visual oddball paradigm
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Despite positive prior results obtained by using event-related potentials (ERPs) in psychiatric patients, they are not routinely used in the clinical setting. This may in part be due to problems regarding a lack of transportable equipment availability. It can be difficult for these patients to repeatedly visit electrophysiological laboratories. To address this issue, we propose using a new, fully portable device for visually evoked potentials (VEP) and cognitive function assessment, that can be used for quick examinations (https://www.veppeak.com). Our device, called "VEPpeak", is built into a headset with a color LED visual stimulator. It weighs 390 g and is connected to a notebook (PC) with evaluation software via USB. In this pilot study, we verified the device's usability in 31 patients with schizophrenia. We used the oddball paradigm with the recognition of colors for the P300 wave and choice reaction time evaluation. The examination lasted only about ten minutes. The results indicated good reproducibility of large cognitive potentials (P300) with prolonged P300 latencies and reduced amplitudes in patients compared to 15 control subjects. The P300 latency and reaction time prolongation in patients correlated with their age and the sedative effect of the pharmacotherapy.
Although deep brain stimulation of the subthalamic nucleus (STN-DBS) in Parkinson's disease (PD) is generally a successful therapy, adverse events and insufficient clinical effect can complicate the treatment in some patients. We studied clinical parameters and cortical oscillations related to STN-DBS to identify patients with suboptimal responses. High-density EEG was recorded during a visual oddball three-stimuli paradigm in DBS "off" and "on" conditions in 32 PD patients with STN-DBS. Pre-processed data were reconstructed into the source space and the time-frequency analysis was evaluated. We identified a subgroup of six patients with longer reaction times (RT) during the DBS "on" state than in the DBS "off" state after target stimuli. These subjects had lower motor responsiveness to DBS and decreased memory test results compared to the other subjects. Moreover, the alpha and beta power decrease (event-related desynchronizations, ERD), known as an activation correlate linked to motor and cognitive processing, was also reduced in the DBS "on" condition in these patients. A subgroup of PD patients with a suboptimal response to STN-DBS was identified. Evaluation of RT could potentially serve as a biomarker for responsiveness to STN-DBS.
- MeSH
- hluboká mozková stimulace * MeSH
- kognice MeSH
- lidé MeSH
- nucleus subthalamicus * MeSH
- Parkinsonova nemoc * terapie MeSH
- reakční čas MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
BACKGROUND: Spatial and temporal resolution of brain network activity can be improved by combining different modalities. Functional Magnetic Resonance Imaging (fMRI) provides full brain coverage with limited temporal resolution, while electroencephalography (EEG), estimates cortical activity with high temporal resolution. Combining them may provide improved network characterization. NEW METHOD: We examined relationships between EEG spatiospectral pattern timecourses and concurrent fMRI BOLD signals using canonical hemodynamic response function (HRF) with its 1st and 2nd temporal derivatives in voxel-wise general linear models (GLM). HRF shapes were derived from EEG-fMRI time courses during "resting-state", visual oddball and semantic decision paradigms. RESULTS: The resulting GLM F-maps self-organized into several different large-scale brain networks (LSBNs) often with different timing between EEG and fMRI revealed through differences in GLM-derived HRF shapes (e.g., with a lower time to peak than the canonical HRF). We demonstrate that some EEG spatiospectral patterns (related to concurrent fMRI) are weakly task-modulated. COMPARISON WITH EXISTING METHOD(S): Previously, we demonstrated 14 independent EEG spatiospectral patterns within this EEG dataset, stable across the resting-state, visual oddball and semantic decision paradigms. Here, we demonstrate that their time courses are significantly correlated with fMRI dynamics organized into LSBN structures. EEG-fMRI derived HRF peak appears earlier than the canonical HRF peak, which suggests limitations when assuming a canonical HRF shape in EEG-fMRI. CONCLUSIONS: This is the first study examining EEG-fMRI relationships among independent EEG spatiospectral patterns over different paradigms. The findings highlight the importance of considering different HRF shapes when spatiotemporally characterizing brain networks using EEG and fMRI.
