CCKergic TCs monosynaptically excite PGCs via dendrodendritic synapses. A, Schematic showing experimental design. B, left, Confocal images showing ChR2-mCherry expression in TCs and GAD65-GFP-tagged PGCs. Right, Blown-up from the left showing the relationship between the GFP-tagged PGCs and apical dendrites (white arrowheads) of mCherry-expressing TCs. C, top and middle, Typical voltage-clamp traces showing EPSCs recorded in a PGC in response to paired optical stimulation delivered to the PGC-affiliated glomerulus to activate CCKergic TC apical dendrites in ACSF (gray, middle) or in the presence of NBQX and APV (N&A, top cyan traces). Bottom, Blown-up from the middle traces showing onset latencies of the first EPSCs. D, Symbol plot showing onset latencies of the TC-evoked EPSCs in 15 PGCs. E, Bar graph showing the average amplitude of the TC-evoked EPSCs in 15 PGCs in ACSF or in the presence of NBQX and APV (N&A). F, G, Symbol plots showing that EPSC onset latency (F) but not its SD (synaptic jitter, G) has a negative linear correlation with the average EPSC amplitude in 14 PGCs (one outlier excluded).