Stereoelectroencephalography (SEEG) records electrical brain activity with intracerebral electrodes. However, it has an inherently limited spatial coverage. Electrical source imaging (ESI) infers the position of the neural generators from the recorded electric potentials, and thus, could overcome this spatial undersampling problem. Here, we aimed to quantify the accuracy of SEEG ESI under clinical conditions. We measured the somatosensory evoked potential (SEP) in SEEG and in high-density EEG (HD-EEG) in 20 epilepsy surgery patients. To localize the source of the SEP, we employed standardized low resolution brain electromagnetic tomography (sLORETA) and equivalent current dipole (ECD) algorithms. Both sLORETA and ECD converged to similar solutions. Reflecting the large differences in the SEEG implantations, the localization error also varied in a wide range from 0.4 to 10 cm. The SEEG ESI localization error was linearly correlated with the distance from the putative neural source to the most activated contact. We show that it is possible to obtain reliable source reconstructions from SEEG under realistic clinical conditions, provided that the high signal fidelity recording contacts are sufficiently close to the source of the brain activity.

• Klíčová slova
• Electrical source localization (ESL), High-density EEG (HD-EEG), Intracranial EEG (iEEG), Inverse problem, Somatosensory evoked potential (SEP, SSEP), Stereo-EEG (SEEG),
• MeSH
• elektroencefalografie metody   MeSH
• elektrokortikografie * metody   MeSH
• epilepsie * chirurgie   MeSH
• lidé MeSH
• magnetická rezonanční tomografie MeSH
• mapování mozku metody   MeSH
• neurozobrazování MeSH
• somatosenzorické evokované potenciály MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

This work presents and evaluates a 12-electrode intracranial electroencephalography system developed at the National Institute of Mental Health (Klecany, Czech Republic) in terms of an electrical source imaging (ESI) technique in rats. The electrode system was originally designed for translational research purposes. This study demonstrates that it is also possible to use this well-established system for ESI, and estimates its precision, accuracy, and limitations. Furthermore, this paper sets a methodological basis for future implants. Source localization quality is evaluated using three approaches based on surrogate data, physical phantom measurements, and in vivo experiments. The forward model for source localization is obtained from the FieldTrip-SimBio pipeline using the finite-element method. Rat brain tissue extracted from a magnetic resonance imaging template is approximated by a single-compartment homogeneous tetrahedral head model. Four inverse solvers were tested: standardized low-resolution brain electromagnetic tomography, exact low-resolution brain electromagnetic tomography (eLORETA), linear constrained minimum variance (LCMV), and dynamic imaging of coherent sources. Based on surrogate data, this paper evaluates the accuracy and precision of all solvers within the brain volume using error distance and reliability maps. The mean error distance over the whole brain was found to be the lowest in the eLORETA solution through signal to noise ratios (SNRs) (0.2 mm for 25 dB SNR). The LCMV outperformed eLORETA under higher SNR conditions, and exhibiting higher spatial precision. Both of these inverse solvers provided accurate results in a phantom experiment (1.6 mm mean error distance across shallow and 2.6 mm across subcortical testing dipoles). Utilizing the developed technique in freely moving rats, an auditory steady-state response experiment provided results in line with previously reported findings. The obtained results support the idea of utilizing a 12-electrode system for ESI and using it as a solid basis for the development of future ESI dedicated implants.

• Klíčová slova
• auditory steady-state response experiment, electrical source imaging, electroencephalography, fieldtrip, preclinical models, translational research,
• Publikační typ
• časopisecké články MeSH

This paper discusses the optimization of domain parameters in electrical impedance tomography-based imaging. Precise image reconstruction requires accurate, well-correlated physical and numerical finite element method (FEM) models; thus, we employed the Nelder-Mead algorithm and a complete electrode model to evaluate the individual parameters, including the initial conductivity, electrode misplacement, and shape deformation. The optimization process was designed to calculate the parameters of the numerical model before the image reconstruction. The models were verified via simulation and experimental measurement with single source current patterns. The impact of the optimization on the above parameters was reflected in the applied image reconstruction process, where the conductivity error dropped by 6.16% and 11.58% in adjacent and opposite driving, respectively. In the shape deformation, the inhomogeneity area ratio increased by 11.0% and 48.9%; the imprecise placement of the 6th electrode was successfully optimized with adjacent driving; the conductivity error dropped by 12.69%; and the inhomogeneity localization exhibited a rise of 66.7%. The opposite driving option produces undesired duality resulting from the measurement pattern. The designed optimization process proved to be suitable for correlating the numerical and the physical models, and it also enabled us to eliminate imaging uncertainties and artifacts.

