Research

Goal


Welcome to the homepage of the Brain, Body, and Self Laboratory. In our lab, we utilize neuroimaging and behavioral methods to investigate how we perceive our own bodies and how the brain represents our bodily self. Our aim is to unravel the perceptual processes and neural mechanisms that determine our bodily self-perception. A particular focus of our research is developing an understanding of how the brain maintains and updates a flexible spatial-perceptual representation of one’s own body. This process involves the inference and integration of sensory information from various modalities, including vision, touch, proprioception, and interoception, combined with stored information from past bodily experiences. Additionally, we investigate how a coherent sense of owning a single, unified body emerges from perceptual experiences of individual body parts. We also explore how the interplay between the sense of own body and the sense of self-location contributes to natural ‘in-body’ experiences and phenomena such as out-of-body experiences. Another question we are interested in is the relationship between the feeling of being in control of voluntary action (the sense of agency) and the sense of the body as one’s own.

In addition to this, our research explores how the representation of bodily self influences our thoughts, emotions, memories, and perceptions of the external world and others (embodied cognition). Finally, we investigate potential clinical and industrial applications of our basic research findings. These efforts include contributing to the design of advanced prosthetic limbs that provide a more realistic sensory experience and developing new methods to probe and understand disturbances in bodily awareness in neuropsychiatric conditions, such as eating disorders and Schizophrenia.

Experimental and theoretical approach

We conduct behavioral and neuroimaging experiments with human participants to address the questions mentioned above. The static and unchangeable nature of the physical body presents a significant challenge in experimental research on bodily self-awareness. Beyond simple tactile and proprioceptive sensations, experimentally manipulating an individual's perceptual experience of their own body in a laboratory setting proves very challenging. This is particularly true when attempting to evoke changes in limb ownership perception or alterations in the size and length of limbs and body segments. Nevertheless, undertaking this task is crucial for isolating and quantifying the underlying brain processes associated with bodily self-awareness. We overcome this obstacle by employing bodily illusions (Ehrsson, 2022, Routledge Handbook of Bodily Awareness) that enable the elicitation of experimentally controlled, specific changes in bodily perception. These include feelings like a limb being part of one’s body (the sense of body ownership) or alterations in the perceived size and shape of body parts. We utilize well-known illusions such as the classic rubber hand illusion (Ehrsson et al., 2004, Science), the Pinocchio illusion (Ehrsson et al., 2005, PLoS Biology), and several discoveries from our lab, including the out-of-body illusion (Ehrsson, 2007, Science), the Barbie-doll illusion (van der Hoort et al., 2011, PLoS One), the three-arm illusion (Ehrsson, 2009, Perception; Fan et al., 2021, JEP: HPP), and the body-swap illusion (Petkova and Ehrsson, 2008, PLoS One). By integrating this perceptual-illusion-based approach with robotically-controlled sensory stimulation and psychophysics, we rigorously quantify illusory changes in specific aspects of one’s body perception at the individual participant level (Chancel and Ehrsson, 2020, Atten Percept Psychophys; Lanfranco et al., 2023, Cognition). This allows us to isolate specific perceptual and learning processes and develop computational models of the perception of one’s own body (Chancel et al., 2022, ELife; O’Kane et al., 2024, Cognition).

Furthermore, by combining behavioral bodily illusion paradigms with neuroimaging and electrophysiological techniques, we can uncover the neural underpinnings of bodily self-perception and test hypotheses about specific neural mechanisms (Chancel et al., 2022, Journal of Neuroscience; Guterstam et al., 2019, Cerebral Cortex; Reader et al., 2023, Brain & Behaviour; Guterstam et al., 2015, Current Biology). This research has elucidated the importance of multisensory integration mechanisms in specific frontal, parietal, and subcortical regions for own-body perception (Ehrsson et al., 2004, Science; Gentile et al., 2013, Journal of Neuroscience; Guterstam et al., 2019, Cerebral Cortex), and revealed how such integration is based on probabilistic perceptual inference, implemented within active fronto-parietal neuronal populations (Ehrsson & Chancel, 2019, PNAS; Chancel et al., 2022, Journal of Neuroscience).

To examine how the perception of one’s own body influences higher cognitive functions, we combine bodily illusions with psychological tests that probe these functions. For example, we investigate how disruptions in the coherent experience of bodily self impair episodic memory encoding in the hippocampus (Bergoingan et al., 2014, PNAS; Iriye et al., 2023, Cerebral Cortex), and how experiencing a friend’s body as one’s own alters one’s self-concept, leading to personal identity and traits becoming more similar to those of the friend (Tacikowski et al., 2022, iScience).

The Lab


Our laboratory is located at Biomedicum at the Karolinska Institutet. We boast a large 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, and a MR-compatible contactless finger movement motion tracking device.

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 (VisualSystem HD, 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 National Facility 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).

Last but not least, Martti Mercurio is our full-time research engineer, instrumental in building, designing, and coding complex experimental setups. As a civil engineer with 12 years of experience in the lab, Martti's expertise spans mechanics, mechatronics, electronics, and computer programming, including proficiency in C++, among other skills.

Lab culture and leadership style

The BBS Lab fosters collaboration among lab members and encourages open discussion on all projects. In our weekly lab meetings, postdocs and students actively present their ongoing projects and the latest findings. These meetings also serve as a journal club, offering a platform to critically evaluate and learn from recent scholarly articles. Our focus is on mutual support and constructive feedback, nurturing a creative and stimulating environment free from competition. After the lab meetings, we have Swedish “fika” (coffee or tea, with something sweet on the side).

Henrik Ehrsson has an open-door policy, and he also schedules regular meetings with PhD students and postdocs. His approach is not to micromanage but to mentor, guiding young investigators towards becoming independent scientists. This philosophy is rooted in providing independence, balanced with the right amount of guidance and support.

We have a flat organization, and each Ph.D. student and postdoc is a leader of their own project. Prof. Ehrsson is called “Henrik”. We strive for a friendly environment in which all are welcome, and we are committed to maintaining a respectful and professional atmosphere.

Funding and international collaborations

The lab is funded by Henrik Ehrsson’s current grants: a Distinguished Professor Grant from the Swedish Research Council; a European Research Council Advanced Grant for the SELF-UNITY project (https://cordis.europa.eu/project/id/787386); and a Project Grant from Hjärnfonden.

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).

International collaborations include Wei Ji Ma (New York University, USA), Prof. Jeffrey Ojemann (University of Washington, USA), Prof Marcin Szwed (Jagiellonian University, Poland) Prof. Chris Dijkerman (Utrecht University, the Netherlands), and Prof. Andres Canales-Johnson (University of Cambridge). At Karolinska, we collaborate with Karin Jensen (Department of Clinical Neuroscience).

External Research Quality Assessment


Our lab received the highest grade ("outstanding; 6/6") in the recent external research assessment of the Karolinska Institutet. This places us in the top 12% of labs at the Karolinska Institutet that received this grade.

Page last modified: January 24 2024 13:27:50.