Previous EEG source localization studies in obsessive-compulsive disorder (OCD) reported ambiguous results. The reason probably lies in different OCD samples included in the studies - obsessive-compulsive subjects selected based on a psychopathology questionnaire (the Symptom Checklist - Revised), drug-naïve OCD cases or patients with a long-term disorder. This study was conceived as a replication of our previous research on OCD population coming to treatment in Prague Psychiatric Centre [9]. We included 50 OCD patients (8 drug-free and 42 medicated with SSRIs) and 50 healthy controls. All subjects were different from those enrolled in the previous study. Resting state EEG was analyzed in 8 frequency bands as well as with 1 Hz frequency resolution using the standardized low-resolution electromagnetic tomography (sLORETA). In OCD, sLORETA indicated low-frequency power excess at 2 and 3 Hz in the cingulate gyrus with maximal t-values in Brodmann area 24. The low-frequency activity was unrelated to the severity of clinical symptoms and illness duration but delta power in the right orbitofrontal cortex positively correlated with age of OCD onset. Our results confirm previous finding of the low-frequency excess in the cingulate gyrus in OCD and document the essential role of delta frequencies. Delta activity in the cingulate gyrus is negatively associated with reward-signalling dopamine release in the ventral striatum and increases in states connected with a need for reinforcement. Thus, delta activity could reflect a repetitive need to perform compulsive behaviour in OCD patients.
- Keywords
- Age of onset, Electroencephalography (EEG), Illness duration, Obsessive–compulsive disorder (OCD), Standardized low-resolution electromagnetic tomography (sLORETA), Symptom severity,
- MeSH
- Delta Rhythm * MeSH
- Diagnosis, Computer-Assisted methods standards MeSH
- Adult MeSH
- Electroencephalography methods standards MeSH
- Humans MeSH
- Brain physiopathology MeSH
- Obsessive-Compulsive Disorder diagnosis physiopathology MeSH
- Reference Values MeSH
- Reproducibility of Results MeSH
- Sensitivity and Specificity MeSH
- Check Tag
- Adult MeSH
- Humans MeSH
- Male MeSH
- Female MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Geographicals
- Czech Republic MeSH
BACKGROUND: Obsessive-compulsive disorder (OCD) is associated with cognitive dysfunction. Although there are several studies focused on the neurobiology of OCD, little is known about the biological correlates of the cognitive deficit linked to this disorder. The aim of our study was to examine the association between cognitive impairment and current source density markers in patients with OCD. METHODS: Resting-state eyes-closed electroencephalography (EEG) data were recorded in 20 patients with OCD and 15 healthy controls who were involved in the study. Cortical EEG sources were estimated by standardized low-resolution electromagnetic tomography in seven frequency bands: delta (1.5-6 Hz), theta (6.5-8 Hz), alpha-1 (8.5-10 Hz), alpha-2 (10.5-12 Hz), beta-1 (12.5-18 Hz), beta-2 (18.5-21 Hz), and beta-3 (21.5-30 Hz). Cognitive performance was measured by the Trail-Making Test (versions A and B), Stroop CW Test, and D2 Test. RESULTS: Frontal delta and theta EEG sources showed significantly higher activity in the whole group of patients with OCD (N=20) than in control subjects (N=15). Subsequent analysis revealed that this excess of low-frequency activity was present only in the subgroup of eleven patients with cognitive impairment (based on the performance in the Trail-Making Test - A). The subgroup of patients with normal cognitive functions (N=9) did not differ in cortical EEG sources from healthy controls. CONCLUSION: The present results suggest that frontal low-frequency cortical sources of resting-state EEG rhythms can distinguish groups of cognitively impaired and cognitively intact patients with OCD. Based on our results, future studies should consider whether the present methodological approach provides clinically useful information for the revelation of cognitive impairment in patients with OCD.
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.
- Keywords
- Electrical source localization (ESL), High-density EEG (HD-EEG), Intracranial EEG (iEEG), Inverse problem, Somatosensory evoked potential (SEP, SSEP), Stereo-EEG (SEEG),
- MeSH
- Electroencephalography methods MeSH
- Electrocorticography * methods MeSH
- Epilepsy * surgery MeSH
- Humans MeSH
- Magnetic Resonance Imaging MeSH
- Brain Mapping methods MeSH
- Neuroimaging MeSH
- Evoked Potentials, Somatosensory MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
OBJECTIVE: The goal of this study was to assess the activity of intracortical EEG sources in patients with OCD. METHODS: We compared resting state EEG from 50 OCD patients and 50 matched controls using standardized low-resolution electromagnetic tomography (sLORETA) and normative independent component analysis (NICA). Data were analyzed with 1 Hz frequency resolution. Group ICA was used to separate seven independent components from the control group data. The resulting weights and norms served to derive the same components from the OCD group and to compare their power with controls. RESULTS: In OCD, sLORETA indicated low-frequency power excess (2-6 Hz) in the medial frontal cortex, whereas group ICA showed increased low-frequency power in a component reflecting the activity of subgenual anterior cingulate, adjacent limbic structures and to a lesser extent also of lateral frontal cortex. CONCLUSIONS: Both methods provided evidence for medial frontal hyperactivation in OCD. SIGNIFICANCE: Our study is the first to use normative ICA in a clinical sample and indicates its potential utility as a diagnostic tool. The findings provide consistent results based on EEG source localization in OCD and are of practical interest for therapeutic interventions.
