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

Rapid improvements and subsequent effects in major depressive disorder patients with somatic pain using rTMS combined with sertraline

This study aims to explore changes in depression and pain for major depressive disorder (MDD) patients with somatic pain after repetitive transcranial magnetic stimulation (rTMS) using the event-related potentials (ERPs) technique. Eighty MDD patients with somatic pain were randomly assigned to drug therapy (DT) and combined therapy (CT) groups. CT group underwent intermittent theta burst stimulation over the left dorsolateral prefrontal cortex (DLPFC) with 800 pulses and 1 Hz over the right DLPFC with 800 pulses, 5 times a week for 3 weeks. All patients were given sertraline at 50-100 mg per day. All subjects were evaluated at baseline and at weeks three and six of therapy using the Hamilton Rating Scale for Depression (HAMD), Hamilton Anxiety Scale (HAMA), and Numerical Rating Scales (NRS), and the latency and amplitude of P300 and mismatch negativity (MMN) were measured. There were no significant differences in all indices between groups at baseline. At 3 weeks, HAMD subscale scores of Cognitive Impairment and NRS scores were significantly lower in the CT group than in the DT group. At 6 weeks, NRS and HAMD total scores in the CT group decreased significantly in the CT group compared with the DT group, especially for anxiety and pain, and the MMN and P300 latencies and P300 amplitude showed greater improvements. Our findings highlight that rTMS in combination with antidepressants is a rapid method of symptom improvement in patients with somatic pain with MDD and is helpful for cognitive impairment and anxiety.

Consumer-Grade Electroencephalogram and Functional Near-Infrared Spectroscopy Neurofeedback Technologies for Mental Health and Wellbeing

Neurofeedback, utilizing an electroencephalogram (EEG) and/or a functional near-infrared spectroscopy (fNIRS) device, is a real-time measurement of brain activity directed toward controlling and optimizing brain function. This treatment has often been attributed to improvements in disorders such as ADHD, anxiety, depression, and epilepsy, among others. While there is evidence suggesting the efficacy of neurofeedback devices, the research is still inconclusive. The applicability of the measurements and parameters of consumer neurofeedback wearable devices has improved, but the literature on measurement techniques lacks rigorously controlled trials. This paper presents a survey and literary review of consumer neurofeedback devices and the direction toward clinical applications and diagnoses. Relevant devices are highlighted and compared for treatment parameters, structural composition, available software, and clinical appeal. Finally, a conclusion on future applications of these systems is discussed through the comparison of their advantages and drawbacks.

Differences in EEG Event-Related Potentials during Dual Task in Parkinson's Disease Carriers and Non-Carriers of the G2019S-LRRK2 Mutation

BACKGROUND

The G2019S-LRRK2 gene mutation is a common cause of hereditary Parkinson's disease (PD), associated with a higher frequency of the postural instability gait difficulty (PIGD) motor phenotype yet with preserved cognition. This study investigated neurophysiological changes during motor and cognitive tasks in PD patients with and without the G2019S-LRRK2 mutation.

METHODS

33 iPD patients and 22 LRRK2-PD patients performed the visual Go/NoGo task (VGNG) during sitting (single-task) and walking (dual-task) while wearing a 64-channel EEG cap. Event-related potentials (ERP) from Fz and Pz, specifically N200 and P300, were extracted and analyzed to quantify brain activity patterns.

RESULTS

The LRRK2-PD group performed better in the VGNG than the iPD group (group*task; p = 0.05). During Go, the iPD group showed reduced N2 amplitude and prolonged N2 latency during walking, whereas the LRRK2-PD group showed only shorter latency (group*task p = 0.027). During NoGo, opposite patterns emerged; the iPD group showed reduced N2 and increased P3 amplitudes during walking while the LRRK2-PD group demonstrated increased N2 and reduced P3 (N2: group*task, p = 0.010, P3: group*task, p = 0.012).

CONCLUSIONS

The LRRK2-PD group showed efficient early cognitive processes, reflected by N2, resulting in greater neural synchronization and prominent ERPs. These processes are possibly the underlying mechanisms for the observed better cognitive performance as compared to the iPD group. As such, future applications of intelligent medical sensing should be capable of capturing these electrophysiological patterns in order to enhance motor-cognitive functions.

Promoting Simple and Engaging Brain-Computer Interface Designs for Children by Evaluating Contrasting Motion Techniques

PURPOSE

There is an increasing focus on using motion in augmentative and alternative communication (AAC) systems. In considering brain-computer interface access to AAC (BCI-AAC), motion may provide a simpler or more intuitive avenue for BCI-AAC control. Different motion techniques may be utilized in supporting competency with AAC devices including simple (e.g., zoom) and complex (behaviorally relevant animation) methods. However, how different pictorial symbol animation techniques impact BCI-AAC is unclear.

METHOD

Sixteen healthy children completed two experimental conditions. These conditions included highlighting of pictorial symbols via both functional (complex) and zoom (simple) animation to evaluate the effects of motion techniques on P300-based BCI-AAC signals and offline (predicted) BCI-AAC performance.

RESULTS

Functional (complex) animation significantly increased attentional-related P200/P300 event-related potential (ERP) amplitudes in the parieto-occipital area. Zoom (simple) animation significantly decreased N400 latency. N400 ERP amplitude was significantly greater, and occurred significantly earlier, on the right versus left side for the functional animation condition within the parieto-occipital bin. N200 ERP latency was significantly reduced over the left hemisphere for the zoom condition in the central bin. As hypothesized, elicitation of all targeted ERP components supported offline (predicted) BCI-AAC performance being similar between conditions.

CONCLUSION

Study findings provide continued support for the use of animation in BCI-AAC systems for children and highlight differences in neural and attentional processing between complex and simple animation techniques.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.24085623.

Maturation of the mismatch response in pre-school children: Systematic literature review and meta-analysis

Event-related potentials (ERPs), specifically the Mismatch Response (MMR), holds promise for investigating auditory maturation in children. It has the potential to predict language development and distinguish between language-impaired and typically developing groups. However, summarizing the MMR's developmental trajectory in typically developing children remains challenging despite numerous studies. This pioneering meta-analysis outlines changes in MMR amplitude among typically developing children, while offering methodological best-practices. Our search identified 51 articles for methodology analysis and 21 for meta-analysis, involving 0-8-year-old participants from 2000 to 2022. Risk of Bias assessment and methodology analysis revealed shortcomings in control condition usage and reporting of study confounders. The meta-analysis results were inconsistent, indicating large effect sizes in some conditions and no effect sizes in others. Subgroup analysis revealed the main effects of age and brain region, as well as an interaction of age and time-window of the MMR. Future research requires a specific protocol, larger samples, and replication studies to deepen the understanding of the auditory discrimination maturation process in children.

