Premium
ELECTRONIC CHARGE TRANSPORT IN CAROTENOID PIGMENTS AND A PRIMITIVE THEORY OF THE ELECTRORETTNOGRAM
Author(s) -
Rosenberg B.
Publication year - 1962
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1962.tb08084.x
Subject(s) - electric field , retina , depolarization , biophysics , photocurrent , polarity (international relations) , receptor potential , physics , materials science , biology , chemistry , optics , receptor , biochemistry , quantum mechanics , cell , genetics
Summary The photoconductive and photovoltaic behaviour of a ß‐carotene glass cell is analyzed with regard to the effects of electric field strengths, polarity, and wave length dependence of the photoliberated electronic charge. These results have lead to a primitive theory of the electroretinogram. The four postulates of the theory are: 1. The generator potentials of the retina arise from a current source in the rod and cone outer segments. These currents are electronic charge transport processes created by the absorption of light by the visual pigments. 2. The component P II of the electroretinogram arises as a photocurrent in the retina due to the presence in the dark of an electric field in the receptor organ. 3. The component P III of the electroretinogram arises as a photovoltaic current in the receptor organ. 4. The electric field in the receptor organ arises from a potential gradient between the synaptic and the free end of the receptor. The polarity of the field being the base of the receptor negative with respect to the free end. These postulates of the theory, taken in conjunction with the experimentally determined characteristics of the photoconduction and photovoltaic effects are capable of commenting on or explaining the signs and shapes of the diphasic and monophasic electroretinograms; the localization measurements on generator potentials; the effects of depolarizing agents on the electroretinograms; the ontogenetic order of development of P III and P II; the similarity of sign of P III in vertebrate and invertebrate eyes; the presence of two components in the monophasic curves of invertebrate eyes; the signs, shapes, time constants, and wave length dependence of the graded photopic response; and lastly the characteristics of on/off receptors. Some difficulties and limitations of the theory are discussed.