Neuroscience-robotics pinpoint the seat of self-consciousness

A new study uses creative engineering to unravel brain mechanisms associated with one of the most fundamental subjective human feelings: self-consciousness. The research, published in the April 28 issue of the journal Neuron, identifies a brain region called the temporo-parietal junction (TPJ) as being critical for the feeling of being an entity localized at a particular position in space and for perceiving the world from this perspective. By comparing results between healthy volunteers and patients reporting out-of-body experiences (OBEs) of neurologic origin—the feeling of being outside of one’s body—the study shows evidence for a link between brain activity in TPJ for self-consciousness in health and disease.

The researchers adapted setups from previous experiments, adding the precision of an MRI-compatible robotic device and detailed analysis of the fMRI data. “This combination of engineering technologies and cognitive neuroscience and neuroimaging techniques creates a powerful tool for understanding the relationship between self-consciousness and brain activity,” explains Silvio Ionta from EPFL’s Laboratory of Cognitive Neurosciences (LNCO).

Full-body illusions during fMRI
Using visual and robotically applied tactile stimuli, the volunteers were tricked into believing that their self was either several feet in front of them or at a distanced and elevated position . For the first time, this technique was coupled with the fMRI neuroimaging technique in order to record brain activity during the induced illusion. Ionta and Olaf Blanke, director of the lab, had healthy volunteers lay down on a bed fitted with the robotic stroking device. The patient, wearing 3D goggles that projected a recorded image of a person’s back a short distance in front of him or her, was then placed into the MRI machine. To create the illusion, the researchers used a robotic device to stroke the patient’s back at precisely the same time that the body in the virtual world was stroked, tricking the mind into believing that the image of the body projected in front of the patient was the patient’s own body—an induced full-body illusion.

The temporo-parietal junction
The results show that when a volunteer is sufficiently tricked and reports that he feels far away from his own body, activity in the brain region where the temporal and parietal lobes meet is weaker than when he reports he feels closer to his body. Lukas Heydrich from EPFL’s Laboratory of Cognitive Neuroscience completed a study of nine neurological patients with out-of-body experiences and found that brain damage was also localized in the TPJ. These findings support the hypothesis already put forth by Blanke that damage to this region is implicated in OBEs.

“Besides guaranteeing safety, one of the major obstacles for a robotic device in an MRI environment is to ensure that it does not interfere with the imaging,” explains Roger Gassert, who at the time of the study was at the Robotics Systems Laboratory at EPFL, and is now heading the Rehabilitation Engineering Laboratory at ETH Zurich. By shielding the cables, filtering the signals and moving the motors as far away from the magnet as possible, his contribution has “opened a whole new field of possibility for controlling visuo-tactile stimulations.”

This publication in Neuron, although a major advance and a culmination of several years of work, is not the skeleton key that will unlock the mysteries of the brain and self-consciousness. Like neurobiological science in general, Blanke is moving step by cautious step towards a deeper understanding of the brain. The team’s novel approach of inducing illusions in order to better comprehend the brain and related disorders will surely become even more precise and technologically-oriented. And with this methodological rigor, the mystery of the origins of self-consciousness may one day be unveiled.