Cognitive load associates prolonged P300 latency during target stimulus processing in individuals with mild cognitive impairment

Alterations in P300 amplitude and latency, as well as neuropsychological tests, are informative to detect early signs of the affected high cognitive processing in Mild Cognitive Impairment (MCI). In the present study, we examined P300 latency and amplitude elicited by visual oddball paradigm in 20 participants with MCI and age, education, and sex-matched healthy controls from frontal, central, and parietal midline electrodes. We performed a mixed-design ANOVA to compare P300 amplitude and latency between groups during target and non-target stimulus presentation. We also assessed the correlation between our electrophysiology findings and neuropsychological tests. Our results indicated that in healthy individuals P300 is elicited earlier in target stimulus processing compared to non-target stimulus processing. On the contrary, in the MCI group, P300 latency was increased during target processing compared to non-target stimulus processing. Moreover, P300 latency in target processing is prolonged in the MCI group compared to controls. Also, our correlation results showed a significant correlation between P300 peak latency and amplitude, and attention required cognitive tasks. In conclusion, our results provide evidence that high-order cognitive processes that are involved in stimulus processing slows down in individuals with MCI due to the high working memory demand for neural processing.

Neuropragmatics: A scientometric review

Neuropragmatics investigates brain functions and neural activities responsible for pragmatic language abilities, often impaired in disorders such as hemisphere damage, autism, schizophrenia, and neurodegenerative disorders. This study examined the development of neuropragmatics and existing neuroimaging evidence using bibliometric and scientometric indicators, analyzing 4,247 documents published between 1967 and 2022 with CiteSpace and VOSviewer. Our cluster analysis revealed key themes. 1) Language comprehension loss due to brain injury: Studies exploring the impact of brain injuries on language comprehension and underlying neural mechanisms. 2) Right hemisphere damage and pragmatic language skills: Research focusing on the relationship between right hemisphere damage and pragmatic language abilities, investigating impairments in social language use and potential neural correlates. 3) Traumatic brain injury and social communication assessment: Research on traumatic brain injury effects on social communication skills, using various assessment tools to evaluate communication effectiveness in social situations. These clusters provide valuable insights into the neuropragmatics field and serve as a framework for future investigations. By building upon existing knowledge, researchers can improve our understanding of brain functions, language behavior, and enhance rehabilitation for individuals with pragmatic language impairments.

Under pressure-the influence of hypergravity on electrocortical activity and neurocognitive performance

The effects of hypergravity and the associated increased pressure on the human body have not yet been studied in detail, but are of great importance for the safety of astronauts on space missions and could have a long-term impact on rehabilitation strategies for neurological patients. Considering the plans of international space agencies with the exploration of Mars and Moon, it is important to explore the effects of both extremes, weightlessness and hypergravity. During parabolic flights, a flight manoeuvre that artificially creates weightlessness and hypergravity, electrocortical activity as well as behavioural parameters (error rate and reaction time) and neuronal parameters (event-related potentials P300 and N200) were examined with an electroencephalogram. Thirteen participants solved a neurocognitive task (mental arithmetic task as a primary task and oddball paradigm as a secondary task) within normal as well as hypergravity condition in fifteen consecutive parabolas for 22 s each. No changes between the different gravity levels could be observed for the behavioural parameters and cortical current density. A significantly lower P300 amplitude was observed in 1 G, triggered by the primary task and the target sound of the oddball paradigm. The N200, provoked by the sounds of the oddball paradigm, revealed a higher amplitude in 1.8 G. A model established by Kohn et al. (2018) describing changes in neural communication with decreasing gravity can be used here as an explanatory approach. The fluid shift increases the intracranial pressure, decreases membrane viscosity and influences the open state probability of ion channels. This leads to an increase in the resting membrane potential, and the threshold for triggering an action potential can be reached more easily. The question now arises whether the observed changes are linear or whether they depend on a specific threshold.

Correlation between cortical auditory evoked potential and auditory speech performance in children with cochlear implants

OBJECTIVES

This study aimed to explore the correlation between the characteristics of cortical auditory evoked potential (CAEP) of children with cochlear implants (CIs) and auditory and speech rehabilitation performance by an objective evaluation technique and subjective auditory and speech skills measurements.

METHODS

All participants were recruited from Beijing Children's Hospital, Beijing, China. 19 children with CIs had their responses to the CAEP and MMN recorded. The LittlEARs® Auditory Questionnaire (LEAQ), Categories of Auditory Performance (CAP), Speech Intelligibility Rating Scale (SIR), Infant-Toddler Meaningful Auditory Integration Scale (IT-MAIS), and Meaningful Use of Speech Scale (MUSS) measures were taken to assess the children's speech and hearing abilities.

RESULTS

P1 and MMN of CAEP were negatively related to the duration of CI usage. The duration of CI usage and scores of auditory-verbal assessment questionnaires all showed significant relationships. Additionally, scores of these questionnaires were significantly inversely associated with the latency of P1 and MMN.

CONCLUSION

P1 and MMN could be used as objective methods to evaluate the effectiveness of hearing and speech rehabilitation in children with CIs. In particular to those who cannot give effectively feedback of auditory and verbal effects, these methods might have a certain guiding significance.

Mismatch negativity and clinical trajectories in psychotic disorders: Five-year stability and predictive utility

BACKGROUND

Mismatch negativity (MMN) amplitude is reduced in psychotic disorders and associated with symptoms and functioning. Due to these robust associations, it is often considered a biomarker for psychotic illness. The relationship between MMN and clinical outcomes has been examined well in early onset psychotic illness; however, its stability and predictive utility in chronic samples are not clear.

METHOD

We examined the five-year stability of MMN amplitude over two timepoints in individuals with established psychotic disorders (cases; N = 132) and never-psychotic participants (NP; N = 170), as well as longitudinal associations with clinical symptoms and functioning.

RESULTS

MMN amplitude exhibited good temporal stability (cases, r = 0.53; never-psychotic, r = 0.52). In cases, structural equation models revealed MMN amplitude to be a significant predictor of worsening auditory hallucinations (β = 0.19), everyday functioning (β = -0.13), and illness severity (β = -0.12) at follow-up. Meanwhile, initial IQ (β = -0.24), negative symptoms (β = 0.23), and illness severity (β = -0.16) were significant predictors of worsening MMN amplitude five years later.

