Information processing and synaptic plasticity at hippocampal mossy fiber terminals

Area of Science:

• Neuroscience
• Cellular Biology
• Systems Neuroscience

Background:

• The dentate gyrus (DG) granule cells are key integrators of cortical input.
• Their axons, the mossy fibers (MFs), form a critical output pathway to the CA3 region of the hippocampus.
• Understanding the MF system is vital for deciphering hippocampal information processing.

Purpose of the Study:

• To review the anatomical and physiological properties of the hippocampal mossy fiber system.
• To elucidate the mechanisms of signal processing by DG granule cells.
• To summarize synaptic interactions and plasticity at MF target cells.

Main Methods:

• Literature review focusing on anatomical and physiological studies of the MF system.
• Analysis of signal processing mechanisms at the single action potential, burst, and sustained activity levels.
• Synthesis of data on synaptic transmission, quantal release, and synaptic plasticity (LTP).

Main Results:

• MFs exhibit diverse synaptic contacts with unique information processing rules based on granule cell activity rates.
• Synaptic interactions involve various parameters including quantal transmission and short- and long-term plasticity.
• DG granule cells process signals from single action potentials to longer stimuli through distinct mechanisms.

Conclusions:

• The MF system displays complex rules for information transfer, modulated by activity-dependent synaptic plasticity.
• Different MF synaptic contacts have distinct functional properties influencing DG to CA3 information flow.
• This review highlights the intricate determinants governing information processing within the hippocampal circuit.