蝶腭神经节电刺激对猫鼻粘膜神经末梢VIP释放的影响

为了解蝶腭神经节刺激对鼻粘膜神经肽释放的调节机制，用免疫组织细胞化学技术（ABC法）及放射免疫学方法观察电刺激蝶腭神经节对猫鼻粘膜神经末梢血管活性肠肽（vasoactiveintestinalpeptide，VIP）释放的影响。实验显示，蝶腭神经节刺激后，鼻粘膜静脉血浆VIP在15秒钟达高峰，随时间变化而逐渐下降。于此同时，分布于小动脉壁、小静脉壁、腺泡周围及上皮细胞间的VIP免疫反应阳性物质明显较神经节刺激前增多。实验结果表明蝶腭神经节刺激可促进猫鼻粘膜神经末梢VIP的释放。     

Thermal stimulation of the vestibular labyrinth during orbital flight

Summary During the European Spacelab mission (SL1) in 1983, caloric testing was performed for the first time in long-term weightlessness. After 2 days into orbital flight an unequivocal caloric nystagmus was observed in both subjects tested which corresponded in both quality and intensity with that measured in one-g conditions on Earth. The subsequent D1 mission enabled the experiment to be repeated on further subjects and with improved measurement procedures. As with the SL1 findings, the observed caloric nystagmus response proved to be equivalent to that measured during baseline testing on Earth. Renewed consideration of peripheral and central mechanisms, which might be involved in the elicitation of the caloric response — both in one-g and zero-g environments — has led to the reopening of a number of associated issues. One important observation which has been addressed by various research groups concerns the influence of the labyrinth's orientation to the gravity vector on the caloric response. The present authors have examined a group of healthy subjects in various body positions in the sagittal plane. The interindividual variability in the response behavior was found to be high; indeed single cases were observed in which the nystagmus response did not invert from the supine to the prone positions. These findings are discussed together with earlier reports in the literature.Part of the Round Table Conference presented at the Collegium ORLAS, Munich, Federal Republic of Germany, 7–10 September 1986     

Thermal stimulation of the vestibular labyrinth during orbital flight

During the European Spacelab mission (SL1) in 1983, caloric testing was performed for the first time in long-term weightlessness. After 2 days into orbital flight an unequivocal caloric nystagmus was observed in both subjects tested which corresponded in both quality and intensity with that measured in one-g conditions on Earth. The subsequent D1 mission enabled the experiment to be repeated on further subjects and with improved measurement procedures. As with the SL1 findings, the observed caloric nystagmus response proved to be equivalent to that measured during baseline testing on Earth. Renewed consideration of peripheral and central mechanisms, which might be involved in the elicitation of the caloric response--both in one-g and zero-g environments--has led to the reopening of a number of associated issues. One important observation which has been addressed by various research groups concerns the influence of the labyrinth's orientation to the gravity vector on the caloric response. The present authors have examined a group of healthy subjects in various body positions in the sagittal plane. The interindividual variability in the response behavior was found to be high; indeed single cases were observed in which the nystagmus response did not invert from the supine to the prone positions. These findings are discussed together with earlier reports in the literature.     

Effect of violation of the labyrinth on the sensory epithelium in the chick cochlea

Models in which a single large systemic dose of gentamicin is used to cause near-synchronous hair cell (HC) loss in the basal end of the chick cochlea have proven increasingly useful in the study of HC regeneration. We quantified the amount of HC death, as a percentage of the length of the basilar papilla, following single doses of 200 mg/kg and 300 mg/kg of gentamicin in 23-day-old chicks. Following 200 mg/kg of gentamicin, there was total HC loss in the basal 18.0% of the sensory epithelium and partial HC loss in the basal 26.3%. Following 300 mg/kg of gentamicin, there was total HC loss in the basal 30.5% of the epithelium and partial HC loss in the basal 40.9%. The second goal of this study was to determine whether cannula implantation in the inner ear, and infusion of bromodeoxyuridine causes HC damage. We found that creation of a fistula in the labyrinth is not associated with HC damage, but that cannula implantation can cause HC death, and can also cause potentiation of gentamicin-induced HC death. Revision of the cannula and surgical technique to ensure minimal penetration into the labyrinth almost entirely eliminated these effects. We conclude that surgical technique is critical in experimental models in which the labyrinth is violated.     

The relationship between electrode area and sensory qualities in electrical human tongue stimulation

The relationship between the size of the stimulated human tongue area, the stimulating electric current intensity and the provoked sensory qualities was examined. Five different electrode areas and four anodal current intensities were used. The observed sensations were of three kinds: sour taste, somatosensory, and undefined ones. At a given current intensity level the proportion of taste increases with the increase in the stimulation area, while somatosensory sensations decrease. These results imply that at the suprathreshold level there is a certain interdependence between the area, current intensity and sensory effects. In order to achieve optimal activation of the taste system alone, it is more effective to use a larger electrode and stronger current, than to use smaller areas and weaker stimuli: in this case the electrical sour taste is satisfactorily clear, since the somatosensory system is still not activated. These findings may have implications in clinical electrogustometry.     

