Spatiotemporal dynamics of low frequency BOLD fluctuations in rats and humans

• Published in: NeuroImage (Orlando, Fla.) Vol. 54; no. 2; pp. 1140 - 1150
• Main Authors: Majeed, Waqas, Magnuson, Matthew, Hasenkamp, Wendy, Schwarb, Hillary, Schumacher, Eric H., Barsalou, Lawrence, Keilholz, Shella D.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 15.01.2011; Elsevier Limited
• Subjects: Adult; Aged; Algorithms; Animals; Behavior; Brain - physiology; Brain mapping; Brain Mapping - methods; Brain research; Cortex (cingulate); Cortex (parietal); Cortex (premotor); Cortex (somatosensory); Cortex (temporal); Female; Functional connectivity; Functional magnetic resonance imaging; Heart rate; Humans; Image Processing, Computer-Assisted - methods; Low frequency fluctuations; Magnetic Resonance Imaging; Male; Middle Aged; Neural networks; Neural Pathways; Neuroimaging; Propagation; Putamen; Rats; Spatiotemporal dynamics; Spontaneous neural activity; Studies; Young Adult; cc; Functional connectivity; Spontaneous neural activity; SII; LFFs; WL; SI; CSF; Low frequency fluctuations; Spatiotemporal dynamics; CP
• ISSN: 1053-8119; 1095-9572; 1095-9572
• DOI: 10.1016/j.neuroimage.2010.08.030

Most studies involving spontaneous fluctuations in the BOLD signal extract connectivity patterns that show relationships between brain areas that are maintained over the length of the scanning session. In this study, however, we examine the spatiotemporal dynamics of the BOLD fluctuations to identify common patterns of propagation within a scan. A novel pattern finding algorithm was developed for detecting repeated spatiotemporal patterns in BOLD fMRI data. The algorithm was applied to high temporal resolution T2*-weighted multislice images obtained from rats and humans in the absence of any task or stimulation. In rats, the primary pattern consisted of waves of high signal intensity, propagating in a lateral to medial direction across the cortex, replicating our previous findings (Majeed et al., 2009a). These waves were observed primarily in sensorimotor cortex, but also extended to visual and parietal association areas. A secondary pattern, confined to subcortical regions consisted of an initial increase and subsequent decrease in signal intensity in the caudate–putamen. In humans, the most common spatiotemporal pattern consisted of an alteration between activation of areas comprising the “default-mode” (e.g., posterior cingulate and anterior medial prefrontal cortices) and the “task-positive” (e.g., superior parietal and premotor cortices) networks. Signal propagation from focal starting points was also observed. The pattern finding algorithm was shown to be reasonably insensitive to the variation in user-defined parameters, and the results were consistent within and between subjects. This novel approach for probing the spontaneous network activity of the brain has implications for the interpretation of conventional functional connectivity studies, and may increase the amount of information that can be obtained from neuroimaging data. ►A novel pattern finding algorithm automatically detects reproducible spatiotemporal patterns of BOLD fluctuations previously observed in rats. ►Similar spatiotemporal patterns of BOLD fluctuations are also present in humans. ►These patterns are reproducible within and across subjects.