says ignorance gives birth to the sanskaras (4th aggregate) that slowly builds on, leading to sense contact, then feelings/cravings for the sensory contact, giving rise to birth (sense of self) which then later dies away.
Also I find like "insights" come without the need to actually memorize things. Just looking at something and I can figure out where it comes from, etc. Almost super-sensory where everything is so intensely picked up.
Curious to hear what Jhanananda says about it.