Collateral projections from vestibular nuclear and inferior olivary neurons to lobules I/II and IX/X of the rat cerebellar vermis: a double retrograde labeling study

Abstract

Axon collateral projections to various lobules of the cerebellar cortex are thought to contribute to the coordination of neuronal activities among different parts of the cerebellum. Even though lobules I/II and IX/X of the cerebellar vermis are located at the opposite poles in the anterior-posterior axis, they have been shown to receive dense vestibular mossy fiber projections. For climbing fibers, there is also a mirror-image-like organisation in their axonal collaterals between the anterior and posterior cerebellar cortex. However, the detailed organisation of mossy and climbing fiber collateral afferents to lobules I/II and IX/X is still unclear. Here, we carried out a double-labeling study with two retrograde tracers (FluoroGold and MicroRuby) in lobules I/II and IX/X. We examined labeled cells in the vestibular nuclei and inferior olive. We found a low percentage of double-labeled neurons in the vestibular nuclei (2.1 ± 0.9% of tracer-labeled neurons in this brain region), and a higher percentage of double-labeled neurons in the inferior olive (6.5 ± 1.9%), especially in its four small nuclei (18.5 ± 8.0%; including the β nucleus, dorsal cap of Kooy, ventrolateral outgrowth, and dorsomedial cell column), which are relevant for vestibular function. These results provide strong anatomical evidence for coordinated information processing in lobules I/II and IX/X for vestibular control.

Body Sway Increases After Functional Inactivation of the Cerebellar Vermis by cTBS

“…Stimulation of the medial bank of the suprasylvian area elicits both mossy and climbing fiber responses, mainly in the vermis: direct cortico-pontine and indirect long-latency cortico-olivary projections are suggested to convey the respective responses [87, 88]. In turn, the inferior olivary nucleus has a substantial projection to the vermis and many axons branch to both the anterior and posterior part of the vermis, as a likely substrate of different segments’ coordination [89]. …”

Motor and non-motor control by neuronal subpopulations within the deep cerebellum

“…In addition, we observed FG labeled mossy fiber rosettes within the IGL of cerebellar vermis, lobules 1 Cb and 4/5 Cb (Figure 22G). Our results and previous studies have shown that mossy fiber collateral projections in 1 Cb, 2 Cb and 4/5 Cb belong to neurons located in the cerebellar nuclei (Ruigrok et al, 2014) (Appendix H) and the vestibular nuclei (Lee et al, 2014).…”

Plasticity of cerebellar Purkinje cells in behavioral training of body balance control

“…Head-body movements encoded by these PCs in our study may result from vestibular [i.e., those in lobules IX–X of the classical vestibulocerebellum (Barlow, 2005 )] as well as non-vestibular [i.e., those in lobules V–VIII of the classical spinocerebellum (Barlow, 2005 )] information, such as neck muscle tension. In addition, very different lobules of the rat cerebellum also appeared to receive similar projections (Ruigrok, 2003 ; Voogd et al, 2003 ; Fujita and Sugihara, 2013 ; Lee et al, 2014 ). Regardless of the type of movement-related information encoded by these PCs, SS firing rates of PCs in the present study showed a linear coding response to the head-body angle measure.…”