| 翻訳と辞書 |
| Accelerating Dark Adaptation in Humans ： ウィキペディア英語版 |
Accelerating Dark Adaptation in Humans
Night vision, or scotopic vision, is the ability to see under low light conditions. In humans, rod cells are exclusively responsible for night vision as cone cells are only able to functions at higher illumination levels.〔Miller, R. E., & Tredici, T. J. (1992). Night vision manual for the flight surgeon. PN.〕 Night vision is of a much poorer quality than day vision because it is limited by a reduced resolution and therefore provides the ability to only discriminate between shades of black and white.〔 In order for humans to transition from day to night vision they must undergo a dark adaptation period in which each eye adjusts from a high luminescence setting to a low luminescence setting.〔 This adaptation period is different for both rod and cone cells and results from the regeneration of photopigments to restore retinal sensitivity.〔 Cone cells are able to regain maximum retinal sensitivity in 9–10 minutes of darkness whereas rods require 30–45 minutes to do so.〔"Sensory Reception: Human Vision: Structure and function of the Human Eye" vol. 27, p. 179 Encyclopaedia Britannica, 1987〕 There exist many ways in which humans can accelerate the dark adaptation period and therefore gain full vision in low luminescence settings in a shorter period of time.
== Advantages of Night Vision ==
Many animals such as cats possess high resolution night vision allowing them to discriminate objects with high efficiency in low illumination settings. The tapetum lucidum is a reflective structure that is responsible for this superior night vision as it mirrors light back through the retina exposing the photoreceptor cells to an increased amount of light.〔(Link ), Ollivier, F. J., Samuelson, D. A., Brooks, D. E., Lewis, P. A., Kallberg, M. E., & Komaromy, A. M. (2004). Comparative morphology of the tapetum lucidum (among selected species).Veterinary Ophthalmology, 7(1), 11-22.〕 Most animals which possess a tapetum lucidum are nocturnal most likely because upon reflection of light back through the retina the initial images become blurred.〔 Humans, like their primate relatives, do not possess a tapetum lucidum and therefore were predisposed to be a diurnal species.〔Schwab, I. R., Yuen, C. K., Buyukmihci, N. C., Blankenship, T. N., & Fitzgerald, P. G. (2002). Evolution of the tapetum. Transaction of the American Ophthalmological Society, 100, 187-200.〕
Despite the fact that the resolution of human day vision is far superior to that of night vision, human night vision provides many advantages. Like many predatory animals humans can use their night vision to prey upon and ambush other animals without their awareness. Furthermore, in the event of an emergency situation occurring at night humans can increase their chances of survival if they are able to perceive their surroundings and get to safety. Both of these benefits can be used to explain why humans did not completely lose the ability to see in the dark from their nocturnal ancestors.〔Hall, M. I., Kamilar, J. M., & Kirk, E. C. (2012). Eye shape and the nocturnal bottleneck of mammals. Proceedings of the Royal Society B, doi: 10.1098/rspb.2012.2258〕
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
■ウィキペディアで「Accelerating Dark Adaptation in Humans」の詳細全文を読む
スポンサード リンク
| 翻訳と辞書 : 翻訳のためのインターネットリソース |
Copyright(C) kotoba.ne.jp 1997-2016. All Rights Reserved.
|
|