Researchers at Karolinska Institutet have identified how alpha oscillations in the brain help distinguish the body from the surroundings. Faster alpha rhythms enable precise integration of visual and tactile signals, strengthening the feeling of bodily self. The findings, published in Nature Communications, could inform treatments for conditions like schizophrenia and improve prosthetic designs.
A new study from Karolinska Institutet reveals that the frequency of alpha brain waves in the parietal cortex plays a key role in maintaining a sense of body ownership. Published in Nature Communications in 2026, the research involved 106 participants and combined behavioral experiments, EEG recordings, brain stimulation, and computational modeling to explore how the brain merges sight and touch.
In the experiments, participants experienced the rubber hand illusion, where a visible fake hand is stroked simultaneously with their hidden real hand, often leading to the sensation that the rubber hand belongs to them. Those with faster alpha waves detected subtle timing mismatches between visual and tactile inputs more accurately, resulting in a sharper boundary between self and environment. Conversely, slower alpha frequencies widened the temporal binding window, making it easier for mismatched signals to blend and blur the sense of self.
To test causality, researchers used non-invasive electrical stimulation to adjust alpha rhythms. Increasing frequency improved timing precision and body ownership perceptions, while decreasing it had the opposite effect. Computational models confirmed that alpha oscillations regulate sensory timing integration.
"We have identified a fundamental brain process that shapes our continuous experience of being embodied," said lead author Mariano D'Angelo, a researcher at Karolinska Institutet's Department of Neuroscience. The study suggests implications for psychiatric disorders like schizophrenia, where self-perception is disrupted, and for technologies such as prosthetics and virtual reality.
"Our findings help explain how the brain solves the challenge of integrating signals from the body to create a coherent sense of self," noted senior author Henrik Ehrsson, a professor at the same department. Conducted in collaboration with Aix-Marseille Université in France, the work was funded by the European Research Council and others, with no reported conflicts of interest.
