Altered physiological brain variation in drug-resistant epilepsy

TY - JOUR

T1 - Altered physiological brain variation in drug-resistant epilepsy

AU - Kananen, Janne

AU - Tuovinen, Timo

AU - Ansakorpi, Hanna

AU - Rytky, Seppo

AU - Helakari, Heta

AU - Huotari, Niko

AU - Raitamaa, Lauri

AU - Raatikainen, Ville

AU - Rasila, Aleksi

AU - Borchardt, Viola

AU - Korhonen, Vesa

AU - LeVan, Pierre

AU - Nedergaard, Maiken

AU - Kiviniemi, Vesa

N1 - © 2018 The Authors. Brain and Behavior published by Wiley Periodicals, Inc.

PY - 2018/9

Y1 - 2018/9

N2 - Introduction: 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) CVMREG 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 CVMREG 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.

AB - Introduction: 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) CVMREG 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 CVMREG 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.

U2 - 10.1002/brb3.1090

DO - 10.1002/brb3.1090

M3 - Journal article

C2 - 30112813

SN - 2162-3279

VL - 8

SP - 1

EP - 17

JO - Brain and Behavior

JF - Brain and Behavior

IS - 9

M1 - e01090

ER -