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Updated: Aug 8, 2026
09:05
Imaging Ca2+ Dynamics in Cone Photoreceptor Axon Terminals of the Mouse Retina
Published on: May 6, 2015
Synaptic plasticity in CNGA3(-/-) mice: cone bipolar cells react on the missing cone input and form ectopic synapses
Silke Haverkamp1, Stylianos Michalakis, Ellen Claes
1Department of Neuroanatomy, Max-Planck-Institute for Brain Research, D-60528 Frankfurt/Main, Germany. Haverkamp@mpih-frankfurt.mpg.de
Summary
In retinal degeneration, cone bipolar cells form new connections with rods when cones are lost. This synaptic plasticity requires functional photoreceptors, highlighting the need for intact cells to guide rewiring.
Area of Science:
- Neuroscience
- Retinal Biology
- Synaptic Plasticity
Background:
- Rods and cones connect to distinct bipolar cells in the mammalian retina.
- Photoreceptor degeneration can lead to synaptic rewiring between cone terminals and rod bipolar cells.
- The plasticity of cone bipolar cells without cone input is not well understood.
Purpose of the Study:
- To investigate cone bipolar cell synaptic plasticity in the absence of cone input.
- To determine the role of functional presynaptic photoreceptors in ectopic synapse formation.
Main Methods:
- Studied cone bipolar cell connectivity in CNGA3(-/-) mice (cone loss).
- Visualized dendritic connections using cell markers and fluorescent dye injections.
- Examined reciprocal connectivity in CNGA3(-/-)Rho(-/-) (both photoreceptors nonfunctional) and Rho(-/-) (rod nonfunctional) mice.
Main Results:
- Cone bipolar cells formed ectopic synapses with rods in CNGA3(-/-) mice.
- Ectopic synapses were not observed in CNGA3(-/-)Rho(-/-) mice, indicating functional cones are necessary.
- Input-deprived rod bipolar cells formed ectopic synapses with functional cones in Rho(-/-) mice, but not inoperable cones.
Conclusions:
- Cone bipolar cells exhibit synaptic plasticity by forming ectopic synapses with rods when deprived of cone input.
- The formation of ectopic synapses in the outer plexiform layer is dependent on the presence of a functional presynaptic photoreceptor.
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