- MeSH
- dospělí MeSH
- elektroencefalografie metody MeSH
- funkční zobrazování neurálních procesů metody MeSH
- lidé MeSH
- magnetická rezonanční tomografie metody MeSH
- mladý dospělý MeSH
- nervová síť diagnostické zobrazování fyziologie MeSH
- neurovaskulární vazba fyziologie MeSH
- psycholingvistika MeSH
- velký mozek diagnostické zobrazování fyziologie MeSH
- zraková percepce fyziologie MeSH
- Check Tag
- dospělí MeSH
- lidé MeSH
- mladý dospělý MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Electroencephalography (EEG) oscillations reflect the superposition of different cortical sources with potentially different frequencies. Various blind source separation (BSS) approaches have been developed and implemented in order to decompose these oscillations, and a subset of approaches have been developed for decomposition of multi-subject data. Group independent component analysis (Group ICA) is one such approach, revealing spatiospectral maps at the group level with distinct frequency and spatial characteristics. The reproducibility of these distinct maps across subjects and paradigms is relatively unexplored domain, and the topic of the present study. To address this, we conducted separate group ICA decompositions of EEG spatiospectral patterns on data collected during three different paradigms or tasks (resting-state, semantic decision task and visual oddball task). K-means clustering analysis of back-reconstructed individual subject maps demonstrates that fourteen different independent spatiospectral maps are present across the different paradigms/tasks, i.e. they are generally stable.
- MeSH
- algoritmy MeSH
- analýza hlavních komponent MeSH
- elektroencefalografie metody statistika a číselné údaje MeSH
- interpretace obrazu počítačem metody MeSH
- lidé MeSH
- magnetická rezonanční tomografie MeSH
- mapování mozku metody MeSH
- mladý dospělý MeSH
- počítačové zpracování signálu MeSH
- psychomotorický výkon fyziologie MeSH
- reprodukovatelnost výsledků MeSH
- rozhodování fyziologie MeSH
- shluková analýza MeSH
- zraková percepce fyziologie MeSH
- Check Tag
- lidé MeSH
- mladý dospělý MeSH
- mužské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
PURPOSE: The implantation of an intraocular telescope increases life quality in patients with end-stage age-related macular degeneration (AMD). The present study monitored changes in electrophysiological markers of visual processing before and during seventeen months after a novel mirror telescope implantation in two patients (OV-male 90 years, MZ-female 70 years) with the final-stage form of AMD. METHODS: Visual evoked potentials were recorded to high-contrast pattern-reversal (PR-VEP for check size 40' and 10'), low-contrast motion-onset stimuli (in visual periphery M-VEP M20°, and in central part M-VEP C8°), and event-related potentials (ERPs) in the oddball visual paradigm. RESULTS: MZ's more systematic responses showed attenuation and prolongation of the M-VEP M20° and the PR-VEP 40' immediately after the telescope implantation with a slow amplitude recovery with unchanged prolonged latency. The implantation completely eradicated the M-VEP C8° without any restoration. The PR-VEP 10' were not readable. Only a part of OV's PR-VEP 40' and M-VEP M20' were of a repeatable and expected morphology. These OV's VEPs were consistent with MZ's findings. The ERPs did not show any effect of implantation in both patients. Post-implantation visual acuity and reaction time overcame the pre-implantation levels. CONCLUSIONS: The mirror telescope preserved peripheral vision in contrast to classic telescopes; however, the telescope concurrently reduced the luminance of the magnified retinal image, which was likely responsible for the prolongation of the VEP latencies.
