Mihran R T, Barnes F S, Wachtel H
Department of Electrical and Computer Engineering, University of Colorado, Boulder 80309-0425.
Biomed Sci Instrum. 1990;26:235-46.
Single pulses of focused ultrasound have been observed to significantly modify neuronal excitability in vitro for a period of 40-50 ms following pulse termination. This window of transient modification includes periods of both relative suppression and enhancement of excitability, the sequences of which generally follow distinct temporal patterns. The ultrasound pulses were focused, 2-7 MHz, nominally of 500 microseconds duration, and of peak intensities of 100-800 W/cm2. Specific absorbed energies were less than 100 mJ/gm, which strongly precludes bulk thermal mechanisms as a basis of this effect. Our current evidence suggests that the low-frequency radiation pressure transient accompanying the envelope of the acoustic pulse is the proximal effector in this phenomenon, acting by the gating of relatively slow stretch-sensitive channels in the neuronal membrane. These observations demonstrate the potential for high peak-power, low total-energy pulses of ultrasound to functionally modulate neuroelectric signals, a finding which could suggest new prosthetic, analgesic, or therapeutic clinical applications.
已观察到，聚焦超声单脉冲在脉冲终止后的40 - 50毫秒内可显著改变体外神经元的兴奋性。这种短暂改变的窗口包括兴奋性相对抑制和增强的时期，其顺序通常遵循不同的时间模式。超声脉冲为聚焦式，频率2 - 7兆赫，标称持续时间500微秒，峰值强度为100 - 800瓦/平方厘米。比吸收能量小于100毫焦/克，这有力地排除了整体热机制作为这种效应的基础。我们目前的证据表明，伴随声脉冲包络的低频辐射压力瞬变是这一现象的近端效应器，其作用方式是通过开启神经元膜中相对缓慢的拉伸敏感通道。这些观察结果证明了高峰值功率、低总能量的超声脉冲在功能上调节神经电信号的潜力，这一发现可能暗示新的假体、镇痛或治疗临床应用。
