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Projections from the bassilar pontine nuclei to the careberral cortex: fluorescent tracing study in the rabbit

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Zguczyński L., Bukowska D., Mierzejewska-Krzyzanowska B.

Acta Neurobiologiae Experimentalis

2009

tom 69

nr 3

Pontine nuclei (PN) are large center transferring cortical afferents to the cerebellum. The study addresses to distribution of PN neurons in the pontocerebellar link. Two different neuroplasmatic and nuclear fl uorescent tracers were injected in separate experiments into: (1) paramedian lobule (PML) and pyramis, and (2) pyramis and uvula. Following both combination of injections, retrogradely labeled neurons were found bilaterally in all PN apart from the ventral nucleus. These neurons, parent for the pontocerebellar projection, clustered in two groups. First larger group occupied the dorsolateral nucleus and the dorsolateral region of lateral and peduncular nuclei. Second smaller group involved the dorsal region of paramedian nucleus and the dorsomedial region of peduncular nucleus. Projection to the uvula arises from nearly entire rostrocaudal extent of PN, and that to the pyramis and PML originates from medial and caudal extent of PN. In spite of substantial overlap of projection area in PN, no neurons were found to project by way of axonal collaterals. The strongest PN projections arise from the dorsolateral nucleus and these from the paramedian, lateral and peduncular nuclei are about two, three and fi ve times weaker, respectively. PML and the uvula receive the most numerous projections (mean 4 744 and 4 283 neurons) whereas projection to the pyramis (mean 1 172 neurons) is apparently smaller. The differences in the projection seem to be cause of different function of these lobules.

Projection from the dorsal column nuclei to the carebellar caudal vermis: comparison of collateral and non-collateral connection

100%

Bukowska D., Zguczynski L., Mierzejewska-Krzyzanowska B.

Acta Neurobiologiae Experimentalis

2009

tom 69

nr 3

The study was performed to determine projection from the dorsal column nuclei (DCN), both independent and by way of axonal collaterals, to the pyramis and uvula. Two different fl uorescent tracers were unilaterally injected into the two vermal targets. Single and double retrogradely labeled neurons, parent for non-collateral and collateral projections, were found in defi ned regions of DCN. Non-collateral bilateral projections directed to the pyramis and uvula are stronger to the latter, and originate from neurons in the lateral cuneate nucleus (CuL; n= 5 040 vs. 6 637), the complex of gracile and medial cuneate nucleus (Gr+CuM; n=820 vs. 2 190) and CuM (n=32 vs. 92). Weak projection from the dorsal Gr (n=57) is destined for the pyramis. Neurons in the rostral and middle CuL, projecting to the pyramis and uvula occupy ventrolateral and ventromedial positions, respectively, and a narrow region between them is common. More caudally, small areas in CuL, Gr+CuM and CuM supply the uvula, but in majority, areas of projection from these subnuclei to both lobules overlap. Weaker ipsilateral projections by way of axonal collaterals (n=175) arise from neurons in common projection areas in CuL and Gr+CuM. To sum up, neurons for the DCN-pyramis and DCN-uvula projections vary in number and distribution, and there is a small population of neurons participating in divergent projection to both lobules. Different extent of DCN infl uences may be due to disparate function of the pyramis and uvula.

Ograniczanie wyników

2 Acta Neurobiologiae Experimentalis

2 Bukowska D.

2 Mierzejewska-Krzyzanowska B.

1 Zguczynski L.

1 Zguczyński L.

2 2009

Wyniki wyszukiwania

Projections from the bassilar pontine nuclei to the careberral cortex: fluorescent tracing study in the rabbit

Projection from the dorsal column nuclei to the carebellar caudal vermis: comparison of collateral and non-collateral connection