- MeSH
- čočky * MeSH
- lidé MeSH
- makulární degenerace * patofyziologie rehabilitace MeSH
- rozpoznávání obrazu fyziologie MeSH
- senioři nad 80 let MeSH
- senioři MeSH
- teleskopy * MeSH
- zraková ostrost MeSH
- zraková percepce fyziologie MeSH
- zrakové evokované potenciály * MeSH
- zrakové protézy * normy MeSH
- Check Tag
- lidé MeSH
- mužské pohlaví MeSH
- senioři nad 80 let MeSH
- senioři MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- kazuistiky MeSH
The manipulation of attention can produce mismatch negativity-like components that are not necessarily connected to the unintentional sensory registration of the violation of probability-based regularity. For clinical purposes, attentional bias should be quantified because it can vary substantially among subjects and can decrease the specificity of the examination. This experiment targets the role of attention in the generation of visual mismatch negativity (vMMN). The visual regularity was generated by a sequence of two radial motions while subjects focused on visual tasks in the central part of the display. Attentional load was systematically varied and had three levels, no-load, easy, and difficult. Rare, deviant, and frequent standard motions were presented with a 10/60 ratio in oddball sequences. Data from 12 subjects was recorded from 64 channels and processed. vMMN was identified within the interval of 142-198 ms. The mean amplitude was evaluated during the aforementioned interval in the parietal and fronto-central regions. A general linear model for repeated measures was applied to the mean amplitude with a three-factor design and showed a significant difference [F (1, 11) = 17.40, p = 0.002] between standard and deviant stimuli and between regions [F (1, 11) = 8.40, p = 0.01]; however, no significant effect of the task [F (2, 22) = 1.26, p = 0.30] was observed. The unintentional detection of irregularity during the processing of the visual motion was independent of the attentional load associated with handling the central visual task. The experiment did not demonstrate an effect of attentional load manipulation on mismatch negativity (MMN) induced by the motion-sequence, which supports the clinical utility of this examination. However, used stimulation paradigm should be further optimized to generate mismatch negativity that is stable enough to be usable not only for group comparisons but also for a single subject assessment.
- Publikační typ
- časopisecké články MeSH
We examined the visual and cognitive functions of a 72-year-old subject, KP, who recovered his sight after 53 years of visual deprivation. We used visual evoked potentials (VEPs) to pattern-reversal and motion-onset stimuli and cognitive responses (ERPs) during the oddball paradigm to assess the effect of long-term deprivation on a mature visual system. KP lost his sight at the age of 17 years, and light projection onto his right retina was restored at 71 years by a corneal implant. Nine months after sight recovery we recorded reproducible responses to all examined stimuli. The response to pattern reversal contained two P100-like peaks with the later peak being dominant and significantly delayed (260 ms) when compared to the P100s of two control subjects, to whom the stimuli were adjusted in size and contrast to mimic KP's vision. KP's motion-onset VEPs to full-field and peripheral stimuli had a characteristic shape with a well-defined N2 peak; however, both peaks were significantly delayed (262 and 272 ms) compared to control responses. Unlike the P100 and N2 peaks, which represent sensory detection, the P3b/P300 component of the ERP to a target event in the oddball paradigm was not further delayed. In spite of degraded vision and sensory deprivation lasting 53 years, KP displayed reproducible responses to all reported stimuli. Long-term visual deprivation and retinal detachment degraded KP's visual sensory processing, assessed by pattern-reversal and motion-onset VEPs, whereas the cognitive processing of appropriate visual stimuli was not compromised.
- MeSH
- časové faktory MeSH
- kognice fyziologie MeSH
- lidé MeSH
- obnova funkce fyziologie MeSH
- senioři MeSH
- senzorické prahy fyziologie MeSH
- slepota patofyziologie MeSH
- vnímání pohybu fyziologie MeSH
- zraková percepce fyziologie MeSH
- zrakové evokované potenciály fyziologie MeSH
- Check Tag
- lidé MeSH
- mužské pohlaví MeSH
- senioři MeSH
- Publikační typ
- časopisecké články MeSH
- kazuistiky MeSH
- práce podpořená grantem MeSH
Gender is presumed to be one of the factors causing interindividual variability in the brain's electrophysiological parameters. Our aim was to characterize the role of gender in visual evoked potentials (VEPs), event-related potentials (ERPs), visual mismatch negativity (vMMN) and the spectral characteristics of the EEG. We examined 42 healthy volunteers (21 women and 21 men, aged 20-29 years). We measured VEPs in response to pattern-reversal and motion-onset stimulation, ERPs in an oddball paradigm and vMMN in response to a combination of motion directions presented in the visual periphery. P100 peak latency for 40' reversal VEPs was significantly shorter in women than in men as determined using a non-parametric Wilcoxon signed-rank test. In addition, women showed higher relative EEG spectral power in the alpha band (p=0.023) and lower power in the theta band (p=0.004). Our results in this small but homogeneous group of subjects confirm previously reported gender influences on pattern-reversal VEPs and the EEG frequency spectrum. Gender should be taken into consideration in establishing norms on these measures. We found no statistically significant differences between women and men for any of the other stimuli presented.
