Contribuição das neurociências para a compreensão das doenças do espetro do autismo

Trabalho Final do Curso de Mestrado Integrado em Medicina, Faculdade de Medicina, Universidade de Lisboa, 2019As doenças do espetro do autismo (DEA) caracterizam-se por alterações na comunicação social e nos comportamentos sensorio-motores, que se instalam precocemente na vida e estão associados a uma etiologia multifatorial e heterogénea. Até aos dias de hoje são muitos os estudos que se dedicaram ao estudo e compreensão das DEA em termos genéticos e das neurociências, o que permitiu a descoberta de fatores ambientais e genéticos intimamente relacionados com esta perturbação; conduziu às várias alterações dos critérios de diagnóstico e permitiu aumentar a eficácia dos rastreio e reconhecimento desta perturbação. O objetivo deste trabalho foi uma revisão e síntese atualizada dos principais contributos das neurociências para a compreensão destas perturbações. A metodologia usada foi a de uma revisão não sistemática da literatura relevante da última década, através de uma pesquisa na PubMed com as seguintes palavras-chave “Autism Spectrum Disorders”, “Neuroimaging”, “Default Mode Network”, “Neurobiology”. Desde o aparecimento da ressonância magnética foi possível um maior esclarecimento relativo à neurobiologia do autismo. Estudos iniciais verificaram um crescimento cerebral precoce exacerbado, bem como anomalias na matéria cinzenta e branca corticais em indivíduos com autismo. A imagem por tensor de difusão elucidou a integridade estrutural e orientação da matéria branca, e as técnicas de RM funcional aumentaram a compreensão dos circuitos neuronais das DEA, evidenciando áreas de ativação cortical disfuncional e alterações da conectividade. Recentemente, foram ainda identificadas alterações na default mode network, uma rede particularmente associada a atividade mental de autorreferenciação e função cognitiva social. Verifica-se que indivíduos com autismo apresentam uma alteração da organização estrutural e funcional da DMN, disfunções nos seus key nodes e nas suas interações que conduzem a uma integração deficitária da informação e défices na resposta a certos estímulos. Com este trabalho procura-se contribuir para uma maior integração entre as neurociências e a clínica na compreensão das doenças do espectro do autismo, o que poderá ter um impacto importante no diagnóstico precoce e intervenção terapêutica.Autism Spectrum Disorders (ASD) are characterized by social communication deficits and sensory-motor behaviours, that settle early in the lifetime and are associated with a multifactorial and heterogenous aetiology. Until nowadays, there are many studies dedicated to understanding ASD genetics and neuroscience, which allowed the discovery of environmental and genetic factors closely related to the disorder, led to changes in diagnostic criteria and enabled an enhancement in screening and acknowledgment efficacy of the disease. The aim of this work was an updated review and synthesis of the main neurosciences’ contributions to the understanding of this disease. Methodology included a non-systematic review of the relevant literature from the last decade, in PubMed, using as keywords “Autism Spectrum Disorders”, “Neuroimaging”, “Default Mode Network”, “Neurobiology”. Since the advent of magnetic resonance imaging (MRI), the neurobiology of autism has become increasingly understood. Initial studies observed an early rapid brain overgrowth, as well as abnormalities in cortical gray and white matter in affected individuals. Diffusion tension imaging (DTI) clarified white matter structural integrity and orientation, and functional MRI led to enhanced understanding of neural circuits of ADS, demonstrating areas of cortical activation and connectivity deficits. Recently, abnormalities in default mode network (DMN) were identified, a network particularly associated to self-referential processing and social cognitive function. Literature suggests that ASD individuals present DMN structural and functional organization deficits, aberrancies in key node of DMN and their interactions that lead to abnormalities in integration of information and impairments in attend to certain stimuli. With this work we intend to contribute to a bigger integration between neurosciences and clinical manifestations on ASD comprehension, which might have a relevant impact in early diagnosis and interventions

Characterisation of microbial attack on archaeological bone

As part of an EU funded project to investigate the factors influencing bone preservation in the archaeological record, more than 250 bones from 41 archaeological sites in five countries spanning four climatic regions were studied for diagenetic alteration. Sites were selected to cover a range of environmental conditions and archaeological contexts. Microscopic and physical (mercury intrusion porosimetry) analyses of these bones revealed that the majority (68%) had suffered microbial attack. Furthermore, significant differences were found between animal and human bone in both the state of preservation and the type of microbial attack present. These differences in preservation might result from differences in early taphonomy of the bones. © 2003 Elsevier Science Ltd. All rights reserved

NEOTROPICAL XENARTHRANS: a data set of occurrence of xenarthran species in the Neotropics

Xenarthrans—anteaters, sloths, and armadillos—have essential functions for ecosystem maintenance, such as insect control and nutrient cycling, playing key roles as ecosystem engineers. Because of habitat loss and fragmentation, hunting pressure, and conflicts with domestic dogs, these species have been threatened locally, regionally, or even across their full distribution ranges. The Neotropics harbor 21 species of armadillos, 10 anteaters, and 6 sloths. Our data set includes the families Chlamyphoridae (13), Dasypodidae (7), Myrmecophagidae (3), Bradypodidae (4), and Megalonychidae (2). We have no occurrence data on Dasypus pilosus (Dasypodidae). Regarding Cyclopedidae, until recently, only one species was recognized, but new genetic studies have revealed that the group is represented by seven species. In this data paper, we compiled a total of 42,528 records of 31 species, represented by occurrence and quantitative data, totaling 24,847 unique georeferenced records. The geographic range is from the southern United States, Mexico, and Caribbean countries at the northern portion of the Neotropics, to the austral distribution in Argentina, Paraguay, Chile, and Uruguay. Regarding anteaters, Myrmecophaga tridactyla has the most records (n = 5,941), and Cyclopes sp. have the fewest (n = 240). The armadillo species with the most data is Dasypus novemcinctus (n = 11,588), and the fewest data are recorded for Calyptophractus retusus (n = 33). With regard to sloth species, Bradypus variegatus has the most records (n = 962), and Bradypus pygmaeus has the fewest (n = 12). Our main objective with Neotropical Xenarthrans is to make occurrence and quantitative data available to facilitate more ecological research, particularly if we integrate the xenarthran data with other data sets of Neotropical Series that will become available very soon (i.e., Neotropical Carnivores, Neotropical Invasive Mammals, and Neotropical Hunters and Dogs). Therefore, studies on trophic cascades, hunting pressure, habitat loss, fragmentation effects, species invasion, and climate change effects will be possible with the Neotropical Xenarthrans data set. Please cite this data paper when using its data in publications. We also request that researchers and teachers inform us of how they are using these data