CONCLUSIONS

These results imply that MMN measures a neural deficit that is reasonably stable up to five years. Results support disordered cognition and negative symptoms as preceding reduced MMN, which then may operate as a mechanism driving reductions in everyday functioning and the worsening of auditory hallucinations in chronic psychotic disorders. This pattern may inform models of illness course, clarifying the relationships amongst biological mechanisms of predictive processing and clinical deficits in chronic psychosis and allowing us to better understand the mechanisms driving such impairments over time.

Assessing the integrity of auditory sensory memory processing in CLN3 disease (Juvenile Neuronal Ceroid Lipofuscinosis (Batten disease)): An auditory evoked potential study of the duration-evoked mismatch negativity (MMN)

Background

We interrogated auditory sensory memory capabilities in individuals with CLN3 disease (juvenile neuronal ceroid lipofuscinosis), specifically for the feature of "duration" processing, a critical cue in speech perception. Given decrements in speech and language skills associated with later-stage CLN3 disease, we hypothesized that the duration-evoked mismatch negativity (MMN) of the event related potential (ERP) would be a marker of progressively atypical cortical processing in this population, with potential applicability as a brain-based biomarker in clinical trials.

Methods

We employed three stimulation rates (fast: 450 ms, medium: 900 ms, slow: 1800 ms), allowing for assessment of the sustainability of the auditory sensory memory trace. The robustness of MMN directly relates to the rate at which the regularly occurring stimulus stream is presented. As presentation rate slows, robustness of the sensory memory trace diminishes. By manipulating presentation rate, the strength of the sensory memory trace is parametrically varied, providing greater sensitivity to detect auditory cortical dysfunction. A secondary hypothesis was that duration-evoked MMN abnormalities in CLN3 disease would be more severe at slower presentation rates, resulting from greater demand on the sensory memory system.

Results

Data from individuals with CLN3 disease (N=21; range 6-28 years of age) showed robust MMN responses (i.e., intact auditory sensory memory processes) at the medium stimulation rate. However, at the fastest rate, MMN was significantly reduced, and at the slowest rate, MMN was not detectable in CLN3 disease relative to neurotypical controls (N=41; ages 6-26 years).

Conclusions

Results reveal emerging insufficiencies in this critical auditory perceptual system in individuals with CLN3 disease.

Mismatch negativity generation in subjects at risk for psychosis: source analysis is more sensitive than surface electrodes in risk prediction

Background

Deficits of mismatch negativity (MMN) in patients with schizophrenia have been demonstrated many times and there is growing evidence that alterations of MMN already exist in individuals at risk for psychosis. The present study examines differences in MMN between subjects fulfilling ultra-high risk (UHR) or only basic symptoms criteria and it addresses the question, if MMN source analysis can improve prediction of transition to psychosis.

Methods

The MMN to duration, frequency, and intensity deviants was recorded in 50 healthy controls and 161 individuals at risk for psychosis classified into three subgroups: only basic symptoms (n = 74), only ultra-high risk (n = 13) and persons who fulfill both risk criteria (n = 74). Based on a three-source model of MMN generation, we conducted an MMN source analysis and compared the amplitudes of surface electrodes and sources among the three groups.

Results

Significant differences in MMN generation among the four groups were revealed at surface electrodes Cz and C4 (p < 0.05) and at the frontal source (p < 0.001) for duration deviant stimuli. The 15 subjects from the risk groups who subsequently developed a manifest psychosis had a significantly lower MMN amplitude at frontal source (p = 0.019) without showing significant differences at surface electrodes. Low activity at frontal MMN source increased the risk of transition to manifest disease by the factor 3.12 in UHR subjects.

Conclusion

MMN activity differed significantly between subjects presenting only basic symptoms and subjects which additionally meet UHR criteria. The largest differences between groups as well as between individuals with and without transition were observed at the frontal source. The present results suggest that source analysis is more sensitive than surface electrodes in psychosis risk prediction by MMN.

The Objective Assessment of Event-Related Potentials: An Influence of Chronic Pain on ERP Parameters

The article presents an original method for the automatic assessment of the quality of event-related potentials (ERPs), based on the calculation of the coefficient ε, which describes the compliance of recorded ERPs with some statistically significant parameters. This method was used to analyze the neuropsychological EEG monitoring of patients suffering from migraines. The frequency of migraine attacks was correlated with the spatial distribution of the coefficients ε, calculated for EEG channels. More than 15 migraine attacks per month was accompanied by an increase in calculated values in the occipital region. Patients with infrequent migraines exhibited maximum quality in the frontal areas. The automatic analysis of spatial maps of the coefficient ε demonstrated a statistically significant difference between the two analyzed groups with different means of migraine attack numbers per month.

Signal Selection Technique based on Statistical Approach for Enhanced Detection of Single-trial Auditory Evoked Potentials

Volume conduction from insignificant neuronal sources in the brain poses a challenge to the detection and classification of single-trial low amplitude evoked potentials in electroencephalograph (EEG). This work presents a statistical signal selection method for enhanced detection of single-trial EEG auditory evoked potential (AEP) elicited in the brain in response to subjects' own name audio stimulus. The proposed method comprises of a signal selection stage based on a statistical analysis followed by a support vector machine (SVM)-based classifier. The EEG signals recorded from the Fp1 electrode of 24 subjects are used to generate a classifier-dependent feature vector. With the selected one-quarter of AEP signals, a single-trial classification accuracy of 70.59% is obtained. To the best of our knowledge, this is the first study that reports the classification of single-trial AEPs evoked by subjects' own-name audio stimulus versus familiar-name audio stimulus.

Optimal Filters for ERP Research II: Recommended Settings for Seven Common ERP Components

In research with event-related potentials (ERPs), aggressive filters can substantially improve the signal-to-noise ratio and maximize statistical power, but they can also produce significant waveform distortion. Although this tradeoff has been well documented, the field lacks recommendations for filter cutoffs that quantitatively address both of these competing considerations. To fill this gap, we quantified the effects of a broad range of low-pass filter and high-pass filter cutoffs for seven common ERP components (P3b, N400, N170, N2pc, mismatch negativity, error-related negativity, and lateralized readiness potential) recorded from a set of neurotypical young adults. We also examined four common scoring methods (mean amplitude, peak amplitude, peak latency, and 50% area latency). For each combination of component and scoring method, we quantified the effects of filtering on data quality (noise level and signal-to-noise ratio) and waveform distortion. This led to recommendations for optimal low-pass and high-pass filter cutoffs. We repeated the analyses after adding artificial noise to provide recommendations for datasets with moderately greater noise levels. For researchers who are analyzing data with similar ERP components, noise levels, and participant populations, using the recommended filter settings should lead to improved data quality and statistical power without creating problematic waveform distortion.

Subsequent and simultaneous electrophysiological investigation of the retina and the visual cortex in neurodegenerative and psychiatric diseases: what are the forecasts for the medicine of tomorrow?

