The afferent connections of the cerebellar cortex of the cat have been extensively in vestigated by Alf Brodal and his collaborators using retrograde degeneration methods. These experiments (reviewed in Larsell and Jansen 1972) established that cerebellar corti cal afferents arise from widespread areas of the brain stem and spinal cord. Brain stem nuclei shown to provide input to the cerebellar cortex included the pontine nuclei, the medial and descending vestibular nuclei, vestibular cell group x, the lateral reticular nucleus, the perihypoglossal nuclei, the paramedian reticular nucleus, the inferior olive, and the external cuneate nucleus. In addition, the red nucleus and certain of the raphe nuclei were thought to send fibers to the intracerebellar nuclei, but not to the cortex. With the advent of the horseradish peroxidase (HRP) technique, new information on the distribution and organization of cerebellar cortical afferents has recently be come available. Thus Gould and Graybiel (1976) demonstrated that afferents to the cat cerebellar cortex arise from a previously undescribed lateral tegmental cell group at the level of the isthmus and from the intracerebellar nuclei, as well as from the classic precerebellar nuclei. Moreover, these studies showed that fibers from the vestibular nuclei, previously thought to be distributed only to the flocculonodular lobe and uvula, reach widespread areas of the cerebellar cortex. Experiments by other investi gators have established that the cerebellar cortex of the cat receives afferents from cer tain of the raphe nuclei (Shinnar et al. 1975; Taber Pierce et al.

1 Introduction

2 Material and Methods
3 Observations from the Author's Investigations
3.1 General Comments
3.2 Results of Large Nonsuperficial Horseradish Peroxidase Injections
3.3 Results of Restricted Cortical Horseradish Peroxidase Injections
4 Review of the Literature and Discussion of Brain Stem Afferents to the Cerebellar Cortex from Particular Precerebellar Nuclei
4.1 Pontine Nuclei, Nucleus Reticularis Tegmenti Pontis, and Corpus Pontobulbare
4.2 Raphe Nuclei
4.3 A Lateral Tegmental Cell Group at the Level of the Isthmus
4.4 Locus Coeruleus
4.5 Trigeminal Nuclei
4.6 Vestibular Nuclei
4.7 Perihypoglossal Nuclei
4.8 Inferior Olive
4.9 Lateral Reticular Nucleus
4.10 Paramedian Reticular Nucleus and Nucleus Interfasciculares Hypoglossi
4.11 External Cuneate Nucleus
4.12 Main Cuneate Nucleus
4.13 Gracile Nucleus
4.14 Nucleus of the Solitary Tract
4.15 Other Brain Stem Nuclei Projecting to the Cerebellar Cortex
5 General Discussion of the Afferent Organization of the Cerebellar Cortex of the Cat
5.1 Overlap and Segregation of Brain Stem Areas Projecting to Different Cerebellar Lobules
5.2 Overlap and Segregation of Afferents from Different Brain Stem Areas Within the Cerebellar Cortex
5.3 Sagittal Organization of the Cerebellar Cortex
5.4 Afferent Organization of the Cerebellar Cortex in Relation to Concepts of Functional Localization
6 Summary
References.