Event-related Evoked Potentials Research Articles

Recording the tactile P300 with the cEEGrid for potential use in a brain-computer interface.

Brain-computer interfaces (BCIs) are scientifically well established, but they rarely arrive in the daily lives of potential end-users. This could be in part because electroencephalography (EEG), a prevalent method to acquire brain activity for BCI operation, is considered too impractical to be applied in daily life of end-users with physical impairment as an assistive device. Hence, miniaturized EEG systems such as the cEEGrid have been developed. While they promise to be a step toward bridging the gap between BCI development, lab demonstrations, and home use, they still require further validation. Encouragingly, the cEEGrid has already demonstrated its ability to record visually and auditorily evoked event-related potentials (ERP), which are important as input signal for many BCIs. With this study, we aimed at evaluating the cEEGrid in the context of a BCI based on tactually evoked ERPs. To compare the cEEGrid with a conventional scalp EEG, we recorded brain activity with both systems simultaneously. Forty healthy participants were recruited to perform a P300 oddball task based on vibrotactile stimulation at four different positions. This tactile paradigm has been shown to be feasible for BCI repeatedly but has never been tested with the cEEGrid. We found distinct P300 deflections in the cEEGrid data, particularly at vertical bipolar channels. With an average of 63%, the cEEGrid classification accuracy was significantly above the chance level (25%) but significantly lower than the 81% reached with the EEG cap. Likewise, the P300 amplitude was significantly lower (cEEGrid R2-R7: 1.87 μV, Cap Cz: 3.53 μV). These results indicate that a tactile BCI using the cEEGrid could potentially be operated, albeit with lower efficiency. Additionally, participants' somatosensory sensitivity was assessed, but no correlation to the accuracy of either EEG system was shown. Our research contributes to the growing amount of literature comparing the cEEGrid to conventional EEG systems and provides first evidence that the tactile P300 can be recorded behind the ear. A BCI based on a thus simplified EEG system might be more readily accepted by potential end-users, provided the accuracy can be substantially increased, e.g., by training and improved classification.

Cross-modal guiding and reweighting network for multi-modal RSVP-based target detection

Rapid Serial Visual Presentation (RSVP) based Brain–Computer Interface (BCI) facilities the high-throughput detection of rare target images by detecting evoked event-related potentials (ERPs). At present, the decoding accuracy of the RSVP-based BCI system limits its practical applications. This study introduces eye movements (gaze and pupil information), referred to as EYE modality, as another useful source of information to combine with EEG-based BCI and forms a novel target detection system to detect target images in RSVP tasks. We performed an RSVP experiment, recorded the EEG signals and eye movements simultaneously during a target detection task, and constructed a multi-modal dataset including 20 subjects. Also, we proposed a cross-modal guiding and fusion network to fully utilize EEG and EYE modalities and fuse them for better RSVP decoding performance. In this network, a two-branch backbone was built to extract features from these two modalities. A Cross-Modal Feature Guiding (CMFG) module was proposed to guide EYE modality features to complement the EEG modality for better feature extraction. A Multi-scale Multi-modal Reweighting (MMR) module was proposed to enhance the multi-modal features by exploring intra- and inter-modal interactions. And, a Dual Activation Fusion (DAF) was proposed to modulate the enhanced multi-modal features for effective fusion. Our proposed network achieved a balanced accuracy of 88.00% (±2.29) on the collected dataset. The ablation studies and visualizations revealed the effectiveness of the proposed modules. This work implies the effectiveness of introducing the EYE modality in RSVP tasks. And, our proposed network is a promising method for RSVP decoding and further improves the performance of RSVP-based target detection systems.

