No one is saying that emotions are strictly caused by chemical reactions in the brain, nor that there isn't a link between those causative reactions and where they are coming from. If someone steps on your toe, you certainly know where that pain came from! I also have heart brain from a broken heart and it is centered exactly where my heart is - on the upper, slightly left quadrant side of my upper torso (more near the middle). No doctor has ever told me different. The scientific term that is used to coordinate brain functions - and organs, tissues, and cells - with the physical body is called physiology.
I have a very severe nerve injury in my brachial plexus due to root avulsion to the C5-T1 nerves in my spinal chord. This is almost half of what Christopher Reeves had. No doctor has ever been able to explain it clearly except as being a "short circuit" in the neurons. The pain is real and intense. Personally, I think that it must be "psychosomatic," i.e., involving both the mind and body as there is definitely a positive correlation between anxiety and pain. Yet, psychologically, when I feel that I am not under any stress, but I reflect on my environment that there is still potential stress present, the pain is the same? Although I am in know way psychologically aware of it.
I have seen many doctors for this condition and many have just come right out and told me that, "We're never going to see a patient like you again." Interesting, aye?