I believe, though dont' have documents to prove, (I have left the religion) that they Used to think your heart did have effects on your thinking. The interesting, if I'm correct, is that, havent' they recently come out saying that the heart does contain some neurons, such as are in the brain? Anyway, at present, I don't think jws would be against the artificial or transplanted hearts, as their policies currently stand. Be aware, those can change any day. To be honest, they used to think that your very being of who you are was held in your blood, because of a scripture that says something like, "the life, the soul, is in the blood." Because of this, they actually believed that if your child were forced by court order to receive a blood transfusion to save it's life, then "it wasn't the same child anymore." Some jws have refused to take their children home from the hospital in years past, and even very recent years in Africa, because a blood transfusion was forced on the child and the parent(s) believed it "was no longer their child anymore.) This used to occur in the United States as well. They have changed their teaching on that, now, so you'll only find old timers make comments like I heard about 25 years ago when a couple had to have their child take blood by court oder. The man, an elder, said to his wife, "That's not their child anymore." By this they meant, they thought the child became, or took on the personality of whomever's blood they were given. I suppose in some cases, that might lead to a case of multiple personalities. lol