Anatomy of superior olivary complex and lateral lemniscus in Etruscan shrew.

Based on the auditory periphery and the small head size, Etruscan shrews (Suncus etruscus) approximate ancestral mammalian conditions. The auditory brainstem in this insectivore has not been investigated. Using labelling techniques, we assessed the structures of their superior olivary complex (SOC) and the nuclei of the lateral lemniscus (NLL). There, we identified the position of the major nuclei, their input pattern, transmitter content, expression of calcium binding proteins (CaBPs) and two voltage-gated ion channels. The most prominent SOC structures were the medial nucleus of the trapezoid body (MNTB), the lateral nucleus of the trapezoid body (LNTB), the lateral superior olive (LSO) and the superior paraolivary nucleus (SPN). In the NLL, the ventral (VNLL), a specific ventrolateral VNLL (VNLLvl) cell population, the intermediate (INLL) and dorsal (DNLL) nucleus, as well as the inferior colliculus's central aspect were discerned. INLL and VNLL were clearly separated by the differential distribution of various marker proteins. Most labelled proteins showed expression patterns comparable to rodents. However, SPN neurons were glycinergic and not GABAergic and the overall CaBPs expression was low. Next to the characterisation of the Etruscan shrew's auditory brainstem, our work identifies conserved nuclei and indicates variable structures in a species that approximates ancestral conditions.

Surface electrical stimulation of the auditory cortex preserves efferent medial olivocochlear neurons and reduces cochlear traits of age-related hearing loss.

The auditory cortex is the source of descending connections providing contextual feedback for auditory signal processing at almost all levels of the lemniscal auditory pathway. Such feedback is essential for cognitive processing. It is likely that corticofugal pathways are degraded with aging, becoming important players in age-related hearing loss and, by extension, in cognitive decline. We are testing the hypothesis that surface, epidural stimulation of the auditory cortex during aging may regulate the activity of corticofugal pathways, resulting in modulation of central and peripheral traits of auditory aging. Increased auditory thresholds during ongoing age-related hearing loss in the rat are attenuated after two weeks of epidural stimulation with direct current applied to the surface of the auditory cortex for two weeks in alternate days (Fernández del Campo et al., 2024). Here we report that the same cortical electrical stimulation protocol induces structural and cytochemical changes in the aging cochlea and auditory brainstem, which may underlie recovery of age-degraded auditory sensitivity. Specifically, we found that in 18 month-old rats after two weeks of cortical electrical stimulation there is, relative to age-matched non-stimulated rats: a) a larger number of choline acetyltransferase immunoreactive neuronal cell body profiles in the ventral nucleus of the trapezoid body, originating the medial olivocochlear system.; b) a reduction of age-related dystrophic changes in the stria vascularis; c) diminished immunoreactivity for the pro-inflammatory cytokine TNFα in the stria vascularis and spiral ligament. d) diminished immunoreactivity for Iba1 and changes in the morphology of Iba1 immunoreactive cells in the lateral wall, suggesting reduced activation of macrophage/microglia; d) Increased immunoreactivity levels for calretinin in spiral ganglion neurons, suggesting excitability modulation by corticofugal stimulation. Altogether, these findings support that non-invasive neuromodulation of the auditory cortex during aging preserves the cochlear efferent system and ameliorates cochlear aging traits, including stria vascularis dystrophy, dysregulated inflammation and altered excitability in primary auditory neurons.

Último minuto en atrofia multisistémica / Latest update on multiple system atrophy

Introducción. La Atrofia Multisistémica (AMS) es un trastorno neurodegenerativo, rápidamente progresivo, esporádico, que se presenta con una combinación de síntomas disautonómicos, parkinsonianos, cerebelosos, y corticospinales. La etiopatogenia es desconocida, pero parece existir un papel genético subyacente que implica a la α-sinucleína. El diagnóstico temprano de la enfermedad ha mejorado con los nuevos criterios clínicos de 2008, apoyados por técnicas de neuroimagen estructural y funcional. El tratamiento sigue siendo sintomático, pero se han publicado recientes ensayos clínicos con opciones terapéuticas que intentan frenar la progresión natural de la enfermedad. Objetivo. Revisar los avances más notorios publicados en la literatura científica en los últimos 5 años en la AMS. Desarrollo. Se ha revisado la literatura de los últimos años y se presentan los avances más significativos en la patogenia, diagnóstico, y tratamiento de la AMS, así como las principales perspectivas futuras en dichos campos. Conclusiones. La patogenia de la AMS sigue siendo desconocida, aunque las variaciones en el locus SNCA del cromosoma 4q22.1 que codifica la α-sinucleína juegan un papel destacado. Los nuevos criterios diagnósticos han permitido mejorar la precisión diagnóstica en los estadios iniciales de la enfermedad. Existen diversos ensayos clínicos con prometedoras terapias modificadoras de la enfermedad, aunque son necesarios más estudios futuros para determinar el verdadero alcance clínico de las mismas (AU)

Introduction. Multiple System Atrophy (MSA) is a neurodegenerative, quickly progressive, sporadic disorder that presents with a combination of dysautonomic, parkinsonian, cerebellar and corticospinal symptoms. The aetiopathogenesis is unknown, but there seems to be an underlying genetic role involving a-synuclein. Early diagnosis of the disease has improved with the new clinical criteria of 2008, backed by structural and functional neuroimaging techniques. Treatment continues to be symptomatic, but recent clinical trails have been conducted with therapeutic options that attempt to curb the natural progression of the disease. www.neurologia.com Rev Neurol 2012; 54 (Supl 4): S45-S51 S51 PONENCIA Aims. The purpose of this study is to review the most significant advances in MSA reported in the scientific literature in the last 5 years. Development. The literature from the last few years was reviewed and we report on the most significant advances in the pathogenesis, diagnosis and treatment of MSA, as well as the main future perspectives in those fields. Conclusions. The pathogenesis of MSA remains unknown, although variations in the SNCA locus of chromosome 4q22.1, which codes for a synuclein, play an important role. The new diagnostic criteria have allowed diagnosis to become more accurate in the early stages of the disease. Several clinical trials have been carried out with promising disease-modifying therapies, although further studies will be needed in the future to determine their true clinical scope (AU)

Transient otoacoustic emissions in infants of diabetic mothers

Tema: lactentes de mães diabéticas necessitam de cuidados especiais. Objetivo: verificar se a alteração metabólica durante a gestação pode alterar função coclear e sistema eferente olivococlear. Método: foram avaliadas emissões otoacústicas transitórias de 30 crianças de mães diabéticas, comparando-os com o grupo controle, de acordo com a ocorrência e amplitude das respostas. Resultado: as crianças de mães diabéticas apresentaram atividade contrátil das células ciliadas externas com amplitude menor de resposta. Conclusão: os resultados não mostraram diferença significante estatisticamente. Estudos com amostras maiores são necessários.