On the square root intensity coding at the level of cone photoreceptors.
In psychophysics as well as in sensory physiology, the response amplitude R is often a power function of the stimulus intensity S over a wide range of S (i.e. R = aSk; a = constant). In vision, there is a recent report that such a power relationship ("square root intensity coding" if k = 0.5) may arise as early as at the cone photoreceptor level if the stimulus is a narrow slit of light. A simple model is presented here to account for this finding: strong electrical coupling with several neighboring cones can act to expand the dynamic range of the impaled cone in such a way as to produce a square root coding region for the responses to fine visual objects such as small spots and narrow slits.
Yasui
S
S
Faculty of Computer Science and Systems Engineering, Kyushu Institute of Technology, Iizuka, Japan.
D004307:Dose-Response Relationship, Radiation; D006801:Humans; D008027:Light; D008433:Mathematics; D008959:Models, Neurological; D010783:Photometry; D010786:Photoreceptor Cells / Q000502:physiology*