RESUMO
The distribution of wheatgerm agglutinin-horseradish peroxidase-labelled mossy fibre terminals of internal and external cuneate projections to the cerebellar anterior and posterior lobes were quantitatively analysed in adult rats. Computer-based image analysis mapped the spatial distribution of labelled cuneocerebellar terminals in two-dimensional reconstructions of the unfolded cortex. Cuneocerebellar projections are mainly ipsilateral in their distribution. Cuneate projections to the anterior lobe vermis-medial paravermis terminate in well-circumscribed, irregularly-shaped patches. These terminal patches are aligned and form a longitudinally continuous, parasagittally oriented stripe in the lateral vermis-medial paravermis of lobules I-V. These terminal patches represent the topographically organized divergent projections of different parts of the internal and external cuneate nuclei. Cuneocerebellar projections to the lateral paravermis-hemisphere, particularly in the posterior part of lobule V, are organized as a transversely oriented band of terminals. Cuneocerebellar projections to the posterior lobe terminate mainly in three transversely oriented bands of terminals located at the junction between lobules. An anterior band of terminals was located in lobule VI anteriorly and was continuous with the band of terminals located in the posterolateral part of lobule V at the junction of these two lobules. Intermediate and posterior transversely oriented bands of terminals were located at the VII-VIII and VIII-IX junctions, respectively. Cuneocerebellar projections to these three bands largely appear to represent convergent projections from different parts of the cuneate nuclei. These findings are discussed in relation to similarly analysed and previously reported findings on the organization of lower thoracic-upper lumbar spinocerebellar projections and in the context of how cuneocerebellar somatosensory input may be differentially organized and processed in disparate areas of the cerebellar cortex.
