Simultaneous stimulation of two connected brain regions was associated with richer multicomponent bodily sensations in three patients.

Osaka, Japan – Researchers at the University of Osaka have shown that stimulating two parts of the brain at the same time may create richer artificial touch sensations. The study tested whether simultaneously stimulating the primary somatosensory cortex (S1) and the insular cortex could produce sensations beyond the tingling or numbness typically elicited by S1 stimulation. This study was published in Brain Stimulation.

Touch combines information about where contact occurs, how it feels, and qualities such as pressure and temperature. S1 is involved in locating bodily sensations, while the insula contributes to temperature, pressure, pain, and internal bodily states. Conventional single-site stimulation usually produces simple sensations.

The team studied three patients with intracranial electrodes implanted for epilepsy evaluation. After identifying sensory-responsive contacts, the researchers stimulated S1 alone, the insula alone, and both regions simultaneously using 50-Hz electrical stimulation. Simultaneous stimulation was associated with qualitatively richer, multicomponent percepts: one patient reported a gentle hand touching the face, another experienced finger dysesthesia with a choking sensation, and a third felt numbness combined with painless warmth. These percepts were not always readily explained as a simple addition of single-site effects.

The study was exploratory and included only three patients. It had no sham-stimulation condition and relied mainly on subjective verbal reports. Most stimulation conditions were tested once, and stimulation intensity was not systematically matched across conditions. The findings therefore cannot distinguish the effects of simultaneous cortical activation from differences in stimulation intensity, delivered charge, or the amount of tissue activated.

The findings support further investigation of whether multisite stimulation can influence how components of touch are combined. If confirmed in larger, controlled studies, this approach may inform sensory neuroprostheses that communicate not only where contact occurs, but also qualities such as warmth or the manner of touch. It may also help reveal how brain networks create unified sensations.

“These observations suggest that stimulating the two regions together may change how sensory qualities combine, sometimes producing experiences closer to everyday sensation,” said Dr. Takamitsu Iwata, lead author of the study.
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The article, “Multicomponent somatosensory percepts during simultaneous stimulation of the insular and primary somatosensory cortices,” was published in Brain Stimulation at DOI: https://doi.org/10.1016/j.brs.2026.103202

About The University of Osaka
The University of Osaka was founded in 1931 as one of the seven imperial universities of Japan and is now one of Japan's leading comprehensive universities with a broad disciplinary spectrum. This strength is coupled with a singular drive for innovation that extends throughout the scientific process, from fundamental research to the creation of applied technology with positive economic impacts. Its commitment to innovation has been recognized in Japan and around the world. Now, The University of Osaka is leveraging its role as a Designated National University Corporation selected by the Ministry of Education, Culture, Sports, Science and Technology to contribute to innovation for human welfare, sustainable development of society, and social transformation.
Website: https://resou.osaka-u.ac.jp/en