Timing and efficacy of transmitter release at mossy fiber synapses in the hippocampal network. (Review) Review Article

Author(s): Bischofberger, Joseph; Engel, Dominique; Frotscher, Michael; Jonas, Peter
Title: Timing and efficacy of transmitter release at mossy fiber synapses in the hippocampal network. (Review)
Abstract: It is widely accepted that the hippocampus plays a major role in learning and memory. The mossy fiber synapse between granule cells in the dentate gyrus and pyramidal neurons in the CA3 region is a key component of the hippocampal trisynaptic circuit. Recent work, partially based on direct presynaptic patch-clamp recordings from hippocampal mossy fiber boutons, sheds light on the mechanisms of synaptic transmission and plasticity at mossy fiber synapses. A high Na(+) channel density in mossy fiber boutons leads to a large amplitude of the presynaptic action potential. Together with the fast gating of presynaptic Ca(2+) channels, this generates a large and brief presynaptic Ca(2+) influx, which can trigger transmitter release with high efficiency and temporal precision. The large number of release sites, the large size of the releasable pool of vesicles, and the huge extent of presynaptic plasticity confer unique strength to this synapse, suggesting a large impact onto the CA3 pyramidal cell network under specific behavioral conditions. The characteristic properties of the hippocampal mossy fiber synapse may be important for pattern separation and information storage in the dentate gyrus-CA3 cell network.
Keywords: Animals; Rats; Patch-Clamp Techniques; Synapses/metabolism; Action Potentials/physiology; Synaptic Transmission/physiology; Presynaptic Terminals/physiology; Neuronal Plasticity; Potassium Channels, Voltage-Gated/physiology; Sodium Channels/physiology; Neurotransmitter Agents/metabolism; Sodium Channels; Neurotransmitter Agents; Potassium Channels, Voltage-Gated; Hippocampus; Mossy Fibers, Hippocampal/metabolism; Autoassociative networks; Episodic memory; Mossy fiber boutons; Mossy fiber synapses; Presynaptic recording; Synaptic efficacy
Publication Title: Pflugers Archiv : European Journal of Physiology
Volume: 453
Issue 3
ISBN: 0031-6768
Publisher: Springer  
Date Published: 2006-12-01
Start Page: 361
End Page: 372
DOI: 10.1007/s00424-006-0093-2
Open access: no