Topographical organisation within the lateral reticular nucleus mossy fibre projection to the c1 and c2 zones in the rostral paramedian lobule of the cat cerebellum
✍ Scribed by Apps, Richard; Trott, Judy R.
- Publisher
- John Wiley and Sons
- Year
- 1997
- Tongue
- English
- Weight
- 455 KB
- Volume
- 381
- Category
- Article
- ISSN
- 0021-9967
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✦ Synopsis
The organisation of the projection from the principal lateral reticular nucleus (LRN) to the electrophysiologically defined cerebellar cortical c 1 and c 2 zones within apical folia of the forelimb-receiving area of the rostral paramedian lobule was investigated in cats. In individual experiments, small injections of either of two retrograde tracers, wheat germ agglutinin-horseradish peroxidase or fluorescent-tagged beads, were made into one or the other of the two zones. The mossy fibre projection from the LRN was found to arise almost entirely from the ipsilateral nucleus, primarily from its magnocellular region. In the pars anterior (folia 1-3) of the paramedian lobule, the projection to the c 1 zone arose from cells located throughout most of the rostrocaudal extent of the magnocellular LRN, whereas the projection to the c 2 zone was from cells in the rostral half of this region. There was also a small projection from cells in the dorsolateral parvicellular LRN to the c 2 zone, but there was none to the c 1 zone. Double-label experiments showed that, in territories within LRN where overlap occurred, cells that target either zone were intermingled, and, at most, about 9% of cells had axons that branched to innervate both zones. In the pars posterior (folia 4-6), cells targeting the two zones arose from largely overlapping areas throughout both the magnocellular and the dorsolateral parvicellular LRN, although cells targeting the c 2 zone appeared to be more restricted in distribution. In addition to these interzonal differences, it was found that the projection to the pars posterior from cells in the parvicellular LRN was stronger than that to the pars anterior, irrespective of the cortical zone injected. Overall, the present study provides evidence that there is at least some topographical organisation within the LRN mossy fibre projection to certain cerebellar cortical zones.