The objective of our work was to find whether the subthalamic nucleus (STN) is directly involved in cognitive activities, specifically in executive functions. Ten patients with idiopathic Parkinson's disease had P3 potentials recorded by externalized deep brain electrodes that were implanted in the STN or in its immediate vicinity. Two contacts of each electrode were positioned inside the STN according to clinical effect, perioperative microrecording, and stimulation. The P3 waves were recorded following the auditory stimulus in a standard oddball paradigm. They were compared with the P3 waves elicited from a protocol modified by a dual task with an increased demand on executive functions. The P3 potentials with a steep amplitude gradient evoked by the modified protocol were detected by the contacts in 8 of the 14 available electrodes, located either inside the STN or in its immediate vicinity. The modified protocol led to an increased latency of the P3 potential in 8 of 14 electrodes. No local field potentials of the standard P3 potentials were recorded. The P3 potentials related to the increased demand on executive functions were detected by the STN contacts known to have the best effect on Parkinsonian motor signs. This could suggest that the STN takes part in the executive function processing. (c) 2007 Movement Disorder Society.
- MeSH
- antiparkinsonika škodlivé účinky MeSH
- evokované potenciály fyziologie MeSH
- financování organizované MeSH
- hluboká mozková stimulace přístrojové vybavení MeSH
- kognitivní poruchy diagnóza patofyziologie MeSH
- levodopa škodlivé účinky MeSH
- lidé středního věku MeSH
- lidé MeSH
- mikroelektrody MeSH
- neuropsychologické testy MeSH
- nucleus subthalamicus patofyziologie MeSH
- Parkinsonova nemoc farmakoterapie patofyziologie patofyziologie MeSH
- polékové dyskineze etiologie patofyziologie MeSH
- Check Tag
- lidé středního věku MeSH
- lidé MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
This study concerns the question of how task modification affects the frequency occurrence of event-related potentials (ERP) inside the active cortical areas. In 13 candidates for epilepsy surgery, 156 sites in the temporal (74), frontal (73), and parietal (9) cortices were recorded by means of depth and subdural electrodes. Four modifications of the somatosensory evoked P3-like potentials were performed; (i) an oddball paradigm with silent counting of target stimuli (P3c); (ii) an oddball paradigm with a hand movement in response to target stimuli (P3m); (iii) an S1-S2 paradigm, ERP in the P300 time window after the S2 stimulus, with silent counting of target stimuli (S2c), and (iv) an S1-S2 paradigm with a hand movement in response to target stimuli (S2m). In comparing the oddball paradigms with the S1-S2 (contingent negative variation, CNV) paradigms, four regions emerge that are significantly linked with the oddball P3; the prefrontal cortex, the cingulate, the amygdalo-hippocampal complex, and the lateral temporal cortex. A prominent role of the cingulate and the fronto-orbital cortex in the cognitive processing of movement was supported when tasks with identical cognitive loads but different required responses were compared. Even relatively simple cognitive tasks activate many cortical regions. The investigated areas were activated in all tests; however, small regions in each field were active or inactive in relation to the nature of the task. The study indicates a variable and task-dependent internal organization of a highly complex and widely distributed system of active cortical areas.
- MeSH
- dospělí MeSH
- duševní procesy fyziologie MeSH
- elektrická stimulace metody MeSH
- elektroencefalografie MeSH
- financování organizované MeSH
- kognice fyziologie MeSH
- kognitivní evokované potenciály P300 fyziologie MeSH
- kontingentní negativní variace fyziologie MeSH
- lidé MeSH
- mapování mozku MeSH
- mladiství MeSH
- mozková kůra fyziologie MeSH
- psychomotorický výkon fyziologie MeSH
- ruka fyziologie MeSH
- vztah dávky záření a odpovědi MeSH
- Check Tag
- dospělí MeSH
- lidé MeSH
- mladiství MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
