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dc.contributor.authorHu, Kun
dc.contributor.authorLo, Men-Tzung
dc.contributor.authorPeng, Chung-Kang
dc.contributor.authorLiu, Yanhui
dc.contributor.authorNovak, Vera
dc.date.accessioned2013-03-22T19:12:34Z
dc.date.issued2012
dc.identifier.citationHu, Kun, Men-Tzung Lo, Chung-Kang Peng, Yanhui Liu, and Vera Novak. 2012. A nonlinear dynamic approach reveals a long-term stroke effect on cerebral blood flow regulation at multiple time scales. PLoS Computational Biology 8(7): e1002601.en_US
dc.identifier.issn1553-734Xen_US
dc.identifier.urihttp://nrs.harvard.edu/urn-3:HUL.InstRepos:10461890
dc.description.abstractCerebral autoregulation (CA) is an important vascular control mechanism responsible for relatively stable cerebral blood flow despite changes of systemic blood pressure (BP). Impaired CA may leave brain tissue unprotected against potentially harmful effects of BP fluctuations. It is generally accepted that CA is less effective or even inactive at frequencies >∼0.1 Hz. Without any physiological foundation, this concept is based on studies that quantified the coupling between BP and cerebral blood flow velocity (BFV) using transfer function analysis. This traditional analysis assumes stationary oscillations with constant amplitude and period, and may be unreliable or even invalid for analysis of nonstationary BP and BFV signals. In this study we propose a novel computational tool for CA assessment that is based on nonlinear dynamic theory without the assumption of stationary signals. Using this method, we studied BP and BFV recordings collected from 39 patients with chronic ischemic infarctions and 40 age-matched non-stroke subjects during baseline resting conditions. The active CA function in non-stroke subjects was associated with an advanced phase in BFV oscillations compared to BP oscillations at frequencies from ∼0.02 to 0.38 Hz. The phase shift was reduced in stroke patients even at > = 6 months after stroke, and the reduction was consistent at all tested frequencies and in both stroke and non-stroke hemispheres. These results provide strong evidence that CA may be active in a much wider frequency region than previously believed and that the altered multiscale CA in different vascular territories following stroke may have important clinical implications for post-stroke recovery. Moreover, the stroke effects on multiscale cerebral blood flow regulation could not be detected by transfer function analysis, suggesting that nonlinear approaches without the assumption of stationarity are more sensitive for the assessment of the coupling of nonstationary physiological signals.en_US
dc.language.isoen_USen_US
dc.publisherPublic Library of Scienceen_US
dc.relation.isversionofdoi:10.1371/journal.pcbi.1002601en_US
dc.relation.hasversionhttp://www.ncbi.nlm.nih.gov/pmc/articles/PMC3395609/pdf/en_US
dash.licenseLAA
dc.subjectBiologyen_US
dc.subjectAnatomy and Physiologyen_US
dc.subjectCardiovascular Systemen_US
dc.subjectCirculatory Physiologyen_US
dc.subjectIntegrative Physiologyen_US
dc.subjectMathematicsen_US
dc.subjectNonlinear Dynamicsen_US
dc.subjectMedicineen_US
dc.subjectCardiovascularen_US
dc.subjectStrokeen_US
dc.subjectNeurologyen_US
dc.subjectCerebrovascular Diseasesen_US
dc.subjectIschemic Strokeen_US
dc.subjectPhysicsen_US
dc.subjectMedical Physicsen_US
dc.titleA Nonlinear Dynamic Approach Reveals a Long-Term Stroke Effect on Cerebral Blood Flow Regulation at Multiple Time Scalesen_US
dc.typeJournal Articleen_US
dc.description.versionVersion of Recorden_US
dc.relation.journalPLoS Computational Biologyen_US
dash.depositing.authorNovak, Vera
dc.date.available2013-03-22T19:12:34Z
dc.identifier.doi10.1371/journal.pcbi.1002601*
dash.contributor.affiliatedHu, Kun
dash.contributor.affiliatedNovak, Vera
dash.contributor.affiliatedPeng, Chung-Kang


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