期刊
SCIENTIFIC REPORTS
卷 6, 期 -, 页码 -出版社
NATURE PUBLISHING GROUP
DOI: 10.1038/srep30895
关键词
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资金
- Brain Network Recovery Group through a grant from the James S. McDonnell Foundation [22002082]
- NIH grant [NIH-NINR-R01-NRO10939]
- TKF foundation grant
- Centre for Stroke Recovery of the Heart and Stroke Foundation of Ontario
- John Templeton Foundation [37775]
- National Science Foundation (NSF) [1632445]
- Division Of Behavioral and Cognitive Sci
- Direct For Social, Behav & Economic Scie [1632445] Funding Source: National Science Foundation
There is growing evidence that fluctuations in brain activity may exhibit scale-free (fractal) dynamics. Scale-free signals follow a spectral-power curve of the form P(f) proportional to f(-beta), where spectral power decreases in a power-law fashion with increasing frequency. In this study, we demonstrated that fractal scaling of BOLD fMRI signal is consistently suppressed for different sources of cognitive effort. Decreases in the Hurst exponent (H), which quantifies scale-free signal, was related to three different sources of cognitive effort/task engagement: 1) task difficulty, 2) task novelty, and 3) aging effects. These results were consistently observed across multiple datasets and task paradigms. We also demonstrated that estimates of H are robust across a range of time-window sizes. H was also compared to alternative metrics of BOLD variability (SDBOLD) and global connectivity (Gconn), with effort-related decreases in H producing similar decreases in SDBOLD and Gconn. These results indicate a potential global brain phenomenon that unites research from different fields and indicates that fractal scaling may be a highly sensitive metric for indexing cognitive effort/task engagement.
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