We studied photoreceptors in the locust (<i>Schistocerca americanus</i>) visual system to determine the extent to which quantal noise and intrinsic neural noise limit temporal sensitivity. Typical computational models of the temporal contrast sensitivity function are deterministic, reflect only filter characteristics, and lack explicit noise sources [J. Opt. Soc. Am. <b>58</b>, 1133 (1968); Vision Res. <b>32</b>, 1373 (1992)]. We report here that the temporal contrast sensitivity function, at low light levels, is not simply the reflection of a filter function. Our evidence suggests that, at low backgrounds, noise, in conjunction with temporal filtering, plays a role in shaping the temporal contrast sensitivity function. At a given low adaptation level, quantal noise limits sensitivity at low temporal frequencies, while intrinsic noise limits sensitivity at relatively higher temporal frequencies.
© 1999 Optical Society of America
(330.1800) Vision, color, and visual optics : Vision - contrast sensitivity
(330.4060) Vision, color, and visual optics : Vision modeling
(330.4270) Vision, color, and visual optics : Vision system neurophysiology
(330.5310) Vision, color, and visual optics : Vision - photoreceptors
Eric P. Hornstein, David R. Pope, and Theodore E. Cohn, "Noise and its effects on photoreceptor temporal contrast sensitivity at low light levels," J. Opt. Soc. Am. A 16, 705-717 (1999)