Frequency Dependence of Ultrasound Neurostimulation in the Mouse Brain
Ultrasound holds great promise as a tool for neurostimulation because, unlike other neurostimulation technologies, it is non-invasive, can target regions deep within the the brain, and can focus to cubic millimeter volumes.
Choosing the frequency of ultrasound for neurostimulation is important for determining the smallest achievable focusing volume as well as maximizing the fraction of ultrasound that gets through the skull. Additionally, understanding how neurostimulation varies as a function of ultrasound frequency could potentially cast light about the mechanisms underlying ultrasound neurostimulation.
While several ultrasound neurostimulation studies have been performed in various animal models and even humans, the frequency dependence of ultrasound neurostimulation had yet to be more fully described. We tested a range of ultrasound frequencies up to 2.9 MHz and showed that higher ultrasound frequencies require more intensity than lower frequencies to achieve the same amount of neurostimulation. This suggests either a cavitation-based or particle displacement mechanism behind ultrasound neurostimulation. We hope this study will help inform the choice of ultrasound frequency for future scientific and clinical neurostimulation applications.
Ye, PP, Brown JR, Pauly KB. Frequency Dependence of Ultrasound Neurostimulation in the Mouse Brain. Ultrasound Med Biol. 2016 Apr 15. DOI: 10.1016/j.ultrasmedbio.2016.02.012