- MeSH
- Adult MeSH
- Electroencephalography MeSH
- Humans MeSH
- Brain physiopathology MeSH
- Obsessive-Compulsive Disorder diagnosis physiopathology MeSH
- Signal Processing, Computer-Assisted * MeSH
- Check Tag
- Adult MeSH
- Humans MeSH
- Male MeSH
- Female MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't 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.
- Keywords
- auditory steady-state response experiment, electrical source imaging, electroencephalography, fieldtrip, preclinical models, translational research,
- Publication type
- Journal Article MeSH
AIMS: The goal of this study was to assess the effect of independent component neurofeedback (NFB) on EEG and clinical symptoms in patients with obsessive-compulsive disorder (OCD). Subsequently, we explored predictors of treatment response and EEG correlates of clinical symptoms. METHODS: In a randomized, double-blind, parallel design, 20 inpatients with OCD underwent 25 sessions of NFB or sham feedback (SFB). NFB aimed at reducing EEG activity in an independent component previously reported abnormal in this diagnosis. Resting-state EEG recorded before and after the treatment was analyzed to assess its posttreatment changes, relationships with clinical symptoms and treatment response. RESULTS: Overall, clinical improvement in OCD patients was not accompanied by EEG change as assessed by standardized low-resolution electromagnetic tomography and normative independent component analysis. Pre- to posttreatment comparison of the trained component and frequency did not yield significant results; however, in the NFB group, the nominal values at the downtrained frequency were lower after treatment. The NFB group showed significantly higher percentage reduction of compulsions compared to the SFB group (p = 0.015). Pretreatment higher amount of delta (1-6 Hz) and low alpha oscillations as well as a lower amount of high beta activity predicted a worse treatment outcome. Source localization of these delta and high beta oscillations corresponded with previous EEG resting-state findings in OCD patients compared to healthy controls. CONCLUSION: Independent component NFB in OCD proved useful in percentage improvement of compulsions. Based on our correlation analyses, we hypothesize that we targeted a network related to treatment resistance.
- MeSH
- Adult MeSH
- Double-Blind Method MeSH
- Humans MeSH
- Young Adult MeSH
- Brain Waves physiology MeSH
- Neurofeedback physiology MeSH
- Obsessive-Compulsive Disorder diagnosis therapy MeSH
- Rest physiology MeSH
- Predictive Value of Tests * MeSH
- Treatment Outcome MeSH
- Check Tag
- Adult MeSH
- Humans MeSH
- Young Adult MeSH
- Male MeSH
- Female MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Randomized Controlled Trial MeSH
BACKGROUND: Low-frequency repetitive transcranial magnetic stimulation (LF-rTMS) diminishes auditory hallucinations (AHs). The aims of our study were a) to assess the efficacy of LF-rTMS in a randomized, sham-controlled double-blind alignment, b) to identify the electrophysiological changes accompanying the LF-rTMS, and c) to identify the influence of LF-rTMS on brain functional connectivity (FC). METHODS: Nineteen schizophrenia patients with antipsychotic-resistant AHs were randomized to either active (n = 10) or sham (n = 9) LF-rTMS administered over the left temporo-parietal region for ten days. The clinical effect was assessed by the Auditory Hallucination Rating Scale (AHRS). The localization of the differences in electrical activity was identified by standardized low resolution brain electromagnetic tomography (sLORETA) and FC was measured by lagged phase synchronization. RESULTS: AHRS scores were significantly improved for patients receiving active rTMS compared to the sham (median reduction: 40 % vs 12 %; p = 0.01). sLORETA revealed a decrease of alpha-2, beta-1,-2 bands in the left hemisphere in the active group. Active rTMS led to a decrease of the lagged phase connectivity in beta bands originating in areas close to the site of stimulation, and to a prevailing increase of alpha-2 FC. No significant differences in current density or FC were observed in the sham group. LIMITATIONS: Limitations to our study included the small group sizes, and the disability of LORETA to assess subcortical neuronal activity. CONCLUSIONS: LF-rTMS attenuated AHs and induced a decrease of higher frequency bands on the left hemisphere. The FC changes support the assumption that LF-rTMS is linked to the modulation of cortico-cortical coupling.
