经颅超声刺激人脑海马的数值仿真研究

颞叶癫痫、阿尔兹海默症等神经系统疾病与大脑海马的异常放电相关。近年兴起的经颅超声刺激治疗脑疾病具有无创、能深入脑组织和可调控海马神经元放电的特点。该文基于128阵元相控阵换能器、人头颅CT数据、水体建立超声经颅刺激海马数值仿真模型，数值仿真优选适应于海马刺激的换能器结构参数，并结合电容模型，探究超声声学参数对海马神经元放电的影响。结果表明曲率半径90 mm、开口半径56 mm、阵元半径2.0 mm、频率0.9 MHz的128阵元相控超声换能器可形成适应于刺激人脑海马大小的焦域；且在超声频率为0.9 MHz时对海马神经元放电有较好的抑制作用；在较小的占空比和较低的空间峰值时间平均声强条件下对神经元放电有较好的抑制作用。

Transcranial ultrasound stimulation of the human hippocampus: A numerical simulation study

Neurological diseases such as Temporal lobe epilepsy, Alzheimer''s disease are associated with abnormal discharges in the hippocampus of the brain. Transcranial ultrasound stimulation, which has emerged in recent years to treat brain diseases, is non-invasive, penetrates deep into brain tissue and can modulate hippocampal neuronal firing. In this paper, a numerical simulation model of ultrasonic transcranial stimulation of hippocampus was established based on the 128-element phase-controlled transducer, human head CT data and water. Numerical simulations were performed to optimize the structural parameters of the transducer adapted to the stimulation of the hippocampal region, then combined with the capacitance model to investigate the effects of ultrasonic acoustic parameters on the firing of hippocampal neurons. The results showed that a 128-element phase-controlled transducer with an opening diameter of 90 mm, a radius of curvature of 56 mm, an array radius of 2.0 mm, and a frequency of 0.9 MHz could form a focal field adapted to the size of the stimulated hippocampus of the human brain; and the ultrasound frequency of 0.9MHz showed a better inhibition effect on hippocampal neuronal discharge. A smaller duty cycle and lower spatial peak temporal average intensity showed a better inhibition effect on neuron discharge.