title: Projection patterns of single mossy fiber axons originating from the dorsal column nuclei mapped on the aldolase C compartments in the rat cerebellar cortex.
abstract: Although cerebellar mossy fibers are the most abundant cerebellar afferents and are deeply involved in cerebellar function, the organization of their projection has remained obscure, particularly in relation to cerebellar compartmentalization. The dorsal column nuclei (DCN) are a major source of cerebellar mossy fibers and possess distinct somatotopic representations of specific somatosensory submodalities. We reconstructed individual dextran-labeled DCN axons completely from serial sections and mapped their terminals on the longitudinal cerebellar compartments that were visualized by aldolase C immunostaining to clarify their projection pattern. Individual axons branched and formed about 100 rosette terminals in the cerebellar cortex, but infrequently projected to the cerebellar nuclei (1 out of 15 axons). Cortical terminals were clustered in multiple areas in the vermis and pars intermedia mostly, but not exclusively, ipsilateral to the origin of the axon. The gracile, cuneate, and external cuneate nuclei (ECuN) mainly projected to the copula pyramidis and lobule V, paramedian and simple lobules, and lobules I-V and VIII-IX, respectively, although there was some overlap. The majority of terminals were located within aldolase C negative or lightly positive compartments. However, terminals of a single axon can be located on aldolase C-negative as well as on aldolase C-positive compartments. In particular, the rostral ECuN, which is responsive to shoulder movements, projected consistently to lobule IX, which were mostly aldolase C-positive. In sum, DCN-cerebellar axons project to multiple compartments with terminals clustered mainly in the conventional spinocerebellar region with a coarse topography, which shows some relationship to the cortical compartments defined by aldolase C.
authors.affiliation: Department of Systems Neurophysiology, Tokyo Medical and Dental University Graduate School, Tokyo, Japan.
authors.forename: Pham Nguyen
authors.initials: PN
authors.lastname: Quy
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Fujita
authors.forename: Yukiyo
authors.initials: Y
authors.lastname: Sakamoto
authors.forename: Jie
authors.initials: J
authors.lastname: Na
authors.forename: Izumi
authors.initials: I
authors.lastname: Sugihara
mesh_terms: D000818:Animals; D001369:Axons / Q000201:enzymology* / Q000648:ultrastructure*; D001931:Brain Mapping / Q000379:methods; D002525:Cerebellar Cortex / Q000033:anatomy & histology*; D002529:Cerebellar Nuclei / Q000033:anatomy & histology*; D005260:Female; D005634:Fructose-Bisphosphate Aldolase / Q000378:metabolism*; D008297:Male; D009434:Neural Pathways / Q000033:anatomy & histology* / Q000201:enzymology*; D051381:Rats; D020318:Rats, Long-Evans; D013194:Staining and Labeling / Q000379:methods
chemical_list: D005634:Fructose-Bisphosphate Aldolase