Department of Biomedical Engineering, New Jersey Institute of Technology, Newark, NJ, USA.
Department of Electrical and Computer Engineering, NC State University, Raleigh, NC, USA.
Brain Stimul. 2021 May-Jun;14(3):598-606. doi: 10.1016/j.brs.2021.03.004. Epub 2021 Mar 24.
Focused ultrasound (FUS) has excellent characteristics over other non-invasive stimulation methods in terms of spatial resolution and steering capability of the target. FUS has not been tested in the cerebellar cortex and cellular effects of FUS are not fully understood.
OBJECTIVE/HYPOTHESIS: To investigate how the activity of cerebellar Purkinje cells (PCs) is modulated by FUS with varying pulse durations and pulse repetition frequencies.
A glass microelectrode was inserted into the cerebellar vermis lobule 6 from the dorsal side to extracellularly record single unit activity of the PCs in anesthetized rats. Ultrasonic stimulation (500 kHz) was applied through a coupling cone, filled with degassed water, from the posterior side to target the recording area with varying pulse durations and frequencies.
Simple spike (SS) activity of PCs was entrained by the FUS pattern where the probability of spike occurrences peaked at around 1 ms following the onset of the stimulus regardless of its duration (0.5, 1, or 2 ms). The level of entrainment was stronger with shorter pulse durations at 50-Hz pulse repetition frequency (PRF), however, peri-event histograms spread wider and the peaks delayed slightly at 100-Hz PRF, suggesting involvement of a long-lasting inhibitory mechanism. There was no significant difference between the average firing rates in the baseline and stimulation periods.
FUS can entrain spiking activity of single cells on a spike-by-spike basis as demonstrated here in the rat cerebellar cortex. The observed modulation potentially results from the aggregate of excitatory and inhibitory effects of FUS on the entire cortical network rather than on the PCs alone.
在空间分辨率和目标导向能力方面，聚焦超声（FUS）优于其他非侵入性刺激方法。FUS 尚未在小脑皮层中进行测试，并且 FUS 的细胞效应尚未完全了解。
目的/假设：研究不同脉冲持续时间和脉冲重复频率的 FUS 如何调节小脑浦肯野细胞（PC）的活动。
从背侧将玻璃微电极插入小脑蚓部 6 小叶，在麻醉大鼠中通过外部记录单个 PC 的单位活动。通过填充脱气水的耦合锥体从后侧施加超声刺激（500 kHz），以不同的脉冲持续时间和频率靶向记录区域。
PC 的简单尖峰（SS）活动被 FUS 模式所调制，无论其持续时间（0.5、1 或 2 ms）如何，尖峰出现的概率都在刺激开始后约 1 ms 时达到峰值。在 50-Hz 脉冲重复频率（PRF）下，较短的脉冲持续时间可增强同步性，但在 100-Hz PRF 下，事件相关直方图的扩散范围更广，峰值略微延迟，表明存在持久的抑制机制。在基线和刺激期间，平均放电率没有显著差异。
正如在本研究中在大鼠小脑皮层中所证明的那样，FUS 可以逐个尖峰地诱发单个细胞的尖峰活动。观察到的调制可能是由于 FUS 对整个皮层网络的兴奋和抑制作用的综合影响，而不仅仅是对 PC 的影响。