Visual electrophysiological deficits have been reported in neurodegenerative disorders as well as in mental disorders. Such alterations have been mentioned in both the retina and the cortex, notably affecting the photoreceptors, retinal ganglion cells (RGCs) and the primary visual cortex. Interestingly, such impairments emphasize the functional role of the visual system. For this purpose, the present study reviews the existing literature with the aim of identifying key alterations in electroretinograms (ERGs) and visual evoked potentials electroencephalograms (VEP-EEGs) of subjects with neurodegenerative and psychiatric disorders. We focused on psychiatric and neurodegenerative diseases due to similarities in their neuropathophysiological mechanisms. Our research focuses on decoupled and coupled ERG/VEP-EEG results obtained with black-and-white checkerboards or low-level visual stimuli. A decoupled approach means recording first the ERG, then the VEP-EEG in the same subject with the same visual stimuli. The second method means recording both ERG and VEP-EEG simultaneously in the same participant with the same visual stimuli. Both coupled and decoupled results were found, indicating deficits mainly in the N95 ERG wave and the P100 VEP-EEG wave in Parkinson’s, Alzheimer’s, and major depressive disorder. Such results reinforce the link between the retina and the visual cortex for the diagnosis of psychiatric and neurodegenerative diseases. With that in mind, medical devices using coupled ERG/VEP-EEG measurements are being developed in order to further investigate the relationship between the retina and the visual cortex. These new techniques outline future challenges in mental health and the use of machine learning for the diagnosis of mental disorders, which would be a crucial step toward precision psychiatry.

Prognosis of consciousness disorders in the intensive care unit

Assessments of consciousness are a critical part of prognostic algorithms for critically ill patients suffering from severe brain injuries. There have been significant advances in the field of coma science over the past two decades, providing clinicians with more advanced and precise tools for diagnosing and prognosticating disorders of consciousness (DoC). Advanced neuroimaging and electrophysiological techniques have vastly expanded our understanding of the biological mechanisms underlying consciousness, and have helped identify new states of consciousness. One of these, termed cognitive motor dissociation, can predict functional recovery at 1 year post brain injury, and is present in up to 15-20% of patients with DoC. In this chapter, we review several tools that are used to predict DoC, describing their strengths and limitations, from the neurological examination to advanced imaging and electrophysiologic techniques. We also describe multimodal assessment paradigms that can be used to identify covert consciousness and thus help recognize patients with the potential for future recovery and improve our prognostication practices.

The role of cerebellum in timing processing: a contingent negative variation study

Time management is an important aspect of human behaviour and cognition. Several brain regions are thought to be involved in motor timing and time estimation tasks. However, subcortical regions such as the basal nuclei and cerebellum seem to play a role in timing control. The aim of this study was to investigate the role of the cerebellum in temporal processing. For this purpose, we transitorily inhibited cerebellar activity by means of cathodal transcranial direct current stimulation (tDCS) and studied the effects of this inhibition on contingent negative variation (CNV) parameters elicited during a S1-S2 motor task in healthy subjects. Sixteen healthy subjects underwent a S1-S2 motor task prior to and after cathodal and sham cerebellar tDCS in separate sessions. The CNV task consisted of a duration discrimination task in which subjects had to determine whether the duration of a probe interval trial was shorter (800 ms), longer (1600 ms), or equal to the target interval of 1200 ms. A reduction in total CNV amplitude emerged only after cathodal tDCS for short and target interval trials, while no differences were detected for the long interval trial. Errors were significantly higher after cathodal tDCS than at baseline evaluation of short and target intervals. No reaction time differences were found for any time interval after the cathodal and sham sessions. These results point to a role of the cerebellum in time perception. In particular, the cerebellum seems to regulate temporal interval discrimination for second and sub-second ranges.

Allocation of cognitive resources in cognitive processing of rhythmic visual stimuli before gait-related motor initiation

Rhythmic visual cues can affect the allocation of cognitive resources during gait initiation (GI) and motor preparation. However, it is unclear how the input of rhythmic visual information modulates the allocation of cognitive resources and affects GI. The purpose of this study was to explore the effect of rhythmic visual cues on the dynamic allocation of cognitive resources by recording electroencephalographic (EEG) activity during exposure to visual stimuli. This study assessed event-related potentials (ERPs), event-related synchronization/desynchronization (ERS/ERD), and EEG microstates at 32 electrodes during presentation of non-rhythmic and rhythmic visual stimuli in 20 healthy participants. The ERP results showed that the amplitude of the C1 component was positive under exposure to rhythmic visual stimuli, while the amplitude of the N1 component was higher under exposure to rhythmic visual stimuli compared to their non-rhythmic counterparts. Within the first 200 ms of the onset of rhythmic visual stimuli, ERS in the theta band was highly pronounced in all brain regions analyzed. The results of microstate analysis showed that rhythmic visual stimuli were associated with an increase in cognitive processing over time, while non-rhythmic visual stimuli were associated with a decrease. Overall, these findings indicated that, under exposure to rhythmic visual stimuli, consumption of cognitive resources is lower during the first 200 ms of visual cognitive processing, but the consumption of cognitive resources gradually increases over time. After approximately 300 ms, cognitive processing of rhythmic visual stimuli consumes more cognitive resources than processing of stimuli in the non-rhythmic condition. This indicates that the former is more conducive to the completion of gait-related motor preparation activities, based on processing of rhythmic visual information during the later stages. This finding indicates that the dynamic allocation of cognitive resources is the key to improving gait-related movement based on rhythmic visual cues.

Attention Modulates the Role of Speakers' Voice Identity and Linguistic Information in Spoken Word Processing: Evidence From Event-Related Potentials

PURPOSE

The human voice usually contains two types of information: linguistic and identity information. However, whether and how linguistic information interacts with identity information remains controversial. This study aimed to explore the processing of identity and linguistic information during spoken word processing by considering the modulation of attention.

METHOD

We conducted two event-related potentials (ERPs) experiments in the study. Different speakers (self, friend, and unfamiliar speakers) and emotional words (positive, negative, and neutral words) were used to manipulate the identity and linguistic information. With the manipulation, Experiment 1 explored the identity and linguistic information processing with a word decision task that requires participants' explicit attention to linguistic information. Experiment 2 further investigated the issue with a passive oddball paradigm that requires rare attention to either the identity or linguistic information.

RESULTS

Experiment 1 revealed an interaction among speaker, word type, and hemisphere in N400 amplitudes but not in N100 and P200, which suggests that identity information interacted with linguistic information at the later stage of spoken word processing. The mismatch negativity results of Experiment 2 showed no significant interaction between speaker and word pair, which indicates that identity and linguistic information were processed independently.