Assessment of event-related evoked potentials and China-Wechsler intelligence scale for cognitive dysfunction in children with obstructive sleep apnea

ObjectiveTo explore the relationship between obstructive sleep apnea (OSA) and cognitive impairment by combining event-related evoked potentials (ERPs) and China-Wechsler Younger Children Scale (C-WISC) in children with sleep-disordered breathing (SDB) with vs. without OSA. MethodsThis was a retrospective case-control study of all consecutive children (n = 148) with adenoid tonsil hypertrophy between July 2017 and March 2019 at the Hospital. ResultsThe children were divided into the OSA (n = 102) and non-OSA (n = 46) groups. The apnea-hypopnea index (AHI), obstructive apnea index (OAI), and obstructive apnea-hypopnea index (OAHI) in the OSA group were elevated compared with those of the non-OSA group (all P < 0.001). The mean oxygen saturation (SaO2) and SaO2 nadir were lower in the OSA group compared with the non-OSA group (both P < 0.001). The respiratory arousal index (RAI) values in the OSA group were larger than those of the non-OSA group (P < 0.001). The P300 and N100 latencies in the OSA group were longer than those of the non-OSA group (both P < 0.001). Pearson's correlation analysis revealed correlations of the P300 peak latency with full-scale intelligence quotient (FIQ) (P < 0.001 and r = −0.527), verbal intelligence quotient (VIQ) (P < 0.001 and r = −0.448), and performance intelligence quotient (PIQ) (P < 0.001 and r = −0.515). There was a correlation between the N100 peak latency and PIQ (P = 0.026 and r = −0.183). ConclusionERPs, as an objective measurement, might help assess cognitive impairment in children with OSA.

Correlation Between Gait Perception and Autistic Traits in the General Population: A Study on Event-Related Evoked Potentials.

Previous studies have shown that people with autistic traits have difficulties in motion perception, such as human gait as depicted on a point-light display. A recent study reported that adults with autism spectrum disorders showed atypical visual event-related evoked potentials (ERPs) in response to radial optic flow. To determine the correlation between gait perception and autistic traits in the general population, the present study recorded ERPs time-locked to the onset of approaching and receding point-light walkers. ERPs were measured using an 8-channel system in 19 adults and the correlation between the ERP components and the Subthreshold Autism Trait Questionnaire (SATQ) score were assessed to quantitatively measure autistic traits in the general population. The results showed that the higher SATQ score was, the longer the latency of the ERP component for an approaching walker was. In conclusion, people with autistic traits have trouble perceiving the approach of other people.

Effects of a specially designed aerobic dance routine on mild cognitive impairment

BackgroundMild cognitive impairment (MCI) is known as a transitional stage or phase between normal aging and dementia. In addition, it is associated with an increased risk of dementia. Research has shown that moderate-intensity exercise is associated with a decreased risk of cognitive impairment. Two recent studies demonstrated that dance interventions are associated with improved cognitive function in the elderly with MCI.PurposeWe evaluated the effect of a moderate-intensity aerobic dance routine on the cognitive function in patients with MCI.Patients and methodsThis is a single-blind randomized controlled trial. Sixty MCI patients were randomized to receive either treatment (aerobic dance routine + usual care) or control (usual care only) for 3 months. All patients received usual care for an additional 3 months thereafter. The aerobic dance routine was a specially designed dance routine which involved cognitive effort for patients to memorize the complex movements. Wechsler memory scale-revised logical memory (WMS-R LM) and event-related evoked potentials (ERPs) P300 latency were used to assess patients’ cognitive function at baseline, 3 months, and 6 months.ResultsTwenty-nine patients received exercise therapy and 31 patients received usual care. Patients in the treatment group showed a greater improvement in memory (difference in WMS-R LM changes over 3 months 4.6; 95% CI 2.2, 7.0; p<0.001) and processing speed (difference in P300 latency changes over 6 months −20.0; 95% CI=−39.5, −0.4; p<0.05) compared to control.ConclusionThis dance routine improves cognitive function, especially episodic memory and processing speed, in MCI patients and merits promotion in communities.

Do Event-Related Evoked Potentials Reflect Apathy Tendency and Motivation?

Apathy is a mental state of diminished motivation. Although the reward system as the foundation of the motivation in the human brain has been studied extensively with neuroimaging techniques, the electrophysiological correlates of motivation and apathy have not been fully explored. Thus, in 14 healthy volunteers, we examined whether event-related evoked potentials (ERP) obtained during a simple number discrimination task with/without rewards reflected apathy tendency and a reward-dependent tendency, which were assessed separately using the apathy scale and the temperament and character inventory (TCI). Participants were asked to judge the size of a number, and received feedback based on their performance in each trial. The P3 amplitudes related to the feedback stimuli increased only in the reward condition. Furthermore, the P2 amplitudes related to the negative feedback stimuli in the reward condition had a positive correlation with the reward-dependent tendency in TCI, whereas the P3 amplitudes related to the positive feedback stimuli had a negative correlation with the apathy score. Our result suggests that the P2 and P3 ERPs to reward-related feedback stimuli are modulated in a distinctive manner by the motivational reward dependence and apathy tendency, and thus the current paradigm may be useful for investigating the brain activity associated with motivation.

