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Synaptic Ribbon Active Zones In Cone Photoreceptors Operate Independently From One Another., Justin J. Grassmeyer, Wallace B. Thoreson
Synaptic Ribbon Active Zones In Cone Photoreceptors Operate Independently From One Another., Justin J. Grassmeyer, Wallace B. Thoreson
Journal Articles: Ophthalmology
Cone photoreceptors depolarize in darkness to release glutamate-laden synaptic vesicles. Essential to release is the synaptic ribbon, a structure that helps organize active zones by clustering vesicles near proteins that mediate exocytosis, including voltage-gated Ca(2+) channels. Cone terminals have many ribbon-style active zones at which second-order neurons receive input. We asked whether there are functionally significant differences in local Ca(2+) influx among ribbons in individual cones. We combined confocal Ca(2+) imaging to measure Ca(2+) influx at individual ribbons and patch clamp recordings to record whole-cell ICa in salamander cones. We found that the voltage for half-maximal activation (V50) of whole …