CONCLUSIONS

The identity information would interact with linguistic information during spoken word processing. However, the interaction was modulated by the task demands on attention involvement. We propose an attention-modulated explanation to explain the mechanism underlying identity and linguistic information processing. Implications of our findings are discussed in light of the integration and independence theories.

Electroencephalogram based brain-computer interface: Applications, challenges, and opportunities

Brain-Computer Interfaces (BCI) is an exciting and emerging research area for researchers and scientists. It is a suitable combination of software and hardware to operate any device mentally. This review emphasizes the significant stages in the BCI domain, current problems, and state-of-the-art findings. This article also covers how current results can contribute to new knowledge about BCI, an overview of BCI from its early developments to recent advancements, BCI applications, challenges, and future directions. The authors pointed to unresolved issues and expressed how BCI is valuable for analyzing the human brain. Humans' dependence on machines has led humankind into a new future where BCI can play an essential role in improving this modern world.

Effects of Healthy Aging and Gender on the Electrophysiological Correlates of Semantic Sentence Comprehension: The Development of Dutch Normative Data

PURPOSE

The clinical use of event-related potentials in patients with language disorders is increasingly acknowledged. For this purpose, normative data should be available. Within this context, healthy aging and gender effects on the electrophysiological correlates of semantic sentence comprehension were investigated.

METHOD

One hundred and ten healthy subjects (55 men and 55 women), divided among three age groups (young, middle aged, and elderly), performed a semantic sentence congruity task in the visual modality during electroencephalographic recording.

RESULTS

The early visual complex was affected by increasing age as shown by smaller P2 amplitudes in the elderly compared to the young. Moreover, the N400 effect in the elderly was smaller than in the young and was delayed compared to latency measures in both middle-aged and young subjects. The topography of age-related amplitude changes of the N400 effect appeared to be gender specific. The late positive complex effect was increased at frontal electrode sites from middle age on, but this was not statistically significant. No gender effects were detected regarding the early P1, N1, and P2, or the late positive complex effect.

CONCLUSION

Especially aging effects were found during semantic sentence comprehension, and this from the level of perceptual processing on. Normative data are now available for clinical use.

Immediate effects and duration of a short and single application of transcutaneous auricular vagus nerve stimulation on P300 event related potential

Introduction

Transcutaneous auricular vagus nerve stimulation (taVNS) is a neuromodulatory technique that stimulates the auricular branch of the vagus nerve. The modulation of the locus coeruleus-norepinephrine (LC-NE) network is one of the potential working mechanisms of this method. Our aims were 1-to investigate if short and single applications of taVNS can modulate the P300 cognitive event-related potential (ERP) as an indirect marker that reflects NE brain activation under control of the LC, and 2-to evaluate the duration of these changes.

Methods

20 healthy volunteers executed an auditory oddball paradigm to obtain P300 and reaction time (RT) values. Then a 7 min active or sham taVNS period was initiated and simultaneously a new P300 paradigm was performed. We successively repeated the paradigm on 4 occasions with different time intervals up to 56 min after the stimulation onset.

Results

During active taVNS an immediate and significant effect of increasing the amplitude and reducing the latency of P300, as well as a shortening in the RT was observed. This effect was prolonged in time up to 28 min. The values then returned to pre-stimulation levels. Sham stimulation did not generate changes.

Discussion

Our results, demonstrate differential facilitating effects in a concrete time window after taVNS. Literature about the modulatory effect of taVNS over P300 ERP shows a wide spread of results. There is not a standardized system for taVNS and currently the great heterogeneity of stimulation approaches concerning targets and parameters, make it difficult to obtain conclusions about this relationship. Our study was designed optimizing several stimulation settings, such as a customized earbud stimulator, enlarged stimulating surface, simultaneous stimulation over the cymba and cavum conchae, a Delayed Biphasic Pulse Burst and current controlled stimulation that adjusted the output voltage and guaranteed the administration of a preset electrical dose. Under our stimulation conditions, targeting vagal nerve fibers via taVNS modulates the P300 in healthy participants. The optimal settings of modulatory function of taVNS on P300, and their interdependency is insufficiently studied in the literature, but our data provides several easily optimizable parameters, that will produce more robust results in future.

Gamification of an n-back working memory task - is it worth the effort? An EEG and eye-tracking study

Gamification of cognitive tasks might positively affect emotional-motivational factors (emotional design perspective) or negatively affect cognitive factors like working memory load (minimalistic design perspective). The current study examined the effects of gamification in a spatial n-back working memory task on task performance, task load (i.e., working memory load and effort), and subjective task experience. Task load was assessed by the physiological process measures pupil dilation and EEG theta (4 - 6Hz) and alpha (8 - 13Hz) frequency band power. Gamification was achieved by elements of emotional design (i.e., the visual screen design using, e.g., color, cartoon figures as n-back stimuli, and a narrative embedding of the task). While EEG and eye-tracking were recorded, participants conducted gamified and non-gamified 1-back and 2-back load levels. The gamification resulted in positive effects on subjective task experience and affect. Despite these effects, gamification did not affect task performance and task load. However, exploratory analyses revealed increased EEG theta power at right-parietal electrodes for gamified task versions compared to non-gamified ones. Potentially, this effect might indicate participants' increased effort or concentration in the gamified n-back task. In line with an emotional design perspective, gamification positively altered subjective task experience and affect without hampering task performance and therefore justify the extra effort of implementing game elements.

The Effects of Directional and Non-Directional Stimuli during a Visuomotor Task and Their Correlation with Reaction Time: An ERP Study

Different visual stimuli can capture and shift attention into different directions. Few studies have explored differences in brain response due to directional (DS) and non-directional visual stimuli (nDS). To explore the latter, event-related potentials (ERP) and contingent negative variation (CNV) during a visuomotor task were evaluated in 19 adults. To examine the relation between task performance and ERPs, the participants were divided into faster (F) and slower (S) groups based on their reaction times (RTs). Moreover, to reveal ERP modulation within the same subject, each recording from the single participants was subdivided into F and S trials based on the specific RT. ERP latencies were analysed between conditions ((DS, nDS); (F, S subjects); (F, S trials)). Correlation was analysed between CNV and RTs. Our results reveal that the ERPs' late components are modulated differently by DS and nDS conditions in terms of amplitude and location. Differences in ERP amplitude, location and latency, were also found according to subjects' performance, i.e., between F and S subjects and trials. In addition, results show that the CNV slope is modulated by the directionality of the stimulus and contributes to motor performance. A better understanding of brain dynamics through ERPs could be useful to explain brain states in healthy subjects and to support diagnoses and personalized rehabilitation in patients with neurological diseases.

