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 main research project addresses the question of how we come to feel that we own our body. This question is fundamental because the feeling of body ownership is a basic aspect of self-awareness. Our goal is to identify the multisensory mechanisms whereby the central nervous system distinguishes between sensory signals from within one's own body and those from the environment. The long-term goal of this project is to develop a physiological model of the central representation of an individual's body.
We are currently extending this line of research to include questions related to how we experience ownership of an entire body-as opposed to fragmented parts-and how we sense its location in the world. We are also interested in how central body representation influences other higher cognitive functions, such as episodic memory, visual size and distance perception, and affective feelings toward the body (embodied cognition).
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.
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).
The lab is funded by Henrik Ehrsson’s current grants:
The lab was established with economic support from Starting-Investigator Grants from the European Research Council (2008-2013), the Swedish Foundation for Strategic Research (2008-2013), the Human Frontier Science Programme (2009-2011), and the James S. McDonnell Foundation (2011-2017).
Diana Johnsson is a medical student at the Karolinska Institutet. She is conducting a research internship full-body illusions and emotional processing under the supervision of Ryu Ohata and Henrik Ehrsson.
Xiaole Luan is a student in Master’s Programme in Biomedicine at Karolinska Institutet. She is conducting a research internship on electrophysiological and psychophysical signatures of the sense of limb ownership, supervised by Renzo Lanfranco and Henrik Ehrsson.
Contact information for the Ehrsson Lab at the Department of Neuroscience, Karolinska Institutet.
Department of Neuroscience
171 77 Stockholm
171 65 Solna
171 65 Solna
If you are interested in joining the group as a post-doc you should contact Henrik Ehrsson at least one year in advance of the planned start date.
Please submit your CV, the names of two references, and a short description of why you want to join our group and what kind of project you would like to conduct.
There are several possible sources of funding for which you can apply to do post-doctoral research, most of which have deadlines of up to one year in advance of starting the project.
For students (at BSc or MSc level) interested in conducting a student internship in the lab, please contact Henrik Ehrsson.
Include a CV and brief motivation for why you would like to conduct an internship in the lab.
Please note that we normally do not consider internships that are shorter than 3 months (with an exception for summer students where 8 weeks is the minimum).
Summer students should contact Henrik Ehrsson before 31 January each year.