Many animal studies have reported on the neural connectivity of the vestibular nuclei（VN）.However,little is reported on the structural neural connectivity of the VN in the human brain.In this study,we attempted to i...Many animal studies have reported on the neural connectivity of the vestibular nuclei（VN）.However,little is reported on the structural neural connectivity of the VN in the human brain.In this study,we attempted to investigate the structural neural connectivity of the VN in 37 healthy subjects using diffusion tensor tractography.A seed region of interest was placed on the isolated VN using probabilistic diffusion tensor tractography.Connectivity was defined as the incidence of connection between the VN and each brain region.The VN showed 100% connectivity with the cerebellum,thalamus,oculomotor nucleus,trochlear nucleus,abducens nucleus,and reticular formation,irrespective of thresholds.At the threshold of 5 streamlines,the VN showed connectivity with the primary motor cortex（95.9%）,primary somatosensory cortex（90.5%）,premotor cortex（87.8%）,hypothalamus（86.5%）,posterior parietal cortex（75.7%）,lateral prefrontal cortex（70.3%）,ventromedial prefrontal cortex（51.4%）,and orbitofrontal cortex（40.5%）,respectively.These results suggest that the VN showed high connectivity with the cerebellum,thalamus,oculomotor nucleus,trochlear nucleus,abducens nucleus,and reticular formation,which are the brain regions related to the functions of the VN,including equilibrium,control of eye movements,conscious perception of movement,and spatial orientation.展开更多
BACKGROUND： Morphological studies have confirmed that vestibular nuclei accepts serotoninergic projections from nucleus raphe magnus, nucleus raphes pallidus, etc. But it is still unclear whether there is bi-directio...BACKGROUND： Morphological studies have confirmed that vestibular nuclei accepts serotoninergic projections from nucleus raphe magnus, nucleus raphes pallidus, etc. But it is still unclear whether there is bi-directional association between vestibular nuclei and nucleus raphe magnus. OBJECTIVE： To observe the characteristics of projective fibers from vestibular nuclei to nucleus raphe magnus using tetramethyl rhodamine （TMR） in rats, so as to provide more sufficient morphological evidence of neural association from vestibular nuclei. DESIGN： An observational experiment. SETTING： Department of Anatomy （K.K. Leung Brain Research Center）, the Fourth Military Medical University of Chinese PLA. MATERIALS： Eighteen male SD rats of clean degree, weighing 250-280 g, were provided by the Experimental Animal Center of the Fourth Military Medical University of Chinese PLA. METHODS： The experiments were carried out in the laboratory of Department of Anatomy （K.K. Leung Brain Research Center）, the Fourth Military Medical University of Chinese PLA from September 2006 to January 2007. All the rats were anesthetized with intraperitoneal injection of pentobarbital sodium, then according to the coordinates on the rat brain atlas, 0.1 μL TMR （100 g/L） was injected into nucleus raphes magnus via the tip of glass microtubule by means of microinjection. Seven days later, the rats were anesthetized, then perfused and fixed to remove brain, and then frozen coronal brain sections were prepared. The retrogradely labeled neurons in the injected and projected sites were observed under fluorescence microscope. Light filters with evoked wave length of 540-553 nm and emission wave length ≥ 1 580 nm were selected to observe the orange TMR-labeled neurons. All the sections were observed and counted under the fluorescence microscope. MAIN OUTCOME MEASURES： Characteristics and number of retrogradely labeled neurons at different sites of nuclei. RESULTS： Totally 18 SD rats were enrolled, 9 of them were excluded due to the deviation of injected site, and the other 9 were involved in the final analysis of results. The concentrated region of TMR injection was mainly restricted to nucleus raphes magnus, and diffused to the surrounding area to different extents. There were obvious differences in the distributions of the labeled neurons among the subdivisions in vestibular nuclei, as well as the distributions of the labeled neurons at different sites in the same subdivision. The majority of the labeled neurons distributed in the rostral levels of medial vestibular nucleus and the lateral vestibular nucleus, while fewer labeled neurons were observed in superior vestibular nucleus. CONCLUSION： ① There might be bi-directional association between vestibular nucli and nucleus raphe magnus, suggesting that nucleus raphe magnus played a role in the transmission and processing of vestibular information. ② The projection from nucleus raphe magnus to vestibular nucleus has certain distributive characteristics in the region.展开更多