Tracking auditory mismatch negativity responses during full conscious state and coma

The mismatch negativity (MMN) is considered the electrophysiological change-detection response of the brain, and therefore a valuable clinical tool for monitoring functional changes associated with return to consciousness after severe brain injury. Using an auditory multi-deviant oddball paradigm, we tracked auditory MMN responses in seventeen healthy controls over a 12-h period, and in three comatose patients assessed over 24 h at two time points. We investigated whether the MMN responses show fluctuations in detectability over time in full conscious awareness, or whether such fluctuations are rather a feature of coma. Three methods of analysis were utilized to determine whether the MMN and subsequent event-related potential (ERP) components could be identified: traditional visual analysis, permutation t-test, and Bayesian analysis. The results showed that the MMN responses elicited to the duration deviant-stimuli are elicited and reliably detected over the course of several hours in healthy controls, at both group and single-subject levels. Preliminary findings in three comatose patients provide further evidence that the MMN is often present in coma, varying within a single patient from easily detectable to undetectable at different times. This highlights the fact that regular and repeated assessments are extremely important when using MMN as a neurophysiological predictor of coma emergence.

No alterations in potential indirect markers of locus coeruleus-norepinephrine function in insomnia disorder

The norepinephrine locus coeruleus system (LC NE) represents a promising treatment target in patients with insomnia disorder (ID) due to its well understood links to arousal and sleep regulation. However, consistent markers of LC NE activity are lacking. This study measured three potential indirect markers of LC NE activity - REM sleep, P3 amplitude during an auditory oddball paradigm (as a marker of phasic LC activation), and baseline pupil diameter (as a marker of tonic LC activation). The parameters were then combined in a statistical model and tested to compare LC NE activity between 20 subjects with insomnia disorder (13 female; age 44.2 ± 15.1 year) and 20 healthy, good sleeping controls (GSC; 11 female; age 45.4 ± 11.6 year). No group differences regarding the primary outcome parameters were detected. Specifically, insomnia disorder did not display the hypothesised changes in markers of LC NE function. While increased LC NE function remains an interesting speculative pathway for hyperarousal in insomnia disorder, the investigated markers do not appear closely related to each other and fail to discriminate between insomnia disorder and good sleeping controls in these samples.

Test-retest reliability of electroencephalographic and magnetoencephalographic measures elicited during language tasks: A literature review

Electroencephalographic (EEG) and magnetoencephalographic (MEG) recordings during language processing can provide relevant insights on neuroplasticity in clinical populations (including patients with aphasia). To use EEG and MEG in a longitudinal way, the outcome measures should be consistent across time in healthy individuals. Therefore, the current study provides a review on the test-retest reliability of EEG and MEG measures elicited during language paradigms in healthy adults. PubMed, Web of Science and Embase were searched for relevant articles based on specific eligibility criteria. In total, 11 articles were included in this literature review. The test-retest reliability of the P1, N1 and P2 is systematically considered to be satisfactory, whereas findings are more variable for event-related potentials/fields occurring later in time. The within subject consistency of EEG and MEG measures during language processing can be influenced by multiple variables such as the stimulus presentation mode, the offline reference choice and the required amount of cognitive resources during the task. To conclude, most of the available results are favourable regarding the longitudinal use of EEG and MEG measures elicited during language paradigms in healthy young individuals. In view to the use of these techniques in patients with aphasia, future research should focus on whether the same findings apply to different age groups.

Neuropsychological correlates of P300 parameters in individuals with aphasia

BACKGROUND

Aphasia is often accompanied by impairment of non-language cognitive functions. Assessment of cognitive capacity in people with aphasia (PWA) with standard neuropsychological methods may be problematic due to their language difficulties. Numerous experimental studies indicate that P300 may be considered as an index of cognitive capacity in both healthy and clinical samples. Accordingly, the measurement of event-related potentials enables the investigation of behaviourally non-observable mental processes underlying the cognitive functions that are assessed with neuropsychological tests.

AIMS

To investigate in PWA the relationship between P300 parameters and cognitive function efficiency measured with neuropsychological methods.

METHODS & PROCEDURES

A total of 25 PWA after left-hemispheric stroke participated in the study. Electrophysiological (EEG) signals were recorded during the performance of a visual Go-No Go task. P300 was identified on nine electrodes, which were then pooled in three lines: left (F3, C3, P3), central (Fz, Cz, Pz) and right (F4, C4, P4). The neuropsychological assessment of cognitive functions included mental speed, short-term memory, divided attention, executive functions, auditory language comprehension and expression.

OUTCOMES & RESULTS

P300 latency correlated with indices of several cognitive functions: temporal resolution, psychomotor speed, spatial short-term memory, planning, word and sentence comprehension, as well as verbal fluency. Shorter P300 latencies were accompanied by greater efficiency of the abovementioned functions. In contrast, significant correlations between P300 amplitudes and cognitive measures were fragmentary.

CONCLUSIONS & IMPLICATIONS

In PWA, P300 latency might be related to cognitive functioning, especially to measures that rely heavily on the speed of information processing. However, P300 seems to be unrelated to more complex cognitive functions. P300 latency may be used as a neurophysiological correlate of cognitive efficiency in PWA and might have potential applications in monitoring the effects of therapeutic interventions in this patient group.

WHAT THIS PAPER ADDS

What is already known on the subject P300 parameters have been reported to be associated with cognitive performance in both healthy individuals and clinical groups (e.g., patients with Alzheimer's disease). Previous studies show that the presence of P300 at the early post-stroke stage may be a predictor of better recovery of comprehension in PWA. What this paper adds to existing knowledge Our results show for the first time that P300 may be used as a neurophysiological correlate of cognitive efficiency in PWA. In our study, P300 latency was associated with several languages and non-language cognitive functions, especially with those whose effectiveness depends mainly on processing speed. In PWA, shorter latency corresponded to more efficient cognitive functioning. What are the potential or actual clinical implications of this work? P300 measurement may be potentially useful in assessing the efficiency of certain cognitive functions in PWA. It may be also used to monitor the recovery process of PWA and to verify the effects of therapeutic interventions.

Functional Hearing Difficulties in Veterans: Retrospective Chart Review of Auditory Processing Assessments in the VA Health Care System

PURPOSE

Approximately 23 million Americans might have functional hearing difficulties (FHDs) that are not well explained by their audiometric thresholds. Clinical management of patients with FHDs is the subject of considerable debate, with few evidence-based guidelines to direct patient care. A better understanding of the characteristics of patients who seek help for FHDs, as well as current audiological management practices, is needed to direct research efforts to the areas greatest opportunity for advancement of clinical care.

