Scientists identify brain waves that define the limits of 'you'
Recorded: Jan. 26, 2026, 3 p.m.
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Scientists Identify Brain Waves That Define The Limits of 'You' : ScienceAlert
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Big breakthroughs. Bold ideas. Straight to your inbox. Daily roundup Spark: Our top stories Contact Scientists Identify Brain Waves That Define The Limits of 'You' Health26 January 2026By Michael Irving At what point do "you" end and the outside world begins?It might feel like a weird question with an obvious answer, but your brain has to work surprisingly hard to judge that boundary. Now, scientists have linked a specific set of brain waves in a certain part of the brain to a sense of body ownership. In a series of new experiments, researchers from Sweden and France put 106 participants through what's called the rubber hand illusion, monitoring and stimulating their brain activity to see what effect it had. Related: Octopuses Fall For The Classic Fake Arm Trick – Just Like We Do This classic illusion involves hiding one of a participant's hands from their view and replacing it with a rubber one instead. When both their real and fake hands are repeatedly touched at the same time, it can evoke the eerie sensation that the rubber hand is part of the person's body. The tests, which in one experiment involved EEG (electroencephalography) readings of brain activity, revealed that a sense of body ownership seems to arise from the frequency of alpha waves in the parietal cortex, a brain region responsible for mapping the body, processing sensory input and building a sense of self. "We have identified a fundamental brain process that shapes our continuous experience of being embodied," says lead author Mariano D'Angelo, a neuroscientist at Karolinska Institute in Sweden. "The findings may provide new insights into psychiatric conditions such as schizophrenia, where the sense of self is disturbed."In one experiment, participants wore an EEG headset and placed their real hand out of view, with a fake hand positioned above, while two robot arms applied stimuli. (Martin Stenmark/Karolinska Institute)In the first batch of experiments, participants had a robotic arm tap the index finger of their real and fake hands, either at the exact same time or with a delay of up to 500 milliseconds between each tap. As expected, participants reported feeling that the fake hand was part of their body more strongly if the taps were synchronized, and the feeling steadily weakened as the gap widened between what they felt and what they saw. The EEG readings from the second experiment added more detail to the story. The frequency of alpha waves in the parietal cortex seemed to correlate with how well participants could detect the time delay between taps. Those with faster alpha waves appeared to rule out fake hands even with a tiny gap in taps, while those with slower waves were more likely to feel the fake hand as their own, even if the taps were farther apart.Finally, the researchers investigated whether the frequency of these brain waves actually controls the sensation of body ownership, or if they were perhaps both effects of some other factor. With a third group of participants, they used a non-invasive technique called transcranial alternating current stimulation to speed up or slow down the frequency of a person's alpha waves. And sure enough, this seemed to correlate with how real a fake hand felt. Speeding up someone's alpha waves gave them a tighter sense of body ownership, making them more sensitive to small timing discrepancies. Slowing down the waves had the opposite effect, making it harder for people to tell the difference between their own body and the outside world. "Our findings help explain how the brain solves the challenge of integrating signals from the body to create a coherent sense of self," says Henrik Ehrsson, neuroscientist at Karolinska. The researchers say that the findings could lead to new understanding of or treatments for conditions where the brain's body maps have gone askew, such as schizophrenia or the sensation of 'phantom limbs' experienced by amputees. It could also help make for more realistic prosthetic limbs or even virtual reality tools.The research was published in the journal Nature Communications. Big breakthroughs. Bold ideas. Big breakthroughs. Bold ideas. Straight to your inbox. Daily roundup Spark: Our top stories
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Scientists Identify Brain Waves That Define The Limits of ‘You’ Researchers have illuminated a fundamental process within the brain – the relationship between the body and the sense of self. A recent study, published in *Nature Communications*, investigated the neural mechanisms underlying the sensation of body ownership, specifically through the exploration of alpha brain waves within the parietal cortex. The research, conducted by a team of scientists from Sweden and France, utilized a classic psychological illusion – the rubber hand illusion – to probe the intricacies of this experience. The core of the experiment involved 106 participants who experienced the rubber hand illusion. In this illusion, one participant’s hand was hidden from view, replaced by a rubber hand, and both hands were repeatedly stimulated simultaneously. The researchers meticulously monitored brain activity via electroencephalography (EEG) readings, focusing on the frequency of alpha waves within the parietal cortex. This region of the brain is responsible for mapping the body, processing sensory input, and constructing a sense of self. The initial experiments focused on the timing of stimuli applied to both the real and fake hands. Participants reported a stronger sensation of body ownership when the taps were synchronized. Conversely, as the time delay between taps increased, the feeling diminished. This established a direct correlation between the frequency of alpha waves and the perceived integration of the fake hand into the participant’s body schema. Rapid alpha wave activity appeared to facilitate the rejection of the fake hand, while slower waves were associated with an increased sense of body ownership, even when there was a temporal discrepancy. Further investigation explored the causal relationship between alpha wave frequency and body ownership. Through a separate experiment, the researchers employed transcranial alternating current stimulation (tACS) to either speed up or slow down a participant's alpha wave activity. The results revealed a clear and significant influence: accelerating alpha wave frequency strengthened the sense of body ownership, enhancing sensitivity to subtle timing discrepancies. Conversely, slowing down alpha waves diminished the perceived connection, making it harder for participants to distinguish between their own body and the external stimulus. Lead author Mariano D’Angelo, a neuroscientist at Karolinska Institute in Sweden, emphasized that these findings represent “a fundamental brain process that shapes our continuous experience of being embodied.” The study’s implications extend beyond the immediate understanding of the rubber hand illusion. The research could provide invaluable insights for understanding and treating psychiatric conditions where the sense of self is disrupted, such as schizophrenia. The ability to manipulate alpha wave activity opens potential avenues for therapeutic interventions. Furthermore, the study’s findings hold relevance for addressing the experiences of amputees, who often struggle with phantom limb sensations – an indication of a fragmented body schema. Beyond clinical applications, this research also has potential implications for the development of more realistic prosthetic limbs and immersive virtual reality technologies. By understanding how the brain builds and maintains a coherent sense of body ownership, scientists can design interfaces that more seamlessly integrate with the user’s nervous system. Henrik Ehrsson, another neuroscientist at Karolinska, articulated this broader significance: “Our findings help explain how the brain solves the challenge of integrating signals from the body to create a coherent sense of self.” |