Projections from the cerebellar interposed and dorsal column nuclei to the thalamus in the rat: A double anterograde labelling study

Abstract

It is generally agreed that cerebellar and lemniscal pathways project to largely separate areas of the thalamus and influence different functional areas of the cerebral cortex. Cerebellar afferents arise from neurones in the deep cerebellar nuclei and terminate in the ventral lateral group of thalamic nuclei or the "motor thalamus," whereas lemniscal afferents arise from the dorsal column nuclei and terminate in the adjacent ventral posterior group of thalamic nuclei or "sensory thalamus." However, it remains unclear whether or not these pathways converge onto thalamic neurones in the border zone between motor and sensory thalamus. The aim of this study was to compare directly the locations of cerebellar interposed and dorsal column nuclei terminals in the rat thalamus by using a double anterograde labelling technique. Microinjections of dextran-tetramethylrhodamine and dextran-fluorescein were made into the interposed and dorsal column nuclei, and labelled terminals in the thalamus were examined in the same sections. The labelled cerebellar and lemniscal terminals were located in separate areas throughout most of the ventral lateral and ventral posterior lateral nuclei, and there was only a limited region around the rostral border between these nuclei where the two groups of terminals came in close proximity to each other. In this common projection zone, however, cerebellar and lemniscal terminals seldom intermingled, and they mostly occupied separate, discreet areas. The results show that cerebellar and lemniscal fibres do indeed project to the border zone between the sensory and cerebellar thalamic nuclei, but they show practically no overlap in this region and are likely to influence separate thalamic neurones.

Anatomical evidence for somatotopic maps in the zona incerta of rats

“…First, both maps are organised in a comparable fashion, with the head being represented medially, and progressively more caudal body regions being represented in progressively more lateral regions of these nuclei (Jones 1985;Nicolelis et al 1992;Waite and Tracey 1995). Our own results show and those found in previous electrophysiological studies note that the mapping strategy is better defined in the VP than in the ZI; for example, there is some overlap in the projections from FL and Par1 in the central regions of the ZI, while no such overlap is apparent in the VP (Aumann et al 1996)Furthermore, our study also shows that cells in ZI have larger receptive fields, often including several whiskers, while cells in the VP represent single whiskers only (Peschanski et al 1983;Nicolelis et al 1992). Secondly, the head and upper body occupy a much larger territory than the lower body (Tracey and .…”

“…Some previous electrophysiological (Peschanski et al 1983;Nicolelis et al 1992) and anatomical (Berkley 1986;Nicolelis et al 1992;Aumann et al 1996) studies suggest that there may be a somatotopic map within the ZI, but these are on the whole rather incomplete. In essence, a thorough portrait of any anatomical somatotopic maps and patterns of projections from many somatosensory centres onto the ZI, particularly in relation to its different sectors, is lacking.…”

Differentiating ascending vestibular pathways to the cortex involved in spatial cognition

“…[134,155,168,211], and the projections from the cerebellum (also shaded in brown) to the thalamus. Anterior interpositus [15,16,72,155,196,239,241] and rostral fastigial nuclei project to thalamus [155,239]. The vestibular nuclei are interconnected with the cerebellum.…”

Functional Organisation and Connectivity of the Dorsal Column Nuclei Complex Reveals a Sensorimotor Integration and Distribution Hub

“…The zona incerta (ZI) is an elongated prethalamic structure in the diencephalon consisting of heterogenous groups of cells, separated into sectors with distinct cytoarchitecture, chemoarchitecture, and connections (Mitrofanis, 2005;. Various types of neurons in rostral DCN project via the ML and terminate in ventral ZI (Figure 7) in rats, cats, and monkeys (Aumann, Rawson, Pichitpornchai, & Horne, 1996;Berkley et al, 1986;Berkley & Hand, 1978a;Boivie, 1971;Hand & Van Winkle, 1977;Lund & Webster, 1967;Roger & Cadusseau, 1985;Shammah-Lagnado, Negrão, & Ricardo, 1985). Projections from the Cu are more numerous and terminate more medially, whereas Gr projections terminate more laterally (Boivie, 1971;Villanueva et al, 1998).…”