METHOD

A retrospective chart review was conducted examining the medical records of a random sample of 100 Veterans who underwent auditory processing assessments across the VA Health Care System between 2008 and 2020.

RESULTS

Patients were young to middle-age, often with previous traumatic brain injury or blast exposure. Mental health, sleep, and pain disorders were common. No consistent relationships emerged between specific patient factors and domains of auditory processing deficits. Low-gain hearing aids were provided to 35 patients, 69% of whom continued wearing their hearing aids for at least 2 years.

CONCLUSION

Future research should address the potential overlap in symptoms and treatment for comorbid health conditions and FHDs, as well as the conditions underlying successful hearing aid use in this patient population.

Neural signatures for the n-back task with different loads: An event-related potential study

The n-back task is widely used in working memory (WM) research. However, it remains unclear how the electrophysiological correlates of WM processes, the P2, N2, P300, and negative slow wave (NSW), are affected by differences in load. Specifically, while previous work has examined the P300, less attention has been paid to the other components assessing the load of the n-back paradigm. The present study aims to investigate whether other sub-processes in WM (such as inhibitory control) are as sensitive to n-back load changes as the update process by observing changes in the above event-related potential (ERP) components. The results showed poorer behavioral performance with increasing WM load. Greater NSW and smaller P300 amplitudes were elicited by n-back task with a higher load compared to that with lower load. In contrast, there was no significant effect of the n-back load on the amplitudes of P2 and N2. These findings suggest that the updating process and the maintenance process are sensitive to the n-back load change. Therefore, changes in the updating and maintenance processes should be considered when using the n-back task to manipulate the WM load in experiments. The present study may contribute to the understanding of the complexity of WM loads. Additionally, a theoretical basis for follow-up research to explore ways of improving WM performance with high load is provided.

Distinct Neural Resource Involvements but Similar Hemispheric Lateralization Patterns in Pre-Attentive Processing of Speaker's Identity and Linguistic Information

The speaker's identity (who the speaker is) and linguistic information (what the speaker is saying) are essential to daily communication. However, it is unclear whether and how listeners process the two types of information differently in speech perception. The present study adopted a passive oddball paradigm to compare the identity and linguistic information processing concerning neural resource involvements and hemispheric lateralization patterns. We used two female native Mandarin speakers' real and pseudo-Mandarin words to differentiate the identity from linguistic (phonological and lexical) information. The results showed that, in real words, the phonological-lexical variation elicited larger MMN amplitudes than the identity variation. In contrast, there were no significant MMN amplitude differences between the identity and phonological variation in pseudo words. Regardless of real or pseudo words, the identity and linguistic variation did not elicit MMN amplitudes differences between the left and right hemispheres. Taken together, findings from the present study indicated that the identity information recruited similar neural resources to the phonological information but different neural resources from the lexical information. However, the identity and linguistic information processing did not show a particular hemispheric lateralization pattern at an early pre-attentive speech perception stage. The findings revealed similarities and differences between linguistic and non-linguistic information processing, contributing to a better understanding of speech perception and spoken word recognition.

Electrophysiological biomarkers and age characterize phenotypic heterogeneity among individuals with major depressive disorder

Introduction: Despite the high need for effective treatments for major depressive disorder (MDD), the development of novel medicines is hampered by clinical, genetic and biological heterogeneity, unclear links between symptoms and neural dysfunction, and tenuous biomarkers for clinical trial contexts of use. Methods: In this study, we examined the International Study to Predict Optimized Treatment in Depression (iSPOT-D) clinical trial database for new relationships between auditory event-related potential (ERP) responses, demographic features, and clinical symptoms and behavior, to inform strategies for biomarker-driven patient stratification that could be used to optimize future clinical trial design and drug development strategy in MDD. Results: We replicate findings from previous analyses of the classic auditory oddball task in the iSPOT-D sample showing smaller than typical N1 and P300 response amplitudes and longer P300 latencies for target and standard stimuli in patients with MDD, suggesting altered bottom-up sensory and top-down attentional processes. We further demonstrate that age is an important contributor to clinical group differences, affecting both topographic distribution of the clinically informative ERP responses and the types of the stimuli sensitive to group differences. In addition, the observed brain-behavior associations indicate that levels of anxiety and stress are major contributing factors to atypical sensory and attentional processing among patients with MDD, particularly in the older subgroups. Discussion: Our novel findings support the possibility of accelerated cognitive aging in patients with MDD and identify the frontal P300 latency as an additional candidate biomarker of MDD. These results from a large, well-phenotyped sample support the view that heterogeneity of the clinical population with MDD can be systematically characterized based on age and neural biomarkers of sensory and attentional processing, informing patient stratification strategies in the design of clinical trials.

Towards thoughtful planning of ERP studies: How participants, trials, and effect magnitude interact to influence statistical power across seven ERP components

In the field of EEG, researchers generally rely on rules of thumb, rather than a priori statistical calculations, when planning the number of trials to include in an ERP study. To aid in this practice, studies have tried to establish minimum numbers of trials required to reliably isolate ERPs. However, these guidelines do not necessarily apply across different study designs, as the reliability of an ERP waveform is not the same as the statistical power of a given experiment. Experiment parameters such as number of participants, trials, and effect magnitude interact to affect power in complex ways. Both under- and over-powered ERP studies represent a waste of time and resources that impedes the progress of the field. The current study fills this gap by subsampling real ERP data to estimate the relationship between experiment design parameters and statistical power. The simulations include seven commonly studied ERP components: the ERN, LRP, N170, MMN, P3, N2pc, and N400. In the first set of experiments, we determined the probability of obtaining a statistically significant ERP effect for each component. In the second and third set of experiments, we determined the probability of obtaining a statistically significant difference in ERP amplitude within and between groups for each component. Results indicate that the rules of thumb for ERP experiment design in the literature often lead to underpowered studies. Going forward, these results provide researchers with experiment design guidelines that are specific to the component under study, allowing for the design of sufficiently powered ERP studies.

