NeuroImage
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DBS depends on precise placement of the stimulating electrode into an appropriate target region. Image-based (direct) targeting has been limited by the ability of current technology to visualize DBS targets. We have recently developed and employed a Fast Gray Matter Acquisition T1 Inversion Recovery (FGATIR) 3T MRI sequence to more reliably visualize these structures. ⋯ The FGATIR scans allowed for localization of the thalamus, striatum, GPe/GPi, RN, and SNr and displayed sharper delineation of these structures. The FGATIR also revealed features not visible on other scan types: the internal lamina of the GPi, fiber bundles from the internal capsule piercing the striatum, and the boundaries of the STN. We hope that use of the FGATIR to aid initial targeting will translate in future studies to faster and more accurate procedures with consequent improvements in clinical outcomes.
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To determine prospectively if qualitative and quantitative diffusion tensor imaging (DTI) metrics of white matter integrity are better than conventional magnetic resonance imaging (MRI) metrics for discriminating cerebellar diseases. ⋯ Qualitative and quantitative reductions in DTI metrics of white matter integrity in the cerebellar peduncles correlated better to clinical features of patients with sporadic and hereditary ataxias than conventional structural MRI measures of pontocerebellar atrophy.
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Although the blood oxygenation level-dependent (BOLD) contrast is widely used in functional MRI (fMRI), its spatial specificity is compromised by the diversity of the participating vasculature, including large draining veins. Previous studies have shown that an alternative contrast mechanism based on functional changes of the apparent diffusion coefficient (ADC) can be sensitized to small vessels more closely tied to the sites of neural activity. ⋯ Our results show that, by using optimal parameters, the functional ADC changes are significantly higher in the middle cortical layers, whereas the BOLD signal changes are higher at the cortical surface and vary much less significantly across the cortex. These results are in good agreement with previous studies performed in anesthetized cats at 9.4 T and demonstrate the improved spatial specificity of the functional ADC contrast as compared to the BOLD contrast.
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We are developing a method for real-time magnetic resonance imaging (MRI) visualization of convection-enhanced delivery (CED) of adeno-associated viral vectors (AAV) to the primate brain. By including gadolinium-loaded liposomes (GDL) with AAV, we can track the convective movement of viral particles by continuous monitoring of distribution of surrogate GDL. In order to validate this approach, we infused two AAV (AAV1-GFP and AAV2-hAADC) into three different regions of non-human primate brain (corona radiata, putamen, and thalamus). ⋯ Co-distribution was weaker with AAV2-hAADC, although in vivo PET scanning with FMT for AADC activity correlated well with immunohistochemistry of AADC. Although this is a relatively small study, it appears that AAV1 correlates better with MRI-monitored delivery than does AAV2. It seems likely that the difference in distribution may be due to differences in tissue specificity of the two serotypes.
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Pain is a sensory and emotional experience that involves numerous brain areas. Among these areas the insular cortex has been shown to be involved in the expectation and processing of pain. Alpha power modulation has been associated with the experience of pain. ⋯ The results revealed that the anterior insula alone was involved during the threat of painful stimuli. Conversely, the posterior insula - as well as other brain areas such as SII - was involved in the processing of somatosensory stimuli regardless their painfulness. Additionally, the involvement of the anterior insula should not be accounted for by fear, arousal, habituation effect or by the occurrence of randomly interleaved different stimuli, but it is likely to be related mainly to expectancy mechanisms enhancing activity of specific neuronal populations.