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Ciências e Tecnologia / Sciences and Technology

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Browsing Ciências e Tecnologia / Sciences and Technology by Field of Science and Technology (FOS) "Engenharia e Tecnologia::Engenharia Médica"

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  • Direct crosstalk between adult human retinas as suggested by interocular transfer of neurovascular coupling through photic stimulation
    Publication . Jordão, João; Figueira, João; Morgado, António Miguel; Guimarães, Pedro; Serranho, Pedro; Castro-Farías, Daniela; DeBuc, Delia Cabrera; Castelo-Branco, Miguel; Paques, Michel; Bernardes, Rui
    Crosstalk mechanisms between retinas were never documented in humans despite being documented for several other species, including non-human primates. Results of the first-in-human study that documents the crosstalk between retinas by measuring the vascular response in one retina to the photic stimulation of the contralateral eye in health and disease are reported herein. A stimulation apparatus was developed and integrated into an adaptive-optics fundus camera to image 32 healthy control (HC) subjects and 20 type 1 diabetes mellitus (DM) patients. Ipsilateral and contralateral neurovascular coupling effects were documented, and criteria were established to consider an actual response and find positive and negative responses. Ten (31.2%) and two (6.2%) subjects of the HC group presented contralateral positive and negative responses, respectively, and three (15.0%) positive and four (20.0%) negative responses were found for the DM group. Also, statistically significant differences in the ipsilateral (p < 0.001) and contralateral (p = 0.027) responses were found for the HC group, rejecting the null (non-response) hypothesis. This finding raises the need to revisit the current knowledge of neurovascular coupling mechanisms and the association between its dysregulation and neurological disorders. Further studies involving distinct populations and imaging centers are necessary to validate the findings herein.
    2025-04-21Journal article Open access Show more
  • Texture for neuroimaging
    Publication . Nunes, Ana; Serranho, Pedro; Castelo-Branco, Miguel; Bernardes, Rui
    Texture analysis is an umbrella term for multiple image analysis techniques that quantify and characterize the distribution of the image’s gray levels. It has a natural application in biomedical image analysis, where texture-based techniques are increasingly being incorporated into neuroimaging research. In this chapter, the role of texture analysis in the field of neuroimaging is addressed. Neuroimaging applications of texture-based approaches are contextualized within past and recent developments in image texture analysis, the categories of texture analysis methods, and the typical texture-based problem types, namely, classification and segmentation. Neuroimaging applications using magnetic resonance imaging, positron emission tomography, and optical coherence tomography are individually reviewed, and some considerations on the future perspectives for texture-based approaches in neuroimaging are made.
    2024-06-13Book part Restricted access Show more