I once pondered upon what I would consider to still "be alive".

Some of these people who are in a coma can, as has been shown, still hear sound and react or even answer by activating certain brain regions which can be measured.

But what if you can't hear anymore? It doesn't seem to imply you're dead. For instance, I could imagine, purely hypothetically, that someone could use your sense of touch to input a bit-pattern or even Morsecode to initiate communication, to which one might be able to react by thinking (communicate back).

Of course, that seems highly impractical and unlikely to happen, but it is an interesting meditation to contemplate what one would consider for themselves to "be alive".