Event-related potentials in clinical research: guidelines for eliciting, recording, and quantifying mismatch negativity, P300, and N400

Using eye-tracking and EEG to study the mental processing demands during learning of text-picture combinations

Using and combining eye-tracking and EEG frequency band power as process measures, in the current study we were interested in the mental processing demands during learning of text-picture combinations that either enabled or prohibited text-picture integration (TPI). In the mismatch condition, the textual and pictorial information being dissimilar, TPI was not possible, whereas in the match and the partial-match condition, the textual and pictorial information being identical respective complementary, TPI was possible. We expected mental processing demands to be higher in the mismatch condition, when pictorial and textual information had to be processed and memorized as separate representations, compared to the match and partial-match conditions when TPI was possible. As expected, on virtually all process measures we observed increased mental processing demands when two mental representations had to be processed and memorized compared to the two conditions where TPI was possible. The EEG alpha and theta frequency band power data corroborated and extended the eye-tracking measures of mental processing demands. In addition, we performed a fixation-related EEG frequency band power analysis that also corroborated the results of the classic stimulus-locked EEG frequency band power analysis, exemplifying the use of this former methodology in the context of complex multimedia task materials.

Individual Differences in Peripheral Hearing and Cognition Reveal Sentence Processing Differences in Healthy Older Adults

When viewed cross-sectionally, aging seems to negatively affect speech comprehension. However, aging is a heterogeneous process, and variability among older adults is typically large. In this study, we investigated language comprehension as a function of individual differences in older adults. Specifically, we tested whether hearing thresholds, working memory, inhibition, and individual alpha frequency would predict event-related potential amplitudes in response to classic psycholinguistic manipulations at the sentence level. Twenty-nine healthy older adults (age range 61-76 years) listened to English sentences containing reduced relative clauses and object-relative clauses while their electroencephalogram was recorded. We found that hearing thresholds and working memory predicted P600 amplitudes early during reduced relative clause processing, while individual alpha frequency predicted P600 amplitudes at a later point in time. The results suggest that participants with better hearing and larger working memory capacity simultaneously activated both the preferred and the dispreferred interpretation of reduced relative clauses, while participants with worse hearing and smaller working memory capacity only activated the preferred interpretation. They also suggest that participants with a higher individual alpha frequency had a higher likelihood of successfully reanalysing the sentence toward the reduced relative clause reading than participants with a lower individual alpha frequency. By contrast, we found no relationship between object-relative clause processing and working memory or hearing thresholds. Taken together, the results support the view that older adults employ different strategies during auditory sentence processing dependent on their hearing and cognitive abilities and that there is no single ability that uniformly predicts sentence processing outcomes.

Dopaminergic modulation of novelty repetition in Parkinson's disease: A study of P3 event-related brain potentials

OBJECTIVE

Parkinson's Disease (PD) is a neurodegenerative disease caused by the loss of dopaminergic neurons. Cognitive impairments have been reported using the event-related potential (ERP) technique. Patients show reduced novelty P3 (nP3) amplitudes in oddball experiments, a response to infrequent, surprising stimuli, linked to the orienting response of the brain. The nP3 is thought to depend on dopaminergic neuronal pathways though the effect of dopaminergic medication in PD has not yet been investigated.

METHODS

Twenty-two patients with PD were examined "on" and "off" their regular dopaminergic medication in a novelty 3-stimulus-oddball task. Thirty-four healthy controls were also examined over two sessions, but received no medication. P3 amplitudes were compared throughout experimental conditions.

RESULTS

All participants showed sizeable novelty difference ERP effects, i.e. n_dP3 amplitudes, during both testing sessions. An interaction of diagnosis, medication and testing order was also found, indicating that dopaminergic medication modulated n_dP3 in patients with PD across the two testing sessions: We observed enhanced n_dP3 amplitudes from PD patients who were off medication on the second testing session.

CONCLUSION

Patients with PD 'off' medication showed ERP evidence for repetition-related enhancement of novelty responses. Dopamine depletion in neuronal pathways that are affected by mid-stage PD possibly accounts for this modulation of novelty processing.

SIGNIFICANCE

The data in this study potentially suggest that repetition effects on novelty processing in patients with PD are enhanced by dopaminergic depletion.

Cognitive Event-Related Potentials-The P300 Wave Is a Prognostic Factor of Long-Term Disability Progression in Patients With Multiple Sclerosis

PURPOSE

Multiple sclerosis (MS) is a chronic disorder with a variable course. The aim of our study was to find out whether cognitive event-related potentials are prognostic for patient disability at the 15-year follow-up.

METHODS

In the observed cohort of patients with MS, we examined the event-related potentials at baseline (2003). Functional status (Expanded Disability Status Scale score) was then assessed 15 years later, and the prognostic model was developed using binary logistic regression analysis. The independent variables included demographic (age, sex, and education), clinical (disability in 2003), radiologic (MRI lesion load), and event-related potentials parameters. The prognostic accuracy of the proposed model was evaluated by calculating the area under the receiver-operating characteristics curve.

RESULTS

The study sample consisted of 85 patients with MS. The mean age was 35.5 (SD, 11.2) years, and the median disability score was 3.0 (1-7) in 2003 and 5.0 (1.5-9.5) in 2018. The significant prognostic factors of poor Expanded Disability Status Scale are higher baseline Expanded Disability Status Scale, longer MS duration, and prolonged P300 latency. The sensitivity and specificity of the cutoff at 5.0 for the disability score were 94% and 89%, respectively, with the area under the receiver-operating characteristics curve 0.94 (95% confidence interval, 0.889-0.984; P < 0.001).

CONCLUSIONS

The results show that out of event-related potentials, the P300 wave latency is a prognostic of long-term disability progression in patients with MS.

Long-term Effects of Unilateral and Bilateral Otitis Media and Myringotomy on Long-Latency Verbal and Non-Verbal Auditory-Evoked Potentials

Introduction  Otitis media (OM) is considered one of the most common reasons patients seek medical care in childhood. The fluctuating nature of hearing loss in cases of OM leads to irregular sound stimulation of the central auditory nervous system. Objectives  To analyze the long-latency auditory-evoked potential (LLAEP) by verbal and nonverbal sounds in children with a history of OM in the first six years of life. Methods  A total of 106 schoolchildren participated in the study, 55 females and 51 males, aged between 8 and 16 years, who were divided into 3 groups: the control group (CG), the bilateral experimental group (BEG), and the unilateral experimental group (UEG). All children underwent a complete audiological evaluation (audiometry, logoaudiometry and immitance testing) and an electrophysiological evaluation (LLAEP with toneburst stimulus - LLAEP-TB, and LLAEP with speech stimulus - LLAEP-S). Results  Both study groups (BEG and UEG) presented a statistically lower performance ( p  < 0.005) when compared with the CG regarding all of the electrophysiological tests with the prolongation of the latency values and decrease in the amplitude values: LLAEP-TB (BEG: latency - N1, P2, N2 [females] and P300, amplitude - N1 and P2), LLAEP-S (BEG: latency - P2 and N2 [females], amplitude - P2 /UEG: latency - P2 and P300, amplitude: N1 and P2). Conclusion  Children who had suffered secretory OM in the first six years of life and who had undergone myringotomy for the placement of a ventilation tube, either unilaterally or bilaterally, presented worse performance in their electrophysiological responses to verbal and nonverbal LLAEPs.

Computer-assisted reading intervention for children with hearing impairment using cochlear implants: Effects on auditory event-related potentials and mismatch negativity

OBJECTIVES

The primary aim was to find out whether a computer-assisted reading intervention program with a phonic approach can affect event-related (ERPs) and mismatch negativity (MMN) in hearing impaired (HI) children using cochlear implants (CIs).

