果蠅光髓質內局部神經元的動態調諧神經模型

日常中光源的差異性其實是很大的，較高階的動物具有瞳孔及水晶體能調節光源進入的量，再經由光受器(photoreceptor)後端的神經及腦區調節使生物在視覺下不會因光源差異而失真。希望了解生物是如何調節光源以確保影像不因光源差異而失真，而使用果蠅為研究對象，果蠅視覺因沒有瞳孔調節入射光，是光線直接進入光受器傳到光髓質(Optic Medulla/Med)後再傳至下游腦區，且果蠅光源視覺的處理方式僅是由位於 Med 內的局部神經元(Local neuron/LN)調節。由之前的研究發現位於 Med 中的 LN 有大小上的差異，且皆為抑制型神經元。因此我們設計多種覆蓋範圍的 LN，希望找到這些型態上差異的功能。而此篇實驗的結果是發現型態與外在刺激的關連性及覆蓋範圍的大小具有調控上功能，能將高刺激區塊調節與低刺激區塊相近且能將於高刺激區塊中的細節明顯。功能類似相機系統中的高動態範圍成像(HDR)技術

關鍵字

果蠅光髓質；局部神經元

並列摘要

Animals are able to perceive detailed visual features in natural scene, which often exhibits high contrast ratio across the field of view. Although being a fundamental feature of the visual system, the circuit mechanism of the high dynamic range is not well understood. To address the problem, we developed a computational model of the local neuron (M6LN) circuit in the sixth layers of the medulla, a neuropil in the early visual area. A recent study revealed that the M6LNs have diverse coverage patterns in the medulla and suggested that M6LNs may take part in tuning the dynamic range of the visual system. 1 We systematically investigated the correlation between the coverage patterns of M6LNs and ability of dynamic range tuning. We tested our model with images of natural scene and found that the combination of N6LNs with specific coverage patterns led to the optimal results. Under this circuit configuration, the visual system is able to process images with high contrast ratio in a way similar to the high-dynamic rang (HDR) technique used in modern cameras.

並列關鍵字

drosophila ； optic medulla ； medulla ； local neurons ； Flysim

參考文獻

and wiring variability of visual local neurons in the Drosophila medulla M6

Neurology, 522(17), 3795–3816. https://doi.org/10.1002/cne.23622

2. Williams, N. (2005). All phaged out. Current Biology, 15(9), R318–R319.

R., & Silies, M. (2015). A Class of Visual Neurons with Wide-Field Properties Is

https://doi.org/10.1016/j.cub.2015.11.018

國際替代計量

果蠅光髓質內局部神經元的動態調諧神經模型

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