3D electron microscopic reconstruction of segments of rat cerebellar Purkinje cell dendrites receiving ascending and parallel fiber granule cell synaptic inputs

Huo Lu, Angelica V. Esquivel, James M. Bower

Research output: Contribution to journalArticle

20 Scopus citations

Abstract

Growing physiological evidence suggests that there are functional differences between synapses made by the ascending and parallel fiber segments of the granule axon on cerebellar Purkinje cells. Supporting this view, our previous electron microscopic studies suggested that these synapses also contacted different regions of the Purkinje cell dendrite, and in particular that ascending segment synapses are made exclusively on the smallest diameter Purkinje cell dendrites. In the current study we used serial electron microscopic techniques to reconstruct Purkinje cell dendritic segments up to almost 10 μm in length. Using a combination of anatomical and immunological labeling techniques we identified the ascending or parallel fiber origins of the excitatory synaptic inputs onto dendritic spines, as well as the location of inhibitory synapses made directly on the dendritic shaft. The results confirmed that there are regions of the Purkinje cell dendrite receiving exclusively ascending or parallel fiber synapses and that ascending segment synapses are only found on small-diameter dendrites. In addition, we describe for the first time smalldiameter dendritic regions contacted by both types of excitatory synapses. While our data suggest that the majority of inhibitory inputs to the Purkinje cell tree are associated with parallel fiber synaptic inputs, we also found inhibitory inputs on dendritic regions with mixed ascending and parallel fiber inputs, or exclusively parallel fiber inputs. The finding that ascending and parallel fiber inputs can be segregated on the Purkinje cell dendritic tree provides further evidence that these excitatory granule cell synaptic inputs may be functionally distinct.

Original languageEnglish (US)
Pages (from-to)583-594
Number of pages12
JournalJournal of Comparative Neurology
Volume514
Issue number6
DOIs
StatePublished - Jun 20 2009

Keywords

  • 3D reconstruction
  • Ascending segment
  • Indexing terms
  • Molecular layer interneuron
  • Parallel fibers
  • Serial section
  • Synapse

ASJC Scopus subject areas

  • Neuroscience(all)

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