METHODS

This study involved a test group of 15 HI children with CIs and a control group of 14 normal hearing (NH) children. The children were 4 years and 10 months to 8 years and 1 month old. ERPs were recorded immediately before and after 4 weeks of training with a computer-assisted reading intervention, GraphoGame. A multi-feature paradigm, Optimum-1, was used, i.e. a standard stimulus alternated with five different deviants: gap intensity, pitch, location and duration. MMN was calculated from the mean amplitude ERP of each deviant minus the standard stimulus response in a specific time interval, 80 - 224 ms. Repeated measures ANOVA was used for the statistical analysis.

RESULTS

The results did not show any significant changes with the computerassisted training in the ERPs and MMNs among the HI children with CIs. The presence of both MMN and a positive mismatch response (pMMR), which might reflect an immaturity, complicates interpreting the results in this age group. Individually, there was a mix of MMNs and pMMRs among all participants, pre and post training, and the change of each deviant after intervention was not predictable.

CONCLUSIONS

There are no significant changes in ERP or MMN after intervention, however lack of significances must be interpreted with caution. Besides the presence of both MMNs and pMMRs, only modest changes are to be expected on an individual basis and small samples hinder making statistical conclusions regarding the training's effects. The study contributes to some more descriptive pieces of ERPs and MMNs among the HI children with CIs. The issues of MMN and pMMR are highlighted.

Trajectories of Mismatch Negativity and P3a Amplitude Development From Ages 9 to 16 Years in Children With Risk Factors for Schizophrenia

BACKGROUND

Mismatch negativity (MMN) and P3a amplitude reductions are robust abnormalities of sensory information processing in schizophrenia, but they are variably present in different profiles of risk (family history vs. clinical high risk) for the disorder. This study aimed to determine whether these abnormalities characterize children presenting replicated risk factors for schizophrenia, using longitudinal assessment over the ages of 9-16 years in children with multiple replicated antecedents of schizophrenia (ASz) and with family history of schizophrenia (FHx), relative to typically developing (TD) peers.

METHODS

A total of 105 children (52 female) sampled from the community were assessed at ages 9-12 years and approximately 2 and 4 years later. Linear mixed models were fitted to MMN and P3a peak amplitudes and latencies, with intercept and slope estimates from 32 ASz and 28 FHx children compared with those of 45 TD peers.

RESULTS

In ASz relative to TD children, MMN amplitude initially increased and then prominently decreased during adolescence. Both ASz and FHx children had greater P3a amplitude than TD children at 11 years, which decreased with age, in contrast to P3a amplitude increasing during adolescence in TD youths. MMN abnormalities were specific to ASz children who continued to present symptoms during follow-up.

CONCLUSIONS

Age-dependent MMN and P3a abnormalities demarcate adolescent development of ASz and FHx from TD children, with auditory change detection abnormalities specific to ASz children with continuing symptoms and attention-orienting abnormalities characterizing both ASz and FHx risk profiles. Follow-up is required to determine whether these abnormalities index vulnerability for schizophrenia or an illness nonspecific developmental delay.

Splitting event-related potentials: Modeling latent components using regression-based waveform estimation

Event-related potentials (ERPs) provide a multidimensional and real-time window into neurocognitive processing. The typical Waveform-based Component Structure (WCS) approach to ERPs assesses the modulation pattern of components-systematic, reoccurring voltage fluctuations reflecting specific computational operations-by looking at mean amplitude in predetermined time-windows. This WCS approach, however, often leads to inconsistent results within as well as across studies. It has been argued that at least some inconsistencies may be reconciled by considering spatiotemporal overlap between components; that is, components may overlap in both space and time, and given their additive nature, this means that the WCS may fail to accurately represent its underlying latent component structure (LCS). We employ regression-based ERP (rERP) estimation to extend traditional approaches with an additional layer of analysis, which enables the explicit modeling of the LCS underlying WCS. To demonstrate its utility, we incrementally derive an rERP analysis of a recent study on language comprehension with seemingly inconsistent WCS-derived results. Analysis of the resultant regression models allows one to derive an explanation for the WCS in terms of how relevant regression predictors combine in space and time, and crucially, how individual predictors may be mapped onto unique components in LCS, revealing how these spatiotemporally overlap in the WCS. We conclude that rERP estimation allows for investigating how scalp-recorded voltages derive from the spatiotemporal combination of experimentally manipulated factors. Moreover, when factors can be uniquely mapped onto components, rERPs may offer explanations for seemingly inconsistent ERP waveforms at the level of their underlying latent component structure.

Direct antivirals and cognitive impairment in hepatitis C: a clinical-neurophysiologic study

Cognition was assessed in hepatitis C virus (HCV) patients, who did not meet the criteria for a minimal hepatic encephalopathy. Their liver function was compensated. We then disentangled potential cognitive changes associated with a sustained virologic response at 12 weeks (SVR-12), following treatment with direct antiviral agents (DAAs). We studied 23 selected HCV patients with a battery of standard neuropsychological tests, and with recordings of the P300 wave, a cerebral potential of “cognitive” significance. There was a baseline evaluation (T0) and a second one 6 months later (T1). We had 2 control groups of comparable age and sex, i.e., 15 patients suffering from non-alcoholic fatty liver disease (NAFLD) and 15 healthy subjects. At T0, we detected a significant (p < 0.05) cognitive impairment in the HCV group, which involved episodic and working memory, attention, visuospatial and verbal abilities, executive functions, and logic reasoning. The P300 latency was significantly (p < 0.05) delayed in the group. At T1, we observed some significant (p < 0.05) HCV recovery in given test domains, e.g., memory, executive functions, and reasoning. Accordingly, the P300 latency shortened significantly (p < 0.05). HCV patients exhibited subtle cognitive defects, somehow independent of their liver condition, possibly linked to direct or indirect brain involvement by the virus. These defects partly recovered following the SVR-12, as achieved through DAAs. The P300 wave was a valid neurophysiologic counterpart of these changes. DAAs can have a role in the early preservation of cognition in HCVs.

Symptoms of depersonalisation/derealisation disorder as measured by brain electrical activity: A systematic review

Depersonalisation/derealisation disorder (DPD) refers to frequent and persistent detachment from bodily self and disengagement from the outside world. As a dissociative disorder, DPD affects 1-2 % of the population, but takes 7-12 years on average to be accurately diagnosed. In this systematic review, we comprehensively describe research targeting the neural correlates of core DPD symptoms, covering publications between 1992 and 2020 that have used electrophysiological techniques. The aim was to investigate the diagnostic potential of these relatively inexpensive and convenient neuroimaging tools. We review the EEG power spectrum, components of the event-related potential (ERP), as well as vestibular and heartbeat evoked potentials as likely electrophysiological biomarkers to study DPD symptoms. We argue that acute anxiety- or trauma-related impairments in the integration of interoceptive and exteroceptive signals play a key role in the formation of DPD symptoms, and that future research needs analysis methods that can take this integration into account. We suggest tools for prospective studies of electrophysiological DPD biomarkers, which are urgently needed to fully develop their diagnostic potential.

Stimulus-specific regulation of visual oddball differentiation in posterior parietal cortex

The frequency at which a stimulus is presented determines how it is interpreted. For example, a repeated image may be of less interest than an image that violates the prior sequence. This process involves integration of sensory information and internal representations of stimulus history, functions carried out in higher-order sensory areas such as the posterior parietal cortex (PPC). Thus far, there are few detailed reports investigating the single-neuron mechanisms for processing of stimulus presentation frequency in PPC. To address this gap in knowledge, we recorded PPC activity using 2-photon calcium imaging and electrophysiology during a visual oddball paradigm. Calcium imaging results reveal differentiation at the level of single neurons for frequent versus rare conditions which varied depending on whether the stimulus was preferred or non-preferred by the recorded neural population. Such differentiation of oddball conditions was mediated primarily by stimulus-independent adaptation in the frequent condition.

