Patterns of Connections between Six Semicircular Canals and Dorsal Neck Motoneurons

Author(s):  
Yoshikazu Shinoda ◽  
Yuriko Sugiuchi ◽  
Takahiro Futami ◽  
Naoto Ando ◽  
Tsutomu Kawasaki ◽  
...  
1994 ◽  
Vol 72 (6) ◽  
pp. 2691-2702 ◽  
Author(s):  
Y. Shinoda ◽  
Y. Sugiuchi ◽  
T. Futami ◽  
N. Ando ◽  
T. Kawasaki

1. The pattern of connections between the six semicircular canals and neck motoneurons of the multifidus muscle group was investigated by recording intracellular potentials from motoneurons in the upper cervical cord of anesthetized cats. 2. Synaptic potentials were recorded in motoneurons of the rectus capitis posterior (RCP) muscle at C1, the obliquus capitis inferior (OCI) muscle at C1 and C2, and the cervical multifidus muscle (Multi) at C4 in response to electrical stimulation of individual ampullary nerves of the six semicircular canals. Excitatory or inhibitory postsynaptic potentials (EPSPs or IPSPs, respectively) were evoked by separate stimulation of individual ampullary nerves in all of the neck motoneurons. Virtually all of the neck motoneurons received convergent inputs from the six ampullary nerves. 3. Motoneurons that supplied a single muscle had a homogeneous pattern of input from the six semicircular canals. There were two patterns of input from the six semicircular canals to motoneurons of the multifidus muscle group. RCP and Multi motoneurons were excited by stimulation of the bilateral anterior canal nerves (ACNs) and the contralateral lateral canal nerve (LCN) and inhibited by stimulation of the bilateral posterior canal nerves (PCNs) and the ipsilateral LCN. This input pattern is similar to that previously observed in other dorsal extensor muscles, whereas the other input pattern observed in OCI motoneurons is entirely new. OCI motoneurons at C1 and C2 were excited by stimulation of the ipsilateral ACN, PCN, and the contralateral LCN and inhibited by stimulation of the contralateral ACN, PCN, and the ipsilateral LCN. 4. Most postsynaptic potentials (PSPs) were disynaptic, but there were trisynaptic inhibitory connections between the contralateral ACN and PCN and OCI motoneurons, and between the contralateral PCN and RCP motoneurons. 5. The pathways for mediating these inputs from different semicircular canals to neck motoneurons were determined by making lesions in the lower medulla. Transection of the ipsilateral medial longitudinal fascicle (MLF) abolished the following potentials: all disynaptic PSPs in RCP motoneurons except the disynaptic EPSPs from the ipsilateral ACN, and in OCI motoneurons, disynaptic PSPs from the bilateral LCNs, and disynaptic IPSPs from the contralateral PCN. Complete bilateral section of the MLF did not affect the disynaptic EPSPs from the ipsilateral ACN in RCP motoneurons, the disynaptic EPSPs from the ipsilateral ACN and PCN in OCI motoneurons, nor the trisynaptic IPSPs from the contralateral ACN and PCN in COI motoneurons and from the contralateral PCN in RCP motoneurons.(ABSTRACT TRUNCATED AT 400 WORDS)


1997 ◽  
Vol 77 (3) ◽  
pp. 1234-1253 ◽  
Author(s):  
Y. Shinoda ◽  
Y. Sugiuchi ◽  
T. Futami ◽  
N. Ando ◽  
J. Yagi

Shinoda, Y., Y. Sugiuchi, T. Futami, N. Ando, and J. Yagi. Input patterns and pathways from the six semicircular canals to motoneurons of neck muscles. II. The longissimus and semispinalis muscle groups. J. Neurophysiol. 77: 1234–1253, 1997. To reveal patterns of input from the six semicircular canals to motoneurons of various neck muscles and their relationship to the mechanical actions of individual neck muscles, patterns of input to neck motoneurons of the longissimus and the semispinalis muscle groups were investigated in the upper cervical spinal cord of anesthetized cats. Intracellular potentials were recorded from motoneurons of the longissimus muscle group (obliquus capitis superior muscle, OCS; splenius muscle, SPL; longissimus muscle, LONG) and the semispinalis muscle group (biventer cervicis muscle, BIV; complexus muscle, COMP), and effects of separate electrical stimulation of the six ampullary nerves on them were analyzed in each preparation. Neck motoneurons usually received convergent inputs from all of the six ampullary nerves, and motoneurons that supplied a particular muscle had a homogeneous pattern of input from the six ampullary nerves. Two different patterns of input were identified for motoneurons of these two muscle groups; one pattern for motoneurons of the longissimus muscle group and the other pattern for motoneurons of the semispinalis muscle group. Motoneurons of the OCS, the SPL, and the LONG muscles received excitation from the three contralateral ampullary nerves and inhibition from the three ipsilateral ampullary nerves. BIV and COMP motoneurons received excitation from the bilateral anterior canal nerves (ACNs) and the contralateral lateral canal nerve (LCN) and inhibition from the bilateral posterior canal nerves (PCNs) and the ipsilateral LCN. Latencies of postsynaptic potentials (PSPs) evoked by stimulation of each of the six ampullary nerves indicated that the earliest component of excitatory PSPs (EPSPs) and inhibitory PSPs (IPSPs) was disynaptic in these motoneurons. However, trisynaptic IPSPs were evoked by stimulation of the contralateral PCN in a considerable number of BIV and COMP motoneurons. In OCS, SPL, and LONG motoneurons, all of the excitation from the contralateral and all of the inhibition from the ipsilateral ampullary nerves were mediated through the ipsilateral medial longitudinal fascicle (MLF). In BIV and COMP motoneurons, disynaptic excitation from the contralateral ACN and LCN and disynaptic inhibition from the ipsilateral LCN and bilateral PCNs were mediated through the ipsilateral MLF, whereas disynaptic excitation from the ipsilateral ACN was mediated through the ipsilateral lateral vestibulospinal tract. The patterns of semicircular canal input to neck motoneurons of these two muscle groups are related closely to the mechanical actions of individual neck muscles and the optimal stimulus to the semicircular canals such that the connections will tend to stabilize head position in response to head perturbations.


