Establishment of a new method detecting neural activity using two-dimensional photon counting of ultraweak biochemiluminescence

利用硅雪崩光电二极管，我们研制了一种能够探测神经系统发出的超弱生物化学发光的单光子探测系统。利用该系统，在400-900 nm波长范围内，总量子效率为3-5%，噪声等效功率为10~(-19)W量级。利用该系统，我们可以制作一种从脑片中检测超弱生物化学发光的装置。在完全黑暗的情况下，这种超微弱的生物化学发光光被直径为150微米的锥形纤维引导到光探测器上并被检测到。用该系统检测培养的大鼠海马脑片的生物化学发光，成功地检测到10~(-18)W/mm~(2)量级的超弱生物化学发光。这种从海马片发出的生物化学发光光通过使用KCl去极化而增加，而通过使用河豚毒素抑制神经而减少。这些结果表明，从海马片发出的化学发光强度与神经活动的强度变化是平行的。此外，大鼠下丘脑视交叉上核(SCN)是哺乳动物的昼夜节律振荡器，其生物化学发光最长可达72小时。SCN的生物化学发光强度在主观昼夜各有2个峰值。这些脑片产生生物化学发光的机制以及为什么在SCN中存在两个峰的原因目前正在研究中。在这项研究中，阐明了大鼠脑片发出的超弱生物化学发光与神经活动平行变化。现在，我们正试图使用ARUGUS-50(日本滨松光电子公司)对这些超弱生物化学发光进行二维测定。

Using a silicon avalanche photodiode we developed a single-photon detector system which could detect ultraweak biochemiluminescence emitted from nervous systems. Within the wavelength of 400-900 nm, the total quantum efficiency was 3-5% and the noise-equivalent power was in the order of 10^<-19>W utilizing this system. Using this system we could make a device detecting ultraweak biochemiluminescence from brain slices. Under complete darkness this ultraweak biochemiluminescence light was guided to a light detector by taperfibers having an opening of 150mum in a diameter and detected. When the biochemiluminescence light emitted from cultured rat hippocampal brain slices was detected using this system, 10^<-18>W/mm^2 order of the ultraweak biochemiluminescence light was successfully detected. This biochemiluminescence light emitted from the hippocampal slices increased by depolarization using KCl and decreased by the neural suppression using tetrodotoxin. From these results, it is shown that the strength of the chemiluminescence emitted from the hippocampal slices altered in parallel with that of neural activity. Furthermore, biochemiluminescence was determined for at most 72h from the hypothalamic suprachiasmatic nuclei (SCN) of rats which is a circadian oscillator in mammals. The strength of the biochemiluminescence from the SCN had 2 peaks in their subjective day and nights, respectively. The mechanism of the generation of biochemiluminescence from these brain slices and the reason why 2 peaks existed in that in the SCN are now under investigation. In this study, it was clarified that ultraweak biochemiluminescence emitted from rat brain slices altered in parallel with neural activity. Now, we are trying to get 2 dimensional determination of these ultraweak biochemiluminescence using ARUGUS-50 (Hamamatsu Photonics, Co., Japan) .