98. Correlations between P300, MRI parameters and neuropsychological tests in multiple sclerosis patients

We aimed to evaluate the correlations among event-related evoked potentials (ERPs), neuropsychological and neuroradiological parameters in multiple sclerosis (MS) patients. We studied 10 patients with definite MS (6 males, 4 females, average age 43.6, SD = 11.3), and moderate disability (EDSS 2.85, SD = 1.45; range: 1.0–6.0). All patients underwent standardized neuropsychological tests, P300 evoked potentials study, and MRI. Registration of ERPs (P300) was performed by random double auditory discrimination task paradigm, recorded through scalp electrodes placed at Fz, Cz and Pz and linked to the referred ears. Pearson bivariate correlation test was used to evaluate correlations among latency and amplitude of P300, neuropsychological tests, clinical (age, EDSS, illness length, relapses), and MRI (cortical atrophy, Apparent Diffusion Coefficient – ADC-maps) parameters. In our small series, latency of P300 was related to ADC of corticospinal tracts (p = 0.001) and illness length (p = 0.001), while no clear correlation between P300 and neuropsychological or other clinical parameters was found. We suggest that P300 and MRI ADC maps could be combined to give a numerical indirect parameter of disease progression.

Cortical event-related potentials in Alzheimer's disease and frontotemporal lobar degeneration

BackgroundThe aim of the present study was to evaluate changes in event-related evoked potentials (ERPs) in patients with Alzheimer's disease (AD) and frontotemporal lobar degeneration (FTLD).Methods: A total of 42AD patients, 29 behavioral variant frontotemporal dementia (bvFTD) patients, and 30 healthy controls were examined. The subjects underwent neuropsychological tests and cognitive (N200 and P300) ERP examination. The amplitudes and latencies of the cortical potentials were compared among AD and bvFTD patients and control subjects. ResultsNo differences in the ERP latencies and amplitudes for the N200 component were observed among the groups. AD patients exhibited significantly longer latencies of P300 at both Pz (p=0.002) and Cz (p=0.007) compared with the controls. Patients with bvFTD displayed longer P300 latencies at Pz (p=0.046) and a smaller amplitude at both Pz (p=0.000) and Cz (p=0.23) than the controls. ConclusionsThe results of the present study confirm the relevance of ERPs in evaluating cognitive disorders. These non-invasive examinations have the potential to contribute to the diagnosis of AD and bvFTD.

Who Are the True Fans? Evidence from an Event-Related Potential Study

Fans of celebrities commonly exist in modern society. Researchers from social science have been concerned with this problem for years. Furthermore, such researchers have attempted to measure people’s involvement with celebrities in various ways. However, no study measured the degree of addiction to a specific celebrity at the neurological level. Therefore, the current study employed visually evoked event related potentials (ERPs) to examine people’s attitude toward celebrities by comparing different brain activities of fans and non-fans when they were shown a set of photos. These photos include a specific celebrity, a familiar person, a stranger and a butterfly. Furthermore, to examine the validity of the detected neural index, we also investigated the correlation between brain activity and the score of the Celebrity Attitude Scale (CAS), which was a questionnaire used to explore people’s attitude toward celebrities at behavioral level. Two groups of subjects were asked to complete an implicit task, i.e., to press a button when a picture of a butterfly appeared. Results revealed that fans showed significant positive N2 and P300 deflection when viewing the photos of their favorite celebrity, whereas in the non-fan group, the subjects only showed larger P300 amplitude as a response to the celebrity’s photos. Furthermore, a positive correlation between P300 amplitude elicited by the stimuli of a celebrity face and CAS scores was also observed. These findings indicated fan attitude to a specific celebrity can also be observed at the neurological level and suggested the potential utility of using ERP component as an index of fandom involvement.

