Never, to my knowledge. It has been done in animals though: https://www.cnbc.com/2018/05/15/two-surgeons-in-china-developing-a-method-to-transplant-a-human-hea

Never, to my knowledge. It has been done in animals though: https://www.cnbc.com/2018/05/15/two-surgeons-in-china-developing-a-method-to-transplant-a-human-head.html https://www.cnbc.com/2018/05/15/two-surgeons-in-china-develo... And anyway, it's not really the point. There is no reason, in principle, that the brain cannot be repaired in place.