1,721,281 research outputs found
A little man of some importance
Full text link: Eighty years ago, Penfield and Boldrey introduced the homunculus in a paper published in Brain. In a reappraisal of the iconic aide-mémoire, Marco Catani reanalyses the original data, and argues that through its extended network the homunculus holds the key to the precise coding that results in coordinated activation of peripheral muscles
Altered white matter connectivity as a neural substrate for social impairment in Autism Spectrum Disorder
No full textBackground: Autism Spectrum Disorder (ASD) symptoms have been hypothesized to result from altered brain connectivity. The 'disconnectivity' hypothesis has been used to explain characteristic impairments in socio-emotional function, observed clinically in ASD. Here, we review the evidence for impaired white matter connectivity as a neural substrate for socio-emotional dysfunction in ASD. A review of diffusion tensor imaging (DTI) studies, and focused discussion of relevant post-mortem, structural, and functional neuroimaging studies, is provided. Methods: Studies were identified using a sensitive search strategy in MEDLINE, Embase and PsycINFO article databases using the OvidSP database interface. Search terms included database subject headings for the concepts of pervasive developmental disorders, and DTI. Seventy-two published DTI studies examining white matter microstructure in ASD were reviewed. A comprehensive discussion of DTI studies that examined white matter tracts linking socio-emotional structures is presented. Results: Several DTI studies reported microstructural differences indicative of developmental alterations in white matter organization, and potentially myelination, in ASD. Altered structure within long-range white matter tracts linking socio-emotional processing regions was implicated. While alterations of the uncinate fasciculus and frontal and temporal thalamic projections have been associated with social symptoms in ASD, few studies examined association of tract microstructure with core impairment in this disorder. Conclusions: The uncinate fasciculus and frontal and temporal thalamic projections mediate limbic connectivity and integrate structures responsible for complex socio-emotional functioning. Impaired development of limbic connectivity may represent one neural substrate contributing to ASD social impairments. Future efforts to further elucidate the nature of atypical white matter development, and its relationship to core symptoms, may offer new insights into etiological mechanisms contributing to ASD impairments and uncover novel opportunities for targeted intervention
Comment on "The geometric structure of the brain fiber pathways"
No full textWedeen et al. (Reports, 30 March 2012, p. 1628) proposed a geometrical grid pattern in the brain that could help the understanding of the brain's organization and connectivity. We show that whole-brain fiber crossing quantification does not support their theory. Our results suggest that the grid pattern is most likely an artifact attributable to the limitations of their method
Grey Matter Leonardo da Vinci: A genius driven to distraction
Full text linkFive hundred years have passed since the death of Leonardo da Vinci, and much has been written about him. Leonardo the artist, the scientist, the architect, the inventor, whose genius has been perceived as the allure of an unfathomable riddle. But some of the words written about Leonardo after he died at Clos-Lucé in France on 2 May 1519, hint at a very different man to the one many of us presume to know. According to his first biographer Giorgio Vasari, Leonardo died lamenting ‘that he had offended God and mankind in not having worked at his art as he should have done’ (Vasari, 1996; Nicholl, 2004; Vecce, 2006)
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