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Brain Connect. 2014 Nov;4(9):677-89. doi: 10.1089/brain.2014.0258. Epub 2014 Sep 26.

Synchronous multiscale neuroimaging environment for critically sampled physiological analysis of brain function: hepta-scan concept.

Author information

1
1 Department of Diagnostic Radiology, Institute of Diagnostics , Medical Research Center of Oulu, Oulu, Finland .

Abstract

Functional connectivity of the resting-state networks of the brain is thought to be mediated by very-low-frequency fluctuations (VLFFs <0.1 Hz) in neuronal activity. However, vasomotor waves and cardiorespiratory pulsations influence indirect measures of brain function, such as the functional magnetic resonance imaging blood-oxygen-level-dependent (BOLD) signal. How strongly physiological oscillations correlate with spontaneous BOLD signals is not known, partially due to differences in the data-sampling rates of different methods. Recent ultrafast inverse imaging sequences, including magnetic resonance encephalography (MREG), enable critical sampling of these signals. In this study, we describe a multimodal concept, referred to as Hepta-scan, which incorporates synchronous MREG with scalp electroencephalography, near-infrared spectroscopy, noninvasive blood pressure, and anesthesia monitoring. Our preliminary results support the idea that, in the absence of aliased cardiorespiratory signals, VLFFs in the BOLD signal are affected by vasomotor and electrophysiological sources. Further, MREG signals showed a high correlation coefficient between the ventromedial default mode network (DMNvmpf) and electrophysiological signals, especially in the VLF range. Also, oxy- and deoxyhemoglobin and vasomotor waves were found to correlate with DMNvmpf. Intriguingly, usage of shorter time windows in these correlation measurements produced significantly (p<0.05) higher positive and negative correlation coefficients, suggesting temporal nonstationary behavior between the measurements. Focus on the VLF range strongly increased correlation strength.

KEYWORDS:

blood oxygen level-dependent; blood pressure; brain; electroencephalography; functional magnetic resonance imaging; magnetic resonance encephalography; multimodal imaging; near-infrared spectroscopy; resting state

PMID:
25131996
PMCID:
PMC4238249
DOI:
10.1089/brain.2014.0258
[Indexed for MEDLINE]
Free PMC Article

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