Fig. 3

TBS Induces a Persistent Increase in Ca²⁺ Responses of BC Axon Terminals(A) In vivo two-photon fluorescence optical section through the retina of a 4 dpf Tg(Gal4-VP16^xfz43,UAS:GCaMP1.6) larva, in which GCaMP1.6 is specifically expressed in some BCs (green), is demonstrated. The soma of GFP-expressing BCs preferentially locates in the distal part of INL, and its axon terminals are at both the sublaminae a and b of IPL. Red indicates the tip of the stimulating electrode (white arrow) loaded with dextran. The calcium responses of BC axon terminals in the region indicated by the white rectangle are shown in (B).(B) Calcium responses of BC axon terminals immediately before (top) and after (bottom) an electrical stimulus, are presented. Pseudocolor images using scale of fractional change in fluorescence intensity relative to average baseline levels are shown.(C) Electrically evoked calcium responses of all five responsive BC axon terminals from a single retina 0?5 min before and 25?30 min after TBS application, are shown. The small black bars (top) indicate electrical stimuli.(D) Summary of data showing that TBS induces a persistent increase in the amplitude of calcium responses in BC axon terminals, is demonstrated. Data were obtained from all 20 responsive BC axon terminals from 4 different retinae. Error bars, ± SEM.See also Figures S2 and S4.