腦波應用於大鼠活體體內之低功率雷射光刺激量測

Abstract

低功率的光刺激的發展已有數十年的時間，但過去對於光刺激的研究多使用生物體外的光照射或是非活體的實驗，對於活體體內的實驗，目前還沒有量測的紀錄，因此本篇研究將利用自行設計的雷射光刺激儀器，來進行生物活體體內的光刺激實驗，想要了解到光刺激實驗對於活體的影響。 為了要證明光刺激對於活體的影響，本次研究我們選擇腦波來做為量測工具，不同於一般專業人士對於腦波的分析，本次我們將把腦波訊號經過快速傅立葉轉換成頻域訊號，利用頻域訊號的強弱我們將可判斷腦波那些波長的值會隨著光刺激而改變。 在儀器設計方面，光刺激儀器的部份我們利用10倍物鏡將雷射光耦合在光纖裡，再利用光纖的可饒性，將雷射光導入被麻醉的生物體體內做光刺激，另外，腦波儀器的部分，為了要放大訊號和濾除周遭雜訊，我們使用了前端放大器、低通濾波器、陷波濾波器和可調式的儀表放大器，最後再利用電腦軟體LABVIEW進行快速傅立葉轉換，以方便我們做頻域的分析。 實驗部分我們分為四組，每組各用五隻大鼠，兩組施打6-OHDA而另外兩組為正常大鼠，再從施打6-OHDA的大鼠和正常大鼠各挑出一組進行光刺激實驗，使用1mW的840nm紅外光雷射刺激1分鐘。由結果發現經過光刺激後兩組大鼠的β波皆有明顯上升的趨勢，但很可能是刺激強度或刺激時間的不足，大約在30分鐘至1個小時之間，光刺激的影響就不再明顯。 由結果可以發現，使用我們所設計的光刺激儀器確實可以對大鼠腦波產生反應，有了此結果後在未來我們希望可以依據β波反應的強弱來找出最適合的光刺激參數，並利用此參數進行光刺激並配合例如化學分析等方式的量測方法，具體的了解到大鼠腦內化學成分的變化，讓低功率光刺激療法能有更大的突破。

The low level light stimulation has been developed for several decades, but the research on low level light stimulation was always in vitro in the past. There is no record about in vivo low level light stimulation. In this paper, the author designed the home-made laser instrument to study the effect of low level light stimulation in vivo. In order to understand the effect of low level light stimulation in vivo, EEG was used to measure the output. Unlike the conventional EEG analysis used by medical professional, we transferred EEG data by Fast Fourier Transform (FFT) to the frequency-domain signal. Judging the frequency-domain signal intensity, we may able to determine which of the brain wave is responded more rapidly to the LLLS. On the instrumental design, we used 10X optical lens to couple the low level light into the optical fiber. With the flexible fiber, we were able to do the laser stimulation on anesthetized rats in vivo. Of the EEG instru- mentation, we composed the pre-amplifier, Low Pass Filter, Notch Filter and instrumentation amplifier in order to filter out ambient noise and to enhance the brainwave. Finally, we applied a LABVIEW software to do Fast Fourier Transform and analysis of frequency-domain signal. We divided twenty rats into four groups, each group with five rats; two groups were injected with 6-OHDA and the other two groups as blank. Then we separated rats into two different groups to do the light stimulation experiment. We used 1mW power and 840 nm infrared laser stimulation for one minute. The results showed distinct β wave increase trend after light stimulation. The increase trend did wear off after 30 min to one hour. It might be due to the insufficient stimulation’s power or time to make permanent change. In this study, we found that low level light stimulation with our instrument can affect the rat’s brainwave. In the future, we hope to develop the optima stimulation parameters by the corresponding β wave’s intensity. With proper light stimulation parameters and measurable chemical markers, we shall able to learn the change of chemical com- position on rat’s brain specifically. Therefore, we may have a break- through development on the in vivo low level light stimulation therapy.