Brain rhythm alpha oscillations help the brain mark parts of the body as its own.

A Karolinska Institutet study in Nature Communications shows that the frequency of alpha waves in the parietal cortex affects how precisely people judge timing between sight and touch, shaping the sense that a body part belongs to oneself; shifting alpha frequency with mild electrical stimulation altered these timing judgments.

Researchers at Karolinska Institutet report a study in Nature Communications linking a rhythmic brain activity, called alpha oscillations, to the experience that a body part belongs to oneself. The team combined behavioural tests, EEG recordings, non‑invasive electrical brain stimulation and computational modelling with 106 participants. They examined how visual and tactile signals are integrated in the parietal cortex to maintain a stable sense of bodily self. The work focuses on timing precision as a key factor in distinguishing self from external objects. Key findings: - The speed (frequency) of alpha waves in the parietal cortex influenced how precisely participants judged the timing between visual and tactile events. - In the rubber hand illusion, participants with faster alpha frequencies were better at detecting small timing mismatches between what they saw and what they felt. - Slower alpha frequencies were linked to a wider "temporal binding window," making out‑of‑sync signals more likely to be treated as simultaneous. - Experimentally increasing or decreasing alpha frequency with mild electrical stimulation changed participants' timing judgments and their reported sense of body ownership. - Computational models supported the idea that alpha frequency regulates timing precision in multisensory integration. Summary: The study links alpha frequency to timing precision in how the brain combines sight and touch and reports that changing that rhythm alters the sense of body ownership. Authors note the findings could inform prosthetic design and more realistic virtual reality, but next steps are undetermined at this time.