• Klíčová slova
• Nelder–Mead optimization, complete electrode model, domain deformation, electrical impedance tomography, electrode locations,
• MeSH
• algoritmy MeSH
• elektrická impedance MeSH
• fantomy radiodiagnostické MeSH
• počítačová simulace MeSH
• počítačové zpracování obrazu * MeSH
• tomografie * MeSH
• Publikační typ
• časopisecké články MeSH

Using functional magnetic resonance imaging (fMRI) and electroencephalographic (EEG) source dipole analysis in 10 normal subjects, two electrical source dipoles in the contralateral fronto-parietal operculum were identified during repetitive painful subepidermal stimulation of the right index finger. The anterior source dipole peaking at 79 +/- 8 ms (mean +/- SD) was located in the frontal operculum, and oriented tangentially toward the cortical surface. The posterior source dipole peaking at 118 +/- 12 ms was located in the upper bank of the Sylvian fissure corresponding to the second somatosensory cortex (S2). The orientations of the posterior source dipoles displayed large variability, but differed significantly (P < 0.05) from the orientations of the anterior source dipoles. Electrical sources and fMRI clusters were also observed in ipsilateral fronto-parietal operculum. However, due to low signal-to-noise ratio of ipsilateral EEG sources in individual recordings, separation of sources into anterior and posterior clusters was not performed. Combined fMRI and source dipole EEG analysis of individual data suggests the presence of two distinct electrical sources in the fronto-parietal operculum participating in processing of somatosensory stimuli. The anterior region of the fronto-parietal operculum shows earlier peak activation than the posterior region.

• MeSH
• aquaeductus cerebri fyziologie   MeSH
• arousal fyziologie   MeSH
• čelní lalok fyziologie   MeSH
• dominance mozková fyziologie   MeSH
• dospělí MeSH
• elektrická stimulace MeSH
• elektroencefalografie * MeSH
• kůže inervace   MeSH
• lidé MeSH
• magnetická rezonanční tomografie * MeSH
• mapování mozku MeSH
• počítačové zpracování obrazu * MeSH
• práh bolesti fyziologie   MeSH
• prsty ruky inervace   MeSH
• reakční čas fyziologie   MeSH
• somatosenzorické evokované potenciály fyziologie   MeSH
• somatosenzorické korové centrum fyziologie   MeSH
• temenní lalok fyziologie   MeSH
• zobrazování trojrozměrné * MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• mužské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Cardiac arrhythmias are a very frequent illness. Pharmacotherapy is not very effective in persistent arrhythmias and brings along a number of risks. Catheter ablation has became an effective and curative treatment method over the past 20 years. To support complex arrhythmia ablations, the 3D X-ray cardiac cavities imaging is used, most frequently the 3D reconstruction of CT images. The 3D cardiac rotational angiography (3DRA) represents a modern method enabling to create CT like 3D images on a standard X-ray machine equipped with special software. Its advantage lies in the possibility to obtain images during the procedure, decreased radiation dose and reduction of amount of the contrast agent. The left atrium model is the one most frequently used for complex atrial arrhythmia ablations, particularly for atrial fibrillation. CT data allow for creation and segmentation of 3D models of all cardiac cavities. Recently, a research has been made proving the use of 3DRA to create 3D models of other cardiac (right ventricle, left ventricle, aorta) and non-cardiac structures (oesophagus). They can be used during catheter ablation of complex arrhythmias to improve orientation during the construction of 3D electroanatomic maps, directly fused with 3D electroanatomic systems and/or fused with fluoroscopy. An intensive development in the 3D model creation and use has taken place over the past years and they became routinely used during catheter ablations of arrhythmias, mainly atrial fibrillation ablation procedures. Further development may be anticipated in the future in both the creation and use of these models.

• MeSH
• akční potenciály MeSH
• chirurgie s pomocí počítače MeSH
• intervenční radiografie MeSH
• katetrizační ablace metody   MeSH
• koronární angiografie metody   MeSH
• lidé MeSH
• multidetektorová počítačová tomografie metody   MeSH
• prediktivní hodnota testů MeSH
• převodní systém srdeční diagnostické zobrazování   patofyziologie   chirurgie   MeSH
• rentgenový obraz - interpretace počítačová * MeSH
• software MeSH
• srdeční arytmie diagnostické zobrazování   patofyziologie   chirurgie   MeSH
• zobrazování trojrozměrné * MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH

