?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Adc&rft.title=Fractal-driven+distortion+of+resting+state+functional+networks+in+fMRI%3A+a+simulation+study&rft.creator=You%2C+Wonsang&rft.creator=Stadler%2C+J%C3%B6rg&rft.subject=Biophysics&rft.subject=Brain+Imaging&rft.subject=Computational+Neuroscience&rft.subject=Statistical+Models&rft.description=Fractals+are+self-similar+and+scale-invariant+patterns+found+ubiquitously+in+nature.+A+lot+of+evidences+implying+fractal+properties+such+as+1%2Ff+power+spectrums+have+been+also+observed+in+resting+state+fMRI+time+series.+While+the+traditional+model+of+fractal+behavior+in+resting+state+fMRI+has+been+a+fractional+Gaussian+noise%2C+it+is+limited+to+describe+the+physical+implication+of+fractal+behavior+on+functional+connectivity+of+the+brain.+To+answer+this+problem%2C+we+have+proposed+the+fractal-based+model+of+resting+state+hemodynamic+response+function+(rs-HRF)+whose+properties+can+be+summarized+by+a+fractal+exponent.+Here+we+show%2C+through+a+simulation+studies%2C+that+the+fractal+behavior+of+cerebral+hemodynamics+may+cause+significant+distortion+of+network+properties+between+neuronal+activities+and+BOLD+signals.+We+simulated+neuronal+population+activities+based+on+the+stochastic+neural+field+model+from+the+Macaque+brain+network%2C+and+then+obtained+their+corresponding+BOLD+signals+by+convolving+them+with+the+rs-HRF+filter.+The+precision+of+centrality+estimated+in+each+node+was+deteriorated+overall+in+three+networks+based+on+transfer+entropy%2C+mutual+information%2C+and+Pearson+correlation%3B+particularly+the+distortion+of+transfer+entropy+was+more+sensitive+to+the+standard+deviation+of+fractal+exponents.+A+node+with+high+centrality+was+resilient+to+desynchronized+fractal+dynamics+over+all+frequencies+while+a+node+with+small+centrality+exhibited+huge+distortion+of+both+wavelet+correlation+and+centrality+over+low+frequencies.+This+theoretical+expectation+indicates+that+the+difference+of+fractal+exponents+between+brain+regions+leads+to+discrepancy+of+statistical+network+properties%2C+especially+at+nodes+with+small+centrality%2C+between+neuronal+activities+and+BOLD+signals%2C+and+that+the+traditional+definitions+of+resting+state+functional+connectivity+may+not+effectively+reflect+the+dynamics+of+spontaneous+neuronal+activities.+As+an+alternative%2C+the+nonfractal+connectivity%2C+which+is+defined+as+the+correlation+of+nonfractal+components+of+resting+state+BOLD+signals%2C+can+be+considered+to+overcome+the+fractal+artifact.+In+conclusion%2C+our+simulation+studies+may+give+us+insight+into+the+influence+of+fractal+behavior+on+complex+networks+of+the+brain.&rft.date=2012-09-05&rft.type=Conference+Poster&rft.type=PeerReviewed&rft.format=application%2Fpdf&rft.identifier=http%3A%2F%2Fcogprints.org%2F8468%2F1%2Fyou2012restingstate.pdf&rft.identifier=++You%2C+Wonsang+and+Stadler%2C+J%C3%B6rg++(2012)+Fractal-driven+distortion+of+resting+state+functional+networks+in+fMRI%3A+a+simulation+study.++%5BConference+Poster%5D+++++&rft.relation=http%3A%2F%2Fcogprints.org%2F8468%2F