Eye blink rate increases as a function of cognitive load during an auditory oddball paradigm

Previous evidence suggests that changes in spontaneous eye blink rate (EBR) in human adults might reflect the amount of attentional demand (i.e. cognitive load) during cognitive tasks. However, the actual direction of this relation is uncertain, since most studies investigated the role of cognitive load on EBR by employing visual tasks only. Here we aimed at elucidating the relationship between EBR and cognitive load in non-visual tasks. Sixteen healthy participants performed two auditory oddball tasks, i.e. passive listening to auditory tones versus active counting of target tones; each oddball task was immediately followed by a rest phase. Throughout the oddball tasks we assessed EBR and recorded the P300 on ERPs as an electrophysiological measure of attention. The results showed that participants' EBR increased during the active task compared to the respective rest phase. Amplitude and latency of the P300 too differed between passive and active tasks, but changes in EBR and P300 features were not correlated with each other. Our findings demonstrated that an increase in cognitive load is associated with an increase in EBR in cognitive tasks not involving visual attention. These findings are consistent with previous evidence suggesting shared neurobiological bases between attention and EBR.

Abnormal Auditory Processing and Underlying Structural Changes in 22q11.2 Deletion Syndrome

The 22q11.2 deletion syndrome (22q11.2 DS), one of the highest genetic risk for the development of schizophrenia, offers a unique opportunity to understand neurobiological and functional changes preceding the onset of the psychotic illness. Reduced auditory mismatch negativity response (MMN) has been proposed as a promising index of abnormal sensory processing and brain pathology in schizophrenia. However, the link between the MMN response and its underlying cerebral mechanisms in 22q11.2 DS remains unexamined. We measured auditory-evoked potentials to frequency deviant stimuli with high-density electroencephalogram and volumetric estimates of cortical and thalamic auditory areas with structural T1-weighted magnetic resonance imaging in a sample of 130 individuals, 70 with 22q11.2 DS and 60 age-matched typically developing (TD) individuals. Compared to TD group, the 22q11.2 deletion carriers reveal reduced MMN response and significant changes in topographical maps and decreased gray matter volumes of cortical and subcortical auditory areas, however, without any correlations between MMN alteration and structural changes. Furthermore, exploratory research on the presence of hallucinations (H+\H-) reveals no change in MMN response in 22q11.2DS (H+ and H-) as compared to TD individuals. Nonetheless, we observe bilateral volume reduction of the superior temporal gyrus and left medial geniculate in 22q11.2DSH+ as compared to 22q11.2DSH- and TD participants. These results suggest that the mismatch response might be a promising neurophysiological marker of functional changes within the auditory pathways that might underlie elevated risk for the development of psychotic symptoms.

Design and evaluation of the effectiveness of a corpus of congruent and incongruent English sentences for the study of event related potentials

OBJECTIVE

To design and evaluate the effectiveness of a stimulus material in eliciting the N400 event related potential (ERP).

DESIGN

A set of 700 semantically congruent and incongruent sentences was developed in accordance with current linguistic norms, and validated with an electroencephalography (EEG) study, in which the influence of age and gender on the N400 ERP magnitude was analysed.

STUDY SAMPLE

Forty-five normal-hearing subjects (19-57 years, 21 females) participated in the EEG study.

RESULTS

The stimulus material used in the EEG study elicited a robust N400 ERP, with a morphology consistent with the literature. Results also showed no statistically significant effect of age or gender on the N400 magnitude.

CONCLUSIONS

The material presented in this paper constitutes the largest complete stimulus set suitable for both auditory and text-based N400 experiments. This material may help facilitate the efficient implementation of future N400 ERP studies, as well as promote standardisation and consistency across studies.

Weaker prepulse exerts stronger suppression of a change-detecting neural circuit

Change-N1 peaking 90-180 ms after changes in a sound feature of a continuous sound is clearly attenuated by a preceding change stimulus (called a "prepulse"). Here, we investigated the effects of a preceding decrease in sound pressure on the degree of inhibition of the subsequent Change-N1 amplitude. Using 100-Hz click train sounds, we obtained Change-N1s from 11 healthy volunteers. The two types of test stimuli were an abrupt 10-dB increase from the baseline (70 dB) and the insertion of a 0.45-ms inter-aural time difference in the middle of the sound. Three consecutive clicks at 30, 40, and 50 ms before the change onset that was used as a prepulse were weaker than the background by 5 or 10 dB. The Change-N1 elicited by the two test stimuli was attenuated more strongly by the weaker prepulse, which was not congruent with the theory that the inhibition of the subsequent sensory/sensory-motor processing depends on the sound pressure level of a prepulse. These results suggest that a change in any type of sound feature elicits a change-related response that is inhibited by any type of preceding change stimulus, which reflects auto-inhibition of the change-responding circuit.

Toward an Individualized Neural Assessment of Receptive Language in Children

Purpose We aimed to develop a noninvasive neural test of language comprehension to use with nonspeaking children for whom standard behavioral testing is unreliable (e.g., minimally verbal autism). Our aims were threefold. First, we sought to establish the sensitivity of two auditory paradigms to elicit neural responses in individual neurotypical children. Second, we aimed to validate the use of a portable and accessible electroencephalography (EEG) system, by comparing its recordings to those of a research-grade system. Third, in light of substantial interindividual variability in individuals' neural responses, we assessed whether multivariate decoding methods could improve sensitivity. Method We tested the sensitivity of two child-friendly covert N400 paradigms. Thirty-one typically developing children listened to identical spoken words that were either strongly predicted by the preceding context or violated lexical-semantic expectations. Context was given by a cue word (Experiment 1) or sentence frame (Experiment 2), and participants either made an overall judgment on word relatedness or counted lexical-semantic violations. We measured EEG concurrently from a research-grade system, Neuroscan's SynAmps2, and an adapted gaming system, Emotiv's EPOC+. Results We found substantial interindividual variability in the timing and topology of N400-like effects. For both paradigms and EEG systems, traditional N400 effects at the expected sensors and time points were statistically significant in around 50% of individuals. Using multivariate analyses, detection rate increased to 88% of individuals for the research-grade system in the sentences paradigm, illustrating the robustness of this method in the face of interindividual variations in topography. Conclusions There was large interindividual variability in neural responses, suggesting interindividual variation in either the cognitive response to lexical-semantic violations and/or the neural substrate of that response. Around half of our neurotypical participants showed the expected N400 effect at the expected location and time points. A low-cost, accessible EEG system provided comparable data for univariate analysis but was not well suited to multivariate decoding. However, multivariate analyses with a research-grade EEG system increased our detection rate to 88% of individuals. This approach provides a strong foundation to establish a neural index of language comprehension in children with limited communication. Supplemental Material https://doi.org/10.23641/asha.12606311.

Future Perspectives on the Relevance of Auditory Markers in Prodromal Parkinson's Disease

Research on auditory processing in Parkinson's disease (PD) has recently made substantial progress. At present, evidence has been found for altered auditory processing in the clinical stage of PD. The auditory alterations in PD have been demonstrated with low-cost and non-invasive assessments that are already used in routine clinical practice. Since auditory alterations have been reported early in disease progression, it would be highly relevant to investigate whether auditory markers could be provided in the prodromal stage of PD. In addition, auditory alterations in early stage PD might be modulated by dopaminergic medication. Therefore, the aim of this review is (1) to summarize the literature on auditory processing in PD with a specific focus on the early disease stages, (2) to give future perspectives on which audiological and electrophysiological measurements could be useful in the prodromal stage of PD and (3) to assess the effect of dopaminergic medication on potential auditory markers in the prodromal stage of PD.

