Differences in transmission properties and susceptibility to long-term depression reveal functional specialization of ascending axon and parallel fiber synapses to Purkinje cells


An understanding of the patterns of mossy fiber transmission to Purkinje cells, via granule cell axons, is fundamental to models of cerebellar cortical signaling and processing. Early theories assumed that mossy fiber input is widely disseminated across the cerebellar cortex along beams of parallel fibers, which spread for several millimeters across the cerebellar cortex. Direct evidence for this has, however, proved controversial, leading to the development of an alternative hypothesis that mossy fiber inputs to the cerebral cortex are in fact vertically organized such that the ascending segment of the granule axon carries a greater synaptic weight than the parallel fiber segment. Here, we report that ascending axon synapses are selectively resistant to cerebellar long-term depression and that they release transmitter with higher mean release probabilities and mean quantal amplitudes than parallel fiber synapses. This novel specialization of synapses formed by different segments of the same axon not only explains the reported patterns of granule cell→ Purkinje cell transmission across the cerebellar cortex but also reveals an additional level of functionality and complexity of cerebellar processing. Consequently, ascending axon synapses represent a new element of cortical signal processing that should be distinguished from parallel fiber synapses in future experimental and theoretical studies of cerebellar function.

Publication DOI: https://doi.org/10.1523/JNEUROSCI.0073-05.2005
Divisions: College of Health & Life Sciences > Aston Pharmacy School
College of Health & Life Sciences > School of Biosciences
Additional Information: Copyright© 2005 Society for Neuroscience. Articles are released under a Creative Commons Attribution License after a 6 months embargo
Uncontrolled Keywords: Cerebellum,Granule cell,Long-term depression,Purkinje cell,Synaptic,Transmission,Neuroscience(all)
Publication ISSN: 1529-2401
Last Modified: 31 May 2024 16:23
Date Deposited: 06 Nov 2019 15:41
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Related URLs: http://www.scop ... tnerID=8YFLogxK (Scopus URL)
PURE Output Type: Article
Published Date: 2005-03-23
Authors: Sims, Robert E.
Hartell, Nicholas A.



Version: Published Version

License: Creative Commons Attribution

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