Brainstem efferents from the interface between the nucleus medialis and the nucleus interpositus in the rat

In a previous report (Buisseret-Delmas et al. [1993] Neurosci. Res. 16:195-207), the authors identified the interface between the cerebellar nuclei medialis and interpositus as the origin of the nuclear output from cortical zone X. They named this nuclear interface the interstitial cell group (icg). In this study, the authors analyzed the icg efferents to the brainstem by using the anterograde and retrograde tracer biotinylated dextran amine. The main targets of these efferents are from rostral to caudal: 1) the accessory oculomotor nuclear region, essentially, the interstitial nucleus of Cajal; 2) the caudoventral region of the red nucleus; 3) a dorsal zone of the nucleus reticularis tegmenti pontis; 4) restricted regions of the four main vestibular nuclei; and 5) three restricted areas in the inferior olive, one that is caudal in the medial accessory subnucleus and two others that are rostral and caudal in the dorsal accessory subnucleus, respectively. These data support the notion that the icg contributes to the control of gaze-orientation mechanisms, particularly those that are related to the vestibuloocular reflex.