Pulse Repetition Frequency Tuned Low-Intensity Focused Ultrasound Neuromodulation for Tibial Nerve Targeted Bladder Function Modulation

OBJECTIVE: This study aims to investigate whether the neuromodulatory efficacy of low-intensity focused ultrasound (LIFU) for peripheral nerve stimulation (PNS) can be systematically tuned by the temporal stimulation parameter, pulse repetition frequency (PRF). METHODS: LIFU-mediated tibial nerve stimulation (LIFU-TNS) was applied with multiple PRF conditions to evaluate PRF-dependent neuromodulatory effects, with micturition inhibition as the primary outcome. Intra-bladder pressure (IBP) was continuously monitored to evaluate changes in micturition intervals. Neural involvement was confirmed using (1) a lidocaine-induced sciatic nerve (tibial branch) block, and the stimulation paradigm was additionally evaluated in (2) an acetic acid-induced overactive bladder model and (3) freely moving, unconstrained animals to assess robustness across physiological and behavioral conditions. RESULTS: A distinct PRF-dependent neuromodulation was observed, where 100 Hz stimulation elicited the most potent inhibition of micturition, whereas 10 Hz and 1 kHz showed comparatively less effective results. Quantitative analysis of normalized micturition interval (post-stimulation / pre stimulation baseline) confirmed this trend. (10 Hz: 0.98±0.16; 100 Hz: 1.72±0.81; 1 kHz: 0.95±0.35). Importantly, consistent inhibition was replicated across the nerve-block, overactive bladder, and freely moving models, indicating robustness of the effect under diverse physiological and behavioral conditions. CONCLUSION: The clear PRF-dependent modulation observed in LIFU-TNS establishes PRF as a feasible and tunable control parameter and highlights its potential for guiding precise neuromodulation. SIGNIFICANCE: Unlike conventional intensity dependent strategies, this study demonstrates that PRF is essential for effective ultrasound neuromodulation in overactive bladder. These findings establish a systematic parameter-based framework for developing robust peripheral nerve interfaces.