- Keywords
- Auditory hallucinations, EEG, Functional connectivity, LORETA, Lagged phase synchronization, Low-frequency rTMS, Schizophrenia, Source localization,
- MeSH
- Electroencephalography MeSH
- Hallucinations therapy MeSH
- Humans MeSH
- Schizophrenia * MeSH
- Transcranial Magnetic Stimulation methods MeSH
- Treatment Outcome MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Randomized Controlled Trial MeSH
BACKGROUND: Standardized low-resolution electromagnetic tomography (sLORETA) is a new quantitative EEG method for determining distribution of neuronal electrical activity in the form of three-dimensional images of current density of the cerebral cortex. Unlike standard quantitative EEG, it allows noninvasive and detailed localization of neuronal generators responsible for surface EEG with zero localization error. The study aimed at finding electrotomographic differences between patients with panic disorder who respond well to cognitive behavioral therapy (CBT) and those with an inadequate response and to determine factors predicting a response to treatment. METHODS: The study comprised 24 patients diagnosed with panic disorder with or without agoraphobia (ICD-10 F41.0). The severity of symptoms was measured with the Beck Anxiety Inventory (BAI), Beck Depression Inventory (BDI), Sheehan Anxiety Scale, subjective and objective Clinical Global Impression (CGI) and Dissociative Experiences Scale (DES). Additionally, quality of life was evaluated using the Q-LES-Q questionnaire. Based on final BAI score decreases by 25%, the patients were classified into two groups - responders and non-responders. 21-channel EEGs were recorded at baseline and after completion of therapy. Power spectra and intracortical tomography were computed by sLORETA in seven frequency bands and compared between (responders vs. non-responders) and within (pre- vs. post-treatment) groups. RESULTS: There were no differences between responders and non-responders with respect to age, gender and baseline disorder symptomatology. Statistical analysis of sLORETA values demonstrated no significant inter-group differences in the pretreatment current density distribution. After treatment, only responders showed a significant decrease of alpha-2 sources (p<0.05) in the occipital lobes and cuneus and a statistical trend for increased beta-3 sources (p<0.10) in the posterior cingulate. In non-responders, there were no statistically significant changes in sLORETA findings following therapy. CONCLUSIONS: The study failed to use pretreatment sLORETA in the prediction of therapeutic response in patients with panic disorder. However, we clearly demonstrated that only treatment response was associated with significant changes of electric neuronal activity. An analysis of demographic data suggested that duration of the disease, age, level of dissociation and employment may be considered as factors influencing the response.
- MeSH
- Analysis of Variance MeSH
- Adult MeSH
- Electroencephalography * MeSH
- Cognitive Behavioral Therapy methods MeSH
- Middle Aged MeSH
- Humans MeSH
- Brain Mapping * methods MeSH
- Young Adult MeSH
- Brain pathology physiopathology MeSH
- Panic Disorder diagnosis therapy MeSH
- Psychiatric Status Rating Scales MeSH
- Treatment Outcome MeSH
- Imaging, Three-Dimensional methods MeSH
- Check Tag
- Adult MeSH
- Middle Aged MeSH
- Humans MeSH
- Young Adult MeSH
- Male MeSH
- Female MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
BACKGROUND: The underlying symptomatology of obsessive-compulsive disorder (OCD) can be viewed as an impairment in both cognitive and behavioral inhibition, regarding difficult inhibition of obsessions and behavioral compulsions. Converging results from neuroimaging and electroencephalographic (EEG) studies have identified changes in activities throughout the medial frontal and orbital cortex and subcortical structures supporting the cortico-striato-thalamo-cortical circuit model of OCD. This study aimed to elucidate the electrophysiological changes induced by autobiographical and general anxiety scenarios in patients with OCD. METHODS: Resting-state eyes-closed EEG data were recorded in 19 OCD patients and 15 healthy controls. Cortical EEG sources were estimated by standardized low-resolution electromagnetic tomography (sLORETA). The changes in the emotional state were induced by two different scenarios: the autobiographical script related to patient's OCD symptoms and the script triggering general anxiety. RESULTS: During the resting state, we proved increased delta activity in the frontal, limbic and temporal lobe and the sub-lobar area in OCD patients. In a comparison of neural activities during general anxiety in OCD patients and the control group, we proved an increase in delta (parietal, temporal, occipital, frontal and limbic lobes, and sub-lobal area), theta (temporal, parietal and occipital lobes) and alpha-1 activities (parietal lobe). Finally, we explored the neural activity of OCD patients during exposure to the autobiographic scenario. We proved an increase in beta-3 activity (left frontal lobe). CONCLUSION: Our study proved differences in neural activation in OCD patients and healthy controls during imagination of general anxiety. Exposure to the autobiographic OCD scenario leads to activation of left frontal brain areas. The results show the possibility of using specific scenarios in OCD therapy.
- Keywords
- anxiety, autobiographical script, cognitive-behavior therapy, electroencephalography, obsessive–compulsive disorder,
- Publication type
- Journal Article MeSH
