Rod inputs arrive at horizontal cell somas in mouse retina solely via rod-cone coupling.

Rod and cone photoreceptor cells selectively contact different compartments of axon-bearing retinal horizontal cells in the retina. Cones synapse exclusively on the soma whereas rods synapse exclusively on a large axon terminal compartment. The possibility that rod signals can travel down the axon from terminal to soma has been proposed to allow spectrally opponent interactions between rods and cones, but there is conflicting data about whether this actually occurs.

Using optogenetics to dissect rod inputs to OFF ganglion cells in the mouse retina.

Introduction: Light responses of rod photoreceptor cells traverse the retina through three pathways. The primary pathway involves synapses from rods to ON-type rod bipolar cells with OFF signals reaching retinal ganglion cells (RGCs) sign-inverting glycinergic synapses. Secondly, rod signals can enter cones through gap junctions.

Correction: Mesnard et al. Eliminating Synaptic Ribbons from Rods and Cones Halves the Releasable Vesicle Pool and Slows Down Replenishment. Int. J. Mol. Sci. 2022, 23, 6429.

The authors wish to make the following corrections to this paper [...

Eliminating Synaptic Ribbons from Rods and Cones Halves the Releasable Vesicle Pool and Slows Down Replenishment.

Glutamate release from rod and cone photoreceptor cells involves presynaptic ribbons composed largely of the protein RIBEYE. To examine roles of ribbons in rods and cones, we studied mice in which GCamP3 replaced the B-domain of RIBEYE. We discovered that ribbons were absent from rods and cones of both knock-in mice possessing GCamP3 and conditional RIBEYE knockout mice.

Properties of multivesicular release from mouse rod photoreceptors support transmission of single-photon responses.

Vision under starlight requires rod photoreceptors to transduce and transmit single-photon responses to the visual system. Small single-photon voltage changes must therefore cause detectable reductions in glutamate release. We found that rods achieve this by employing mechanisms that enhance release regularity and its sensitivity to small voltage changes.

Resting and stimulated mouse rod photoreceptors show distinct patterns of vesicle release at ribbon synapses.

The vertebrate visual system can detect and transmit signals from single photons. To understand how single-photon responses are transmitted, we characterized voltage-dependent properties of glutamate release in mouse rods. We measured presynaptic glutamate transporter anion current and found that rates of synaptic vesicle release increased with voltage-dependent Ca2+ current.

Ocular Hypertension Drives Remodeling of AMPA Receptors in Select Populations of Retinal Ganglion Cells.

AMPA-type glutamate receptors in the CNS are normally impermeable to Ca, but the aberrant expression of Ca-permeable AMPA receptors (CP-AMPARs) occurs in pathological conditions such as ischemia or epilepsy, or degenerative diseases such as ALS. Here, we show that select populations of retinal ganglion cells (RGCs) similarly express high levels of CP-AMPARs in a mouse model of glaucoma. CP-AMPAR expression increased dramatically in both On sustained alpha and Off transient alpha RGCs, and this increase was prevented by genomic editing of the GluA2 subunit.