Topography of olivo‐cortico‐nuclear modules in the intermediate cerebellum of the rat

Abstract

This study provides a detailed anatomical description of the relation between olivo-cortico-nuclear modules of the intermediate cerebellum of the rat and the intrinsic zebrin pattern of the Purkinje cells. Strips of climbing fibers were labeled using small injections of biotinylated dextran amine into either the medial or dorsal accessory olives, while, in some cases, simultaneous retrograde labeling of Purkinje cells was obtained using gold-lectin injections into selected parts of the interposed nuclei. Our data are represented in a new, highly detailed, cortical surface reconstruction of the zebrin pattern and in relation to the collateral labeling of the climbing fibers to the cerebellar nuclei. We show that the somatotopic regions of the dorsal accessory olive behave differently in their projections to essentially zebrin-negative regions that represent the C1 and C3 zones of the anterior and posterior parts of the cortex. The rostral part of the medial accessory olive projects to zebrin-positive areas, in particular to the P4+ band of the anterior lobe and lobule VI and to the P5+ band of the posterior lobe, indicating that C2 has two noncontiguous representations in the SL and crus 1. By relating the areas of overlap that resulted from the injections in the accessory olives, i.e., labeling of climbing fiber strips and patches of climbing fiber nuclear collaterals, with the results from the injections in the interposed nuclei, i.e., retrograde labeling of Purkinje cells and of inferior olivary neurons, direct verification of the concept of modular cerebellar connections was obtained.

Selective Impairment of the Cerebellar C1 Module Involved in Rat Hind Limb Control Reduces Step-Dependent Modulation of Cutaneous Reflexes

“…2 B). These locations are in perfect agreement with earlier data on topography of olivocorticonuclear connections and show that the tracer characteristics of CTb-S are very similar to those of unconjugated CTb (Pardoe and Apps, 2002;Voogd et al, 2003;Pijpers et al, 2005;. Note that both types of injections also resulted in retrograde labeling of nucleocortical neurons, which were mostly confined to regions that also harbored anterograde terminal labeling (Provini et al, 1998) (Fig.…”

“…Bottom, Three three-dimensional representations of precerebellar nuclei: from top to bottom, the basal pontine nuclei , the lateral reticular nuclei , and the left inferior olivary complex (Ruigrok, 2004). Purkinje cells of the C1 and C3 zones (middle, blue stripes) of the anterior lobe and of the C1 zone of lobule VIII (COP) are believed to be involved in processing hindlimb information and to project to the medial part of the AIN (Atkins and Apps, 1997;Voogd et al, 2003;Pijpers et al, 2005). To study the function of the related module, all blue areas would need to be affected simultaneously.…”

“…In order for the CTb-S to have the desired effect of affecting related regions at different parts of the cerebellar cortex, it was necessary to show that, apart from degeneration of the neurons within the injection site, the afferent systems that reach a specific injection site also degenerate. Because the modular relation between areas of the inferior olive, cerebellar nuclei, and Purkinje cell zones are well known and provide identification of the targeted cerebellar module (Ruigrok, 1997;Voogd et al, 2003;Pijpers et al, 2005), we focus our description on these areas.…”

“…E, Aspects of argyrophilic degeneration in case R5 with an injection of C1 in COP and a survival time of 21 d. E1, White matter degeneration within the anterior lobe and all three cerebellar peduncles. E2, Enlargement of the boxed area in E1, showing degeneration in granular and molecular layers (arrows) at an area corresponding to C1 (Pijpers et al, 2005). E4, Degeneration of nucleobulbar fibers in the ipsilateral superior cerebellar peduncle (scp; arrows) but not in the contralateral scp (E3).…”

“…This module is present as the C1 zone in the copula pyramidis (COP) and has related regions in the C1 and C3 zones of lobules II-V of the anterior lobe (Atkins and Apps, 1997;Voogd et al, 2003;Pijpers et al, 2005). Indeed, we show that a small targeted injection of CTb-S into C1 of COP results in degeneration within well circumscribed regions of the precerebellar nuclei.…”