Somewhat recently scientist put a worm brain in a robotic body and it responded! Does this mean the brain in vat theory is possible? Certainly, it may be even possible for human brains (much more complicated) in the future! Here is a article and a quick video about it.
Video: https://www.youtube.com/watch?v=eYS7UIUM_SQ
Article: https://medium.com/future-today/scientists-put-a-worm-brain-in-a-lego-robot-body-fcead1838a7c