The all-cone retina of the garter snake: spectral mechanisms and photopigment |
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Authors: | Gerald H. Jacobs John A. Fenwick Michael A. Crognale Jess F. Deegan II |
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Affiliation: | (1) Department of Psychology, University of California, 93106 Santa Barbara, California, USA;(2) Present address: School of Optometry, University of California, 94720 Berkeley, California, USA |
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Abstract: | Summary The retina of the garter snake contains 3 morphologically distinct classes of cone photoreceptor. The spectral mechanisms in the retinas of garter snakes (Thamnophis sirtalis and T. marcianus) were studied by recording a retinal gross potential, the electroretinogram, using a flicker photometric procedure. Spectral sensitivity functions recorded with stimuli presented at high temporal frequency (62.5 Hz) are broadly peaked in the region of 550–570 nm. These functions remain spectrally invariant (a) in the face of significant changes in stimulus pulse rate (8–62.5 Hz), (b) whether the eye is light or dark adapted, and (c) under conditions of intense chromatic adaptation. It is concluded that the garter snake has only a single class of cone pigment. The results from a curve fitting analysis suggests that this pigment has peak absorbance at about 556 nm. |
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Keywords: | Garter snake Thamnophis Spectral mechanisms Cone photopigment All-cone retina Electroretinogram |
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