Abstract
The organization of the patterns and fields generated by dorsal column fibers terminating in the dorsal column nuclei was studied in Golgi preparations. Five main categories of dorsal column fiber terminal patterns were noted: (a) Numerous collaterals generated as microbundles from dorsal column stem axons stream ventrally into the nuclei. These microbundles later develop secondary and tertiary branchings in a moderately replicative, wide-field pattern, with considerable overlap between the terminal fields of adjoining microbundles. (b) Other collaterals take a dorsal course and terminate in the form of small, discrete, flame-shaped arbors. Both ventrally and dorsally directed dorsal column collaterals frequently end on dendritic agglomerations or dendritic nests formed by dendrites of certain neurons of the nuclei. (c) Some dorsal column stem axons project directly into the nuclei. These may also generate discrete or wide-field terminals. (d) Another category of terminal fiber pattern is generated by border fibers which end with a transverse spread on neurons situated superficially in the nuclei. (e) The last category is represented by running fiber terminal patterns. The fibers with such terminal endings presumably originate from the dorsal column, singly or in small groups, and run ventrally into the cuneo-gracile nuclei with very little secondary or tertiary branchings. I suggest that these different terminal patterns may represent structural expressions of functional relevance to receptive field determination and modality representation in the cuneo-gracile nuclei.
Published Version
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