Author(s):  
Charles H. Markham

ABSTRACT:The vestibulospinal system helps to maintain upright posture and head stability. The semicircular canals and their short latency connections to the neck motoneurons, largely via the medial vestibulospinal tract, respond to angular accelerations so as to stabilize the head in space. The paired otolith organs, the utricles placed approximately horizontally, and the saccules vertically, respond to linear acceleration including gravity. Their influence leads, via the lateral vestibulospinal tract, to excitation of ipsilateral extensor motoneurons of the limbs and trunk, and to inhibition of reciprocal flexor motoneurons. Linear displacement of the otoliths leads to bracing of the limbs and body so as to maintain upright posture, and to extend the limbs so as to help in landing after sudden falls.


1992 ◽  
Vol 656 (1 Sensing and C) ◽  
pp. 957-959 ◽  
Author(s):  
Y. SUGIUCHI ◽  
T. FUTAMI ◽  
N. ANDO ◽  
T. KAWASAKI ◽  
J. YAGI ◽  
...  

Author(s):  
D.J. Lim ◽  
W.C. Lane

The morphology and function of the vestibular sensory organs has been extensively studied during the last decade with the advent of electron microscopy and electrophysiology. The opening of the space age also accelerated active investigation in this area, since this organ is responsible for the sensation of balance and of linear, angular and gravitational acceleration.The vestibular sense organs are formed by the saccule, utricle and three ampullae of the semicircular canals. The maculae (sacculi and utriculi) have otolithic membranes on the top of the sensory epithelia. The otolithic membrane is formed by a layer of thick gelatin and sand-piles of calcium carbonate crystals (Fig.l).


Skull Base ◽  
2009 ◽  
Vol 19 (01) ◽  
Author(s):  
Cristian Gragnaniello ◽  
Mahmoud Kamel ◽  
Ossama Al-Mefty

2002 ◽  
Vol 61 (6) ◽  
pp. 391-402
Author(s):  
Yasuko Arai

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Xuewen Wu ◽  
Li Zhang ◽  
Yihui Li ◽  
Wenjuan Zhang ◽  
Jianjun Wang ◽  
...  

AbstractMutations in voltage-gated potassium channel KCNE1 cause Jervell and Lange-Nielsen syndrome type 2 (JLNS2), resulting in congenital deafness and vestibular dysfunction. We conducted gene therapy by injecting viral vectors using the canalostomy approach in Kcne1−/− mice to treat both the hearing and vestibular symptoms. Results showed early treatment prevented collapse of the Reissner’s membrane and vestibular wall, retained the normal size of the semicircular canals, and prevented the degeneration of inner ear cells. In a dose-dependent manner, the treatment preserved auditory (16 out of 20 mice) and vestibular (20/20) functions in mice treated with the high-dosage for at least five months. In the low-dosage group, a subgroup of mice (13/20) showed improvements only in the vestibular functions. Results supported that highly efficient transduction is one of the key factors for achieving the efficacy and maintaining the long-term therapeutic effect. Secondary outcomes of treatment included improved birth and litter survival rates. Our results demonstrated that gene therapy via the canalostomy approach, which has been considered to be one of the more feasible delivery methods for human inner ear gene therapy, preserved auditory and vestibular functions in a dose-dependent manner in a mouse model of JLNS2.


1995 ◽  
Vol 83 (3) ◽  
pp. 559-560 ◽  
Author(s):  
Tomio Sasaki ◽  
Makoto Taniguchi ◽  
Ichiro Suzuki ◽  
Takaaki Kirino

✓ The authors report a new technique for en bloc petrosectomy using a Gigli saw as an alternative to drilling the petrous bone in the combined supra- and infratentorial approach or the transpetrosal—transtentorial approach. It is simple and easy and avoids postoperative cosmetic deformity. This technique has been performed in 11 petroclival lesions without injuring the semicircular canals, the cochlea, or the facial nerve.


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