Low-intensity ultrasound is an emerging modality for neuromodulation. Yet, transcranial neuromodulation using low-frequency piezo-based transducers offers poor spatial confinement of excitation volume, often bigger than a few millimeters in diameter. In addition, the bulky size limits their implementation in a wearable setting and prevents integration with other experimental modalities. Here, we report spatially confined optoacoustic neural stimulation through a miniaturized Fiber-Optoacoustic Converter (FOC). The FOC has a diameter of 600 μm and generates omnidirectional ultrasound wave locally at the fiber tip through the optoacoustic effect. We show that the acoustic wave generated by FOC can directly activate individual cultured neurons and generate intracellular Ca2+ transients. The FOC activates neurons within a radius of 500 μm around the fiber tip, delivering superior spatial resolution over conventional piezo-based low-frequency transducers. Finally, we demonstrate direct and spatially confined neural stimulation of mouse brain and modulation of motor activity in vivo.

中文翻译：

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亚毫米空间精度的光声脑刺激。

低强度超声是一种新兴的神经调节手段。然而，使用基于低频压电的换能器的经颅神经调制提供的激励体积的空间限制较差，其激励直径通常大于几毫米。另外，笨重的尺寸限制了它们在可穿戴环境中的实现，并阻止了与其他实验模式的集成。在这里，我们报告通过小型化的光纤声转换器（FOC）进行空间限制的光声神经刺激。FOC的直径为600μm，并通过光声效应在光纤尖端局部产生全向超声波。我们显示FOC生成的声波可以直接激活单个培养的神经元，并生成细胞内Ca2 +瞬变。FOC激活纤维尖端周围500μm半径内的神经元，与传统的基于压电的低频换能器相比，具有更高的空间分辨率。最后，我们展示了对小鼠大脑的直接和空间限制的神经刺激以及体内运动活动的调节。