Data 1 of 3 for: Optical coherence tomography imaging of evoked neural activity in sciatic nerve of rat

Objective: To investigate changes in intensity, phase retardation, phase, and frequency spectra obtained from optical coherence tomography (OCT) images in response to evoked neural activity in sciatic nerve of rat in vitro. Approach: M-scans with 20 μs temporal resolution were obtained on peripheral nerves of rat using a swept source polarisation sensitive optical coherence tomography (PS-OCT) system, while a nerve cuff acquired electrical neural recordings. From a total of 10 subjects: 3 had no stimulation (controls), 3 had paw stimulation, and 4 had nerve stimulation. Changes in the OCT signal intensity, phase retardation, phase, and frequency spectra were calculated for each subject and compared to the control subjects as well as reference samples of a mirror and microspheres in solution. Main results: Observed changes in phase retardation and phase were not above the noise level of reference mirror sample. Observed changes in intensity in 3 paw stimulation and 2 nerve stimulation subjects and changes in frequency spectra amplitude in 2 paw stimulation were above the reference noise level. The delayed onset and extended duration of the changes in intensity and frequency spectra amplitude were temporally consistent with osmotic swelling from potassium ion currents in myelinated fibres which has previously been characterised in squid and crab nerve using light scattering techniques but has not been reported using OCT on myelinated fibres. Significance: Imaging osmotic swelling in neural tissue using OCT signal intensity and frequency spectra creates exciting new possibilities for functional imaging in peripheral nerves and white matter of the brain.

目的：探究大鼠坐骨神经体外诱发神经活动时，光学相干断层扫描（OCT）图像中强度、相位延迟、相位及频谱的变化规律。方法：采用扫频光源偏振敏感光学相干断层扫描（PS-OCT）系统，对大鼠外周神经进行时间分辨率为20微秒的M扫描，同时通过神经袖套记录神经电活动。研究共纳入10只样本：3只无刺激（对照组）、3只接受爪部刺激、4只接受神经刺激。计算每个样本的OCT信号强度、相位延迟、相位及频谱变化，并与对照组及溶液中镜子和微球的参考样本进行对比分析。主要结果：观察到的相位延迟与相位变化未超出参考镜子样本的噪声水平；3只爪部刺激样本的强度变化及2只爪部刺激样本的频谱振幅变化显著高于参考噪声水平。强度与频谱振幅变化的延迟起始及延长持续时间，在时间特征上与有髓纤维中钾离子电流引发的渗透性肿胀一致——该现象此前已通过光散射技术在鱿鱼及螃蟹神经中得到表征，但尚未见OCT技术应用于有髓纤维的相关报道。意义：利用OCT信号强度与频谱对神经组织渗透性肿胀进行成像，为外周神经及脑白质的功能成像领域开辟了极具前景的新方向。