Ophthalmology Commons^™

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 …