Angular vestibulo-ocular reflexes (VORs) produce conjugate eye movements in the plane of head rotation. Angular VORs are thought to be mediated by modular cerebellar and brainstem pathways that connect coplanar pairs of semicircular canals with pairs of extraocular muscles (EOMs). However the organization of circuits controlling single EOMs, coplanar pairs of EOMs in the plane of a semicircular canal or primary and accessory EOMs, has not been identified fully. The proposed studies will characterize the topography of pathways innervating individual EOMs using transsynaptic retrograde transport of antigenically distinct recombinant strains of pseudorabies virus from EOM injection sites. Areas containing transsynaptically-labeled cells in the vestibular nuclei and vestibulo-cerebellum will be mapped at different survival times to identify pathways underlying angular VORs. Injections of two EOMs per animal will determine common and distinct components of the pathways underlying horizontal, vertical and torsional controls. These findings will provide new insights into the spatial organization of angular VOR control, and will trace in their entirety the multi-neuronal pathways underlying eye movement control and supplying each individual EOM. Furthermore, the experimental approach used in the proposed studies, transneuronal tracing, gives the unique opportunity to identify dually labeled neurons in the vestibular nuclei and vestibulo-cerebellum. These dual labeled neurons are candidates for controlling activity of two or more EOMs.
| Billig, I; Yeager, M S; Blikas, A et al. (2007) Neurons in the cochlear nuclei controlling the tensor tympani muscle in the rat: a study using pseudorabies virus. Brain Res 1154:124-36 |
| Giaconi, E; Deriu, F; Tolu, E et al. (2006) Transneuronal tracing of vestibulo-trigeminal pathways innervating the masseter muscle in the rat. Exp Brain Res 171:330-9 |
| Billig, I; Balaban, C D (2005) Zonal organization of the vestibulo-cerebellar pathways controlling the horizontal eye muscles using two recombinant strains of pseudorabies virus. Neuroscience 133:1047-59 |
| Billig, I; Balaban, C D (2004) Zonal organization of the vestibulo-cerebellum in the control of horizontal extraocular muscles using pseudorabies virus: I. Flocculus/ventral paraflocculus. Neuroscience 125:507-20 |
