NeuroImage
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Myelin water imaging (MWI) promises to be invaluable in understanding neurological diseases like MS. However, a limitation of MWI is signal to noise ratio. Recently, a number of investigators have performed MWI at field strengths higher than 1.5 T. ⋯ Ten formalin-fixed MS brain samples underwent a 32-echo T(2) relaxation experiment which measured myelin water fraction (MWF) on a 7-T animal MRI scanner. MWF correlated strongly qualitatively and quantitatively with luxol fast blue staining for myelin [mean (range): R(2)=0.78 (0.56-0.95), p<0.0001]. The quality and detail of 7 T myelin water maps were far superior to that previously seen at 1.5 T, allowing for visualization of fine structures such as the normal prominent myelination of the deeper cortical layers, the alveus of the hippocampus and rings of preserved myelin in a concentric Balo's lesion. 7 T imaging will allow detailed assessment of myelin pathology to a degree not possible with lower field strengths.
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Evaluation of measurement uncertainties (or errors) in diffusion tensor-derived parameters is essential to quantify the sensitivity and specificity of these quantities as potential surrogate biomarkers for pathophysiological processes with diffusion tensor imaging (DTI). Computational methods such as the Monte Carlo simulation have provided insights into characterization of the measurement uncertainty in DTI. However, due to the complexity of real brain data as well as different sources of variations during the image acquisition, a robust estimator for DTI measurement uncertainty in human brain is required. ⋯ In this study, we further optimized the DTI application of the wild bootstrap method for typical clinical applications. We evaluated the validity of wild bootstrap utilizing numerical simulations with different combinations of DTI protocol parameters and wild bootstrap experimental designs, and quantitatively compared estimates of uncertainties from wild bootstrapping with those from Monte Carlo simulations. Our results demonstrate that a wild bootstrap implementation using at least 1000 wild bootstrap iterations with a type II or type III heteroskedasticity consistent covariance matrix estimator provides robust evaluations of most DTI protocols.
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Seeing actions, emotions and feelings of other individuals may activate resonant mechanisms that allow the empathic understanding of others' states. Being crucial for implementing pro-social behaviors, empathy is considered as inherently altruistic. Here we explored whether the personal experience of pain make individuals less inclined to share others' pain. ⋯ Conversely, the N2a-P2 component, supposedly associated to affective pain qualities, did not show any specific modulation during observation of others' pain. Thus, viewing 'flesh and bone' pain in others specifically modulates neural activity in the pain matrix sensory node. Moreover, this socially-derived inhibitory effect is correlated with the intensity of the pain attributed to self rather than to others suggesting that being in pain may bias the empathic relation with stranger models towards self-centred instead than other-related stances.
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This study has shown that murine monocytes/macrophages (Mo/Ma) can be labeled simply and efficiently with large, green-fluorescent, micrometer-sized particles of iron-oxide (MPIO). Neither size nor proliferation rate of the Mo/Ma is significantly affected by this labeling. ⋯ MRI observations were confirmed by Prussian blue staining, lectin staining and fluorescence histology. Overall, the results of this study suggest that the use of Mo/Ma may be envisaged in the clinic for vectorizing therapeutic agents toward gliomas.
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Although depressive mood is an important psychological determinate of chronic pain, the neural circuitry that mediates its influence on the pain experience is largely unknown. We used functional magnetic resonance imaging (FMRI) to investigate the neurophysiological interactions between depressive symptoms and disease-relevant pain in rheumatoid arthritis (RA) patients. RA is associated with chronic joint pain and swelling, but peripheral joint pathology often does not fully explain the amount of pain a patient experiences. ⋯ The association between BDI scores and T/S was partly mediated by the MPFC activation. Furthermore, the MPFC activation co-varied significantly with the FMRI signal in limbic areas and in areas that process self-relevant information. These results suggest that the MPFC may play an important role in mediating the relationship between depressive symptoms and clinical pain severity in RA, possibly by engaging brain areas important for affective and self-relevant processing.