Primary cold and warm afferent fibers show a robust overshoot in their firing during periods of temperature change, which subsides during tonic thermal stimulation. Our objective was to analyze cortical activation, on a scale of hundreds of milliseconds, occurring during the process of dynamic cooling and warming, based on an evaluation of the amplitude changes seen in 10 Hz electroencephalographic oscillations. Eleven right-handed subjects were exposed to innocuous cold ramp stimuli (from 32 degrees C to 22 degrees C, 10 degrees C/s) and warm ramp stimuli (32 degrees C to 42 degrees C, 10 degrees C/s) on the thenar region of their right palm, using a contact thermode. EEG was recorded from 111 scalp sites, and the 10 Hz current source densities were modeled using low-resolution electromagnetic tomography. During cooling, the earliest amplitude decreases of 10 Hz oscillations were seen in the contralateral posterior insula and secondary somatosensory cortex (SII), and the premotor cortex (PMC). During warming, the earliest events were only observed in the PMC and occurred approximately 0.7 s later than during cooling. Linear regression analysis between 10 Hz current source densities and temperature variations revealed cooling-sensitive activation in the bilateral posterior insula, PMC and the anterior cingulate cortex. During warming, the amplitude of 10 Hz oscillations in the PMC and posterior insula correlated with stimulus temperature. Dynamic thermal stimulation activates, in addition to the posterior insula and parietal operculum, the lateral PMC. The activation of the anterior cingulate cortex during cooling may aid in the anticipation of the cold temperature end-point and provide continuous evaluation of the thermal stimulus.

• MeSH
• aferentní nervové dráhy fyziologie   MeSH
• dospělí MeSH
• elektroencefalografie MeSH
• lidé MeSH
• mapování mozku MeSH
• mladiství MeSH
• mozková kůra fyziologie   MeSH
• nervová vlákna fyziologie   MeSH
• nízká teplota MeSH
• reakční čas MeSH
• referenční hodnoty MeSH
• termoregulace * MeSH
• vysoká teplota MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• mladiství MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

This study aimed to directly compare electroencephalography (EEG) whole-brain patterns of neural dynamics with concurrently measured fMRI BOLD data. To achieve this, we aim to derive EEG patterns based on a spatio-spectral decomposition of band-limited EEG power in the source-reconstructed space. In a large dataset of 72 subjects undergoing resting-state hdEEG-fMRI, we demonstrated that the proposed approach is reliable in terms of both the extracted patterns as well as their spatial BOLD signatures. The five most robust EEG spatio-spectral patterns not only include the well-known occipital alpha power dynamics, ensuring consistency with established findings, but also reveal additional patterns, uncovering new insights into brain activity. We report and interpret the most reproducible source-space EEG-fMRI patterns, along with the corresponding EEG electrode-space patterns, which are better known from the literature. The EEG spatio-spectral patterns show weak, yet statistically significant spatial similarity to their functional magnetic resonance imaging (fMRI) blood oxygenation level-dependent (BOLD) signatures, particularly in the patterns that exhibit stronger temporal synchronization with BOLD. However, we did not observe a statistically significant relationship between the EEG spatio-spectral patterns and the classical fMRI BOLD resting-state networks (as identified through independent component analysis), tested as the similarity between their temporal synchronization and spatial overlap. This provides evidence that both EEG (frequency-specific) power and the BOLD signal capture reproducible spatio-temporal patterns of neural dynamics. Instead of being mutually redundant, these only partially overlap, providing largely complementary information regarding the underlying low-frequency dynamics.

• Klíčová slova
• EEG-fMRI integration, EEG-informed fMRI, electrical source imaging, independent component analysis, resting-state networks, spatio-spectral decomposition,
• Publikační typ
• časopisecké články MeSH

INTRODUCTION: Accurate localization of the epileptogenic zone is essential for surgical treatment of drug-resistant epilepsy. Standard presurgical evaluations rely on multimodal neuroimaging techniques, but these may be limited by availability and interpretive challenges. This study aimed to assess the concordance between zones identified by ictal semiology and a novel distributed electrical source localization technique, CLARA, and to evaluate their impact on postsurgical outcomes. METHODS: This retrospective study included 16 patients with at least three recorded seizures. Ictal semiology was analyzed subjectively using video electroencephalography (VEEG) by a multidisciplinary team of neurologists, neurophysiologists, and radiologists, who determined the presumed epileptogenic zone at the lobar level. CLARA was subsequently applied to identify the computed zone based on ictal and/or interictal biomarker activities. The concordance between the presumed and computed zones was assessed qualitatively. Postsurgical outcomes were examined in relation to the extent of resection of the CLARA-defined zones. RESULTS: Among thirteen patients with sufficient data for analysis, qualitative comparison showed 77% concordance and 23% partial concordance between the presumed and computed zones. Postsurgical follow-up revealed seizure freedom in one patient with cavernoma following complete resection of the CLARA-defined zone. In contrast, patients with incomplete resection of this region continued to experience seizures. DISCUSSION: The findings support the potential value of CLARA as an adjunctive neuroimaging technique in the presurgical evaluation of epilepsy. By providing an additional layer of verification, CLARA may improve the accuracy of epileptogenic zone localization when used alongside established modalities such as PET, SPECT, fMRI, and MRI. Its adaptability and lower resource requirements suggest particular utility in centers with limited access to advanced medical equipment and specialized personnel. Broader implementation of CLARA could enhance presurgical decision-making and contribute to improved surgical outcomes for epilepsy patients.

