Summary
This study identifies exceptions to the fundamental ON/OFF stratification rule of the retina, showing that calbindin-positive ON cone bipolar cells form ribbon synapses in the OFF sublayer with dopaminergic amacrine cells, intrinsically photosensitive ganglion cells (ipRGCs), and bistratified diving ganglion cells. For lighting designers and researchers, this clarifies how ipRGCs receive direct ON bipolar input, which has implications for understanding the neural basis of non-visual light responses such as circadian entrainment and pupillary reflexes.
Key Findings
- ON cone bipolar cell axons make functional ribbon synapses in the OFF sublayer (sublamina a) with three distinct cell types: dopaminergic amacrine cells, intrinsically photosensitive retinal ganglion cells (ipRGCs), and bistratified diving ganglion cells.
- Postsynaptic AMPA receptor subunit GluR4 was identified at these ectopic synapse sites, indicating functional glutamatergic transmission from ON bipolar cells in the OFF layer.
- Findings resolve the long-standing question of anomalous ON inputs to dopaminergic amacrine cells, demonstrating that ON bipolar axons can provide significant synaptic output prior to their terminal specializations.
Categories
The Science of Light: Describes synaptic connectivity between ON bipolar cells and intrinsically photosensitive retinal ganglion cells (ipRGCs), directly relevant to photoreceptor circuitry and phototransduction pathways.
Author(s)
H Hoshi, WL Liu, SC Massey, SL Mills
Publication Year
2009
Number of Citations
155
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