I don’t think it can be in the heart [yet somehow must be separate but linked with the heart] simply b/c people who have heart transplants do not lose their souls nor get someone else’s soul - do they?
It is said that the soul rests in the heart, but is not “stuck” there, so if there is a heart transplant, the soul just rests in the new heart.
Scientists who think that the brain is the seat of consciousness are wrong; consciousness comes from the soul, which is seated in the heart; the brain is a computer which is used by the consciousness. Consciousness emanates from the soul like light from the sun, it’s inseparable.