• Klíčová slova
• VEEG, brain imaging, brain signals, classical LORETA analysis recursively applied (CLARA), epilepsy,
• Publikační typ
• časopisecké články MeSH

If corpus callosum (CC) mediates the activation of the secondary somatosensory area (SII) ipsilateral to the side of stimulation, then the peak latencies of the contra- and ipsilateral SII activity as well as the amplitude of the ipsilateral SII activity should correlate with the size of CC. Innocuous electrical stimuli of five different intensities were applied to the ventral surface of the right index finger in 15 right-handed men. EEG was recorded using 82 closely spaced electrodes. The size of CC and of seven callosal regions was measured from the mid-sagittal slice of a high-resolution anatomical MRI. The activation in the contralateral and ipsilateral SII was evaluated using spatio-temporal source analysis. At the strongest stimulus intensity, the size of the intermediate part of the callosal truncus correlated negatively with the interpeak latency of the sources in ipsi- and contralateral SII (r = -0.83, P < 0.01). Stepwise regression analysis showed that the large size of the intermediate truncus of CC was paralleled by a latency reduction of peak activity of the ipsilateral SII, whereas both contra- and ipsilateral peak latencies were positively correlated. The peak amplitude of the ipsilateral SII source correlated positively with the size of the intermediate truncus of CC, and with the peak amplitudes of sources in the primary somatosensory cortex (SI) and in the mesial frontal cortex. The results suggest that in right-handed neurologically normal men, the size of the intermediate callosal truncus contributes to the timing and amplitude of ipsilateral SII source activity.

• MeSH
• aferentní nervové dráhy anatomie a histologie   fyziologie   MeSH
• corpus callosum anatomie a histologie   fyziologie   MeSH
• dospělí MeSH
• elektrická stimulace MeSH
• elektroencefalografie MeSH
• funkční lateralita fyziologie   MeSH
• hmat fyziologie   MeSH
• lidé MeSH
• magnetická rezonanční tomografie MeSH
• mapování mozku MeSH
• mechanoreceptory fyziologie   MeSH
• modely neurologické MeSH
• motorické korové centrum anatomie a histologie   fyziologie   MeSH
• nervové vedení fyziologie   MeSH
• reakční čas fyziologie   MeSH
• somatosenzorické evokované potenciály fyziologie   MeSH
• somatosenzorické korové centrum anatomie a histologie   fyziologie   MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• mužské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

OBJECTIVES: To investigate spatial patterns of gray matter (GM) atrophy and their association with disability progression in patients with early relapsing-remitting multiple sclerosis (MS) in a longitudinal setting. METHODS: Brain MRI and clinical neurological assessments were obtained in 152 MS patients at baseline and after 10 years of follow-up. Patients were classified into those with confirmed disability progression (CDP) (n = 85) and those without CDP (n = 67) at the end of the study. An optimized, longitudinal source-based morphometry (SBM) pipeline, which utilizes independent component analysis, was used to identify eight spatial patterns of common GM volume co-variation in a data-driven manner. GM volume at baseline and rates of change were compared between patients with CDP and those without CDP. RESULTS: The identified patterns generally included structurally or functionally related GM regions. No significant differences were detected at baseline GM volume between the sub-groups. Over the follow-up, patients with CDP experienced a significantly greater rate of GM atrophy within two of the eight patterns, after correction for multiple comparisons (corrected p-values of 0.001 and 0.007). The patterns of GM atrophy associated with the development of CDP included areas involved in motor functioning and cognitive domains such as learning and memory. CONCLUSION: SBM analysis offers a novel way to study the temporal evolution of regional GM atrophy. Over 10 years of follow-up, disability progression in MS is related to GM atrophy in areas associated with motor and cognitive functioning.

• Klíčová slova
• Atrophy, Disability, Gray matter, MRI, Multiple sclerosis,
• MeSH
• atrofie MeSH
• lidé středního věku MeSH
• lidé MeSH
• longitudinální studie MeSH
• magnetická rezonanční tomografie MeSH
• mapování mozku MeSH
• mozek diagnostické zobrazování   patologie   MeSH
• progrese nemoci * MeSH
• relabující-remitující roztroušená skleróza diagnostické zobrazování   patologie   MeSH
• šedá hmota diagnostické zobrazování   patologie   MeSH
• Check Tag
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH