PMID- 26321936 OWN - NLM STAT- PubMed-not-MEDLINE DCOM- 20150831 LR - 20201001 IS - 1662-5161 (Print) IS - 1662-5161 (Electronic) IS - 1662-5161 (Linking) VI - 9 DP - 2015 TI - Detection of short-term activity avalanches in human brain default mode network with ultrafast MR encephalography. PG - 448 LID - 10.3389/fnhum.2015.00448 [doi] LID - 448 AB - Recent studies pinpoint visually cued networks of avalanches with MEG/EEG data. Co-activation pattern (CAP) analysis can be used to detect single brain volume activity profiles and hemodynamic fingerprints of neuronal avalanches as sudden high signal activity peaks in classical fMRI data. In this study, we aimed to detect dynamic patterns of brain activity spreads with the use of ultrafast MR encephalography (MREG). MREG achieves 10 Hz whole brain sampling, allowing the estimation of spatial spread of an avalanche, even with the inherent hemodynamic delay of the BOLD signal. We developed a novel computational method to separate avalanche type fast activity spreads from motion artifacts, vasomotor fluctuations, and cardio-respiratory noise in human brain default mode network (DMN). Reproducible and classical DMN sources were identified using spatial ICA prior to advanced noise removal in order to assure that ICA converges to reproducible networks. Brain activity peaks were identified from parts of the DMN, and normalized MREG data around each peak were extracted individually to show dynamic avalanche type spreads as video clips within the DMN. Individual activity spread video clips of specific parts of the DMN were then averaged over the group of subjects. The experiments show that the high BOLD values around the peaks are mostly spreading along the spatial pattern of the particular DMN segment detected with ICA. With also the spread size and lifetime resembling the expected power law distributions, this indicates that the detected peaks are parts of activity avalanches, starting from (or crossing) the DMN. Furthermore, the split, one-sided sub-networks of the DMN show different spread directions within the same DMN framework. The results open possibilities to follow up brain activity avalanches in the hope to understand more about the system wide properties of diseases related to DMN dysfunction. FAU - Rajna, Zalan AU - Rajna Z AD - Biomedical Engineering Research Group, Department of Computer Science and Engineering, Faculty of Information Technology and Electrical Engineering, University of Oulu Oulu, Finland. FAU - Kananen, Janne AU - Kananen J AD - Oulu Functional Neuroimaging Research Group, Department of Diagnostic Radiology, Medical Research Center, Oulu University Hospital Oulu, Finland. FAU - Keskinarkaus, Anja AU - Keskinarkaus A AD - Biomedical Engineering Research Group, Department of Computer Science and Engineering, Faculty of Information Technology and Electrical Engineering, University of Oulu Oulu, Finland. FAU - Seppanen, Tapio AU - Seppanen T AD - Biomedical Engineering Research Group, Department of Computer Science and Engineering, Faculty of Information Technology and Electrical Engineering, University of Oulu Oulu, Finland. FAU - Kiviniemi, Vesa AU - Kiviniemi V AD - Oulu Functional Neuroimaging Research Group, Department of Diagnostic Radiology, Medical Research Center, Oulu University Hospital Oulu, Finland. LA - eng PT - Journal Article DEP - 20150811 PL - Switzerland TA - Front Hum Neurosci JT - Frontiers in human neuroscience JID - 101477954 PMC - PMC4531800 OTO - NOTNLM OT - activity avalanche detection OT - default mode network OT - functional magnetic resonance imaging OT - human brain OT - resting state EDAT- 2015/09/01 06:00 MHDA- 2015/09/01 06:01 PMCR- 2015/01/01 CRDT- 2015/09/01 06:00 PHST- 2015/05/31 00:00 [received] PHST- 2015/07/27 00:00 [accepted] PHST- 2015/09/01 06:00 [entrez] PHST- 2015/09/01 06:00 [pubmed] PHST- 2015/09/01 06:01 [medline] PHST- 2015/01/01 00:00 [pmc-release] AID - 10.3389/fnhum.2015.00448 [doi] PST - epublish SO - Front Hum Neurosci. 2015 Aug 11;9:448. doi: 10.3389/fnhum.2015.00448. eCollection 2015.