NeuroImage
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Comparative Study Clinical Trial
Patterns of cerebral atrophy in dementia with Lewy bodies using voxel-based morphometry.
Previous cross-sectional MRI studies based on region-of-interest analyses have shown that increased cerebral atrophy is a feature of both Dementia with Lewy bodies (DLB) and Alzheimer's disease (AD). Relative preservation of the hippocampus and temporal lobe structures in DLB compared to AD has been reported in region-of-interest-based studies. Recently, image processing techniques such as voxel-based morphometry (VBM) have been developed to provide an unbiased, visually informative, and comprehensive means of studying patterns of cerebral atrophy. ⋯ Regional gray matter volume loss was observed bilaterally in the temporal and frontal lobes and insular cortex of patients with DLB compared to control subjects. Comparison of dementia groups showed preservation of the medial temporal lobe, hippocampus, and amygdala in DLB relative to AD. Significant gray matter loss was also observed in the thalamus of AD patients compared to DLB.
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The aim of the present study was the investigation of neural correlates of music processing with fMRI. Chord sequences were presented to the participants, infrequently containing unexpected musical events. ⋯ To what extent this network might also be activated by the processing of non-linguistic information has remained unknown. The present fMRI-data reveal that the human brain employs this neuronal network also for the processing of musical information, suggesting that the cortical network known to support language processing is less domain-specific than previously believed.
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Clinical Trial
Cortical processing of noxious somatosensory stimuli in the persistent vegetative state.
The persistent vegetative state (PVS) is a devastating medical condition characterized by preserved wakefulness contrasting with absent voluntary interaction with the environment. We used positron emission tomography to assess the central processing of noxious somatosensory stimuli in the PVS. Changes in regional cerebral blood flow were measured during high-intensity electrical stimulation of the median nerve compared with rest in 15 nonsedated patients and in 15 healthy controls. ⋯ Moreover, in PVS patients, the activated primary somatosensory cortex was functionally disconnected from secondary somatosensory, bilateral posterior parietal, premotor, polysensory superior temporal, and prefrontal cortices. In conclusion, somatosensory stimulation of PVS patients, at intensities that elicited pain in controls, resulted in increased neuronal activity in primary somatosensory cortex, even if resting brain metabolism was severely impaired. However, this activation of primary cortex seems to be isolated and dissociated from higher-order associative cortices.
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Clinical Trial
The influence of nitrous oxide and remifentanil on cerebral hemodynamics in conscious human volunteers.
Remifentanil is increasingly used in the context of anesthesia, e.g., in patients presenting for MRI examinations, not only as an analgesic but also to replace nitrous oxide. Therefore, a comparative analysis of the effects of commonly used doses of remifentanil and of nitrous oxide on cerebral hemodynamics is warranted. The present study used contrast-enhanced magnetic resonance (MR) perfusion measurement to compare the effects of nitrous oxide (N(2)O/O(2) = 50%; n = 9) and remifentanil (0.1 microg/kg/min; n = 10) on regional cerebral blood flow (rCBF), regional cerebral blood volume (rCBV), and regional mean transit time (rMTT) in spontaneously breathing human volunteers. ⋯ In contrast, nitrous oxide produced a greater increase in rCBV in gray-matter regions than did remifentanil. In summary, nitrous oxide increased rCBV in all gray-matter regions more than did remifentanil. However, the increase in rCBF, especially in basal ganglia, was typically less pronounced than during infusion of remifentanil.
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Motor imagery is a state of mental rehearsal of single movements or movement patterns and has been shown to recruit motor networks overlapping with those activated during movement execution. We wished to examine whether the brain areas subserving control of sequential processes could be delineated by pure mental imagery, their activation levels reflecting the processing demands of a sequential task. We studied six right-handed volunteers (39.0 +/- 14 years) with H(2)(15)O positron emission tomography (PET) while they continuously mentally pursued with their right hand one of five sequences differing in complexity (i.e., increases in sequence length, single-finger repetitions, and reversals). ⋯ Activation decreases occurred in bilateral prefrontal and right temporo-occipital cortex. Activation increases that correlated with sequence complexity were observed only in specific areas of the activated network, notably in left PMd, right superior parietal cortex, and right cerebellar vermis (P < 0.05, corrected). In conclusion, our study, by varying the sequence structure of imagined finger movements, identified task-related activity changes in parietopremotor-cerebellar structures, reflecting their role in mediating sequence control.