Vestibulocerebellar Connections
The vestibular system projects onto the cerebellum via three major pathways that are composed of primary and secondary vestibular mossy fiber afferents and tertiary vestibular climbing fibers. Vestibular primary afferent mossy fibers project to the ipsila
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Neal H. Barmack and Vadim Yakhnitsa
Abstract
The vestibular system projects onto the cerebellum via three major pathways that are composed of primary and secondary vestibular mossy fiber afferents and tertiary vestibular climbing fibers. Vestibular primary afferent mossy fibers project to the ipsilateral uvula-nodulus (folia 9d and 10). Secondary vestibular mossy fibers originate from three of the five vestibular nuclei: medial, descending, and superior (MVN, DVN, and SVN). These mossy fibers terminate in the uvula-nodulus and flocculus. The MVN, DVN, and SVN receive convergent vestibular, optokinetic, and neck proprioceptive information. Vestibular tertiary afferents originate from two subnuclei of the inferior olive, the b-nucleus and dorsomedial cell column (DMCC), and send climbing fibers to the contralateral uvula-nodulus. The b-nucleus and DMCC receive direct projections from the parasolitary nucleus (Psol). The Psol, b-nucleus, and DMCC convey information to the cerebellum from the vertical semicircular canals and otoliths, but not from the horizontal semicircular canals. Climbing fiber projections are arrayed in sagittal zones, establishing a mediolateral map on the uvula-nodulus of the 180 of possible head angles during roll-tilt. Signals conveyed from climbing fibers are preeminent in modulating the discharge of both complex and simple spikes (CSs and SSs) in cerebellar Purkinje cells. This discharge is fed back onto a fraction of neurons in the dorsal aspect of the descending and medial vestibular nuclei as well as the prepositus hypoglossal nucleus. The vestibulocerebellum imposes a climbing fiber-constructed coordinate system on postural responses and permits adaptive guidance of movement.
N.H. Barmack (*) • V. Yakhnitsa Department of Physiology & Pharmacology, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, 97239 Portland, OR, USA e-mail: [email protected], [email protected] M. Manto, D.L. Gruol, J.D. Schmahmann, N. Koibuchi, F. Rossi (eds.), 357 Handbook of the Cerebellum and Cerebellar Disorders, DOI 10.1007/978-94-007-1333-8_18, # Springer Science+Business Media Dordrecht 2013
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N.H. Barmack and V. Yakhnitsa
Introduction The vestibulocerebellum participates in sensorimotor integration and motor control. While reflexive and reactive movements can be executed with or without an intact cerebellum, the cerebellum adds accuracy and modifiability to movements using sensory feedback and superimposing centrally generated commands (Morton and Bastian 2006). Cerebellar circuitry itself is modifiable (Eccles et al. 1967; Ito 1976, 2002). For this reason, the cerebellum attracts interest from both basic and clinical neurobiologists. Impaired cerebellar function can be the consequence of chronic alcoholism (Schapiro et al. 1984), genetic mutation (Zee et al. 1976; Falk et al. 1999; Koeppen 2005), immunological disorders (Hida et al. 1994; Sakai et al. 1995), and neural trauma. This chapter describes one of the key sensory inputs to the cerebellum, the vestibular system. It chara
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