Nasal Chemosensory-Stimulation Evoked Activity Patterns in the Rat Trigeminal Ganglion Visualized by In Vivo Voltage-Sensitive Dye Imaging

Mammalian nasal chemosensation is predominantly mediated by two independent neuronal pathways, the olfactory and the trigeminal system. Within the early olfactory system, spatiotemporal responses of the olfactory bulb to various odorants have been mapped in great detail. In contrast, far less is known about the representation of volatile chemical stimuli at an early stage in the trigeminal system, the trigeminal ganglion (TG), which contains neurons directly projecting to the nasal cavity. We have established an in vivo preparation that allows high-resolution imaging of neuronal population activity from a large region of the rat TG using voltage-sensitive dyes (VSDs). Application of different chemical stimuli to the nasal cavity elicited distinct, stimulus-category specific, spatiotemporal activation patterns that comprised activated as well as suppressed areas. Thus, our results provide the first direct insights into the spatial representation of nasal chemosensory information within the trigeminal ganglion imaged at high temporal resolution

Estudo comparativo dos mecanorreceptores dos discos intervertebrais normais e degenerados da coluna lombar de humanos pela radiografia, ressonância magnética e estudo anatomopatológico Comparative study of normal and degenerated intervertebral discs' mechanoreceptors of human lumar spine X-ray, magnetic resonance and anatomopathologic study

Os autores fizeram um estudo da coluna lombar de humanos, objetivando avaliar e determinar os diferentes tipos de fibras nervosas no disco intervertebral normal e no degenerado. Foram usadas dez colunas lombares de cadáveres com aproximadamente 48 a 72 horas de óbito. As peças foram submetidas a exames de radiografia simples e ressonância magnética. Após os exames, os discos foram classificados em normais e degenerados. Em seguida, foram dissecados, divididos em regiões anterior e posterior, incluídos em parafina e realizado estudo de imuno-histoquímica com a proteína S100. Com o auxílio de um programa de computador Image-Pro Plus (media cybernetics®), as fibras nervosas tiveram seu diâmetro medidos em micrômetros e classificadas em quatro tipos de fibras. Foram encontrados quatro tipos de fibras nervosas nas diferentes regiões discais. O número e o tipo de fibras variaram de acordo com a região e grau de degeneração do disco intervertebral. Concluíram que as fibras do tipo III são mais freqüentes na região anterior; as fibras dos tipos II e IV são mais freqüentes na região posterior, e as fibras do tipo I não apresentaram diferenças entre a região anterior e a posterior; além disso, o disco degenerado tem mais fibras nervosas que o disco normal.<br>The authors conducted a study on human lumbar spine, aiming to assess and determine the different kinds of nervous fibers in normal and degenerated intervertebral discs. Ten cadaver’s lumbar spines with approximately 48 - 72 of death have been used. The pieces were submitted to simple X-ray and magnetic resonance tests. Subsequently to the tests, discs were divided into normal and degenerated. Then, they were dissected, divided into anterior and posterior according to the region, included in paraffin and an immunohistochemical study with S100 protein was performed. With the aid of Image-Pro Plus computer software (media cybernetics) ®, nervous fibers’ diameters were measured as micrometers and classified into four kinds of fibers. Four types of nervous fibers were found on different disc regions. The number and kind of fibers varied according to the region and degree of intervertebral disc degeneration. It was concluded that type-III fibers are more common at the anterior region; type-II and type-IV fibers are more common at the posterior region, and type-I fibers do not show any differences regarding anterior and posterior regions; in addition, a degenerated disc has a higher number of nervous fibers than a normal one