scholarly journals Distributed source modeling of intracranial stereoelectroencephalographic measurements

2020 ◽  
Author(s):  
Fa-Hsuan Lin ◽  
Hsin-Ju Lee ◽  
Jyrki Ahveninen ◽  
Iiro P. Jääskeläinen ◽  
Hsiang-Yu Yu ◽  
...  
Keyword(s):  
Signal To Noise Ratio ◽  
Event Related Potentials ◽  
Gamma Activity ◽  
Test Case ◽  
Minimal Distance ◽  
Neural Firing ◽  
Source Modeling ◽  
Related Potentials ◽  
Source Models ◽  
Leave One Out

AbstractIntracranial stereoelectroencephalography (sEEG) provides unsurpassed sensitivity and specificity for human neurophysiology. However, sEEG group analyses are complicated because the electrode implantations differ greatly across individuals. Here, using an auditory experiment as the test case, we developed a distributed, anatomically realistic sEEG source-modeling approach for within- and between-subject analyses. In addition to intracranial event-related potentials (iERP), we also estimated the sources of high broadband gamma activity (HBBG), a putative correlate of local neural firing. The source models accounted for a significant portion of the variance of the sEEG measurements in leave-one-out cross-validation. After logarithmic transformations, the sensitivity and signal-to-noise ratio were linearly inversely related to the minimal distance between the brain location and electrode contacts (slope≈-3.6). The HGGB source estimates were remarkably consistent with analyses of intracranial-contact data. In conclusion, distributed sEEG source modeling provides a powerful neuroimaging tool, which facilitates anatomically-normalized group analyses of both iERP and HBBG.

Induced Gamma Band Deficits in Early Psychosis

2009 ◽  
Vol 24 (S1) ◽  
pp. 1-1
Author(s):  
M. Constante ◽  
M. Shaikh ◽  
I. Williams ◽  
R. Murray ◽  
E. Bramon
Keyword(s):  
Cognitive Processing ◽  
Psychotic Disorders ◽  
Event Related Potentials ◽  
Gamma Band ◽  
Early Psychosis ◽  
Gamma Activity ◽  
Total Power ◽  
Oddball Paradigm ◽  
Time Frequency ◽  
Related Potentials

Objective:Abnormalities in event related potentials (ERPs) have long been looked at as markers of disease in Schizophrenia. Over recent years there is a trend in the field to move from averaged trials ERPs analysis in the time-voltage domain, to time-frequency single trials analysis. Oscillations in the Gamma band (30-50Hz) have received particular attention in the context of the theories of core deficits in neuronal synchronization in Schizophrenia. in this study we aimed at replicating previously found Gamma band deficits in a sample of Early Psychosis patients.Methods:EEG was collected from 15 patients and 15 age matched controls using an auditory oddball paradigm. Time-frequency analysis in the Gamma band was performed using a Morlet wavelet transform. We tested differences between the groups using the Wilcoxon rank sum test, given the nonparametric nature of the data, to compare each group's average single trial Gamma power, maximizing the signal-to-noise ratio.Results:Patients with Early Psychosis showed, following target tones, a reduction in the total power of Gamma band activation (p< 0.01) as well as in induced Gamma band activation (p< 0.01). This was observed in a late latency interval at 400-500ms. the late burst of Gamma activity was not found in the frequent condition, for neither subjects group.Conclusion:The findings are compatible with previous studies suggesting deficits in the late intrinsically generated cognitive processing of auditory stimuli in Schizophrenia, already present in its early stage. They add further evidence of deficits in neuronal synchronisation in the early stages of psychotic disorders.

scholarly journals Capturing Human Perceptual and Cognitive Activities via Event-Related Potentials Measured with Candle-Like Dry Microneedle Electrodes

Micromachines ◽  
2020 ◽  
Vol 11 (6) ◽  
pp. 556
Author(s):  
Yuri Yoshida ◽  
Takumi Kawana ◽  
Eiichi Hoshino ◽  
Yasuyo Minagawa ◽  
Norihisa Miki
Keyword(s):  
Near Infrared ◽  
Signal To Noise Ratio ◽  
Cognitive Activity ◽  
Event Related Potentials ◽  
Signal To Noise ◽  
Skin Preparation ◽  
Auditory Oddball ◽  
Related Potentials ◽  
Noise Ratio ◽  
Noise Contamination