Synaptogenesis of the efferent vestibular nerve endings of the cat: Ultrastructural study

Summary The maturation of the innervation of the sensory hair cells of the cristae ampullares was studied in the newborn cat. The essential characteristics of the adult are already present in the type II cells at this age. The type I cells on the contrary reveal different degrees of maturation. It was observed that in the immature stages the efferent endings which were already filled with synaptic vesicles were in direct contact with the membrane of the sensory cell. The nerve chalice as it settles into place breaks this contact and simultaneously a synapse is created between the efferent endings and the afferent chalice.This Research was supported by grants from the C.N.R.S. (ERA 187) and the I.N.S.E.R.M. (ATP 6.74.27)     

Magnetic stimulation of the facial nerve

Electrical testing of the facial nerve has evolved into an important means of assessing neural injury. However, the inability to stimulate the intratemporal facial nerve electrically results in a delay in diagnosis, because axonal degeneration must progress distal to the stylomastoid foramen before testing can be meaningful. To circumvent this problem, we began an investigation of magnetic stimulation of the facial nerve, because pulsed magnetic fields can pass unattenuated through all body structures, including bone. Normal volunteers and one patient with acute facial paralysis were studied with both magnetic and electric stimulation of the facial nerve. The results indicate that (1) magnetic stimulation was more comfortable because high current levels were not required at the skin surface to assure indepth stimulation, (2) magnetic and electric stimulation of the extratemporal facial nerve resulted in nearly identical compound muscle action potentials, indicating that the sites and mechanisms of neural depolarization are similar, and (3) transtemporal magnetic stimulation appears to allow depolarization of the proximal intratemporal nerve. These preliminary results are encouraging and indicate that magnetic stimulation of the facial nerve warrants further investigation.     

Magnetic stimulation of the facial nerve

Intracranial activation of the facial nerve is now possible with the noninvasive techniques of magnetic stimulation. Brief magnetic pulses generated by a coil overlying the parietal scalp elicit compound muscle action potentials of similar shape and amplitude and greater latency than those produced by electroneurography. Mapping studies demonstrate the compound muscle action potentials to be of constant latency and varying amplitude with changing coil location. Maximum compound muscle action potential amplitudes are obtained with the coil center located in a rectangular area superior and posterior to the ear canal. A comparison of large and small diameter coils showed them to be equally effective for painless facial nerve stimulation; however, the smaller coil allowed for a more localized field of activation. Magnetic stimulation has the potential to provide cross-the-lesion testing of facial nerve function.     

A hydrodynamic model of labyrinth to study the stimulation of perilymph compartments by audioprostheses

Conclusions. The hydrodynamic model of the labyrinth spaces (LHM) is a useful tool for research on implantable audioprostheses, in particular to develop suitable actuators using MEMS technology (micro-electromechanic machine system). It has other potential applications for auditory research. Objectives. The energy reaching the labyrinth fluids is crucial information for developing prostheses to substitute the tympanic-ossicular system because adequate stimulation of the cochlear partition is essential. However, in vivo measurements in human ears are not currently available. Therefore a model of the normal labyrinth resembling its hydrodynamic properties becomes a valuable tool. It could allow comparison of different processing systems, algorithms and transducers, to develop new audioprostheses and improve their effectiveness and efficiency. Materials and methods. This work presents one LHM that emulates the conduction of the stimuli from the stapes footplate through the labyrinthine fluids, including its dimensions and physical properties, and some examples of measurements of perilymph stimulation by different audioprostheses and algorithms. Results. As shown in the reported examples, this LHM provided effective measurement of acoustic stimulation across the whole human auditory frequency and intensity spectrum. Air-delivered and direct stimulation methods are possible. This provided convenient information for the actuator development and allowed comparison between different prototypes, stimulation patterns and algorithms.     

Synaptogenesis of the efferent vestibular nerve endings of the cat: ultrastructural study.

The maturation of the innervation of the sensory hair cells of the cristae ampullares was studied in the newborn cat. The essential characteristics of the adult are already present in the type II cells at this age. The type I cells on the contrary reveal different degrees of maturation. It was observed that in the immature stages the efferent endings which were already filled with synaptic vesicles were in direct contact with the membrane of the sensory cell. The nerve chalice as it settles into place breaks this contact and simultaneously a synapse is created between the efferent endings and the afferent chalice.