Human brain mapping
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Human brain mapping · Dec 2009
Entorhinal cortex structure and functional MRI response during an associative verbal memory task.
Entorhinal cortex (ERC) volume in adults with mild cognitive impairment has been shown to predict prodromal Alzheimer's disease (AD). Likewise, neuronal loss in ERC has been associated with AD, but not with normal aging. Because ERC is part of a major pathway modulating input to the hippocampus, structural changes there may result in changes to cognitive performance and functional brain activity during memory tasks. ⋯ This result was independent of hippocampal volume. Anterior cingulate cortex is directly connected to ERC, and is, along with medial frontal cortex, implicated in error detection, which is impaired in AD. Our results suggest that in healthy older adults, processes that engage frontal regions during memory retrieval are related to ERC structure.
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Human brain mapping · Dec 2009
Test-retest reliability of fMRI verbal episodic memory paradigms in healthy older adults and in persons with mild cognitive impairment.
This study investigated test-retest functional magnetic resonance imaging (fMRI) reproducibility in 10 healthy older adults and in 10 mild cognitive impairment (MCI) persons using a two-condition (encoding and retrieval) verbal episodic memory task as well as a two-condition (with and without a motor response) phonological processing task. Reproducibility measures included an overlap ratio with four different thresholds, statistical comparisons of the condition contrasts across sessions (test-retest contrasts), ANCOVAs, and intraclass correlation (ICC) on selected regions of interests (ROIs). In all four conditions and for all reproducibility measures, MCI individuals showed fMRI test-retest reproducibility indices that were comparable to those of healthy older adults. ⋯ Overall, these findings indicate that MCI individuals show fMRI test-retest reproducibility comparable to those of healthy controls and hence that MCI do not alter fMRI reproducibility. Furthermore, they indicate that monitoring treatment effects is reliable when comparing groups but reduced when comparing single individuals. These results have precise implications for the design of longitudinal studies relying on fMRI measures in older adults.
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Human brain mapping · Dec 2009
Facial expressions of pain modulate observer's long-latency responses in superior temporal sulcus.
The strength of brain responses to others' pain has been shown to depend on the intensity of the observed pain. To investigate the temporal profile of such modulation, we recorded neuromagnetic brain responses of healthy subjects to facial expressions of pain. ⋯ Furthermore, the responses to Provoked pain faces were about 40% stronger in the right than the left STS, and they decreased from the first to the second measurement session by one-fourth, whereas no similar decrease in responses was found for Chronic pain faces. Thus, the STS responses to the pain expressions were modulated by the intensity of the observed pain and by stimulus repetition; the location and latency of the responses suggest close similarities between processing of pain and other affective facial expressions.
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Human brain mapping · Dec 2009
Relation between brain lesion location and clinical outcome in patients with severe traumatic brain injury: a diffusion tensor imaging study using voxel-based approaches.
The early prediction of consciousness recovery from traumatic brain injury (TBI) is crucial to make decisions about the appropriate use of prolonged intensive care. Diffusion tensor imaging (DTI) has been proposed as a biomarker of white matter injury that could be used in a classification purpose. ⋯ Our results showed that (1) ADC is not a relevant biomarker for early 1-year outcome prognosis; (2) FA measured in inferior longitudinal fasciculus, in cerebral peduncle, in posterior limb of the internal capsule, and in posterior corpus callosum is specifically decreased in unfavorable outcome group compare to the favorable one; (3) a linear discriminant analysis using the FA measured in these four regions showed good classification performance (sensitivity = 86% and specificity = 86%). These findings confirm the relevance of the use of DTI as biomarkers for consciousness recovery after TBI and support the possible use of these biomarkers for early classification of patients.