以活體共軛焦影像技術觀測視網膜波

Abstract

過去科學家研究證實在脊椎動物早期發育的視網膜上有神經訊號同步放電的現象，稱之為視網膜波，會影響視網膜與腦部的連結。過去研究神經訊號現象使用電生理學測量活體或離體培養視網膜的電訊號或是使用光學影像技術觀測離體培養視網膜的鈣離子螢光影像，這些都是侵入式的方法或需將動物犧牲。因為眼睛的可穿透性質，身為中樞神經系統一部分的視網膜是唯一可藉由非侵入式光顯微技術觀察的組織，所以我們利用ICON技術去觀察剛出生幼鼠視網膜的神經活動現象。ICON此種觀察方法可以讓同隻幼鼠被重複的觀測而不被犧牲或造成細胞的傷害，且提供了細胞解析度的眼底觀測方法，將可以更深入的研究神經細胞的活動。 我們的實驗雖然因為取樣範圍而無法看出視網膜波的空間性質，但是確認了活體生物內的神經活動現象，並且將可以長時間且重複的觀察同一個樣本的發育，所以對於神經細胞放電訊號研究提供了活體螢光影像的可能，未來可研究規律性自發神經活動作用所引發的神經細胞群間之連線改變（一般在數日或數週後發生）或動作電位引發神經細胞間的突觸可塑性（在數毫秒發生）。

It has been shown that the spontaneous activity of neurons, called retinal wave, in immature retina of vertebrate will influence retina growth and connection between CNS.The phenomenon using electrophysiological measurment in vivo or in vitro and observation of optical microscope from cultured retina were successfully detected, but those technology were invasive.Because of the transparency of the eyes, retina is the only part of central nervous system (CNS) that can be investigated noninvasively by optical imaging. In this report, we applied in vivo confocal neuroimaging (ICON) to detect the electrical activities of neurons in postnatal rat retina. ICON permits repeated observation of rats, preventing cell damage as well as rat sacrifice. In addition, ICON has the potential to provide subcellular resolution at fundus, so that the retinal neuron activities can be studied in more detail. Our experiments can’t approve the spatial property of the retinal waves, but confirmed that the neural activity within living organisms. The same rat can be repeatedly observed for a long time, thus provideing a possibility of detcting neural activity in vivo. We can investigate the relationship between the effects triggered by patterned spontaneous activity on the connectivity between different neuron populations (happening from days to weeks after birth) and the plasticity of the synapses between neurons as induced by action potential (occurring in milliseconds to seconds).