Previous studies have indicated that the presence of microbubbles (MBs) during sonication has an impact on neuronal activity, while the underlying mechanisms remain to be revealed. In this study, a model for the scattered pressures produced by the pulsating lipid-encapsulated MBs in mouse brain was developed to numerically investigate the effect of MBs on neuronal activity during transcranial focused ultrasound stimulation. The additional summed scattered pressure (Psummed_scat) from the oscillating MBs was calculated from the model. The level of neuronal activity was experimentally verified using an immunofluorescence assay with antibodies against c-fos. The pressure difference (ΔP) between acoustic pressures at which the same level of neuronal activity is excited by ultrasound stimulation with and without MBs was obtained from the experiments. The results showed that Psummed_scat accounts for about half of the ΔP when the MBs experience a "compression-only" response. The Psummed_scat suddenly increased at a critical acoustic pressure, around which a rapid enhancement of ΔP obtained from experiment also occurred. This work suggested that the additional scattered pressures from pulsating MBs are probably a mechanism that affects neuronal activity under transcranial focused ultrasound stimulation.

中文翻译：

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在经颅聚焦超声刺激下，微气泡振荡产生的分散压力对小鼠大脑神经元活动的影响。

先前的研究表明，超声处理过程中微泡（MBs）的存在会对神经元活动产生影响，而其潜在机制仍有待揭示。在这项研究中，建立了由脉冲脂质包裹的MBs在小鼠脑中产生的分散压力的模型，以数值研究MBs对经颅聚焦超声刺激过程中神经元活动的影响。从模型中计算出了来自振荡MB的附加总分散压力（Psummed_scat）。使用针对c-fos的抗体进行的免疫荧光试验，通过实验验证了神经元活性的水平。从实验中获得了通过超声刺激在有或没有MBs的情况下激发相同水平的神经元活动的声压之间的压力差（ΔP）。结果表明，当MB经历“仅压缩”响应时，Psummed_scat约占ΔP的一半。Psummed_scat在临界声压下突然增加，在此附近，也发生了从实验获得的ΔP的快速增强。这项工作表明，脉动MB产生的额外分散压力可能是影响经颅聚焦超声刺激下神经元活动的一种机制。