Self-consciousness is a heartbeat away
With a virtual-reality experiment, EPFL neuroscientists have shown how the brain receives heartbeat signals to produce bodily self-consciousness.
Bodily self-consciousness is an integral part of our everyday life. It allows us to be instinctively aware of where we are and how we move. While this seems trivial, it requires a lot of computation and processing from our brain. But how does the brain produce and regulate it? Using a virtual reality experiment, EPFL scientists have now shown that bodily self-consciousness involves the brain monitoring heartbeat. The work is published in the Journal of Neuroscience.
The lab of Olaf Blanke at EPFL designed an experiment combining brain imaging, heartbeat analysis, and virtual reality. Participants wore a virtual reality device and a high-density electroencephalogram cap, while their heartbeat and brain activity were measured at the same time in order to monitor the brain’s response to the heart throughout the experiment.
The study, extending previous research from the group, was led by EPFL postdoc Hyeong-Dong Park. The researchers specifically focused on a part of the brain called the “posterior cingulate cortex” and the “insula”. Both areas receive signals from internal organs and also process spatial information about the body.
The experimental design of this study (© Journal of Neuroscience)
Through the virtual reality headset, the participants watched an image of their back in sitting position. At irregular time intervals, they received gentle strokes on their back with a stick, which acted as a stimulus to test their bodily self-consciousness as they saw it touch their back in the virtual reality feed. This was carried out in real-time and after a delay.
At the end of the experiment, the participants were asked to report the level of self-identification with the avatar that they saw. The study found that the response of the posterior cingulate and insula to heartbeat signals reflected the changes in the participant’s conscious self-identification induced by the virtual reality experiment. As the authors state: “Our finding provides important neural evidence… that self-consciousness is linked to the cortical processing of internal bodily signals.”
This is an important experimental confirmation of a longstanding idea that self-consciousness is linked to signals by our organs. This theory has influenced both philosophy and psychology (e.g. William James), but has lacked definitive experimental support, despite various pieces of evidence linking it to modern neuroscience.
This study provides an experimental link between the cortical mapping of the internal body in the brain and actual self-consciousness, placing inquiry out of the realm of philosophy within the empirical sciences; the study’s findings may also be important for future treatments of chronic pain using virtual reality technology, which are also pursued in Blanke’s lab.
This work was funded by the Fondation Bertarelli.
Park H-D, Bernasconi F, Bello-Ruiz J, Pfeiffer C, Salomon R, Blanke O. Transient Modulations of Neural Responses to Heartbeats Covary with Bodily Self-Consciousness. The Journal of Neuroscience, 10 August 2016, 36(32):8453–8460. DOI: 10.1523/jneurosci.0311-16.2016