Multicenter prospective study on predictors of short-term outcome in disorders of consciousness

OBJECTIVE

This international multicenter, prospective, observational study aimed at identifying predictors of short-term clinical outcome in patients with prolonged disorders of consciousness (DoC) due to acquired severe brain injury.

METHODS

Patients in vegetative state/unresponsive wakefulness syndrome (VS/UWS) or in minimally conscious state (MCS) were enrolled within 3 months from their brain injury in 12 specialized medical institutions. Demographic, anamnestic, clinical, and neurophysiologic data were collected at study entry. Patients were then followed up for assessing the primary outcome, that is, clinical diagnosis according to standardized criteria at 6 months postinjury.

RESULTS

We enrolled 147 patients (44 women; mean age 49.4 [95% confidence interval 46.1-52.6] years; VS/UWS 71, MCS 76; traumatic 55, vascular 56, anoxic 36; mean time postinjury 59.6 [55.4-63.6] days). The 6-month follow-up was complete for 143 patients (VS/UWS 70; MCS 73). With respect to study entry, the clinical diagnosis improved in 72 patients (VS/UWS 27; MCS 45). Younger age, shorter time postinjury, higher Coma Recovery Scale-Revised total score, and presence of EEG reactivity to eye opening at study entry predicted better outcome, whereas etiology, clinical diagnosis, Disability Rating Scale score, EEG background activity, acoustic reactivity, and P300 on event-related potentials were not associated with outcome.

CONCLUSIONS

Multimodal assessment could identify patients with higher likelihood of clinical improvement in order to help clinicians, families, and funding sources with various aspects of decision-making. This multicenter, international study aims to stimulate further research that drives international consensus regarding standardization of prognostic procedures for patients with DoC.

Language-Related Neurophysiological Deficits in Schizophrenia

Schizophrenia is a severe psychiatric disorder that affects all aspects of one's life with several cognitive and social dysfunctions. However, there is still no objective and universal index for diagnosis and treatment of this disease. Many researchers have studied language processing in schizophrenia since most of the patients show symptoms related to language processing, such as thought disorder, auditory verbal hallucinations, or delusions. Electroencephalography (EEG) and magnetoencephalography (MEG) with millisecond order high temporal resolution, have been applied to reveal the abnormalities in language processing in schizophrenia. The aims of this review are (a) to provide an overview of recent findings in language processing in schizophrenia with EEG and MEG using neurophysiological indices, providing insights into underlying language related pathophysiological deficits in this disease and (b) to emphasize the advantage of EEG and MEG in research on language processing in schizophrenia.

Vitamin B-12 Supplementation during Pregnancy and Early Lactation Does Not Affect Neurophysiologic Outcomes in Children Aged 6 Years

BACKGROUND

Deficiency of vitamin B-12 is common in pregnant Indian women. Assessment of neurophysiological measures using event-related potentials (ERPs) may yield additional information on the effects of maternal B-12 supplementation on child brain function.

OBJECTIVES

The objective of the study was to evaluate the effects of vitamin B-12 supplementation (50 μg daily orally) during pregnancy on the childhood ERP measures of positive waveform ∼300 ms after stimulus (P300) and mismatch negativity.

METHODS

This study was a follow-up of children born to pregnant women who received oral vitamin B-12 supplements (n = 62) compared with children of pregnant women who received placebo (n = 70) from a randomized controlled trial. The mean ± SD child age was 72 ± 1 mo. We used the Enobio system to assess the ERP measures P300 and mismatch negativity.

RESULTS

There were no significant differences in the primary outcomes, amplitudes, and latencies of the P300 results and the mismatch negativity between children in the supplementation and placebo groups. We combined the intervention and placebo groups for secondary analyses. On multiple variable regression analysis after adjusting for treatment group, intrauterine growth restriction, and home environment, P300 amplitude in children was significantly higher in the lowest tertile of third-trimester maternal methylmalonic acid (MMA) concentrations (β = 3034.04; 95% CI: 923.24, 5144.83) compared with the highest MMA tertile (β = 1612.12; 95% CI: -258.86, 3483.10, P = 0.005).

CONCLUSIONS

While no significant effects of maternal vitamin B-12 supplementation on children's ERP measures were seen at 72 mo, elevated maternal MMA concentrations in the third trimester were negatively associated with P300 amplitude in children. It may be worthwhile to study the impact of maternal and infant vitamin B-12 supplementation on childhood brain structure and function in longer and larger trials. The parent trial was registered at clinicaltrials.gov as NCT00641862.

Predictors of chronicity in alcohol use disorder: an evoked response potential study

INTRODUCTION

Evoked response potentials (ERP) can reliably map key neurocognitive processes which are putatively responsible for chronic alcohol use disorder (AUD). Aim of the present study was to study P300 auditory odd ball and N400 visual semantic incongruity paradigm mapping executive functions rubric as a potential biomarker predicting chronicity in AUDs. Methodology: 60 right handed 18 to 54 years age subjects were divided into chronic "CAD" and non chronic alcohol dependence "NAD" in addition to healthy control "HC" (N = 30). Subjects were assessed by Addiction Severity Index (ASI), P300 auditory odd ball paradigm in midline region and visual N400 semantic incongruity task in centro-parietal region in a cross sectional design. Results: All the three groups differed significantly for P300 and N400 amplitude in all the leads with maximum attenuation seen in CAD. On discriminant function analysis (DFA), P300 Pz and N 400 C2 amplitude values could accurately classified 78.3% subjects. Composite sensitivity and specificity of the two predictor variables differentiating CAD subjects from NAD were 79.31 and 77.41%. receiver operating characteristic curve generated an area under the curve of .758 and .847 i.e., "fair to good" ability to predict CAD from NAD. Conclusion: We conclude that specific ERP paradigm can be used as a state marker to map the cognitive deficits and as a biomarker to detect chronic AUDs.

Attentional Interactions Between Vision and Hearing in Event-Related Responses to Crossmodal and Conjunct Oddballs

Are alternation and co-occurrence of stimuli of different sensory modalities conspicuous? In a novel audio-visual oddball paradigm, the P300 was used as an index of the allocation of attention to investigate stimulus- and task-related interactions between modalities. Specifically, we assessed effects of modality alternation and the salience of conjunct oddball stimuli that were defined by the co-occurrence of both modalities. We presented (a) crossmodal audio-visual oddball sequences, where both oddballs and standards were unimodal, but of a different modality (i.e., visual oddball with auditory standard, or vice versa), and (b) oddball sequences where standards were randomly of either modality while the oddballs were a combination of both modalities (conjunct stimuli). Subjects were instructed to attend to one of the modalities (whether part of a conjunct stimulus or not). In addition, we also tested specific attention to the conjunct stimuli. P300-like responses occurred even when the oddball was of the unattended modality. The pattern of event-related potential (ERP) responses obtained with the two crossmodal oddball sequences switched symmetrically between stimulus modalities when the task modality was switched. Conjunct oddballs elicited no oddball response if only one modality was attended. However, when conjunctness was specifically attended, an oddball response was obtained. Crossmodal oddballs capture sufficient attention even when not attended. Conjunct oddballs, however, are not sufficiently salient to attract attention when the task is unimodal. Even when specifically attended, the processing of conjunctness appears to involve additional steps that delay the oddball response.

