TI-TMS system design for deep brain stimulation with higher focus in neural modulation

• A TI-TMS (temporal interference TMS) system design targets deeper and more focused neural modulation.¹
• The work represents a technological step for transcranial stimulation and future device development.¹
• It is published in Nature.^{1 1}

Gardner updates

• TI-TMS system design targets deeper, more focused neural modulation for non-invasive neuromodulation (Nature). ¹

Weekly enrichment (2026-07-20)

• The Google News item resolves to a peer-reviewed paper in Nature’s Scientific Reports (2025) proposing a TI-TMS design that raises the half-value stimulation depth to 5.02 cm while holding the focal area (S1/2) to 18.61 cm², evaluated on a five-layer spherical head model.²
• The key hardware element is a double curved-elliptical coil pair shaped to conform to the scalp; finite-element simulations drove the two coils at 5.00 kHz and 5.02 kHz (a 20 Hz difference envelope) with 100 A amplitude, versus conventional TMS whose fields reach only ~1–2 cm into the brain.²
• The method relies on the neural membrane’s low-pass filtering property (Grossman et al., 2017): neurons ignore the individual high-frequency fields but follow the low-frequency envelope formed where the two fields intersect, giving a modeled stimulation intensity of ~28 V/m at the target.²
• Decreasing the angle between the coils increased TI-TMS depth, and TI-TMS depth exceeded conventional TMS at every tested angle, directly addressing the depth–focality trade-off that limits standard coils.²
• A physical TI-TMS system was built and validated, centered on an insulated-gate bipolar transistor (IGBT) driving circuit and a coil-capacitor resonance stage, with coil current amplitude and frequency measured to confirm operation.²
• An earlier four-coil TI-TMS configuration (Xin et al.) reached only 2.2 cm depth, so the double curved-elliptical design more than doubles that penetration while keeping a bounded focal area.²
• For context, TI-TMS remains at the simulation and animal stage: Khalifa et al. (2023) showed c-Fos expression in deeper mouse-brain layers from the interfering envelope but not from a single high-frequency field; human efficacy and safety data are not reported.³

Footnotes

1. https://news.google.com/rss/articles/CBMiX0FVX3lxTE1KcVlIRFZ3SHV5akNvUjBfRHhza1J3MldvcXpXS2R4OTdTVllOd1BxRDdic21IMFJKcWpGVllMWXBvTU1hNTZDcWpPLUlxMmR4dTFvVTREdnpXel8tWVNv?oc=5 ↩ ↩² ↩³ ↩⁴ ↩⁵

2. https://www.nature.com/articles/s41598-025-08598-8 ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶

3. https://www.frontiersin.org/journals/human-neuroscience/articles/10.3389/fnhum.2023.1266753/full ↩