We demonstrate capture of event-related potentials (ERPs) using candle-like dry microneedle electrodes (CMEs). CMEs can record an electroencephalogram (EEG) even from hairy areas without any skin preparation, unlike conventional wet electrodes. In our previous research, we experimentally verified that CMEs can measure the spontaneous potential of EEG from the hairy occipital region without preparation with a signal-to-noise ratio as good as that of the conventional wet electrodes which require skin preparation. However, these results were based on frequency-based signals, which are relatively robust compared to noise contamination, and whether CMEs are sufficiently sensitive to capture finer signals remained unclear. Here, we first experimentally verified that CMEs can extract ERPs as good as conventional wet electrodes without preparation. In the auditory oddball tasks using pure tones, P300, which represent ERPs, was extracted with a signal-to-noise ratio as good as that of conventional wet electrodes. CMEs successfully captured perceptual activities. Then, we attempted to investigate cerebral cognitive activity using ERPs. In processing the vowel and prosody in auditory stimuli such as /itta/, /itte/, and /itta?/, laterality was observed that originated from the locations responsible for the process in near-infrared spectroscopy (NIRS) and magnetoencephalography experiments. We simultaneously measured ERPs with CMEs and NIRS in the oddball tasks using the three words. Laterality appeared in NIRS for six of 10 participants, although laterality was not clearly shown in the results, suggesting that EEGs have a limitation of poor spatial resolution. On the other hand, successful capturing of MMN and P300 using CMEs that do not require skin preparation may be readily applicable for real-time applications of human perceptual activities.

A Hybrid Optimization Method OWGWA for EEG/ERP Adaptive Noise Canceller With Controlled Search Space

2020 ◽  
Vol 11 (3) ◽  
pp. 30-48
Author(s):  
Rachana Nagal ◽  
Pradeep Kumar ◽  
Poonam Bansal
Keyword(s):  
Optimization Algorithm ◽  
Signal To Noise Ratio ◽  
Event Related Potentials ◽  
Search Space ◽  
Optimization Method ◽  
Optimization Techniques ◽  
Grey Wolf ◽  
Related Potentials ◽  
Adaptive Noise ◽  
Adaptive Noise Canceller

In this paper, a system for filtering event-related potentials/electroencephalograph is exhibited by adaptive noise canceller through an optimization algorithm, oppositional hybrid whale-grey wolf optimization algorithm (OWGWA). The OWGWA can choose the control parameters of the grey wolf algorithm utilizing whale parameters. To balance out the randomness of optimization strategies another methodology is implemented called controlled search space. Adaptive filter's noise reduction capability has been tested through adding adaptive white Gaussian noise over contaminated EEG signals at different noise levels. The performance of the proposed OWGWA-CSS algorithm is evaluated by signal to noise ratio in dB, mean value, and the relationship between resultant and input ERP. In this work, ANCs are also implemented by utilizing other optimization techniques. In average cases of noisy environment, comparative analysis shows that the proposed OWGWA-CSS technique provides higher SNR value, significantly lower mean and higher correlation as compared to other techniques.

scholarly journals In search for the most optimal EEG method: A practical evaluation of a water-based electrode EEG system

2021 ◽  
Author(s):  
M. Topor ◽  
B. Opitz ◽  
P. J. A. Dean
Keyword(s):  
Signal To Noise Ratio ◽  
Flanker Task ◽  
Low Frequency ◽  
Event Related Potentials ◽  
Event Related Potential ◽  
Specific System ◽  
Time Frequency ◽  
Beta Power ◽  
Water Based ◽  
Related Potentials

