Gap junctions with amacrine cells provide a feedback pathway for ganglion cells within the retina

In primates, one type of retinal ganglion cell, the parasol cell, makes gap junctions with amacrine cells, the inhibitory, local circuit neurons. To study the effects of these gap junctions, we developed a linear, mathematical model of the retinal circuitry providing input to parasol cells. Electrop...

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Bibliographic Details
Published in:Proceedings of the Royal Society. B, Biological sciences Biological sciences, 1998-05, Vol.265 (1399), p.919-925
Main Authors: Kenyon, Garrett T., Marshak, David W.
Format: Article
Language:English
Subjects:
Action potentials
Amacrine cells
Axons
Cell lines
Feedback
Ganglia
Gap junctions
Gap Junctions - physiology
Lateral Inhibition
Linear Models
M Cell
Models, Biological
Neurons
Oscillation
Parasol Cell
Parasols
Primate
Retina
Retina - cytology
Retinal Ganglion Cells - physiology
Synapses
Synapses - physiology
Synchrony
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Summary:In primates, one type of retinal ganglion cell, the parasol cell, makes gap junctions with amacrine cells, the inhibitory, local circuit neurons. To study the effects of these gap junctions, we developed a linear, mathematical model of the retinal circuitry providing input to parasol cells. Electrophysiological studies have indicated that gap junctions do not enlarge the receptive field centres of parasol cells, but our results suggest that they make other contributions to their light responses. According to our model, the coupled amacrine cells enhance the responses of parasol cells to luminance contrast by disinhibition. We also show how a mixed chemical and electrical synapse between two sets of amacrine cells presynaptic to the parasol cells might make the responses of parasol cells more transient and, therefore, more sensitive to motion. Finally, we show how coupling via amacrine cells can synchronize the firing of parasol cells. An action potential in a model parasol cell can excite neighbouring parasol cells, but only when the coupled amacrine cells also fire action potentials. Passive conduction was ineffective due to low-pass temporal filtering. Inhibition from the axons of the coupled amacrine cells also produced oscillations that might synchronize the firing of more distant ganglion cells.
ISSN:0962-8452
1471-2954
DOI:10.1098/rspb.1998.0379