From my understanding, scientifically, there's no connection between emotions and feelings, and the heart.
The way I understand מאמרי חז''ל and דא''ח, it refers to the brain as the source of everything that's cool, calm and levelheaded and it refers to the heart as the source for all that is constantly moving, excited, heated up and very active.
This is my humble understanding and I'd appreciate if anyone agrees or disagrees.