Hippocampal and cerebellar mossy fibre boutons – same name, different function

Authors

  • Igor Delvendahl,

    1. European Neuroscience Institute Göttingen, University Medical Center Göttingen, Göttingen, Germany
    Search for more papers by this author
  • Annika Weyhersmüller,

    1. European Neuroscience Institute Göttingen, University Medical Center Göttingen, Göttingen, Germany
    Search for more papers by this author
  • Andreas Ritzau-Jost,

    1. European Neuroscience Institute Göttingen, University Medical Center Göttingen, Göttingen, Germany
    2. Carl-Ludwig-Institute of Physiology, Medical Faculty, University of Leipzig, Leipzig, Germany
    Search for more papers by this author
  • Stefan Hallermann

    1. European Neuroscience Institute Göttingen, University Medical Center Göttingen, Göttingen, Germany
    2. Carl-Ludwig-Institute of Physiology, Medical Faculty, University of Leipzig, Leipzig, Germany
    Search for more papers by this author

  • This review was presented at The Journal of Physiology Symposium entitled Size matters: formation and function of GIANT synapses, which took place at the Annual meeting of the Society for Neuroscience, New Orleans, LA, USA on 12 October 2012. It was commissioned by the Editorial Board and reflects the views of the authors.

S. Hallermann: Carl-Ludwig Institute for Physiology, University of Leipzig, 04103 Leipzig, Germany. Email: hallermann@medizin.uni-leipzig.de

Abstract

Abstract  Over a century ago, the Spanish anatomist Ramón y Cajal described ‘mossy fibres’ in the hippocampus and the cerebellum, which contain several presynaptic boutons. Technical improvements in recent decades have allowed direct patch-clamp recordings from both hippocampal and cerebellar mossy fibre boutons (hMFBs and cMFBs, respectively), making them ideal models to study fundamental properties of synaptic transmission. hMFBs and cMFBs have similar size and shape, but each hMFB contacts one postsynaptic hippocampal CA3 pyramidal neuron, while each cMFB contacts ∼50 cerebellar granule cells. Furthermore, hMFBs and cMFBs differ in terms of their functional specialization. At hMFBs, a large number of release-ready vesicles and low release probability (<0.1) contribute to marked synaptic facilitation. At cMFBs, a small number of release-ready vesicles, high release probability (∼0.5) and rapid vesicle reloading result in moderate frequency-dependent synaptic depression. These presynaptic mechanisms, in combination with faster postsynaptic currents of cerebellar granule cells compared with hippocampal CA3 pyramidal neurons, enable much higher transmission frequencies at cMFB compared with hMFB synapses. Analysing the underling mechanisms of synaptic transmission and information processing represents a fascinating challenge and may reveal insights into the structure–function relationship of the human brain.

Ancillary