TY - JOUR TI - Mechanisms and functional roles of glutamatergic synapse diversity in a cerebellar circuit AU - Zampini, Valeria AU - Liu, Jian K AU - Diana, Marco A AU - Maldonado, Paloma P AU - Brunel, Nicolas AU - Dieudonné, Stéphane A2 - Raman, Indira M VL - 5 PY - 2016 DA - 2016/09/19 SP - e15872 C1 - eLife 2016;5:e15872 DO - 10.7554/eLife.15872 UR - https://doi.org/10.7554/eLife.15872 AB - Synaptic currents display a large degree of heterogeneity of their temporal characteristics, but the functional role of such heterogeneities remains unknown. We investigated in rat cerebellar slices synaptic currents in Unipolar Brush Cells (UBCs), which generate intrinsic mossy fibers relaying vestibular inputs to the cerebellar cortex. We show that UBCs respond to sinusoidal modulations of their sensory input with heterogeneous amplitudes and phase shifts. Experiments and modeling indicate that this variability results both from the kinetics of synaptic glutamate transients and from the diversity of postsynaptic receptors. While phase inversion is produced by an mGluR2-activated outward conductance in OFF-UBCs, the phase delay of ON UBCs is caused by a late rebound current resulting from AMPAR recovery from desensitization. Granular layer network modeling indicates that phase dispersion of UBC responses generates diverse phase coding in the granule cell population, allowing climbing-fiber-driven Purkinje cell learning at arbitrary phases of the vestibular input. KW - cerebellum KW - sensory processing KW - AMPA receptor KW - metabotropic receptor KW - computational model KW - desensitization JF - eLife SN - 2050-084X PB - eLife Sciences Publications, Ltd ER -