Thayer School of Engineering, Dartmouth College, Hanover, NH 03755, USA.
Department of Biology and Health Science, New England College, Henniker, NH 03242, USA.
J Neurosci Methods. 2022 Apr 15;372:109536. doi: 10.1016/j.jneumeth.2022.109536. Epub 2022 Feb 25.
A growing body of research demonstrates that focused ultrasound stimulates activity in human and other mammalian nervous systems. However, there is no consensus on which sonication parameters are optimal. Furthermore, the mechanism of action behind ultrasound neurostimulation remains poorly understood. An invertebrate model greatly reduces biological complexity, permitting a systematic evaluation of sonication parameters suitable for ultrasound neurostimulation.
Here, we describe the use of focused ultrasound stimulation with an ex-vivo abdominal ganglion preparation of the California sea hare, Aplysia californica, a long-standing model system in neurobiology. We developed a system for stimulating an isolated ganglion preparation while obtaining extracellular recordings from nerves. The focused ultrasound stimulation uses one of two single-element transducers, enabling stimulation at four distinct carrier frequencies (0.515 MHz, 1.l MHz, 1.61 MHz, 3.41 MHz).
Using continuous wave ultrasound, we stimulated the ganglion at all four frequencies, and we present quantitative evaluation of elicited activation at four different sonication durations and three peak pressure levels, eliciting up to a 57-fold increase in spiking frequency.
We demonstrated that ultrasound-induced activation is repeatable, and the response consistency is comparable to electrical stimulation.
Due to the relative ease of long-term recordings for many hours, this ex-vivo ganglion preparation is suitable for investigating sonication parameters and the effects of focused ultrasound stimulation on neurons.
越来越多的研究表明，聚焦超声刺激了人类和其他哺乳动物神经系统的活动。然而，对于哪种超声参数是最佳的，目前还没有共识。此外，超声神经刺激的作用机制仍知之甚少。无脊椎动物模型大大降低了生物复杂性，从而可以系统地评估适合超声神经刺激的超声参数。
在这里，我们描述了使用聚焦超声刺激加利福尼亚海兔（Aplysia californica）的离体腹神经节制备物的方法，加利福尼亚海兔是神经生物学中一种长期使用的模型系统。我们开发了一种系统，可在对神经进行细胞外记录的同时刺激离体神经节制备物。聚焦超声刺激使用两个单元素换能器之一，可在四个不同载波频率（0.515MHz、1.lMHz、1.61MHz、3.41MHz）下进行刺激。
我们使用连续波超声在所有四个频率下刺激神经节，并展示了在四个不同超声持续时间和三个峰值压力水平下激发的激活的定量评估，激发的尖峰频率最高增加了 57 倍。
我们证明了超声诱导的激活是可重复的，并且响应一致性与电刺激相当。
由于可以进行长达数小时的长期记录，因此这种离体神经节制备物非常适合研究超声参数以及聚焦超声刺激对神经元的影响。
