biostudies-literatureKananen JPohjois-Pohjanmaan RahastoNIA NIH HHSSuomen KulttuurirahastoNINDS NIH HHSSuomen Lääketieteen SäätiöNovo Nordisk FondenLundbeck FoundationOrionin Tutkimussäätiöe01090https://www.ebi.ac.uk/biostudies/studies/S-EPMC6160661biostudies-literatureUnknown8(9)<h4>Introduction</h4>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.<h4>Methods</h4>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).<h4>Results</h4>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.<h4>Conclusions</h4>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.Brain and behaviorAltered physiological brain variation in drug-resistant epilepsy.PMC6160661NNF13OC0004258R01 AG048769R155-2016-552RF1 AG057575R01 NS100366RF1 NS110049Rytky SHelakari HRaitamaa LTuovinen TLeVan PKiviniemi VNedergaard MRaatikainen VHuotari NRasila AKananen JAnsakorpi HKorhonen VBorchardt VfalseAltered physiological brain variation in drug-resistant epilepsy.<h4>Introduction</h4>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.<h4>Methods</h4>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).<h4>Results</h4>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.<h4>Conclusions</h4>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.2018-01-01T00:00:00Z2018 Sep2026-06-14T03:19:22.975Z2019-03-26T23:58:29ZS-EPMC61606613011281310.1002/brb3.1090