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Contrasting short‐term plasticity at two sides of the mitral–granule reciprocal synapse in the mammalian olfactory bulb
Author(s) -
Dietz Shelby B.,
Murthy Venkatesh N.
Publication year - 2005
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.2005.095844
Subject(s) - neuroscience , olfactory bulb , synapse , granule cell , excitatory postsynaptic potential , biology , inhibitory postsynaptic potential , synaptic plasticity , central nervous system , dentate gyrus , biochemistry , receptor
The mitral–granule reciprocal synapse shapes the response of the olfactory bulb to odour stimuli by mediating lateral and reciprocal inhibition. We investigated the short‐term plasticity of both the mitral‐to‐granule excitatory synapse and the granule‐to‐mitral inhibitory synapse in rat olfactory bulb slices, using whole‐cell patch clamp recordings. The granule‐to‐mitral inhibitory synapse invariably exhibited paired‐pulse depression at interstimulus intervals of less than a second, while the mitral‐to‐granule excitatory synapse showed heterogeneous responses, which on average yielded a moderate facilitation. Trains of stimuli led to a much greater depression at the granule‐to‐mitral synapse than at the mitral‐to‐granule synapse. Since mitral cells commonly respond to odours by burst firing with each inhalation cycle, we used bursts of stimuli to study recovery from depression. We found that recovery from depression induced by fast trains of stimuli was more rapid at the mitral‐to‐granule synapse than at the granule‐to‐mitral synapse. In addition, depression was enhanced by higher calcium concentrations, suggesting at least partial contribution of presynaptic mechanisms to short‐term depression. The observed short‐term plasticity could enable mitral cells to overcome autoinhibition and increase action potential propagation along lateral dendrites by burst firing.