title: Sustained pupillary constrictions mediated by an L- and M-cone opponent process.
abstract: We show that irradiance-coding alone cannot explain the sustained pupillary constrictions evoked by chromatic and luminance variations in a stimulus. For example, stimulus modulations that decremented the contrasts in L- and M-cones as well as rods and melanopsin photoreceptors produced sustained constrictions rather than the predicted dilations. Although the sustained responses are unidirectional, we confirm that they are at least partially mediated by an L- and M-cone opponent interaction. We discuss the implications of sustained unidirectional chromatic responses in view of the function of the pupil to improve the clarity of vision.
authors.affiliation: Department of Psychology, Faculty of Letters, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba-shi, Chiba 263-8522, Japan. kimura@L.chiba-u.ac.jp <kimura@L.chiba-u.ac.jp>
authors.forename: Eiji
authors.initials: E
authors.lastname: Kimura
authors.forename: Rockefeller S L
authors.initials: RS
authors.lastname: Young
mesh_terms: D006801:Humans; D008027:Light; D020419:Photoreceptor Cells, Vertebrate / Q000502:physiology; D011680:Pupil / Q000528:radiation effects*; D017949:Retinal Cone Photoreceptor Cells / Q000502:physiology*; D012684:Sensory Thresholds; D014785:Vision, Ocular / Q000502:physiology*