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3D electron microscopic reconstruction of segments of rat cerebellar purkinje cell dendrites receiving ascending and parallel fiber granule cell synaptic inputs
Author(s) -
Lu Huo,
Esquivel Angelica V.,
Bower James M.
Publication year - 2009
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.22041
Subject(s) - parallel fiber , excitatory postsynaptic potential , purkinje cell , dendrite (mathematics) , inhibitory postsynaptic potential , biology , neuroscience , granule cell , dendritic spine , synapse , axon , cerebellum , anatomy , central nervous system , dentate gyrus , geometry , mathematics , hippocampal formation
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 small‐diameter 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. J. Comp. Neurol. 514:583–594, 2009. © 2009 Wiley‐Liss, Inc.