Open AccessAltered physiological brain variation in drug‐resistant epilepsy
Author(s) -
Kananen Janne,
Tuovinen Timo,
Ansakorpi Hanna,
Rytky Seppo,
Helakari Heta,
Huotari Niko,
Raitamaa Lauri,
Raatikainen Ville,
Rasila Aleksi,
Borchardt Viola,
Korhonen Vesa,
LeVan Pierre,
Nedergaard Maiken,
Kiviniemi Vesa
Publication year - 2018
Publication title -
brain and behavior
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.915
H-Index - 41
ISSN - 2162-3279
DOI - 10.1002/brb3.1090
Subject(s) - magnetoencephalography , brainstem , epilepsy , brain activity and meditation , electroencephalography , neuroscience , audiology , functional magnetic resonance imaging , analysis of variance , brain mapping , magnetic resonance imaging , voxel , white matter , coefficient of variation , neuroimaging , human brain , resting state fmri , medicine , psychology , radiology , chemistry , chromatography
Functional magnetic resonance imaging ( fMRI ) combined with simultaneous electroencephalography ( EEG ‐ fMRI ) has become a major tool in mapping epilepsy sources. In the absence of detectable epileptiform activity, the resting state fMRI may still detect changes in the blood oxygen level‐dependent signal, suggesting intrinsic alterations in the underlying brain physiology. Methods In this study, we used coefficient of variation ( CV ) of critically sampled 10 Hz ultra‐fast fMRI (magnetoencephalography, MREG ) signal to compare physiological variance between healthy controls ( n = 10) and patients ( n = 10) with drug‐resistant epilepsy ( DRE ). Results We showed highly significant voxel‐level ( p < 0.01, TFCE ‐corrected) increase in the physiological variance in DRE patients. At individual level, the elevations range over three standard deviations ( σ ) above the control mean ( μ ) CV MREG values solely in DRE patients, enabling patient‐specific mapping of elevated physiological variance. The most apparent differences in group‐level analysis are found on white matter, brainstem, and cerebellum. Respiratory (0.12–0.4 Hz) and very‐low‐frequency ( VLF = 0.009–0.1 Hz) signal variances were most affected. Conclusions The CV MREG increase was not explained by head motion or physiological cardiorespiratory activity, that is, it seems to be linked to intrinsic physiological pulsations. We suggest that intrinsic brain pulsations play a role in DRE and that critically sampled fMRI may provide a powerful tool for their identification.