AbstractThe study assessed a new mobile electroencephalography (EEG) system with water-based electrodes for its applicability in time-frequency and event related potential research. It was compared to a standard gel-based wired system. EEG was recorded on two occasions as participants completed the flanker task, first with the gel-based system followed by the water-based system. Technical and practical considerations for the application of the new water-based system are reported based on the participant and experimenter experiences. Empirical comparisons focused on EEG data noise levels, frequency power across four bands including theta, alpha, low beta and high beta and P300 and ERN event related potential components. The water-based system registered more noise compared to the gel-based system which resulted in increased loss of data during artefact rejection. Signal to noise ratio was significantly lower for the water-based system in the parietal channels which impacted the observed parietal beta power. It also led to a shift in topography of the maximal P300 activity from parietal to frontal regions. It is also evident, that the water-based system may be prone to slow drift noise which may affect the reliability and consistency of low frequency band analyses. Considerations for the use of this specific system for time-frequency and event related potentials are discussed.

scholarly journals Prefrontal control of visual distraction

2017 ◽  
Author(s):  
Joshua D. Cosman ◽  
Geoffrey F. Woodman ◽  
Jeffrey D. Schall
Keyword(s):  
Prefrontal Cortex ◽  
Target Selection ◽  
Event Related Potentials ◽  
Relevant Information ◽  
Irrelevant Information ◽  
Sensory Cortex ◽  
Extrastriate Cortex ◽  
Neural Firing ◽  
Related Potentials ◽  
Task Irrelevant

SummaryAvoiding distraction by salient irrelevant stimuli is critical to accomplishing daily tasks. Regions of prefrontal cortex control attention by enhancing the representation of task-relevant information in sensory cortex, which can be measured directly in modulation of both single neurons and averaging of the scalp-recorded electroencephalogram [1,2]. However, when irrelevant information is particularly conspicuous, it may distract attention and interfere with the selection of behaviorally relevant information. Many studies have shown that that distraction can be minimized via top-down control [3–5], but the cognitive and neural mechanisms giving rise to this control over distraction remain uncertain and vigorously debated [6–8]. Bridging neurophysiology to electrophysiology, we simultaneously recorded neurons in prefrontal cortex and event-related potentials (ERPs) over extrastriate visual cortex to track the processing of salient distractors during a visual search task. Critically, we observed robust suppression of salient distractor representations in both cortical areas, with suppression arising in prefrontal cortex before being manifest in the ERP signal over extrastriate cortex. Furthermore, only prefrontal neurons that participated in selecting the task-relevant target also showed suppression of the task-irrelevant distractor. This suggests a common prefrontal mechanism for target selection and distractor suppression, with input from prefrontal cortex being responsible for both selecting task-relevant and suppressing task-irrelevant information in sensory cortex. Taken together, our results resolve a long-standing debate over the mechanisms that prevent distraction, and provide the first evidence directly linking suppressed neural firing in prefrontal cortex with surface ERP measures of distractor suppression.

scholarly journals Assessment of nonlinear interactions in event-related potentials elicited by stimuli presented at short interstimulus intervals using single-trial data

2015 ◽  
Vol 113 (10) ◽  
pp. 3623-3633 ◽  
Author(s):  
Charalambos Loizides ◽  
Achilleas Achilleos ◽  
Gian Domenico Iannetti ◽  
Georgios D. Mitsis
Keyword(s):  
Cognitive Processing ◽  
Fast Rate ◽  
Signal To Noise Ratio ◽  
Event Related Potentials ◽  
Additive Effects ◽  
Single Trial ◽  
Neural Basis ◽  
Statistical Framework ◽  
Related Potentials ◽  
Interstimulus Intervals

