NeuroImage
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Nowadays, several types of brain imaging device are available to provide images of the functional activity of the cerebral cortex based on hemodynamic, metabolic, or electromagnetic measurements. However, static images of brain regions activated during particular tasks do not convey the information of how these regions communicate with each other. In this study, advanced methods for the estimation of cortical connectivity from combined high-resolution electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) data are presented. ⋯ The reliability of these techniques was further demonstrated by elaboration of high-resolution EEG and fMRI signals collected during visually triggered finger movements in four healthy subjects. Connectivity patterns estimated for this task reveal an involvement of right parietal and bilateral premotor and prefrontal cortical areas. This cortical region involvement resembles that revealed in previous studies where visually triggered finger movements were analyzed with the use of separate EEG or fMRI measurements.
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To investigate whether a physiological change in the orthostatic condition is associated with a deterioration of cerebrovascular and metabolic homeostasis in patients with neurocardiovascular compromises, we examined 10 patients with unilateral carotid artery occlusive disease (CVD), 6 CVD patients with coronary artery disease (CVDC), and 10 healthy subjects scanned twice under supine and sitting conditions by positron emission tomography (PET). Repeated measures analysis of variance showed significant reductions in regional cerebral blood flow (rCBF) and cerebral oxygen metabolism (rCMRO2) and tendency of increase in oxygen extraction fraction (OEF) in the affected-side parietal cortex during assuming of upright posture in the CVDC group, and there was a significant OEF increase to maintain rCMRO2 constant during sitting in the CVD counterpart. ⋯ While rCBF remained constant with mean arterial blood pressure (MABP) in healthy subjects, an rCBF reduction was found in the affected parietal cortex in proportion to the upright posture-induced MABP decrease in the CVDC group. These results indicate that patients suffering from both cerebral and coronary artery diseases may be at greater risk of deterioration of local perfusion pressure and metabolic regulation in the hemodynamically susceptible brain region during upright posture.
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Brain single photon emission computed tomographic (SPECT) images acquired after injecting Tc-99m-HMPAO into the internal carotid artery (ICA) during an intracarotid amobarbital procedure (IAP SPECT) provide anatomical information on the blood flow distribution from the ICA. In this study, probabilistic maps of the distribution of blood supply from the ICA were developed using the IAP SPECT images. Twenty-two sets of basal and IAP SPECT were collected from an existing database. ⋯ Of the subcortical regions, the striatum was found to be most likely to derive its blood supply from ICA. In patients with cerebral occlusive disease, improvements in basal perfusion and perfusion reserve in the bypass-grafted ICA territory were well identified and were increased by 6.2% and 4.6%, respectively, on average. The probabilistic maps developed in this study illustrate the perfusion distribution and extent of vascular territory for ICA and would be useful for objective evaluations of perfusion status in cerebrovascular disease.
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Randomized Controlled Trial Multicenter Study Clinical Trial
A multicenter in vivo proton-MRS study of HIV-associated dementia and its relationship to age.
Differences in diagnostic criteria and methods have led to mixed results regarding the metabolite pattern of HIV-associated brain injury in relation to neurocognitive impairment. Therefore, a multicenter MRS consortium was formed to evaluate the neurometabolites in HIV patients with or without cognitive impairment. ⋯ The results suggest that glial activation occurs during the NAS stages of HIV infection, whereas further inflammatory activity in the basal ganglia and neuronal injury in the white matter is associated with the development of cognitive impairment. Aging may further exacerbate brain metabolites associated with inflammation in HIV patient and thereby increase the risk for cognitive impairment.
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Multicenter Study Clinical Trial
Regional patterns of brain metabolites in AIDS dementia complex.
The relationship of the cellular changes in the HIV-infected brain to the onset and progression of AIDS dementia complex (ADC) remains uncertain. We undertook an in vivo proton magnetic resonance spectroscopy (MRS) study and used factor analysis to identify specific cellular and regional brain changes that may serve as metabolic markers of ADC. ⋯ Logistic regression analysis revealed that, adjusted for age, basal ganglia and neuronal pattern scores were strongly associated with ADC but inflammatory levels were not. We conclude that by using factor analysis, we are able to combine multiple metabolites across brain regions in a biologically plausible manner and construct a predictive model of ADC adjusting for relevant factors such as age.