Background Anatomic and electrophysiological studies have revealed that the neurons located in the media vestibular nuclei （MVN） receive most of the sensory vestibular input coming from the ipsilateral labyrinth and...Background Anatomic and electrophysiological studies have revealed that the neurons located in the media vestibular nuclei （MVN） receive most of the sensory vestibular input coming from the ipsilateral labyrinth and the responses of MVN neurons to caloric stimulation directly reflect changes in primary vestibular afferent activity. The aim of this study was to clarify the intrinsic characteristics of serotonin （5-hydroxytryptamine, 5-HT） release in the MVN during the period of vertigo induced by caloric stimulation. Methods We used an in vivo microdialysis technique to examine the effects of caloric stimulation on the serotoninergic system in MVN. Twenty four guinea pigs were randomly divided into the groups of irrigation of the ear canal with hot water （n=6）, ice water （n=6） and 37℃ water （n=4）, and the groups of irrigation of the auricle with hot water （n=-4） and ice water （n=4）, according to different caloric vestibular stimulation. We examined the animal＇s caloric nystagmus with a two-channel electronystagmographic recorder （ENG）, and meanwhile examine serotonin （5-hydroxytryptamine, 5-HT） level in the MVN with microdialysis technique after caloric stimulation. Results In the caloric test the hot water （44℃） irrigation of the right external auditory canal induced horizontal nystagmus towards the right side lasting about 60 seconds and the ice water irrigation of the right external auditory canal induced it towards the left side lasting for about 90 seconds. No nystagmus was induced by 37℃ water irrigation of the external ear canal. Therefore, it was used as a negative control stimulation to the middle ear. The MVN 5-HT levels significantly increased in the first 5-minute collecting interval and increased to 254% and 189% of the control group in the second collecting interval in response to caloric vestibular stimulation with ice water and hot water respectively. The serotonin release was not distinctly changed by the irrigation of the auricle with ice water or hot water. Conclusions Neither somato-sensory stimulation of the middle ear nor nonspecific cold or hot stress affects the serotonin release. The rise of 5-HT in MVN may be involved in the mechanism of vertigo induced by caloric stimulation.展开更多
基金supported by Basic Science Research Program through the National Research Foundation of Korea(NRF) funded by the Ministry of Education(2015R1D1A4A01020385)
文摘Many animal studies have reported on the neural connectivity of the vestibular nuclei（VN）.However,little is reported on the structural neural connectivity of the VN in the human brain.In this study,we attempted to investigate the structural neural connectivity of the VN in 37 healthy subjects using diffusion tensor tractography.A seed region of interest was placed on the isolated VN using probabilistic diffusion tensor tractography.Connectivity was defined as the incidence of connection between the VN and each brain region.The VN showed 100% connectivity with the cerebellum,thalamus,oculomotor nucleus,trochlear nucleus,abducens nucleus,and reticular formation,irrespective of thresholds.At the threshold of 5 streamlines,the VN showed connectivity with the primary motor cortex（95.9%）,primary somatosensory cortex（90.5%）,premotor cortex（87.8%）,hypothalamus（86.5%）,posterior parietal cortex（75.7%）,lateral prefrontal cortex（70.3%）,ventromedial prefrontal cortex（51.4%）,and orbitofrontal cortex（40.5%）,respectively.These results suggest that the VN showed high connectivity with the cerebellum,thalamus,oculomotor nucleus,trochlear nucleus,abducens nucleus,and reticular formation,which are the brain regions related to the functions of the VN,including equilibrium,control of eye movements,conscious perception of movement,and spatial orientation.
