BDNF signaling regulates release probability at PF synapses. (A) Average PPR of PF–EPSC (interstimulus interval = 50 ms) in K252a-, anti-BDNF IgG-, BDNF-, or anti-NT3-treated PCs (n = 5–10). Open and solid bars represent results for PCs recorded from lobules 1–4/5 (distant from the implants) and lobules 6–7 (closest to the implants), respectively (A and B). These results suggest that an ongoing activation of TrkB by BDNF in vivo is necessary for the maintenance of the presynaptic function at PF synapses. Representative EPSC data are shown in Fig. 9A. (B) Average CV of PF–EPSC amplitude (n = 5–10) in K252a-, anti-BDNF IgG-, BDNF-, or anti-NT3-treated PCs. ∗, Differences were considered significant when P < 0.05.