Computer data simulator to assess the accuracy of estimates of visual N2/N2pc event-related potential components

OBJECTIVE

Event-related potentials (ERPs) evoked by visual stimulations comprise several components, with different amplitudes and latencies. Among them, the N2 and N2pc components have been demonstrated to be a measure of subjects' allocation of visual attention to possible targets and to be involved in the suppression of irrelevant items. Unfortunately, the N2 and N2pc components have smaller amplitudes compared with those of the background electroencephalogram (EEG), and their measurement requires employing techniques such as conventional averaging, which in turn necessitates several sweeps to provide acceptable estimates. In visual search studies, the number of sweeps (Nswp) used to extrapolate reliable estimates of N2/N2pc components has always been somehow arbitrary, with studies using 50-500 sweeps. In-silico studies relying on synthetic data providing a close-to-realistic fit to the variability of the visual N2 component and background EEG signals are therefore needed to go beyond arbitrary choices in this context.

APPROACH

In the present work, we sought to take a step in this direction by developing a simulator of ERP variations in the N2 time range based on real experimental data while monitoring variations in the estimation accuracy of N2/N2pc components as a function of two factors, i.e. signal-to-noise ratio (SNR) and number of averaged sweeps.

MAIN RESULTS

The results revealed that both Nswp and SNR had a strong impact on the accuracy of N2/N2pc estimates. Critically, the present simulation showed that, for a given level of SNR, a non-arbitrary Nswp could be parametrically determined, after which no additional significant improvements in noise suppression and N2/N2pc accuracy estimation were observed.

SIGNIFICANCE

The present simulator is thought to provide investigators with quantitative guidelines for designing experimental protocols aimed at improving the detection accuracy of N2/N2pc components. The parameters of the simulator can be tuned, adapted, or integrated to fit other ERP modulations.

Effects of Signal Type and Noise Background on Auditory Evoked Potential N1, P2, and P3 Measurements in Blast-Exposed Veterans

OBJECTIVES

Veterans who have been exposed to high-intensity blast waves frequently report persistent auditory difficulties such as problems with speech-in-noise (SIN) understanding, even when hearing sensitivity remains normal. However, these subjective reports have proven challenging to corroborate objectively. Here, we sought to determine whether use of complex stimuli and challenging signal contrasts in auditory evoked potential (AEP) paradigms rather than traditional use of simple stimuli and easy signal contrasts improved the ability of these measures to (1) distinguish between blast-exposed Veterans with auditory complaints and neurologically normal control participants, and (2) predict behavioral measures of SIN perception.

DESIGN

A total of 33 adults (aged 19-56 years) took part in this study, including 17 Veterans exposed to high-intensity blast waves within the past 10 years and 16 neurologically normal control participants matched for age and hearing status with the Veteran participants. All participants completed the following test measures: (1) a questionnaire probing perceived hearing abilities; (2) behavioral measures of SIN understanding including the BKB-SIN, the AzBio presented in 0 and +5 dB signal to noise ratios (SNRs), and a word-level consonant-vowel-consonant test presented at +5 dB SNR; and (3) electrophysiological tasks involving oddball paradigms in response to simple tones (500 Hz standard, 1000 Hz deviant) and complex speech syllables (/ba/ standard, /da/ deviant) presented in quiet and in four-talker speech babble at a SNR of +5 dB.

RESULTS

Blast-exposed Veterans reported significantly greater auditory difficulties compared to control participants. Behavioral performance on tests of SIN perception was generally, but not significantly, poorer among the groups. Latencies of P3 responses to tone signals were significantly longer among blast-exposed participants compared to control participants regardless of background condition, though responses to speech signals were similar across groups. For cortical AEPs, no significant interactions were found between group membership and either stimulus type or background. P3 amplitudes measured in response to signals in background babble accounted for 30.9% of the variance in subjective auditory reports. Behavioral SIN performance was best predicted by a combination of N1 and P2 responses to signals in quiet which accounted for 69.6% and 57.4% of the variance on the AzBio at 0 dB SNR and the BKB-SIN, respectively.

CONCLUSIONS

Although blast-exposed participants reported far more auditory difficulties compared to controls, use of complex stimuli and challenging signal contrasts in cortical and cognitive AEP measures failed to reveal larger group differences than responses to simple stimuli and easy signal contrasts. Despite this, only P3 responses to signals presented in background babble were predictive of subjective auditory complaints. In contrast, cortical N1 and P2 responses were predictive of behavioral SIN performance but not subjective auditory complaints, and use of challenging background babble generally did not improve performance predictions. These results suggest that challenging stimulus protocols are more likely to tap into perceived auditory deficits, but may not be beneficial for predicting performance on clinical measures of SIN understanding. Finally, these results should be interpreted with caution since blast-exposed participants did not perform significantly poorer on tests of SIN perception.

Cognitive and neurophysiological assessment of patients with minimal hepatic encephalopathy in Brazil

Minimal hepatic encephalopathy is a syndrome caused by cirrhosis, with a broad spectrum of clinical manifestations. Its diagnosis is based on abnormal results of cognitive and neurophysiological tests, but there are no universally available criteria, especially in Brazil, where local testing standards are required. The objective of the present study was to compare the performance of the mini-mental state examination (MMSE), Rey’s auditory-verbal learning test (RAVLT), psychometric score of hepatic encephalopathy (PHES), topographic mapping of brain electrical activity (TMBEA) and long-latency auditory evoked potential (P300) in the detection of minimal hepatic encephalopathy in Brazil. From 224 patients with cirrhosis included in the global sample, 82.5% were excluded due to secondary causes responsible for cognitive or neurophysiological dysfunction. The final sample consisted of 29 cirrhotics, with predominance of A5 Child-Pugh classification, and 29 controls paired in critical variables such as age, educational level, gender, professional category, scores suggestive of mild depression, association with compensated type 2 diabetes mellitus and sociodemographic characteristics. Overall, performance on cognitive tests and TMBEA did not show a statistically significant difference. There was a marked difference in P300 latency adjusted for age, with patients with cirrhosis showing a mean of 385 ± 78 ms (median of 366.6 ms) and healthy volunteers exhibiting a mean of 346.2 ± 42.8 ms (median of 348.2 ms) (p < 0.01). These findings suggest that, in the earliest stages of cirrhosis, age-adjusted P300 latency was superior to cognitive assessment and TMBEA for detection of minimal hepatic encephalopathy.

Pearls and pitfalls in brain functional analysis by event-related potentials: a narrative review by the Italian Psychophysiology and Cognitive Neuroscience Society on methodological limits and clinical reliability-part I

Event-related potentials (ERPs) are obtained from the electroencephalogram (EEG) or the magnetoencephalogram (MEG, event-related fields (ERF)), extracting the activity that is time-locked to an event. Despite the potential utility of ERP/ERF in cognitive domain, the clinical standardization of their use is presently undefined for most of procedures. The aim of the present review is to establish limits and reliability of ERP medical application, summarize main methodological issues, and present evidence of clinical application and future improvement. The present section of the review focuses on well-standardized ERP methods, including P300, Contingent Negative Variation (CNV), Mismatch Negativity (MMN), and N400, with a chapter dedicated to laser-evoked potentials (LEPs). One section is dedicated to proactive preparatory brain activity as the Bereitschaftspotential and the prefrontal negativity (BP and pN). The P300 and the MMN potentials have a limited but recognized role in the diagnosis of cognitive impairment and consciousness disorders. LEPs have a well-documented usefulness in the diagnosis of neuropathic pain, with low application in clinical assessment of psychophysiological basis of pain. The other ERP components mentioned here, though largely applied in normal and pathological cases and well standardized, are still confined to the research field. CNV, BP, and pN deserve to be largely tested in movement disorders, just to explain possible functional changes in motor preparation circuits subtending different clinical pictures and responses to treatments.