基金National Natural Science Foundation of China, No. 30600339
文摘BACKGROUND： Morphological studies have confirmed that vestibular nuclei accepts serotoninergic projections from nucleus raphe magnus, nucleus raphes pallidus, etc. But it is still unclear whether there is bi-directional association between vestibular nuclei and nucleus raphe magnus. OBJECTIVE： To observe the characteristics of projective fibers from vestibular nuclei to nucleus raphe magnus using tetramethyl rhodamine （TMR） in rats, so as to provide more sufficient morphological evidence of neural association from vestibular nuclei. DESIGN： An observational experiment. SETTING： Department of Anatomy （K.K. Leung Brain Research Center）, the Fourth Military Medical University of Chinese PLA. MATERIALS： Eighteen male SD rats of clean degree, weighing 250-280 g, were provided by the Experimental Animal Center of the Fourth Military Medical University of Chinese PLA. METHODS： The experiments were carried out in the laboratory of Department of Anatomy （K.K. Leung Brain Research Center）, the Fourth Military Medical University of Chinese PLA from September 2006 to January 2007. All the rats were anesthetized with intraperitoneal injection of pentobarbital sodium, then according to the coordinates on the rat brain atlas, 0.1 μL TMR （100 g/L） was injected into nucleus raphes magnus via the tip of glass microtubule by means of microinjection. Seven days later, the rats were anesthetized, then perfused and fixed to remove brain, and then frozen coronal brain sections were prepared. The retrogradely labeled neurons in the injected and projected sites were observed under fluorescence microscope. Light filters with evoked wave length of 540-553 nm and emission wave length ≥ 1 580 nm were selected to observe the orange TMR-labeled neurons. All the sections were observed and counted under the fluorescence microscope. MAIN OUTCOME MEASURES： Characteristics and number of retrogradely labeled neurons at different sites of nuclei. RESULTS： Totally 18 SD rats were enrolled, 9 of them were excluded due to the deviation of injected site, and the other 9 were involved in the final analysis of results. The concentrated region of TMR injection was mainly restricted to nucleus raphes magnus, and diffused to the surrounding area to different extents. There were obvious differences in the distributions of the labeled neurons among the subdivisions in vestibular nuclei, as well as the distributions of the labeled neurons at different sites in the same subdivision. The majority of the labeled neurons distributed in the rostral levels of medial vestibular nucleus and the lateral vestibular nucleus, while fewer labeled neurons were observed in superior vestibular nucleus. CONCLUSION： ① There might be bi-directional association between vestibular nucli and nucleus raphe magnus, suggesting that nucleus raphe magnus played a role in the transmission and processing of vestibular information. ② The projection from nucleus raphe magnus to vestibular nucleus has certain distributive characteristics in the region.
基金a grant from National Science Foundation of China(No.30500556)
文摘Background Anatomic and electrophysiological studies have revealed that the neurons located in the media vestibular nuclei （MVN） receive most of the sensory vestibular input coming from the ipsilateral labyrinth and the responses of MVN neurons to caloric stimulation directly reflect changes in primary vestibular afferent activity. The aim of this study was to clarify the intrinsic characteristics of serotonin （5-hydroxytryptamine, 5-HT） release in the MVN during the period of vertigo induced by caloric stimulation. Methods We used an in vivo microdialysis technique to examine the effects of caloric stimulation on the serotoninergic system in MVN. Twenty four guinea pigs were randomly divided into the groups of irrigation of the ear canal with hot water （n=6）, ice water （n=6） and 37℃ water （n=4）, and the groups of irrigation of the auricle with hot water （n=-4） and ice water （n=4）, according to different caloric vestibular stimulation. We examined the animal＇s caloric nystagmus with a two-channel electronystagmographic recorder （ENG）, and meanwhile examine serotonin （5-hydroxytryptamine, 5-HT） level in the MVN with microdialysis technique after caloric stimulation. Results In the caloric test the hot water （44℃） irrigation of the right external auditory canal induced horizontal nystagmus towards the right side lasting about 60 seconds and the ice water irrigation of the right external auditory canal induced it towards the left side lasting for about 90 seconds. No nystagmus was induced by 37℃ water irrigation of the external ear canal. Therefore, it was used as a negative control stimulation to the middle ear. The MVN 5-HT levels significantly increased in the first 5-minute collecting interval and increased to 254% and 189% of the control group in the second collecting interval in response to caloric vestibular stimulation with ice water and hot water respectively. The serotonin release was not distinctly changed by the irrigation of the auricle with ice water or hot water. Conclusions Neither somato-sensory stimulation of the middle ear nor nonspecific cold or hot stress affects the serotonin release. The rise of 5-HT in MVN may be involved in the mechanism of vertigo induced by caloric stimulation.
