Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, United States of America.
Biophotonics Center, Vanderbilt University, Nashville, TN, United States of America.
J Neural Eng. 2021 Apr 8;18(5). doi: 10.1088/1741-2552/abf00d.
. Infrared neural inhibition (INI) is a method of blocking the generation or propagation of neural action potentials through laser heating with wavelengths strongly absorbed by water. Recent work has identified that the distance heated along axons, the block length (BL), modulates the temperature needed for inhibition; however, this relationship has not been characterized. This study explores how BL during INI can be optimized towards minimizing its temperature threshold.. To understand the relationship between BL and the temperature required for INI, excised nerves fromwere laser-heated over different lengths of axon during electrical stimulation of compound action potentials. INI was provided by irradiation (= 1470 nm) from a custom probe (= 6 nerves), and subsequent validation was performed by providing heat block using perfused hot media over nerves (= 5 nerves).. Two BL regimes were identified. Short BLs (thermal full width at half maximum (tFWHM) = 0.81-1.13 mm) demonstrated that increasing the tFWHM resulted in lower temperature thresholds for INI (< 0.0125), while longer BLs (tFWHM = 1.13-3.03 mm) showed no significant change between the temperature threshold and tFWHM (> 0.0125). Validation of this longer regime was performed using perfused hot media over different lengths of nerves. This secondary heating method similarly showed no significant change (> 0.025) in the temperature threshold (tFWHM = 1.25-4.42 mm).. This work characterized how the temperature threshold for neural heat block varies with BL and identified an optimal BL around tFWHM = 1.13 mm which minimizes both the maximum temperature applied to tissue and the volume of tissue heated during INI. Understanding how to optimally target lengths of nerve to minimize temperature during INI can help inform the design of devices for longitudinal animal studies and human implementation.
. 红外神经抑制（INI）是一种通过激光加热来阻断神经动作电位产生或传播的方法，其加热波长被水强烈吸收。最近的研究已经确定，轴突加热的距离，即阻断长度（BL），会调节抑制所需的温度；然而，这种关系尚未得到表征。本研究探讨了如何优化 INI 期间的 BL，以最小化其温度阈值。. 为了了解 BL 与 INI 所需温度之间的关系，在复合动作电位的电刺激下，对从离体神经中激光加热的不同长度的轴突进行了激光加热。INI 通过来自定制探头（= 6 根神经）的照射（= 1470nm）提供，随后通过在神经上用灌注热介质提供热块来进行后续验证（= 5 根神经）。. 确定了两种 BL 机制。短 BL（热半最大值全宽（tFWHM）= 0.81-1.13mm）表明，增加 tFWHM 会导致 INI 的温度阈值降低（<0.0125），而较长的 BL（tFWHM = 1.13-3.03mm）表明温度阈值与 tFWHM 之间没有显著变化（>0.0125）。使用不同长度的神经上的灌注热介质对较长的机制进行了验证。这种二次加热方法同样表明，在温度阈值（tFWHM = 1.25-4.42mm）方面没有显著变化（>0.025）。. 本工作描述了神经热阻断的温度阈值如何随 BL 而变化，并确定了一个最佳的 BL，约为 tFWHM = 1.13mm，这可以最小化 INI 期间应用于组织的最大温度和加热的组织体积。了解如何最佳地靶向神经长度以在 INI 期间最小化温度，可以帮助为纵向动物研究和人体实施的设备设计提供信息。