An ERP-based BCI using an oddball paradigm with different faces and reduced errors in critical functions.

Recent research has shown that a new face paradigm is superior to the conventional "flash only" approach that has dominated P300 brain-computer interfaces (BCIs) for over 20 years. However, these face paradigms did not study the repetition effects and the stability of evoked event related potentials (ERPs), which would decrease the performance of P300 BCI. In this paper, we explored whether a new "multi-faces (MF)" approach would yield more distinct ERPs than the conventional "single face (SF)" approach. To decrease the repetition effects and evoke large ERPs, we introduced a new stimulus approach called the "MF" approach, which shows different familiar faces randomly. Fifteen subjects participated in runs using this new approach and an established "SF" approach. The result showed that the MF pattern enlarged the N200 and N400 components, evoked stable P300 and N400, and yielded better BCI performance than the SF pattern. The MF pattern can evoke larger N200 and N400 components and more stable P300 and N400, which increase the classification accuracy compared to the face pattern.

Event related evoked potentials in pregnancies complicated with preeclampsia

Background and Aim: Preeclampsia is the most significant cause of neurocognitive disturbances in pregnancy. These symptoms may persist for many years after the index pregnancy even if the somatic symptoms of preeclampsia disappear. In the present study, we have assessed the early cognitive changes in preeclamptic females with the help of event related evoked potentials (EREPs). Methods: EREPs were recorded in 20 diagnosed patients of preeclampsia with the help of computerized evoked potential recorder using the standard auditory 'oddball' paradigm. An equal number of age and gestation matched healthy pregnant females served as controls. The latencies and amplitudes of different waves of EREPs in both the groups were analyzed by using student's unpaired T-test. Correlation of P3 (main tool for cognition assessment) with blood pressure parameters was done by using Pearson's correlation coefficient. Results: Latencies of waves N 2 and P 3 from frontal, central and parietal ( FzA 1 A 2 , CzA 1 A 2, and PzA 1 A 2 , respectively) were found to be significantly delayed in preeclamptic females when compared to their normal contemporizes. Neither latencies nor amplitudes of P 3 were found to be significantly correlated with systolic blood pressure, diastolic blood pressure, or mean arterial pressure. Conclusion: Our results conclude that there are cognitive disturbances during the preeclamptic pregnancy. Prolonged latencies of EREP waves indicate that the cognitive functions such as information discrimination and reaction take longer time in preeclamptic patients when compared to their normal counterparts. This could be an electrophysiological manifestation of future memory loss in patients having preeclampsia.

126. P300 and early Multiple Sclerosis: A study on 11 patients

The role of event-related evoked potentials (ERPs) in multiple sclerosis (MS) is controversial. Previously we found P300 abnormalities (increased latency and lower amplitude) related with attention and executive functions in advanced MS patients. Our aim was to evaluate possible impairment of P300 in early stages of disease related to cognitive dysfunctions. We recruited 11 patients (mean age 33.5 ± 8.1 years, EDSS 2 ± 1.1). Registration of ERPs was performed by random double auditory discrimination task paradigm and recorded through scalp electrodes placed at Fz, Cz and Pz and linked to the referred ears. RAO battery was used to examine patients cognitive functions. Spearman test was used to evaluate correlation between neurophysiologic and neuropsychological parameters. No significant change in P300 parameters compared to reference values of our laboratory normalized to age and gender stratified population. Neuropsychological Tests showed mild alterations in procedural memory and attention functions not statistically correlating with a non significant reduction in amplitude of P300 in only 2 cases. Despite the limited MS-cohort we find it useful to undergo ERP and neuropsychological tests in MS early phases to identify subclinical cognitive impairment possibly present in a small percentage of cases.

Ageing affects brain activity in highly educated older adults: An ERP study using a word-stem priming task

In this event-related evoked potentials (ERP) study, the neural correlates of a group of highly educated older adults were compared with those of a group of young adults while performing a word-stem completion priming task under semantic and lexical encoding conditions. The results revealed that both age groups exhibited robust priming. The older participants showed better performance than the young adults. Both groups exhibited ERP repetition effects at posterior sites, but only the older adults showed additional frontal activity. The results suggest that highly performing older adults compensate for their lower level of parieto-occipital functioning, reflected by smaller P300 amplitude at posterior sites, by recruiting frontal sites as a mode of brain adaptation.

