利用840 nm低功率雷射光刺激 活體大鼠黑質之腦波量測

Abstract

低功率光刺激研究至今已有數十年的歷史，但回顧過去的光刺激研究，多為生物體外的光照刺激或非活體的試管光刺激研究，而對於活體體內之光刺激研究，至今仍鮮有量測記錄，因此本篇研究將使用自行設計的雷射光刺激器來對生物活體之體內進行光刺激實驗，目的是想要探討光刺激對於活體體內的影響。 儀器設計的方面，光刺激器為使用10倍的物鏡，經過校正後將雷射光源導入光纖中，再利用光纖的可撓性及分離式設計，可精確的埋入生物體內進行光刺激；另外，腦波儀在設計上為了將雜訊濾除，我們使用了一組前端放大器、低通濾波器、陷波濾波器與可調式儀表放大器，將原始腦波經過濾波之後，再藉由軟體LabVIEW中的快速傅立葉轉換，使腦波訊號以頻率的方式呈現以便分析。 本實驗分為時間組、能量組以及功率組等三組，利用不同組合的刺激方式，從中找出共同的腦波變化現象。在時間組中發現以波長840 nm、固定刺激功率1 mW、不同光刺激時間作為變數時，以刺激5分鐘光刺激前後腦波差異最明顯，並利用此關鍵，以其刺激的能量300 mJ作為能量組依據；在能量組中，亦發現光刺激5分鐘時刺激前後腦波反應最為明顯，所以我們再以時間、能量這兩組腦波反應最明顯的共同點，光刺激時間5分鐘作為功率組的根據，以相同刺激時間5分鐘，不同刺激功率下，結果顯示在刺激功率為1 mW是功率組中對腦波反應最有影響之參數。 由實驗結果發現，使用所設計的儀器的確可對生物體造成反應，並於三組實驗交叉分析得到良好反應之參數，且在未來可整合化學或其他分析的方式，以具體了解光對於大鼠腦內化學成分的影響，也希望以此研究方法能促進低功率光刺激療法的研究向前邁進。

Low-level light stimulation has been studied for several decades. However, most of the previous studies focused on external light stimulation on living bodies or in vitro light stimulation. Studies on in vivo low-level light stimulation are relatively rare. Therefore, we designed a laser stimulation instrument to investigate the effects of in vivo low-level light stimulation. We used a 10× object lens to couple the laser light with an optical fiber. By using a flexible fiber and special separate design, we were able to accurately implement in vivo light stimulation on rats. In addition, in order to filter out the random signals in electroencephalogram, we used a combination of pre-amplifier, lowpass filter, notch filter, and instrumentation amplifier to filter brainwaves. We then used LabVIEW software to conduct fast Fourier transform and frequency-domain signal analysis. The experiment was divided into three groups, namely, the time, energy, and power groups. Different combinations of experimental parameters were used for light stimulation to observe the common EEG phenomenon of these groups. For the time group, an infrared laser with 1 mW power and 840 nm wavelength was used for stimulation at 1, 3, 5, and 10 min. We found that stimulation for 5 min resulted in the most brainwave differences between the before and after light stimulation states. On the basis of this implication, a stimulating energy of 300 mJ was used as the baseline for the energy group. For the energy group, an 840 nm laser with the same stimulating energy but with different time and power combinations was used. We found that stimulation for 5 min had the most apparent brainwave response. Consequently, we proceeded to use a stimulus duration of 5 min for the power group with varied stimulation powers at 0.5, 1, 1.66, 5, and 10 mW. The results showed that 1 mW power induced the most brainwave differences between the before and after light stimulation states in this experiment. Therefore, we found that low-level light stimulation with our instrument could affect rat brainwaves. We then performed cross-experiment analysis in the three groups to obtain fine response parameters. In the future, we could coordinate chemical analysis or other analysis methods to investigate the changes in the chemical composition of rat brains. Finally, through this study, we hope to promote the advancement of low-level light stimulation therapy.