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Updated: Jul 14, 2026

Combined Optogenetic and Freeze-fracture Replica Immunolabeling to Examine Input-specific Arrangement of Glutamate Receptors in the Mouse Amygdala
Published on: April 15, 2016
Multiple climbing fibers signal to molecular layer interneurons exclusively via glutamate spillover
Germán Szapiro1, Boris Barbour
1Laboratoire de Neurobiologie, Ecole Normale Supérieure, CNRS, 46 rue d'Ulm, 75005 Paris, France.
Abstract:
Spillover of glutamate under physiological conditions has only been established as an adjunct to conventional synaptic transmission. Here we describe a pure spillover connection between the climbing fiber and molecular layer interneurons in the rat cerebellar cortex. We show that, instead of acting via conventional synapses, multiple climbing fibers activate AMPA- and NMDA-type glutamate receptors on interneurons exclusively via spillover. Spillover from the climbing fiber represents a form of glutamatergic volume transmission that could be triggered in a regionalized manner by experimentally observed synchronous climbing fiber activity. Climbing fibers are known to direct parallel fiber synaptic plasticity in interneurons, so one function of this spillover is likely to involve controlling synaptic plasticity.
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