The recording of brain event-related potentials (ERPs) is a widely used technique to investigate the neural basis of sensory perception and cognitive processing in humans. Due to the low magnitude of ERPs, averaging of several consecutive stimuli is typically employed to enhance the signal to noise ratio (SNR) before subsequent analysis. However, when the temporal interval between two consecutive stimuli is smaller than the latency of the main ERP peaks, i.e., when the stimuli are presented at a fast rate, overlaps between the corresponding ERPs may occur. These overlaps are usually dealt with by assuming that there is a simple additive superposition between the elicited ERPs and consequently performing algebraic waveform subtractions. Here, we test this assumption rigorously by providing a statistical framework that examines the presence of nonlinear additive effects between overlapping ERPs elicited by successive stimuli with short interstimulus intervals (ISIs). The results suggest that there are no nonlinear additive effects due to the time overlap per se but that, for the range of ISIs examined, the second ERP is modulated by the presence of the first stimulus irrespective of whether there is time overlap or not. In other words, two ERPs that overlap in time can still be written as an addition of two ERPs but with the second ERP being different from the first. This difference is also present in the case of nonoverlapping ERPs with short ISIs. The modulation effect elicited on the second ERP by the first stimulus is dependent on the ISI value.

Split-Second Sequential Selective Activation in Human Secondary Visual Cortex

2002 ◽  
Vol 14 (1) ◽  
pp. 48-61 ◽  
Author(s):  
J. Leon Kenemans ◽  
Marijn Lijffijt ◽  
Gert Camfferman ◽  
Marinus N. Verbaten
Keyword(s):  
Spatial Frequency ◽  
Specific Activity ◽  
Event Related Potentials ◽  
Dipole Source ◽  
High Temporal Resolution ◽  
Source Modeling ◽  
Selective Activation ◽  
Location Selection ◽  
Related Potentials ◽  
Dipole Source Modeling

This work addressed early selection based on nonspatial visual features, using event-related potentials (ERPs) with high temporal resolution and dipole-source modeling. Subjects were presented rapid sequences of gratings varying in spatial frequency and orientation, and were instructed to attend to gratings with one spatial frequency and ignore those with another. Attention effects started at 120-msec latency as anterior positivity and proceeded as posterior negativity (200 msec) and anterior negativity (265 msec). Dipole-source modeling suggested that these effects reflect the sequential selective activation of, on average, posterior dorsal–medial, posterior ventral–lateral, and anterior medial cortical areas. In contrast, stimulus-specific activity was observed well before 100-msec latency and characterized by dipoles with locations significantly posterior to those of the attention-modulated activity. These results indicate that even with highly discriminable spatial frequencies, selection is not as early as before the 100-msec latency, unlike what is often found for location selection. It is also separated in time and anatomically from the earliest stimulus-specific cortical activity. Reducing discriminability of the selection feature resulted in longer selection latencies, becoming manifest only at 175 msec as an apparent combination of posterior and anterior negativities, and in an elevated criterion for overt responding.

scholarly journals A Signature of Attention-Elicited Electrocortical Activity Distinguishes Response From Non-Response to the Non-Stimulant Atomoxetine in Children and Adolescents With ADHD

2017 ◽  
Vol 23 (7) ◽  
pp. 744-753
Author(s):  
Kristi R. Griffiths ◽  
Barbora G. Jurigova ◽  
John E. Leikauf ◽  
Donna Palmer ◽  
Simon D. Clarke ◽  
...  
Keyword(s):  
Controlled Trial ◽  
Event Related Potentials ◽  
Attractive Alternative ◽  
Typically Developing ◽  
First Line ◽  
Auditory Oddball ◽  
Related Potentials ◽  
The Right ◽  
Leave One Out ◽  
Youth With Adhd

Objective: Atomoxetine has several characteristics that make it an attractive alternative to stimulants for treating ADHD, but there are currently no tests identifying individuals for whom the medication should be a first-line option. Method: Within the ADHD Controlled Trial Investigation Of a Non-stimulant (ACTION) study, we examined neuro-cortical activity in 52 youth with ADHD. Baseline event-related potentials (ERP) were compared between those who subsequently responded to 6 weeks of atomoxetine versus those who did not. Results: Responders were distinguished by significantly lower auditory oddball N2 amplitudes than both non-responders and typically developing controls, particularly in the right frontocentral region ( p = .002, Cohen’s d = 1.1). Leave-one-out cross validation determined that N2 amplitude in this region was able to accurately predict non-responders with a specificity of 80.8%. There were no P3 differences between responders and non-responders. Conclusion: The N2 amplitude is a biomarker that may have utility in predicting response to atomoxetine for youth with ADHD.

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