A new study suggests that the inner sense of our cardiovascular state, our "interoceptive awareness" of the heart pounding, relies on two independent pathways, contrary to what had been asserted by prominent researchers.

The University of Iowa study was published online this week in the journal Nature Neuroscience by researchers in the department of neurology in the Roy J. and Lucille A. Carver College of Medicine and the graduate programs in neuroscience and psychology.

The researchers found that, in addition to a pathway involving the insular cortex of the brain -- the target of most recent research on interoception -- an additional pathway contributing to feeling your own heartbeat exists. The second pathway goes from fibers in the skin to most likely the somatosensory cortex, a part of the brain involved in mapping the outside of the body and the sense of posture.

The UI team also confirmed the widely held belief by researchers that the insula and anterior cingulate cortex (ACC) regions of the brain are important, but not necessary, for a person to feel his or her own heartbeat. The insula helps with such higher-order functions as self-awareness, while the ACC is believed to regulate heart rate.

"What's shown in this study is there are probably two pathways that can participate in the conscious representation of these sensations," said David Rudrauf, Ph.D., assistant professor of neurology and radiology and director of the laboratory of brain imaging and cognitive neuroscience. Rudrauf is lead author of the study along with Sahib Khalsa, M.D., Ph.D., who received medical and doctoral degrees from the UI and is currently working on his psychiatry residency at UCLA…