, 2005). A sine wave (30 mV in amplitude; 1,000 Hz) was superimposed on a holding potential of −80 mV. Release rates were estimated by the deconvolution method, adapted for the calyx of Held (Neher and Sakaba, 2001). Cumulative release, obtained by integrating the release rate, was fitted by a double exponential after correction for SV replenishment (Neher and Sakaba, 2001). For fiber stimulation, either glass pipette or bipolar stimulation electrodes were used to evoke presynaptic APs. To measure Ca2+ currents during a train of depolarizing stimuli, the presynaptic compartment was whole-cell voltage clamped at −80 mV and 1 ms step depolarizations ABT-888 concentration to 0 mV

(in P9–P11 calyces) or to +40 mV (in P14–P17 calyces) were applied at various frequencies. Details of electrophysiological procedures are provided in the Supplemental Information. All data are presented as mean ± SEM. Statistical significance of changes was tested using Student’s t test. p values smaller that 0.05 were considered to indicate statistically significant differences. This work was Protein Tyrosine Kinase inhibitor supported by the Max Planck Society (N.B., E.N.), the German Research Foundation (SFB889/B1, J.-S.R., N.B.; SFB889/A6, N.S.), the European Commission (EUROSPIN, E.N., N.B.; SynSys, N.B.), the Uehara Foundation (T.S.), the Toray Foundation

(T.S.), and Grants-in-Aid for Scientific Research of the Japanese Ministry of Education, Sports, and Culture (Number 24300144, to T.S.). N.L. was a recipient of a Feodor Lynen Fellowship of the Minerva Foundation. We are grateful to A. Betz and A. Ivanovic for discussions and advice, to F. Benseler, I. Thanhäuser, D. Schwerdtfeger, and S. Thom for excellent technical support, and to the staff of the MPIEM animal facility for the management of mouse colonies. “
“The vertebrate retina receives efferent inputs from different parts of the central nervous system but we still do not understand

how these regulate visual processing (Ramon y Cajal, 1894 and Repérant et al., 1989). In not teleosts, the main source of retinopetal fibers is the terminal nerve (TN), which receives dense afferents from the olfactory bulb and in turn projects GnRH- and FMRFamide-containing fibers to the retina (Springer, 1983, Zucker and Dowling, 1987, Demski, 1993, Yamamoto and Ito, 2000 and Repérant et al., 2007). The TN is tonically active, with a firing frequency that changes according to the physiological conditions of the animal, including arousal, motivational state, hormonal milieu, and glutamatergic inputs from various sensory systems (Abe and Oka, 2006 and Wang et al., 2011). Together, the pathways linking the olfactory bulb to the retina through the TN are known as the olfacto-retinal circuit (ORC).