MECHANISMS SUBSERVING COLOR CODING IN THE VERTEBRATE RETINA.
Rept. no. 6 (Final) Oct 66-Jan 68,
KEIO UNIV TOKYO (JAPAN) SCHOOL OF MEDICINE
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The responses used as indices of studying color reception are potential changes with latencies of several msec recorded from within single photoreceptors using micropipette electrodes having tip diameters less than 0.1 micron. Single carp cones are used for the study, but single octopus photoreceptors are also used to provide matrials for discussion of the significance of the receptor potential upon the flow of information within the receptor. The intracellular placement of the electrode is achieved by mounting the retina on a vibrating table which gives it a large acceleration against the slowly advancing electrode tip. The electrode penetration is signalled by the appearance of a resting potential of 30 - 40 mV. In single carp cones, responses to light are hyperpolarizing. The response spectra studied statistically are classified into three groups in terms of wavelengths of maximum sensitivity. These are in close agreement with those of the absorption spectra of single goldfish cones reported by Marks and MacNichol. The response of single octopus photoreceptors, studied as a control, is a graded sustained depolarization, as common in most invertebrate photoreceptors. The action spectrum calculated therefrom agrees well with the absorption spectrum of the receptor photopigment. Evidence is provided that each octopus photoreceptor is selectively sensitive to a certain plane of polarized light. Author
- Anatomy and Physiology