Cognitive mechanism for meaning of emotive words in depressed personality: an event-related potential study.

We investigated the relationship between the ERP modulation of emotive words and the depression score in thirty-five healthy subjects with both high and low Beck Depression Inventory scores. The event-related evoked potentials (ERP) were measured following a visual presentation of emotive adjectives. Each word was classified into two sets of categories by each subject, i.e., positive or negative, and fit or unfit to his/her personality. The ERP signals were then separately averaged according to the subject's classifications. After stimulation, positive and negative ERP components at 200 ms (P2) and 400 ms (N2), respectively, were enhanced in amplitude in subjects with a high depression score. The enhancement of the P2 and N2 components was not related to the subject's categorization of the words. The results suggest that hypersensitivity to non-specific emotive words might be a neurophysiological phenomenon in a depressive state in healthy subjects.

Impaired novelty processing in apathy after subcortical stroke.

Apathy is associated with decreased novelty-seeking behaviors and is a prevailing behavioral symptom after stroke affecting cortical and subcortical regions. We studied the relationship between apathetic state after subcortical stroke and neural orienting response to novel events using an event-related evoked potential (ERP) technique. Twenty-nine patients with subcortical ischemic stroke were grouped according to whether they showed apathy or not. We analyzed apathy state scaled by the modified Starkstein apathy score and auditory P3 ERP components evoked by task-relevant target stimuli (target P3) and task-irrelevant novel stimuli (novelty P3). The apathetic group showed a significantly lower score of verbal fluency test and global cognitive function test compared with the nonapathetic group. The novelty P3 latency was significantly prolonged, and its amplitude was reduced over the frontal site in the apathy group. The apathy scale was correlated with the novelty P3 latency and amplitude at the frontal site. The target P3 measures were related to global cognitive function. The present study suggests that apathy after subcortical stroke is associated with impaired neural processing of novel events within the frontal-subcortical system and that the novelty P3 is a useful physiological measure for assessing apathy after stroke.

The impact of transcranial magnetic stimulation on cognitive processing: an event-related potential study.

Several neuropsychological studies have shown that repetitive transcranial magnetic stimulation (rTMS) can improve cognitive processing. We performed a study on the impact of rTMS on cognitive processing as measured by a neurophysiological method. In 14 healthy subjects, visually evoked event-related potentials (ERP) and mean choice reaction time were measured before and after 20 Hz rTMS of the left and of the right prefrontal cortex. The data were compared to sham stimulation and to 1 Hz single TMS. P3 latencies and reaction time were significantly decreased by rTMS of the left but not of the right prefrontal cortex, single TMS did not have any significant impact on the ERP components. We conclude that the facilitating effects of rTMS on cognitive processing can be proven even by objective neurophysiological measures.

Effect of ketamine on the neuromagnetic mismatch field in healthy humans

Mismatch negativity (MMN) is a component of the auditory evoked event-related potentials (ERP) that assesses automatic sound change detection and is disturbed in schizophrenic patients. Animal experimental evidence has linked the generation of MMN to the N-methyl- d-aspartate (NMDA) receptor. We investigated the neuromagnetic mismatch field (MMF) in healthy volunteers before and after intravenous application of a subanesthetic dose of the NMDA receptor antagonist ketamine (0.3 mg/kg). Ketamine had a significant influence on latency and dipole moment of the MMF, whereas the N100m latency of the standard tone was not prolonged and its dipole moment remained stable. Our results suggest that ketamine interferes with aspects of preattentive information processing and is in line with the view that disturbed NMDA receptor function may mediate the deficient auditory mismatch response in patients with schizophrenia.

The impact of ergotamine-induced headache and ergotamine withdrawal on information processing.

