Non-invasive brain stimulation is central to treating neurological and psychiatric disorders, yet existing methods lack the spatial and temporal precision required to modulate the deep and distributed circuits implicated in these conditions. Techniques such as transcranial electric or magnetic stimulation have limited focality, substantial inter-individual variability, and operate in open-loop mode because stimulation artifacts obscure real-time brain activity. As a result, no current non-invasive tool enables millimeter- and millisecond-precise, brain-state-contingent modulation in both superficial and deep structures - an essential prerequisite for next-generation, bidirectional brain-computer interfaces (BCIs).

Temporal Interference Magnetic Stimulation (TIMS) offers a solution. TIMS uses pairs of electromagnetic coils driven by high-frequency carrier signals whose phase is modulated at lower frequencies. When combined in the brain, these fields produce amplitude-modulated electric fields that selectively stimulate tissue only where modulation is maximal. Because magnetic fields pass through biological tissue with minimal distortion, TIMS enables precise targeting up to ~60 mm depth. Its waveform flexibility, including phase-locked waveforms and short pulses, creates opportunities for cell-type–specific modulation.

By integrating TIMS with real-time signal processing pipelines capable of suppressing stimulation artifacts, the system enables closed-loop stimulation during active BCI control. Recent work shows that reliable motor-imagery BCI performance can be maintained during amplitude-modulated stimulation, overcoming a longstanding limitation in adaptive neuromodulation.

Together, TIMS and closed-loop artifact suppression establish a pathway toward non-invasive, bidirectional BCIs capable of testing causal neural mechanisms and modulating pathological circuit dynamics with unprecedented precision.