Scale-free dynamics of global functional connectivity in the human brain Export

@article{citeulike:258781, abstract = {Higher brain functions depend upon the rapid creation and dissolution of ever changing synchronous cell assemblies. We examine the hypothesis that the dynamics of this process displays scale-free, self-similar properties. EEGs (19 channels, average reference, sample frequency 500 Hz) of 15 healthy subjects (10 men; mean age 22.5 years) were analyzed during eyes-closed and eyes-open no-task conditions. Mean level of synchronization as a function of time was estimated with the synchronization likelihood for five frequency bands (0.5-4, 4-8, 8-13, 13-30, and 30-48 Hz). Scaling in these time series was investigated with detrended fluctuation analysis (DFA). DFA analysis of global synchronization time series showed scale-free characteristics, suggesting neuronal dynamics do not necessarily have a characteristic time constant. The scaling exponent as determined with DFA differed significantly for different frequency bands and conditions. The exponent was close to 1.5 for low frequencies (<IMG SRC="/giflibrary/12/delta.gif" BORDER="0">, <IMG SRC="/giflibrary/12/thetas.gif" BORDER="0">, and <IMG SRC="/giflibrary/12/alpha.gif" BORDER="0">) and close to 1 for <IMG SRC="/giflibrary/12/beta.gif" BORDER="0" ALIGN="ABSBOTTOM"> and <IMG SRC="/giflibrary/12/gamma.gif" BORDER="0"> bands. Eye opening decreased the exponent, in particular in <IMG SRC="/giflibrary/12/alpha.gif" BORDER="0"> and <IMG SRC="/giflibrary/12/beta.gif" BORDER="0" ALIGN="ABSBOTTOM"> bands. Fluctuations of EEG synchronization in <IMG SRC="/giflibrary/12/delta.gif" BORDER="0">, <IMG SRC="/giflibrary/12/thetas.gif" BORDER="0">, <IMG SRC="/giflibrary/12/alpha.gif" BORDER="0">, <IMG SRC="/giflibrary/12/beta.gif" BORDER="0" ALIGN="ABSBOTTOM">, and <IMG SRC="/giflibrary/12/gamma.gif" BORDER="0"> bands exhibit scale-free dynamics in eyes-closed as well as eyes-open no-task states. The decrease in the scaling exponent following eye opening reflects a relative preponderance of rapid fluctuations with respect to slow changes in the mean synchronization level. The existence of scaling suggests that the underlying dynamics may display self-organized criticality, possibly representing a near-optimal state for information processing. Hum. Brain Mapping 22:99-111, 2004. \&copy; 2004 Wiley-Liss, Inc.}, author = {Stam, Cornelis J. and de Bruin, Eveline A.}, citeulike-article-id = {258781}, citeulike-linkout-0 = {http://dx.doi.org/10.1002/hbm.20016}, citeulike-linkout-1 = {http://view.ncbi.nlm.nih.gov/pubmed/15108297}, citeulike-linkout-2 = {http://www.hubmed.org/display.cgi?uids=15108297}, citeulike-linkout-3 = {http://www3.interscience.wiley.com/cgi-bin/abstract/107632603/ABSTRACT}, day = {5}, doi = {10.1002/hbm.20016}, issn = {1097-0193}, journal = {Human Brain Mapping}, keywords = {fmri, functional\_connectivity, network}, month = {March}, number = {2}, pages = {97--109}, posted-at = {2005-07-28 02:35:01}, priority = {4}, title = {Scale-free dynamics of global functional connectivity in the human brain}, url = {http://dx.doi.org/10.1002/hbm.20016}, volume = {22}, year = {2004} }

TY - JOUR ID - citeulike:258781 L3 - citeulike-article-id:258781 N2 - Higher brain functions depend upon the rapid creation and dissolution of ever changing synchronous cell assemblies. We examine the hypothesis that the dynamics of this process displays scale-free, self-similar properties. EEGs (19 channels, average reference, sample frequency 500 Hz) of 15 healthy subjects (10 men; mean age 22.5 years) were analyzed during eyes-closed and eyes-open no-task conditions. Mean level of synchronization as a function of time was estimated with the synchronization likelihood for five frequency bands (0.5-4, 4-8, 8-13, 13-30, and 30-48 Hz). Scaling in these time series was investigated with detrended fluctuation analysis (DFA). DFA analysis of global synchronization time series showed scale-free characteristics, suggesting neuronal dynamics do not necessarily have a characteristic time constant. The scaling exponent as determined with DFA differed significantly for different frequency bands and conditions. The exponent was close to 1.5 for low frequencies (<IMG SRC="/giflibrary/12/delta.gif" BORDER="0">, <IMG SRC="/giflibrary/12/thetas.gif" BORDER="0">, and <IMG SRC="/giflibrary/12/alpha.gif" BORDER="0">) and close to 1 for <IMG SRC="/giflibrary/12/beta.gif" BORDER="0" ALIGN="ABSBOTTOM"> and <IMG SRC="/giflibrary/12/gamma.gif" BORDER="0"> bands. Eye opening decreased the exponent, in particular in <IMG SRC="/giflibrary/12/alpha.gif" BORDER="0"> and <IMG SRC="/giflibrary/12/beta.gif" BORDER="0" ALIGN="ABSBOTTOM"> bands. Fluctuations of EEG synchronization in <IMG SRC="/giflibrary/12/delta.gif" BORDER="0">, <IMG SRC="/giflibrary/12/thetas.gif" BORDER="0">, <IMG SRC="/giflibrary/12/alpha.gif" BORDER="0">, <IMG SRC="/giflibrary/12/beta.gif" BORDER="0" ALIGN="ABSBOTTOM">, and <IMG SRC="/giflibrary/12/gamma.gif" BORDER="0"> bands exhibit scale-free dynamics in eyes-closed as well as eyes-open no-task states. The decrease in the scaling exponent following eye opening reflects a relative preponderance of rapid fluctuations with respect to slow changes in the mean synchronization level. The existence of scaling suggests that the underlying dynamics may display self-organized criticality, possibly representing a near-optimal state for information processing. Hum. Brain Mapping 22:99-111, 2004. &copy; 2004 Wiley-Liss, Inc. IS - 2 JF - Human Brain Mapping SN - 1097-0193 EP - 109 TI - Scale-free dynamics of global functional connectivity in the human brain VL - 22 SP - 97 KW - fmri KW - functional_connectivity KW - network AU - Stam, Cornelis AU - de Bruin, Eveline PY - 2004/03/05/ UR - http://dx.doi.org/10.1002/hbm.20016 ER -