TY - JOUR T1 - A Novel Form of Low-Frequency Hippocampal Mossy Fiber Plasticity Induced by Bimodal mGlu1 Receptor Signaling JF - The Journal of Neuroscience JO - J. Neurosci. SP - 16897 LP - 16906 DO - 10.1523/JNEUROSCI.1264-11.2011 VL - 31 IS - 47 AU - Shanti F. Frausto AU - Koichi Ito AU - William Marszalec AU - Geoffrey T. Swanson Y1 - 2011/11/23 UR - http://www.jneurosci.org/content/31/47/16897.abstract N2 - Mossy fiber synapses act as the critical mediators of highly dynamic communication between hippocampal granule cells in the dentate gyrus and CA3 pyramidal neurons. Excitatory synaptic strength at mossy fiber to CA3 pyramidal cell synapses is potentiated rapidly and reversibly by brief trains of low-frequency stimulation of mossy fiber axons. We show that slight modifications to the pattern of stimulation convert this short-term potentiation into prolonged synaptic strengthening lasting tens of minutes in rodent hippocampal slices. This low-frequency potentiation of mossy fiber EPSCs requires postsynaptic mGlu1 receptors for induction but is expressed presynaptically as an increased release probability and therefore impacts both AMPA and NMDA components of the mossy fiber EPSC. A nonconventional signaling pathway initiated by mGlu1 receptors contributes to induction of plasticity, because EPSC potentiation was prevented by a tyrosine kinase inhibitor and only partially reduced by guanosine 5′-O-(2-thiodiphosphate). A slowly reversible state of enhanced synaptic efficacy could serve as a mechanism for altering the integrative properties of this synapse within a relatively broad temporal window. ER -