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Journal Articles NeuroImage Year : 2014

Interplay between functional connectivity and scale-free dynamics in intrinsic fMRI networks

Abstract

Studies employing functional connectivity-type analyses have established that sponta-neous fluctuations in functional magnetic resonance imaging (fMRI) signals are orga-nized within large-scale brain networks. Meanwhile, fMRI signals have been shown to exhibit 1/f-type power spectra – a hallmark of scale-free dynamics. We studied the interplay between functional connectivity and scale-free dynamics in fMRI signals, utilizing the fractal connectivity framework – a multivariate extension of the univari-ate fractional Gaussian noise model, which relies on a wavelet formulation for robust parameter estimation. We applied this framework to fMRI data acquired from healthy young adults at rest and performing a visual detection task. First, we found that scale-invariance existed beyond univariate dynamics, being present also in bivariate cross-temporal dynamics. Second, we observed that frequencies within the scale-free range do not contribute evenly to inter-regional connectivity, with a systematically stronger contribution of the lowest frequencies, both at rest and during task. Third, in addition to a decrease of the Hurst exponent and inter-regional correlations, task performance modified cross-temporal dynamics, inducing a larger contribution of the highest fre-quencies within the scale-free range to global correlation. Lastly, we found that across individuals, a weaker task modulation of the frequency contribution to inter-regional Rev.#1, Q5
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hal-01084242 , version 1 (18-11-2014)

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Philippe Ciuciu, Patrice Abry, Biyu Jade He. Interplay between functional connectivity and scale-free dynamics in intrinsic fMRI networks. NeuroImage, 2014, 95, pp.248 - 263. ⟨10.1016/j.neuroimage.2014.03.047⟩. ⟨hal-01084242⟩
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