TY - JOUR T1 - Anatomical development of the cerebellothalamic tract in embryonic mice JF - bioRxiv DO - 10.1101/731968 SP - 731968 AU - Daniƫl B. Dumas AU - Simona V. Gornati AU - Youri Adolfs AU - Tomomi Shimogori AU - R. Jeroen Pasterkamp AU - Freek E. Hoebeek Y1 - 2019/01/01 UR - http://biorxiv.org/content/early/2019/08/12/731968.abstract N2 - Cerebellar projections to the thalamus are a pivotal connection in cerebello-cerebral interactions. Apart from its role in coordinating sensorimotor integration in the adult brain, the cerebello-thalamic projection has also been implemented in developmental disorders, such as autism spectrum disorders. Although the development of the cerebellum, thalamus and cerebral cortex have been studied in many species, a detailed description of the ontogeny of the mammalian cerebello-thalamic tract (CbT) is currently missing. Here we investigated the development of the CbT at embryonic stages using transgenic Ntsr1-Cre/Ai14 mice and in utero electroporation (IUE) of wild type mice. Wide-field, confocal and 3D light-sheet imaging of immunohistochemical stainings showed that CbT fibers arrive in the prethalamus between E14.5 and E15.5, but only invade the thalamus after E16.5. We quantified the spread of CbT fibers throughout the various thalamic nuclei and found that at E17.5 and E18.5 the ventrolateral, ventromedial and parafascicular nuclei, but also the mediodorsal and posterior complex become increasingly innervated. Several CbT fiber varicosities colocalize with vGluT2, indicating that already from E18.5 the CbT synapse in various thalamic nuclei. Our results contribute to the construction of a frame of reference on the anatomical development of the CbT, which will help to guide future experiments investigating neurodevelopmental disorders.Significance statement Using various microscopic approaches, we investigated the anatomical development of the fiber tract between the cerebellum and thalamus, one of the major mammalian brain connections. Our results show that in mice cerebellar axons wait outside of the thalamus from embryonic day (E)15.5 until E17.5 before invading the thalamic complex. Cerebellar axons establish vGluT2-positive synapses at E18.5 throughout various thalamic nuclei, each of which subsequently develops its connections with dedicated cerebral cortical regions. Our data thereby advocate the cerebellar influence on the maturation of the thalamus and connected cerebral cortex. This knowledge can help to guide future experiments into neurodevelopmental disorders affecting cerebello-thalamo-cortical networks.List of abbreviationsCbTcerebellothalamic tractCbXdecussation of the cerebellothalamic tractCNcerebellar nucleiCPCaudate PutamenCTCTCtxcerebral cortexThthalamusfrfasciculus retroflexusHbHabenulaHchippocampusHypHypothalamusICinferior colliculusIntinterposed nucleus of the cerebellumLCNlateral nucleus of the cerebellumLGlateral geniculate nucleus of the thalamusdLGNdorsal lateral geniculate nucleusLPlateral posterior nucleus of the thalamusMCNmedial nucleus of the cerebellumMDmediodorsal nucleus of the thalamusMGmedial geniculate nucleus of the thalamusMLmidline nucleimRFmedullary reticular formationmtmamillothalamic tractNHSnormal horse serumPBSphosphate buffer salinePBSGTphosphate buffer saline with gelatin and tritonPfparafascicular nucleus of the thalamusPOmPosterior complex of the thalamuspSAOpercentage of summed area occupied by above threshold RFP signalPtpretectumRFPred fluorescent proteinRNred nucleusrpmrounds per minuteRtreticular nucleus of the thalamusSCsuperior colliculusTCthalamocorticalTHFtetrahydrofuranVBventrobasal complex of the thalamusVLventrolateral nucleus of the thalamusVMventromedial nucleus of the thalamuspThprethalamusZIzona incerta ER -