Vestibulotrigeminal pathways in the frog, Rana esculenta

Abstract

The aim of this study was to investigate whether primary vestibular afferent fibers establish direct connections with the motor and sensory trigeminal system in the brainstem of the frog. The experiments were carried out on Rana esculenta. In anaesthetized animals the trigeminal and vestibular nerves were prepared, and their proximal stumps were labeled either with fluorescein binding dextran amine (trigeminal nerve) or tetramethylrhodamine dextran amine (vestibulocochlear nerve). With a confocal laser scanning microscope we could detect close connections between the vestibular fibers and branches of the dorsal dendritic array of the jaw-closing motoneurons, suggestive of monosynaptic contacts. In the other parts of the brainstem, vestibular terminals were detected in the termination areas of the mesencephalic trigeminal nucleus and of the Gasserian (Vth) ganglion and they were probably involved in polysynaptic connections. In agreement with the results obtained in mammalian species, the present findings suggest that the vestibulotrigeminal relationship is quite complex and uses multiple pathways to connect the vestibular apparatus with the motor and sensory nuclei of the trigeminal nerve in the anurans as well.

Possible neural network mediating jaw opening during prey-catching behavior of the frog

“…5 summarizes the present and previous data concerning the direct and indirect sensory input to the brainstem networks of preycatching behavior in the frog (Anderson, 2001;Antal et al, 1980;Corbacho et al, 2005;Deak et al, 2009;Harwood and Anderson, 2000;Kecskes et al, 2013Kecskes et al, , 2015Mandal and Anderson, 2010;Matesz, 1994;Matesz et al, 2008Matesz et al, , 2014Nishikawa, 2000). We can hypothesize that direct contacts of the trigeminal fibers with the trigeminal and facial motoneurons can be the morphological background of the synchronization and timing of the jaw closing and opening during the feeding movements.…”

“…Several studies (Anderson, 2001;Corbacho et al, 2005;Mandal and Anderson, 2010;Matsushima et al, 1986;Nishikawa, 2000) suggested polysynaptic pathways between sensory fibers and motoneurons involved in the prey catching behavior. Although the possible influence of the primary afferents on the activity of jaw opening muscle is not yet determined, direct contacts have been verified between sensory fibers and various motoneurons supplying jaw closing and tongue muscles as well as those involved in swallowing (Deak et al, 2009;Kecskes et al, 2013Kecskes et al, , 2015Matesz et al, 2008). The jaw opening is executed by the contraction of depressor mandibulae muscle (DMm) under the control of the facial nerve (Gans and Gorniak, 1982;Gaupp, 1904).…”

Comparative Electrophysiological Analysis of the Cerebellar Control of the Vestibular Nuclear Complex and Medial Reticular Formation Neurons in Frog

“…У низших позвоночных вестибулярные волокна составляют основной источник афферентов к аурикулярной области коры мозжечка. Известно, что нейроны МРФ амфибии обильно снабжаются вестибулярными волокнами [4]. Вестибулярные афференты влияют на нейроны МРФ также через интернейроны, локализованные в ВЯК [2].…”