Cognitive Neuroscience of Bodily Awareness and Self-Cognition – Henrik Ehrsson Group

Our core line of research is centered on the question of how we come to perceive ownership over our bodies. This question can be framed in terms of a multisensory binding problem: how is visual, tactile and proprioceptive information combined to obtain a single coherent object that is one's own body?

Our research

Research focus

Our core line of research focuses on the question of how we come to feel ownership over our bodies. This problem can be formulated in terms of a multisensory binding problem: how is visual, tactile, and proprioceptive information combined to perceive a single coherent object that is one's limb? We also want to improve our understanding of how we come to experience an entire body as our own and how we perceive the location of this body in the world with respect to environmental landmarks. Another line of questioning addresses how the brain represents the position, force, and movements of limbs, as well as how a sense of being in voluntary control of one's actions (sense of agency) is generated. Moreover, we are interested in learning more about how mental imagery can influence basic multisensory perception and how the brain knows the difference between internally produced thoughts and real percepts produced by events in the external world. Finally, we want to investigate how central body representation influences other higher cognitive functions, such as one's ability to recall personal events, one's visual perception of size and distance of external objects, and the capacity to self-reflect and become aware of one's own identity.

To address these questions, we conduct behavioral and neuroimaging experiments with human participants. The static and unchangeable nature of the body poses a particular challenge to experimental research because it makes it difficult to experimentally manipulate body perception in the laboratory setting. We have overcome this obstacle by using perceptual body illusions that enable controlled manipulation of specific aspects of body perception in otherwise equivalent conditions. By studying such illusions, we can learn more about the basic processes that underpin body perception. This information, in combination with the findings of state-of-the-art neuroimaging experiments, can provide important insights into the underlying neural mechanisms.

This research has important clinical and industrial applications. The projection of ownership onto external objects represents a new direction in human-machine interfacing, neuroprosthetics, and computer science. To this end, we collaborate with engineers, neurosurgeons, and hand -surgeons to develop advanced prostheses that feel more like real limbs. Moreover, identifying the neural substrate of the sense of bodily self has a strong bearing on clinical research into psychiatric and neurological disorders that involve an impaired sense of self and body perception, including schizophrenia, depression, autism, and eating disorders and other body-image disorders.

Laboratory

Our laboratory is located at Biomedicum at the Karolinska Institutet. We boast a comprehensive virtual and augmented reality lab equipped with numerous digital high-resolution head-mounted displays, analog and digital video cameras, and video editing software. Additionally, we have two behavioral testing rooms outfitted with physiological recording devices. These include multichannel electromyograms, skin-temperature recording sensors, a magnetic motion-capturing system, equipment for assessing skin-conductance responses, heartbeat counting task, thermosensation, and eye tracking, among other devices. Our facilities also feature a state-of-the-art transcranial magnetic stimulation (TMS) lab with advanced neuronavigation (Magstim) software, a high-density 128-electrode electroencephalography (EEG) system (active-two Biosemi with active electrodes), and Neuroconn DC-STIMULATOR PLUS for non-invasive transcranial electrical stimulation (tDCS, tACS, and tRNS). For psychophysics experiments focused on bodily awareness and the sense of body ownership, we have developed two robotically controlled setups, each featuring three robots. These robots can stimulate two rubber hands and the participant's real hand with high temporal precision and can be used in combination with EEG and TMS. Furthermore, for selective activation of nociceptive C and Aδ fibers in the skin, we have a Nd:YAP laser stimulator (Stimul 1340 Neurolas, Deka, Calenzano, Italy). We have engineered a motor-based lever system equipped with force sensors for force-perception experiments.

For functional magnetic resonance imaging, we have full access to one 3 T Siemens Prisma scanner at Stockholm University Brain Imaging center SUBIC (Director: Rita Almeida), and one GE SIGNA Premier XT with high-performance gradient coils at the hospital's Solna MR-Centre (Director: Dr. Tobias Granberg). For fMRI experiments, we have MR-compatible head mounted displays (Nordic Neurolab) and MR-compatible EMG and SCR recording systems; we have also developed a robotically controlled MR-compatible system for rubber hand illusion psychophysics experiments and a setup for “moving rubber hand illusion” in the scanner. For ultra-high-field MR imaging, we have access to a state-of-the-art second-generation clinical 7 Tesla MRI system (Siemens MAGNETOM Terra.X with a 32-channel receive and 8-channel transmit head coil) at Karolinska Hospital's Huddinge MR-Centre. In addition, we have local access to a state-of-the-art MEG system (Electa Neuromag TRIUX) at the The National Faciliy For Magnetoencephalography NatMeg (Head: Christoph Pfeiffer) with complementary physiological recording devices (MEG compatible 128-channel EEG, plethysmography, EMG, ECG, and eye tracking) and sophisticated stimulus-delivery platforms (visual, auditory, olfactory, pain, and somatosensory, including a robot system for tactile stimulation of the hands with high temporal precision).