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International audience; Intercellular communication is essential for tissue homeostasis and function. Understanding how cells interact with each other is paramount, as crosstalk between cells is often dysregulated in diseases and can contribute to their progression. Cells communicate with each other through several modalities, including paracrine secretion and specialized structures ensuring physical contact between them. Among these intercellular specialized structures, tunneling nanotubes (TNTs) are now recognized as a means of cell-to-cell communication through the exchange of cellular cargo, controlled by a variety of biological triggers, as described here. Intercellular communication is fundamental to brain function. It allows the dialogue between the many cells, including neurons, astrocytes, oligodendrocytes, glial cells, microglia, necessary for the proper development and function of the brain. We highlight here the role of TNTs in connecting these cells, for the physiological functioning of the brain and in pathologies such as stroke, neurodegenerative diseases, and gliomas. Understanding these processes could pave the way for future therapies.

Nos ?ltimos dois s?culos, ocorreram importantes mudan?as demogr?ficas acompanhadas por um crescimento da expectativa m?dia de vida, aumentando a popula??o com mais de 60 anos. Como consequ?ncia desse processo, houve o aumento na incid?ncia das doen?as associadas ao envelhecimento, conhecidas como doen?as neurodegenerativas, que podem afetar partes cerebrais relacionadas ao sistema olfat?rio, levando a uma perda prevalente da percep??o do olfato. A avalia??o da capacidade olfativa pode ser realizada de diversas formas, atrav?s de m?todos espec?ficos, com o aux?lio de t?cnicas de neuroimagem ou de testes cl?nicos. H? dois tipos de testes cl?nicos, os eletrofisiol?gicos, baseados em potenciais olfativos detectados no c?rebro, e os psicof?sicos, que avaliam a capacidade olfativa, ou seja, o limiar olfativo, a discrimina??o e a identifica??o de odores. Estes ?ltimos, por?m, s?o feitos de forma manual, o que torna o procedimento sujeito ? perda de informa??es e contamina??o ambiental. Em conjunto com esses m?todos de avalia??o, existem ainda sistemas/equipamentos (olfat?metros) que auxiliam na avalia??o olfativa, fornecendo o est?mulo olfativo. Este trabalho prop?e o desenvolvimento de um sistema de entrega controlada de est?mulo olfativo, chamado olfat?metro. O sistema desenvolvido ? avaliado de acordo com tr?s par?metros, s?o eles: fluxo de ar adequado para uma suficiente exposi??o ao est?mulo olfativo, reprodutibilida deste est?mulo e resposta temporal do sistema. Os par?metros fluxo de ar e reprodutibilidade do est?mulo olfativo s?o analisados atrav?s de processamento digital de imagens, substituindo a subst?ncia odor?fera por uma subst?ncia corante e borrifando-a em um papel branco, gerando amostras que s?o digitalizadas. A resposta temporal do sistema ? medida atrav?s de um sensor de oxig?nio. Por fim, ? proposta uma interface que al?m de controlar o olfat?metro, reproduz o teste olfativo Sniffin? Sticks, possibilitando ao m?dico a realiza??o da avalia??o olfativa atrav?s de um computador. Assim sendo, a contribui??o da presente disserta??o reside no desenvolvimento de um m?todo e um sistema eletr?nico que visam aumentar o grau de automa??o do procedimento de entrega controlada de est?mulo olfativo e com isto, aumentar a confiabilidade dos resultados e a capacidade de repetibilidade do processo. Over the past two centuries, significant demographic changes have occurred accompanied by a rise in average life expectancy, increasing the population over 60 years. As a consequence of this process, there has been an increase in the incidence of aging-related diseases (neurodegenerative diseases), which can affect olfactoryrelated brain parts, leading to a prevalent loss of smell perception in these diseases. The assessment of olfactory capacity is performed in several ways, can be by specific methods, with the aid of neuroimaging techniques or through clinical tests. There are two types of clinical tests, electrophysiological, based on olfactory potentials detected in the brain, which gives this method a high cost of execution and day-to-day unfeasibility, and psychophysicists, which assess olfactory capacity, that is, the olfactory threshold, the discrimination and the identification of odors. However, these methods are carried out manually, which makes the procedure subject to information loss and environmental contamination. In conjunction with these evaluation methods, there are also systems/equipment (olfactometers) that assist in the olfactory evaluation, providing the olfactory stimulus. Given this scenario, this work proposes the development of a controlled delivery system of olfactory stimulus, called olfactometer. The developed system is evaluated according to three parameters, they are: adequate air flow for sufficient exposure to the olfactory stimulus, reproducible from this stimulus and the system?s temporal response. The parameters of air flow and reproducibility of the olfactory stimulus are analyzed through the processing of digital images, replacing an odorous substance with a coloring substance and spraying it on a white paper, generating the samples that are digitized. The system?s temporal response is measured using an oxygen sensor. To this end, an interface is proposed that, in addition to controlling the olfactometer, still reproducing the test Sniffin? Sticks, allows the doctor to carry out an evaluation of the olfactory evaluation through a computer. Therefore, a contribution of the present dissertation does not lie in the development of a method and an electronic system that aim to increase or decrease the degree of automation of the delivery procedure controlled by olfactory stimulus and, with that, increase the results indexes and the repeatability capacity. of the process.

OBJECTIVE In an attempt to interpret neglect as a disconnection syndrome, it is currently proposed that the disorder results from disorganization of large-scale networks involved in attentional spatial processes rather than of individual brain areas. We hypothesize that as degenerative brain diseases are "system pathologies," degeneration could be restricted to some of the neural subsystems implicated in the functional organization of spatial attention and different neglect syndromes could emerge depending on the patterns of the subsystems involved. METHOD We studied five neglect patients: one with corticobasal degeneration (CBD), three with Posterior Cortical Atrophy (PCA) and one with frontotemporal dementia (FTD). RESULTS The patient with CBD and left parietoccipital atrophy showed right allocentric neglect; the three patients with PCA mostly distributed in the right posterior regions showed left egocentric extrapersonal neglect; the patient with FTD, who displayed more severe frontotemporal atrophy on the right, had left motor-executive neglect for both personal and extrapersonal space. All patients also presented a deep breakdown of spatial working memory. CONCLUSION Our data would confirm that left neglect is more frequent than right neglect also in degenerative pathology and that damage to different neural substrates can produce different types of neglect. Our findings are also consistent with the hypothesis that both lateralized and nonlateralized attention disorders contribute to generate the syndrome. We suggest that evidence from degenerative diseases may contribute to construction of models of spatial attention.

It is well known that neurodegenerative diseases may affect different areas of the brain, thereby giving rise to different patterns of cognitive deficits. We investigated reading performance in patients suffering from Alzheimer’s Disease (AD, n=19), Primary Progressive Aphasia (PPA, n=6: 4 logopenic, 1 semantic and 1 purely anomic aphasia) and Posterior Cortical Atrophy (PCA, n=4), plus a control group of healthy subjects (n=20). Participants were examined by means of tasks of auditory and visual lexical decision, word and non-word reading, reading trisyllabic words with unpredictable stress position (Toraldo et al, 2006) and word and non-word repetition. The lexical decision tasks proved relevant to differentiate AD and PCA patients, the former being disproportionately impaired in the auditory task while the opposite pattern emerged in the latter. Non-word reading was more impaired with respect to word reading in both AD and PPA patients. A multiple single case analysis of reading tasks identified phonological dyslexia in two out of four PCA participants (50%), much less so in AD (15.8%) and PPA (16.7%). Surface dyslexia occurred in one AD case only. We suggest that these results may be related to the different distribution of pathological changes in the three groups.