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This Article Full Text Full Text (PDF) All Versions of this Article: 582/2/629    most recent jphysiol.2007.133561v1 Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Johnson, E. M. Articles by Yeh, H. H. Search for Related Content PubMed PubMed Citation Articles by Johnson, E. M. Articles by Yeh, H. H. Related Collections Neuroscience

¹ Department of Physiology, Dartmouth Medical School, Lebanon, NH 03756, USA

TrkB, the cognate receptor for brain-derived neurotrophic factor and neurotrophin-4, has been implicated in regulating synapse formation in the central nervous system. Here we asked whether TrkB plays a role in the maturation of the climbing fibre–Purkinje cell (CF–PC) synapse. In rodent cerebellum, Purkinje cells are initially innervated by multiple climbing fibres that are subsequently culled to assume the mature mono-innervated state, and whose contacts translocate from the soma to the dendrites. By employing transgenic mice hypomorphic or null for TrkB expression, our results indicated that perturbation of TrkB in the immature cerebellum resulted in ataxia, that Purkinje cells remained multiply innervated by climbing fibres beyond the normal developmental time frame, and that synaptic transmission at the parallel fibre–Purkinje cell synapse remained functionally unaltered. Mechanistically, we present evidence that attributes the persistence of multiple climbing fibre innervation to an obscured discrimination of relative strengths among competing climbing fibres. Soma-to-dendrite translocation of climbing fibre terminals was unaffected. Thus, TrkB regulates pruning but not translocation of nascent CF–PC synaptic contacts.

(Received 28 March 2007; accepted after revision 20 April 2007; first published online 26 April 2007)
Corresponding author Hermes H. Yeh: Department of Physiology, Dartmouth Medical School, One Medical Center Drive, Lebanon, NH 03756, USA. Email: hermes.yeh{at}dartmouth.edu

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