The ventral spine-olivocerebellar system in the cat. II. Termination zones in the cerebellar posterior lobe.

1. Five spine-olivocerebellar paths ascending through the ventral funiculus (VF-SOCPs) have previously been distinguished on the basis of different receptive fields, different response latencies and different projection zones in the cerebellar anterior lobe (Oscarsson and Sjölund, 1977). These paths are denoted the a-, b1-, b2-, c1 and c3-VF-SOCPs according to the labelling of their projection zones. The projection zones of these paths in the posterior lobe have noew been investigated. 2. The a-VF-SOCP projects to a medial zone in the pyramis. 3. The b1-and b2-VF-SOCPs do not project to the posterior lobe. 4. The c1-VF-SOCP projects to the medial one third of the pars copularis and caudalmost folium of the pars posterior of the paramedian lobule and to the most lateral part of the pyramis. 5. The c3-VF-SOCP projects mainly laterally to the caudalmost one or two folia of the pars copularis of the paramedian lobule. The c3 projection zone merges medially with the c1-zone. 6. The a-, c1- and c3-zones in the posteior lobe are innervated by climbing fibres which also send branches to the corresponding zones in the anterior lobe. 7. The VF-SOCP projection zones are tentatively identified with the sagittal zones described by Groenewegen and Voogd (1976) on the basis of anatomical studies.