Physiologic aspects of event related paradigms in magnetic resonance functional neuroimaging
作者:
Peter Fransson,
Gunnar Krüger,
Klaus-Dietmar Merboldt,
Jens Frahm,
期刊:
NeuroReport
(OVID Available online 1998)
卷期:
Volume 9,
issue 9
页码: 2001-2005
ISSN:0959-4965
年代: 1998
出版商: OVID
关键词: Brain function;Cerebral blood oxygenation;Functional activation;Human brain;Magnetic resonance imaging;Neuroimaging;Visual cortex
数据来源: OVID
摘要:
IN order to substantiate event related paradigms in magnetic resonance functional neuroimaging, we assessed the temporal and spatial characteristics of oxygenation-sensitive MRI responses to 1 s periods of visual activation in repetitive protocols. A main finding is a reduction of the functional contrast between conditions (reversing checkerboard vs. darkness) for decreasing interstimulus intervals yielding 4.5% signal change for 89 s, 4% for 9 s, 3% for 6 s, and 1% for 3 s, respectively. Although rapid repetitions of identical stimuli preclude the development of the full positive and negative MRI signal deflections, pertinent responses leave the spatial pattern of activated brain regions unaffected and result in identical maps. These findings suggest the use of interstimulus intervals of the order of the response time from stimulus onset to maximum signal strength (5–6 s in the visual system). The resulting distinction in time will allow for separate mapping of stimulus-related responses with spatially overlapping cortical representations.
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