Comparison of Common Amplitude Metrics in Event-Related Potential Analysis

Waveform data resulting from time-intensive longitudinal designs require careful treatment. In particular, the statistical properties of summary metrics in this area are crucial. We draw on event-related potential (ERP) studies, a field with a relatively long history of collecting and analyzing such data, to illustrate our points. In particular, three summary measures for a component in the average ERP waveform feature prominently in the literature: the maximum (or peak amplitude), the average (or mean amplitude) and a combination (or adaptive mean). We discuss the methodological divide associated with these summary measures. Through both analytic work and simulation study, we explore the properties (e.g., Type I and Type II errors) of these competing metrics for assessing the amplitude of an ERP component across experimental conditions. The theoretical and simulation-based arguments in this article illustrate how design (e.g., number of trials per condition) and analytic (e.g., window location) choices affect the behavior of these amplitude summary measures in statistical tests and highlight the need for transparency in reporting the analytic steps taken. There is an increased need for analytic tools for waveform data. As new analytic methods are developed to address these time-intensive longitudinal data, careful treatment of the statistical properties of summary metrics used for null hypothesis testing is crucial.

Intra- and Inter-Rater Reliability of Manual Feature Extraction Methods in Movement Related Cortical Potential Analysis

Event related potentials (ERPs) provide insight into the neural activity generated in response to motor, sensory and cognitive processes. Despite the increasing use of ERP data in clinical research little is known about the reliability of human manual ERP labelling methods. Intra-rater and inter-rater reliability were evaluated in five electroencephalography (EEG) experts who labelled the peak negativity of averaged movement related cortical potentials (MRCPs) derived from thirty datasets. Each dataset contained 50 MRCP epochs from healthy people performing cued voluntary or imagined movement, or people with stroke performing cued voluntary movement. Reliability was assessed using the intraclass correlation coefficient and standard error of measurement. Excellent intra- and inter-rater reliability was demonstrated in the voluntary movement conditions in healthy people and people with stroke. In comparison reliability in the imagined condition was low to moderate. Post-hoc secondary epoch analysis revealed that the morphology of the signal contributed to the consistency of epoch inclusion; potentially explaining the differences in reliability seen across conditions. Findings from this study may inform future research focused on developing automated labelling methods for ERP feature extraction and call to the wider community of researchers interested in utilizing ERPs as a measure of neurophysiological change or in the delivery of EEG-driven interventions.

30+ years of P300 brain-computer interfaces

Brain-computer interfaces (BCIs) directly measure brain activity with no physical movement and translate the neural signals into messages. BCIs that employ the P300 event-related brain potential often have used the visual modality. The end user is presented with flashing stimuli that indicate selections for communication, control, or both. Counting each flash that corresponds to a specific target selection while ignoring other flashes will elicit P300s to only the target selection. P300 BCIs also have been implemented using auditory or tactile stimuli. P300 BCIs have been used with a variety of applications for severely disabled end users in their homes without frequent expert support. P300 BCI research and development has made substantial progress, but challenges remain before these tools can become practical devices for impaired patients and perhaps healthy people.

Mismatch Negativity Elicited by Verbal and Nonverbal Stimuli: Comparison with Potential N1

Introduction  Mismatch negativity (MMN) is a long latency auditory evoked potential, represented by a negative wave, generated after the potential N1 and visualized in a resulting wave. Objective  To identify the time of occurrence of MMN after N1, elicited with verbal and nonverbal stimuli. Methods  Ninety individuals aged between 18 and 56 years old participated in the study, 39 of whom were male and 51 female, with normal auditory thresholds, at least 8 years of schooling, and who did not present auditory processing complaints. All of them underwent audiologic anamnesis, visual inspection of external auditory meatus, pure tone audiometry, speech audiometry, acoustic immittance measures and the dichotic sentence identification test as a screening for alterations in auditory processing, a requirement to participate in the sample. The MMN was applied with two different stimuli, with these being da/ta (verbal) and 750 Hz and 1,000 Hz (nonverbal). Results  There was a statistically significant difference between the latency values of the N1 potential and the MMN with the two stimuli, as well as between the MMN with verbal and nonverbal stimuli, and the latency of the MMN elicited with da/ta being greater than that elicited with 750 Hz and 1,000 Hz, which facilitated its visualization. Conclusion  The time of occurrence of MMN after the N1 elicited with verbal stimuli was 100.4 ms and with nonverbal stimuli 85.5 ms. Thus, the marking of the MMN with verbal stimuli proved to be more distant from N1 compared with the nonverbal stimuli.

Changes in Speech-Related Brain Activity During Adaptation to Electro-Acoustic Hearing

Objectives: Hearing improves significantly with bimodal provision, i.e., a cochlear implant (CI) at one ear and a hearing aid (HA) at the other, but performance shows a high degree of variability resulting in substantial uncertainty about the performance that can be expected by the individual CI user. The objective of this study was to explore how auditory event-related potentials (AERPs) of bimodal listeners in response to spoken words approximate the electrophysiological response of normal hearing (NH) listeners. Study Design: Explorative prospective analysis during the first 6 months of bimodal listening using a within-subject repeated measures design. Setting: Academic tertiary care center. Participants: Twenty-seven adult participants with bilateral sensorineural hearing loss who received a HiRes 90K CI and continued use of a HA at the non-implanted ear. Age-matched NH listeners served as controls. Intervention: Cochlear implantation. Main Outcome Measures: Obligatory auditory evoked potentials N1 and P2, and the event-related N2 potential in response to monosyllabic words and their reversed sound traces before, as well as 3 and 6 months post-implantation. The task required word/non-word classification. Stimuli were presented within speech-modulated noise. Loudness of word/non-word signals was adjusted individually to achieve the same intelligibility across groups and assessments. Results: Intelligibility improved significantly with bimodal hearing, and the N1-P2 response approximated the morphology seen in NH with enhanced and earlier responses to the words compared to their reversals. For bimodal listeners, a prominent negative deflection was present between 370 and 570 ms post stimulus onset (N2), irrespective of stimulus type. This was absent for NH controls; hence, this response did not approximate the NH response during the study interval. N2 source localization evidenced extended activation of general cognitive areas in frontal and prefrontal brain areas in the CI group. Conclusions: Prolonged and spatially extended processing in bimodal CI users suggests employment of additional auditory-cognitive mechanisms during speech processing. This does not reduce within 6 months of bimodal experience and may be a correlate of the enhanced listening effort described by CI listeners.

Moving beyond belief: A narrative review of potential biomarkers for transcutaneous vagus nerve stimulation

Transcutaneous vagus nerve stimulation (tVNS) is a non-invasive neurostimulation technique that is currently being tested as a potential treatment for a myriad of neurological and psychiatric disorders. However, the working mechanisms underlying tVNS are poorly understood and it remains unclear whether stimulation activates the vagus nerve for every participant. Finding a biological marker of tVNS is imperative, as it can help guide research on clinical applications and can inform researchers on optimal stimulation sites and parameters to further optimize treatment efficacy. In this narrative review, we discuss five potential biomarkers for tVNS and review currently available evidence for these markers for both invasive and tVNS. While some of these biomarkers hold promise from a theoretical perspective, none of the potential biomarkers provide clear and definitive indications that tVNS increases the vagal activity or augments activity in the locus coeruleus-noradrenaline network. We conclude the review by providing several recommendations for how to tackle the challenges and opportunities when researching potential biomarkers for the effects of tVNS.

Processing network emojis in Chinese sentence context: An ERP study

As network emojis play an increasingly important role in modern communications, the question of how semantic processing of emojis is performed in the context arises. By comparing the N400 and P600 effects of emojis and words in contextually incongruent conditions, we investigated the neural basis of semantic processing of emojis. We found that incongruent words elicited robust N400 and P600 effects, while emojis only generated a more conspicuous and sustained N400 effect. This suggests that emojis may have more difficult semantic retrieval versus words in the context, with potentially inefficient semantic integration. These data suggest that the semantic processing of network emojis in context is not the same as words and the meaning of emojis is more difficult to process at sentence level.