Ergotamine abuse and subsequent ergotamine-induced headache is a common problem in the pharmacological treatment of migraine and other headache types; often, withdrawal therapy is necessary. This study investigated whether ergotamine abuse affects information processing and whether withdrawal therapy can lead to an improvement of information processing. We designed a standardized neurophysiological retrospective (ergotamine abuse) and prospective (ergotamine withdrawal) study in a supraregional headache outpatient clinic. Seventy-one patients abusing ergotamine derivatives with subsequent daily headache were enrolled and compared to 36 migraine patients without ergotamine intake and 36 healthy subjects. Information processing was evaluated by latencies and amplitudes of visually evoked event-related potentials (ERP) before and after ergotamine withdrawal therapy. P3 latency of the ERP was significantly increased in ergotamine abuse (442 +/- 45 ms) versus migraine (415 +/- 40 ms) and healthy subjects (410 +/- 33 ms), there was no difference between ergotamine tartrate and dihydroergotamine abuse. The migraine specific loss of habituation in information processing as measured by P3 latency could not be observed in migraine patients with ergotamine abuse. After successful withdrawal therapy in 36 patients, the abnormally prolonged P3 latency was significantly shortened (452 +/- 47 ms versus 433 +/- 30 ms; P < 0.004). Our findings imply that information processing is impaired by ergotamine abuse and can be improved but not normalized after withdrawal therapy. Furthermore, our data provide strong evidence that ergotamine, besides its peripheral effects, has a central mode of action.

Neuropsychological investigations and event-related potentials in obstructive sleep apnea syndrome before and during CPAP-therapy.

Patients with obstructive sleep apnea syndrome (OSAS) suffer from daytime sleepiness and a decline of cognitive functions. The study evaluated whether special cognitive disabilities predominate in OSAS. Besides the number connection test (ZVT), judging information processing and working velocity, computer-assisted (Wiener Testsystem and Zimmermann Testbatterie) neuropsychological testing was performed in 31 OSAS patients (50.1 +/- 9.4 years) before starting nasal continuous positive airway pressure (nCPAP) therapy. Identical test battery was performed in 10 male healthy volunteers (48 +/- 9.9 years). In addition visual evoked event-related potentials (ERPs) were recorded, the P3-component was evaluated. Impairment of alertness (P < 0.001), selective attention (P < 0.001) and continuous attention (P < 0.001) could be revealed, vigilance was not altered. Cognitive deficits were correlated with the degree of nocturnal hypoxemia. They were not linked to the apnea/hypopnea-index (AHI), arousal index or vigilance parameters. During 6 months of nCPAP-therapy (15 patients) alertness and continuous attention improved significantly (P < 0.01), intra-individual different pathological results persisted however. P3 latencies also remained prolonged. Chronic intermittent nocturnal hypoxemia in OSAS-patients obviously leads to cognitive deficits. ERP partially generated in subcortical cerebral structures represent a neurophysiological tool indicating brain dysfunction which cannot be evaluated by neuropsychological tests. Objective neuropsychological testing is needed in revealing therapeutic effects in OSAS-patients. Remaining deficits during sufficient nCPAP-therapy may reflect irreversible hypoxic cerebral damage.

Contributions of the Dopaminergic System to Voluntary and Automatic Orienting of Visuospatial Attention

Visuospatial attention can be directed by voluntary or involuntary control independent of eye movement. The involvement of cortical and subcortical neural structures in this covert orienting mechanism has been studied using neuroimaging and electrophysiological techniques. This study was designed to investigate the role of the dopaminergic system in both voluntary and automatic orienting mechanisms of visuospatial attention. We recorded event-related evoked potentials (ERPs) and reaction time (RT) during a cued priming task in both patients with idiopathic Parkinson's disease (PD) and control subjects. Voluntary and automatic shifts in attention were studied by using central and peripheral cues, respectively. In the experiment using a central cue, the RT data showed that when the cue-target interval was long, PD patients' responses were delayed, and cue validity effects were reduced, whereas in the peripheral cue experiment the validity effects persisted across all trials. The ERPs demonstrated reduced sustained negativities preceding the imperative targets in both the central and peripheral cue experiments in PD patients. Furthermore, during the long cue-target interval in the central cue experiment, PD patients showed reduced attention shift-related negativities (ARNs) at the anterior scalp sites, whereas ARNs were generated widely in the peripheral cue experiment. The ERP findings were consistent with the RT data. These findings suggest that the dopaminergic system may contribute to voluntary and sustained control of visuospatial attention as well as to the neural system for response preparation, whereas automatic control of visuospatial attention is relatively independent of the dopamine system.