This project aims to determine the principal factors governing the transfer of information from retinal photoreceptors to bipolar cells.
Specific aims i nclude i) to evaluate the sources of noise that limit the signal-to-noise ratio of the process of signal transfer, ii) to establish which classes of ionic channels are modulated by synaptic transmitter, iii) to determine the electrical properties of the bipolar cell membrane and to study the spatial distribution of conductance over the surface of the bipolar cell, iv) to determine the mechanism responsible for the band-pass filtering of the rod/bipolar cell synapse and v) to incorporate these findings into a comprehensive picture of the transfer of a signal from the receptor to the bipolar cell's axon terminal. We have concentrated so far on the transfer of weak signals initiated by rods following absorption of only a few photons since this permits a linear systems analysis to be carried out. We plan to continue, at least initially, with this approach. A new facet of the work will be a study of enzymatically dissociated cells studied under voltage clamp. This will be set against a background of similar experiments on bipolar cells in the intact, isolated retina and an ongoing electron-microscopic study of the functional morphology of these cells. An analysis of the voltage gain of synaptic transfer between receptors and bipolar cells will be tested. This project should add considerably to our understanding of the process of signal transfer, not only in the retina but in the nervous system in general. It should provide information contributing to our knowledge of visual function at very low luminances and may contribute to an understanding of certain clinical disorders involving low-vision loss.

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Project (R01)
Project #
5R01EY003785-08
Application #
3258232
Study Section
Visual Sciences A Study Section (VISA)
Project Start
1980-10-01
Project End
1990-04-30
Budget Start
1988-05-01
Budget End
1990-04-30
Support Year
8
Fiscal Year
1988
Total Cost
Indirect Cost
Name
University of California Berkeley
Department
Type
Schools of Arts and Sciences
DUNS #
094878337
City
Berkeley
State
CA
Country
United States
Zip Code
94704
Hare, W A; Owen, W G (1998) Effects of bicarbonate versus HEPES buffering on measured properties of neurons in the salamander retina. Vis Neurosci 15:263-71
Krizaj, D; Gabriel, R; Owen, W G et al. (1998) Dopamine D2 receptor-mediated modulation of rod-cone coupling in the Xenopus retina. J Comp Neurol 398:529-38
Vu, T Q; McCarthy, S T; Owen, W G (1997) Linear transduction of natural stimuli by dark-adapted and light-adapted rods of the salamander, Ambystoma tigrinum. J Physiol 505 ( Pt 1):193-204
Younger, J P; McCarthy, S T; Owen, W G (1996) Light-dependent control of calcium in intact rods of the bullfrog Rana catesbeiana. J Neurophysiol 75:354-66
McCarthy, S T; Younger, J P; Owen, W G (1996) Dynamic, spatially nonuniform calcium regulation in frog rods exposed to light. J Neurophysiol 76:1991-2004
Hare, W A; Owen, W G (1996) Receptive field of the retinal bipolar cell: a pharmacological study in the tiger salamander. J Neurophysiol 76:2005-19
Hare, W A; Owen, W G (1995) Similar effects of carbachol and dopamine on neurons in the distal retina of the tiger salamander. Vis Neurosci 12:443-55
McCarthy, S T; Younger, J P; Owen, W G (1994) Free calcium concentrations in bullfrog rods determined in the presence of multiple forms of Fura-2. Biophys J 67:2076-89
Hare, W A; Owen, W G (1992) Effects of 2-amino-4-phosphonobutyric acid on cells in the distal layers of the tiger salamander's retina. J Physiol 445:741-57
Bialek, W; Owen, W G (1990) Temporal filtering in retinal bipolar cells. Elements of an optimal computation? Biophys J 58:1227-33

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