Uniquely Human
Dr. Arthur Craig of the Barrow Neurological Institute in Phoenix has detailed a network of sensory pathways from body tissues to the lowest and highest levels of the brain. The pathway finally feeds into regions of the cortex called the insula, one on either side of the brain. These are the areas of the brain that "light up" in the fMRI studies of people experiencing various types of sensory information. Craig says that the insula is "a system that represents the material me." It is in these insulae that information becomes feelings and self-awareness emerges. More precisely, it is in the front part of the insula where the realizations happen.
Other research into nervous system circuitry:
Dr. John Allman at the California Institute of Technology has found spindle cells in the brain that "function like air traffic controllers for emotion." He found that humans have many, many more of these cells in their brain than any other species. In fact no other species than humans or apes had any. Allman has found spindle cells in an older part of the brain that is part of the autonomic nervous system. Any intense emotion or difficult task activates this region. From there they send information all over the brain. The spindle cells aren't present at birth and develop during infancy and childhood.
Humans are unique in their ability to sense themselves and process the complex emotional states that often arise from this sensory ability. But you don't have to have a person under an MRI machine to know this. As movement educators see every day, just observing the way a person uses themselves in movement tells you a lot about the whole person. Putting hands on them is even more revealing.
This brings to mind a story of Moshe Feldenkrais working with a client who was a professor of physiology. After the lesson, she said something like "you just showed me the tonic neck reflexes in myself. I've taught them for many years, but I never thought about making that knowledge practical." [Moshe Feldenkrais: The Master Moves]
So, while the research is interesting, even fascinating, the even greater challenge is the practicality that will hopefully arise from such knowledge.