Signal integration at the pedicle of turtle cone photoreceptors: an anatomical and electrophysiological study

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Publication Type Journal Article
School or College School of Medicine; College of Engineering
Department Ophthalmology; Bioengineering; Surgery; Physiology
Creator Normann, Richard A.; Kolb, Helga; Lasater, Eric M.
Title Signal integration at the pedicle of turtle cone photoreceptors: an anatomical and electrophysiological study
Date 1989
Description The morphology of the axon which connects the cell body and pedicle of turtle cone photoreceptors was studied by light and electron microscopy. The axon which contains numerous synaptic vesicles, some endoplasmic reticulum, and a few cisternae is basically filled with cytoplasm. The length of the axon is related to the class of cone and varies slightly with retinal location, with axons as short as 3-6 microns found in red cones, and as long as 60 microns in cones containing colorless oil droplets. By simultaneously voltage clamping the cell body and pedicle regions of single isolated cones, we measured the longitudinal axonal resistance and the cell body and pedicle membrane resistances. For each cell studied, the axonal resistance of cones with short axons was lower than the cell and pedicle membrane resistances. Thus, the cell can be considered to be an isopotential structure. However, in some cones with long axons, the axonal, cell body, and pedicle resistances were comparable. The pedicles of these cones, therefore, could act like summing points and may provide a locus for spatial signal integration. Electrical coupling between the principal and accessory members of double cones was also studied. Electron-microscopic observation of the membrane junction between the apposed inner segments of the double cones in the intact retina show narrow segments which resemble gap junctions. However, in every double cone studied in culture, passing currents into one member of the double cone did not result in measurable current flow in the adjacent cell. Thus, the two members of the double cone, isolated from the turtle retina, are not electrically coupled.
Type Text
Publisher Cambridge University Press
Volume 2
Issue 6
First Page 553
Last Page 564
Subject Cone Photoreceptor, Voltage Clamp; Isolated Cells; Input Resistance; Cell Body-Pedicle Coupling
Subject MESH Turtles; Electrophysiology; Axons; Time Factors; Cell Membrane
Language eng
Bibliographic Citation Lasater EM, Normann RA, Kolb H. (1989). Signal integration at the pedicle of turtle cone photoreceptors: an anatomical and electrophysiological study. Vis Neurosci, 2(6), 553-64
Rights Management © Cambridge University Press
Format Medium application/pdf
Identifier ir-main,12765
ARK ark:/87278/s6ms49vg
Setname ir_uspace
Date Created 2012-06-13
Date Modified 2012-06-13
ID 702606
Reference URL https://collections.lib.utah.edu/ark:/87278/s6ms49vg
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