Fig. 2.

Bilateral Temporal Interfering fields for hypoglossal nerves stimulation. Bilateral TI focuses TI stimulation on both hypoglossal nerves to create a behavioral output with lower exposure strengths than regular TI (A). The direct output of hypoglossal nerve stimulation is tongue movement, which increases airflow and avoids sleep apnea. In our protocol, we combine tongue movement recording (Connor et al. 2008; Gilliam and Goldberg 1995)and electromyography (EMG) (Fleury Curado et al. 2017; Meadows et al. 2014) to demonstrate the value of non-invasive bilateral TI as a means for replacing implantable devices (B). bTI and TI simulations were simulated in Sim4Life to optimize electrode placement along the nerves and minimize unwanted stimulation in the neighboring areas. Temporal interference using a 5Hz offset efficiently stimulates hypoglossal nerves in mice. However, when stimulating one side only, the stimulation amplitude needed to elicit tongue movement and an EMG response (D and E) must be increased and as a result, creates unwanted stimulation of nontarget muscles. When stimulated with our bTI protocol, the stimulation amplitude of each side can be reduced, leading to selective stimulation of both hypoglossal nerves without any unwanted stimulation (F). Looking at characteristics of the evoked CMAPs, we could not find any differences between unilateral TI stimulation- and the bilateral stimulation-evoked CMAPs. No significant differences between duration, and amplitude were apparent, but the bTI required much lower stimulation amplitudes to evoke the same activity (G). The example CMAP depicted in this figure have been bandpass filtered (100-400Hz)