Limitations of Standard Accessible Captioning of Sounds and Music for Deaf and Hard of Hearing People: An EEG Study

Captioning is the process of transcribing speech and acoustical information into text to help deaf and hard of hearing people accessing to the auditory track of audiovisual media. In addition to the verbal transcription, it includes information such as sound effects, speaker identification, or music tagging. However, it just takes into account a limited spectrum of the whole acoustic information available in the soundtrack, and hence, an important amount of emotional information is lost when attending just to the normative compliant captions. In this article, it is shown, by means of behavioral and EEG measurements, how emotional information related to sounds and music used by the creator in the audiovisual work is perceived differently by normal hearing group and hearing disabled group when applying standard captioning. Audio and captions activate similar processing areas, respectively, in each group, although not with the same intensity. Moreover, captions require higher activation of voluntary attentional circuits, as well as language-related areas. Captions transcribing musical information increase attentional activity, instead of emotional processing.

The response relevance of visual stimuli modulates the P3 component and the underlying sensorimotor network

The functional meaning and neural basis of the P3b component of ERPs are still under debate. One of the main issues is whether P3b reflects only stimulus-related processes (stimulus evaluation hypothesis) or response-related processes as well (stimulus-response or S-R link activation hypothesis). Here, we conducted an EEG experiment examining whether P3b may indeed reflect an S-R link activation, followed by an fMRI experiment in which we explored the brain areas and functional connectivity possibly constituting the neural basis of these sensorimotor links. In both experiments, two successive visual stimuli, S1 and S2, were presented with a 1 sec interval, and responses were defined either by S1 or S2, while participants responded only after S2 onset. The obtained EEG results suggest that P3b may be interpreted in terms of the S-R link activation account, although further studies are needed to disentangle P3-related activity from overlapping anticipatory activity. The obtained fMRI results showed that processing of the relevant S1 involved activation of a distributed postero-anterior sensorimotor network, and increased strength of functional connectivity within this network. This network may underlie activation of the S-R links, thus possibly also the P3b component, forming a bridging step between sensory encoding and response execution.

Auditory Dysfunction in Parkinson's Disease

PD is a progressive and complex neurological disorder with heterogeneous symptomatology. PD is characterized by classical motor features of parkinsonism and nonmotor symptoms and involves extensive regions of the nervous system, various neurotransmitters, and protein aggregates. Extensive evidence supports auditory dysfunction as an additional nonmotor feature of PD. Studies indicate a broad range of auditory impairments in PD, from the peripheral hearing system to the auditory brainstem and cortical areas. For instance, research demonstrates a higher occurrence of hearing loss in early-onset PD and evidence of abnormal auditory evoked potentials, event-related potentials, and habituation to novel stimuli. Electrophysiological data, such as auditory P3a, also is suggested as a sensitive measure of illness duration and severity. Improvement in auditory responses following dopaminergic therapies also indicates the presence of similar neurotransmitters (i.e., glutamate and dopamine) in the auditory system and basal ganglia. Nonetheless, hearing impairments in PD have received little attention in clinical practice so far. This review summarizes evidence of peripheral and central auditory impairments in PD and provides conclusions and directions for future empirical and clinical research. © 2020 International Parkinson and Movement Disorder Society.

Comparison of the ERP-Based BCI Performance Among Chromatic (RGB) Semitransparent Face Patterns

Objective

Previous studies have shown that combing with color properties may be used as part of the display presented to BCI users in order to improve performance. Build on this, we explored the effects of combinations of face stimuli with three primary colors (RGB) on BCI performance which is assessed by classification accuracy and information transfer rate (ITR). Furthermore, we analyzed the waveforms of three patterns.

Methods

We compared three patterns in which semitransparent face is overlaid three primary colors as stimuli: red semitransparent face (RSF), green semitransparent face (GSF), and blue semitransparent face (BSF). Bayesian linear discriminant analysis (BLDA) was used to construct the individual classifier model. In addition, a Repeated-measures ANOVA (RM-ANOVA) and Bonferroni correction were chosen for statistical analysis.

Results

The results indicated that the RSF pattern achieved the highest online averaged accuracy with 93.89%, followed by the GSF pattern with 87.78%, while the lowest performance was caused by the BSF pattern with an accuracy of 81.39%. Furthermore, significant differences in classification accuracy and ITR were found between RSF and GSF (p < 0.05) and between RSF and BSF patterns (p < 0.05).

Conclusion

The semitransparent faces colored red (RSF) pattern yielded the best performance of the three patterns. The proposed patterns based on ERP-BCI system have a clinically significant impact by increasing communication speed and accuracy of the P300-speller for patients with severe motor impairment.

Mismatch Negativity Occurrence with Verbal and Nonverbal Stimuli in Normal-Hearing Adults

Introduction  The mismatch negativity (MMN) is a long-latency auditory evoked potential related to a passive elicited auditory event.

Objective  To verify the occurrence of MMN with different stimuli, to describe reference values in normal-hearing adults with verbal and nonverbal stimuli and to compare them with each other, besides analyzing the latency, area, and amplitude regarding gender and between the ears.

Method  Normal-hearing individuals, aged between 18 and 59 years old, participated in the study. As inclusion criterion in the study, all of them underwent tone threshold audiometry, logoaudiometry, tympanometry, and the Dichotic Sentence Identification (DSI) test, and later the MMN with 4 different stimuli, being 2 verbal (da/ta and ba/di) and 2 nonverbal stimuli (750/1,000Hz and 750/4,000Hz), which are considered stimuli with low and high contrast.

Results  A total of 90 individuals composed the sample, being 39 males and 51 females, with an average age of 26.9 years old. In the analysis of the latency, amplitude, and area of the four stimuli between the ears, they were not considered statistically different. There was a significant difference between all of the stimuli in terms of latency, amplitude and area, with the highest latency found in da/ta, and the greatest amplitude and area in ba/di. Regarding gender, there was only difference in the latency of the da/ta stimulus.

Conclusion  The da/ta and 750/1,000Hz stimuli elicited the most MMN in the population of normal-hearing adults. Among the genders, there was difference only regarding the latency of the verbal stimulus da/ta, and there was no difference between the ears.

The CI MuMuFe - A New MMN Paradigm for Measuring Music Discrimination in Electric Hearing

Cochlear implants (CIs) allow good perception of speech while music listening is unsatisfactory, leading to reduced music enjoyment. Hence, a number of ongoing efforts aim to improve music perception with a CI. Regardless of the nature of these efforts, effect measurements must be valid and reliable. While auditory skills are typically examined by behavioral methods, recording of the mismatch negativity (MMN) response, using electroencephalography (EEG), has recently been applied successfully as a supplementary objective measure. Eleven adult CI users and 14 normally hearing (NH) controls took part in the present study. To measure their detailed discrimination of fundamental features of music we applied a new multifeature MMN-paradigm which presented four music deviants at four levels of magnitude, incorporating a novel "no-standard" approach to be tested with CI users for the first time. A supplementary test measured behavioral discrimination of the same deviants and levels. The MMN-paradigm elicited significant MMN responses to all levels of deviants in both groups. Furthermore, the CI-users' MMN amplitudes and latencies were not significantly different from those of NH controls. Both groups showed MMN strength that was in overall alignment with the deviation magnitude. In CI users, however, discrimination of pitch levels remained undifferentiated. On average, CI users' behavioral performance was significantly below that of the NH group, mainly due to poor pitch discrimination. Although no significant effects were found, CI users' behavioral results tended to be in accordance with deviation magnitude, most prominently manifested in discrimination of the rhythm deviant. In summary, the study indicates that CI users may be able to discriminate subtle changes in basic musical features both in terms of automatic neural responses and of attended behavioral detection. Despite high complexity, the new CI MuMuFe paradigm and the "no-standard" approach provided reliable results, suggesting that it may serve as a relevant tool in future CI research. For clinical use, future studies should investigate the possibility of applying the paradigm with the purpose of assessing discrimination skills not only at the group level but also at the individual level.

