RT Journal Article
SR Electronic
T1 Tailoring of the axon initial segment shapes the conversion of synaptic inputs into spiking output in OFF-α T retinal ganglion cells
JF Science Advances
JO Sci Adv
FD American Association for the Advancement of Science
SP eabb6642
DO 10.1126/sciadv.abb6642
VO 6
IS 37
A1 Werginz, Paul
A1 Raghuram, Vineeth
A1 Fried, Shelley I.
YR 2020
UL http://advances.sciencemag.org/content/6/37/eabb6642.abstract
AB Recently, mouse OFF-α transient (OFF-α T) retinal ganglion cells (RGCs) were shown to display a gradient of light responses as a function of position along the dorsal-ventral axis; response differences were correlated to differences in the level of excitatory presynaptic input. Here, we show that postsynaptic differences between cells also make a strong contribution to response differences. Cells in the dorsal retina had longer axon initial segments (AISs)—the greater number of Nav1.6 channels in longer AISs directly mediates higher rates of spiking and helps avoid depolarization block that terminates spiking in ventral cells with shorter AISs. The pre- and postsynaptic specializations that shape the output of OFF-α T RGCs interact in different ways: In dorsal cells, strong inputs and the long AISs are both necessary to generate their strong, sustained spiking outputs, while in ventral cells, weak inputs or the short AISs are both sufficient to limit the spiking signal.