Mechanisms and functional roles of glutamatergic synapse diversity in a cerebellar circuit

Elife. 2016 Sep 19;5:e15872. doi: 10.7554/eLife.15872.


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.

Keywords: AMPA receptor; cerebellum; computational model; desensitization; metabotropic receptor; neuroscience; rat; sensory processing.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Action Potentials
  • Animals
  • Cerebellar Cortex / physiology*
  • Excitatory Amino Acid Agents / metabolism*
  • Glutamic Acid / metabolism*
  • Models, Neurological
  • Nerve Fibers / physiology*
  • Nerve Net / physiology*
  • Rats
  • Receptors, Glutamate / metabolism*
  • Vestibule, Labyrinth / physiology*


  • Excitatory Amino Acid Agents
  • Receptors, Glutamate
  • Glutamic Acid

Grant support

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.