They think there will be no such thing as thought processes because your brain can't make them anymore.
Well... yeah. Your thoughts do come from your brain, after all.
I haven't read up on it, although I should, but I haven't read many of the arguments against "afterdeath hallucinations" from people who have been medically dead and were able to be revived.
I believe this is called a "near-death experience", where your brain hallucinates (much like a dream) during, well, near-death circumstances. It can also be triggered by extreme g-force from centrifuges because of blood being drained away from the brain.
Clinical death is also defined as the cessation of blood circulating and breathing, which can be reversed during a short period of time, I think.
(I realize it says "against" and not "for", but I think this is relevant somehow.)