Kilohertz electrical stimulation drives widespread neuronal activation and temporal interference imposes focal rhythmic modulation

Temporal interference (TI) stimulation has attracted attention as a non-invasive approach that can target deep brain structures through interacting kilohertz-frequency electric fields. Its basic premise is that TI stimulation evokes neuronal responses through low-frequency amplitude modulation (AM), while the underlying kilohertz-frequency stimulation is ineffective to induce activity, the latter of which has not been tested rigorously at the cellular level. Here, we combined two-photon imaging in mouse models with immunohistochemistry and computational modeling to characterize spatiotemporal patterns of neuronal responses during TI stimulation. We found that kilohertz-frequency stimulation was sufficient to evoke activity without AM. In contrast, AM organized neuronal activity into rhythmic responses at AM frequency, with the strongest entrainment near the center of interference. Thus, kilohertz-frequency stimulation can drive widespread neuronal activation, upon which TI imposes focal rhythmic modulation. Our results provide a framework for refining TI stimulation and highlight the potential of kilohertz-frequency stimulation for brain stimulation.