Nervous mechanisms and dark-adaptation
نویسندگان
چکیده
منابع مشابه
Mechanisms of visual sensitivity: backgrounds and early dark adaptation.
There is substantial physiological and psychophysical evidence for an adaptation mechanism whose effect, under many circumstances, is equivalent to placing a neutral density filter in front of the eye. Furthermore, this mechanism is of sufficient strength to predict the generalized Weber's law for increment thresholds on steady backgrounds. However, it was shown that an additional transient mec...
متن کاملLight and dark adaptation.
The high-frequency cutoff of the semicircular canals is unknown but probably also lies above 5 Hz. The high-frequency cutoff of the extraocular muscles is 1 Hz. so that central mechanisms (that introduce phase lead) must compensate from 1 to 5 Hz. The pursuit system begins to cut off between 0.5 to 1 Hz. so that it can compensate for slow head movements while the vestibular system compensates f...
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Older adults have serious difficulty seeing under low illumination and at night, even in the absence of ocular disease. Optical changes in the aged eye, such as pupillary miosis and increased lens density, cannot account for the severity of this problem, and little is known about its neural basis. Dark adaptation functions were measured on 94 adults ranging in age from the 20s to the 80s to ass...
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The level of dark adaptation of the whirligig beetle can be measured in terms of the threshold intensity calling forth a response. The course of dark adaptation was determined at levels of light adaptation of 6.5, 91.6, and 6100 foot-candles. All data can be fitted by the same curve. This indicates that dark adaptation follows parts of the same course irrespective of the level of light adaptati...
متن کاملDark Adaptation in Agriolimax
A method is described which measures the excitation of Agriolimax by light, during the progress of light adaptation, by assuming that the orientating effect of continuous excitation is expressed as a directly proportionate tension difference in the orienting muscles of the two sides of the body. The tendency toward establishment of such a tension difference is caused to work against a similar g...
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ژورنال
عنوان ژورنال: The Journal of Physiology
سال: 1954
ISSN: 0022-3751
DOI: 10.1113/jphysiol.1954.sp005169