Interaction of Background Noise and Auditory Hallucinations on Phonemic Mismatch Negativity (MMN) and P3a Processing in Schizophrenia

Auditory hallucinations (AHs) are among the cardinal symptoms of schizophrenia (SZ). During the presence of AHs aberrant activity of auditory cortices have been observed, including hyperactivation during AHs alone and hypoactivation when AHs are accompanied by a concurrent external auditory competitor. Mismatch negativity (MMN) and P3a are common ERPs of interest within the study of SZ as they are robustly reduced in the chronic phase of the illness. The present study aimed to explore whether background noise altered the auditory MMN and P3a in those with SZ and treatment-resistant AHs.

METHODS

MMN and P3a were assessed in 12 hallucinating patients (HPs), 11 non-hallucinating patients (NPs) and 9 healthy controls (HCs) within an auditory oddball paradigm. Standard (P = 0.85) and deviant (P = 0.15) stimuli were presented during three noise conditions: silence (SL), traffic noise (TN), and wide-band white noise (WN).

RESULTS

HPs showed significantly greater deficits in MMN amplitude relative to NPs in all background noise conditions, though predominantly at central electrodes. Conversely, both NPs and HPs exhibited significant deficits in P3a amplitude relative to HCs under the SL condition only.

SIGNIFICANCE

These findings suggest that the presence of AHs may specifically impair the MMN, while the P3a appears to be more generally impaired in SZ. That MMN amplitudes are specifically reduced for HPs during background noise conditions suggests HPs may have a harder time detecting changes in phonemic sounds during situations with external traffic or "real-world" noise compared to NPs.

Hyper-Activated Brain Resting-State Network and Mismatch Negativity Deficit in Schizophrenia With Auditory Verbal Hallucination Revealed by an Event-Related Potential Evidence

Schizophrenia is a holergasia with unclear mechanism and high heterogeneity. Auditory verbal hallucination (AVH) study might help in understanding schizophrenia from the perspective of individual symptoms. This study aimed to investigate the activities of the resting-state networks (RSN) in the electroencephalogram (EEG) and mismatch negativity (MMN) in task-related state of schizophrenia patients with AVH. We recruited 30 schizophrenia patients without any medication for more than 4 weeks (15 AVH patients and 15 Non-AVH patients) and 15 healthy controls. We recorded the EEG data of the participants in the resting-state for 7 min and the event-related potential (ERP) data under an auditory oddball paradigm. In the resting-state EEG network, AVH patients exhibited a higher clustering coefficient than Non-AVH patients and healthy controls on delta and beta bands and a shorter characteristic path length than Non-AVH patients and healthy controls on all frequency bands. For ERP data, AVH patients showed a lower MMN amplitude than healthy controls (p = 0.017) and Non-AVH patients (p = 0.033). What's more, MMN amplitude was positively correlated with clustering coefficient, and negatively correlated with characteristic path length on delta, theta, beta and gamma band in AVH patients. Our results indicate that AVH patients showed a hyper-activity in resting-state and may have impaired higher-order auditory expectations in the task-related state than healthy controls and Non-AVH patients. And it seems reasonable to conclude that the formation of AVH may occupy certain brain resources and compete for brain resources with external auditory stimuli.

Sleep quality and its effect on event related potential P300 in adolescents with and without sleep disturbances

OBJECTIVES

The present study aimed: (i) to investigate the sleep quality and cortical arousal (ERP P300) in adolescents with and without sleep disturbances, and (ii) to examine whether P300 vary as a function of quality of the previous night's sleep in sleep disturbed adolescents and to compare the findings with healthy controls.

METHODS

Fifteen sleep disturbed adolescents and 15 age-matched controls were recruited. Participants filled 10 days of sleep logs to identify their good (GN) and bad nights (BN). GN and BN were scored as a measure of sleep efficiency (SE), with nights having greater SE defined as GN and nights with lower SE scores labelled as BN. Afterwards, subjects were summoned to the lab for recording ERP P300 once after a night of good sleep (GN) and once after a night of bad sleep (BN).

RESULTS

The findings demonstrate that sleep disturbed adolescents exhibited poorer quality of sleep than controls. The ERP P300 also revealed significant difference in participants with and without sleep disturbance. Moreover, the P300 amplitude was higher and the latency was shorter after a GN in sleep disturbed as well as in controls, however, the values were better for adolescents without disturbed sleep. Similarly, amplitude and latency of P300 was lower and longer, respectively, after a BN in both the groups, however, participants with sleep disturbance demonstrated very penurious scores for amplitude and latency than the controls.

CONCLUSION

Adolescents with sleep disturbance have poorer sleep quality and ERP characteristics than their healthy counterparts. Moreover, the quality of the previous night sleep determines cortical arousal in both sleep disturbed and healthy controls.

Staging model in psychiatry: Review of the evolution of electroencephalography abnormalities in major psychiatric disorders

AIM

Clinical staging in psychiatry aims to classify patients according to the severity of their symptoms, from stage 0 (increased risk, asymptomatic) to stage 4 (severe illness), enabling adapted treatment at each stage of the illness. The staging model would gain specificity if one or more quantifiable biological markers could be identified. Several biomarkers reflecting possible causal mechanisms and/or consequences of the pathophysiology are candidates for integration into the clinical staging model of psychiatric illnesses.

METHODS

This review covers the evolution (from stage 0 to stage 4) of the most important brain functioning impairments as measured with electroencephalography (EEG), in psychosis spectrum and in severe mood disorders.

RESULTS

The present review of the literature demonstrates that it is currently not possible to draw any conclusion with regard to the state or trait character of any of the EEG impairments in both major depressive disorder and bipolar disorder. As for schizophrenia, the most promising markers of the stage of the illness are the pitch mismatch negativity as well as the p300 event-related potentials, as these components seem to deteriorate with increasing severity of the illness.

CONCLUSIONS

Given the complexity of major psychiatric disorders, and that not a single impairment can be observed in all patients, future research should most likely consider combinations of markers in the quest for a better identification of the stages of the psychiatric illnesses.

Neurophysiological Correlates of Concussion: Deep Learning for Clinical Assessment

Concussion has been shown to leave the afflicted with significant cognitive and neurobehavioural deficits. The persistence of these deficits and their link to neurophysiological indices of cognition, as measured by event-related potentials (ERP) using electroencephalography (EEG), remains restricted to population level analyses that limit their utility in the clinical setting. In the present paper, a convolutional neural network is extended to capitalize on characteristics specific to EEG/ERP data in order to assess for post-concussive effects. An aggregated measure of single-trial performance was able to classify accurately (85%) between 26 acutely to post-acutely concussed participants and 28 healthy controls in a stratified 10-fold cross-validation design. Additionally, the model was evaluated in a longitudinal subsample of the concussed group to indicate a dissociation between the progression of EEG/ERP and that of self-reported inventories. Concordant with a number of previous studies, symptomatology was found to be uncorrelated to EEG/ERP results as assessed with the proposed models. Our results form a first-step towards the clinical integration of neurophysiological results in concussion management and motivate a multi-site validation study for a concussion assessment tool in acute and post-acute cases.