Age effects on cognitive functions and speech-in-noise processing: An event-related potential study with cochlear-implant users and normal-hearing listeners

A cochlear implant (CI) can partially restore hearing in individuals with profound sensorineural hearing loss. However, electrical hearing with a CI is limited and highly variable. The current study aimed to better understand the different factors contributing to this variability by examining how age affects cognitive functions and cortical speech processing in CI users. Electroencephalography (EEG) was applied while two groups of CI users (young and elderly; N = 13 each) and normal-hearing (NH) listeners (young and elderly; N = 13 each) performed an auditory sentence categorization task, including semantically correct and incorrect sentences presented either with or without background noise. Event-related potentials (ERPs) representing earlier, sensory-driven processes (N1-P2 complex to sentence onset) and later, cognitive-linguistic integration processes (N400 to semantically correct/incorrect sentence-final words) were compared between the different groups and speech conditions. The results revealed reduced amplitudes and prolonged latencies of auditory ERPs in CI users compared to NH listeners, both at earlier (N1, P2) and later processing stages (N400 effect). In addition to this hearing-group effect, CI users and NH listeners showed a comparable background-noise effect, as indicated by reduced hit rates and reduced (P2) and delayed (N1/P2) ERPs in conditions with background noise. Moreover, we observed an age effect in CI users and NH listeners, with young individuals showing improved specific cognitive functions (working memory capacity, cognitive flexibility and verbal learning/retrieval), reduced latencies (N1/P2), decreased N1 amplitudes and an increased N400 effect when compared to the elderly. In sum, our findings extend previous research by showing that the CI users' speech processing is impaired not only at earlier (sensory) but also at later (semantic integration) processing stages, both in conditions with and without background noise. Using objective ERP measures, our study provides further evidence of strong age effects on cortical speech processing, which can be observed in both the NH listeners and the CI users. We conclude that elderly individuals require more effortful processing at sensory stages of speech processing, which however seems to be at the cost of the limited resources available for the later semantic integration processes.

Mismatch Negativity Responses to Different Auditory Attributes in Normally Developing Infants and Children

Introduction Mismatch negativity (MMN) is a change-specific component of the event-related potentials that is elicited by an irregularity in repetitive auditory stimulation. As it is developmentally stable and can be measured in the absence of the participant's attention, it can be a valuable method for assessing auditory discrimination in infants and young children. The classic MMN paradigm involves tone frequency as the mismatching attribute. Multi-feature MMN paradigms which involve different auditory attributes can assess discrimination abilities in a wider group of disorders. The study aimed to report standardised MMN values obtained with MMN paradigms including several auditory attributes to extend the clinical applicability of the test in infants and young children. Methods MMN responses were recorded in 42 normal infants and young children (2 months to 5 years) with multi-feature MMN paradigms. MMN variables in different trials were compared by one-way ANOVA. Pearson's correlation coefficient and independent sample t-test were performed for finding an association with the age and gender of the participants respectively. P<0.05 was considered as statistically significant. Results MMN amplitude exhibited statistically significant differences in different MMN paradigms (p<0.05). An increase in the degree of standard and deviant differences and double deviant responses also resulted in larger MMN. MMN latency variation in the trials was not statistically significant. The age and gender of the participants did not influence the MMN variables with statistical significance. Conclusion MMN paradigms with different auditory attributes report significant amplitude variations. Multi-feature MMN paradigms can optimize the clinical applicability of the test and can determine the profile of different auditory discrimination abilities.

Multi-feature mismatch negativity: How can reliable data be recorded in a short time?

OBJECTIVE

The aim of the study was to conduct multi-feature mismatch negativity (MMN) implementations and identify via a test-retest study the reliability of MMN responses obtained through a 5-stimulus version of the MMN paradigm. It was also aimed to identify a reliable MMN recording number by comparing the MMN responses obtained under conditions of ten and four recordings conditions while making the recording time shorter.

METHODS

Twenty-one healthy volunteers, aged between 18 and 36 years, were included in the study. A 5-stimulus version of the multi-feature MMN paradigm was presented to participants. Ten recordings were obtained for each participant under both test and retest conditions. The MATLAB program was utilized in the evaluation of MMN amplitude and latency. The Fz was chosen for the statistical analysis. Four of the ten recordings were chosen at random, and statistical analyses were performed again for those four recordings.

RESULTS

There was no statistically significant difference in amplitudes obtained from test and retest conditions with ten recordings. With four recordings, for frequency, intensity, duration, and gap deviants, there were no statistically significant differences between amplitudes obtained under test and retest conditions. However, there was a statistically significant difference between amplitudes of the location deviant. No statistically significant difference was observed among latencies under test-retest conditions with both ten and four recordings.

CONCLUSIONS

These findings demonstrate that MMN amplitudes could be used reliably as short-time evaluations with four recordings, but more recordings are required for MMN latencies. In terms of practicality, four recordings are more advantageous and comfortable for both clinicians and patients in MMN practice.

SIGNIFICANCE

When behavioral tests are required, MMN is regarded as an objective test that can be used reliably for adults, children, and infants who cannot be evaluated using behavioral methods. It is concluded that conditions with four recordings aremore advantageous and comfortable for both clinicians and patients in MMN practice.

Comparing Clinically Applicable Behavioral and Electrophysiological Measures of Speech Detection, Discrimination, and Comprehension

Effective communication requires good speech perception abilities. Speech perception can be assessed with behavioral and electrophysiological methods. Relating these two types of measures to each other can provide a basis for new clinical tests. In audiological practice, speech detection and discrimination are routinely assessed, whereas comprehension-related aspects are ignored. The current study compared behavioral and electrophysiological measures of speech detection, discrimination, and comprehension. Thirty young normal-hearing native Danish speakers participated. All measurements were carried out with digits and stationary speech-shaped noise as the stimuli. The behavioral measures included speech detection thresholds (SDTs), speech recognition thresholds (SRTs), and speech comprehension scores (i.e., response times). For the electrophysiological measures, multichannel electroencephalography (EEG) recordings were performed. N100 and P300 responses were evoked using an active auditory oddball paradigm. N400 and Late Positive Complex (LPC) responses were evoked using a paradigm based on congruent and incongruent digit triplets, with the digits presented either all acoustically or first visually (digits 1-2) and then acoustically (digit 3). While no correlations between the SDTs and SRTs and the N100 and P300 responses were found, the response times were correlated with the EEG responses to the congruent and incongruent triplets. Furthermore, significant differences between the response times (but not EEG responses) obtained with auditory and visual-then-auditory stimulus presentation were observed. This pattern of results could reflect a faster recall mechanism when the first two digits are presented visually rather than acoustically. The visual-then-auditory condition may facilitate the assessment of comprehension-related processes in hard-of-hearing individuals.

Predictive Power of Cognitive Biomarkers in Neurodegenerative Disease Drug Development: Utility of the P300 Event-Related Potential

Neurodegenerative diseases, such as Alzheimer's disease (AD), and their associated deterioration of cognitive function are common causes of disability. The slowly developing pathology of neurodegenerative diseases necessitates early diagnosis and monitored long-term treatment. Lack of effective therapies coupled with an improved rate of early diagnosis in our aging population have created an urgent need for the development of novel drugs, as well as the need for reliable biomarkers for treatment response. These issues are especially relevant for AD, in which the rate of clinical trial drug failures has been very high. Frequently used biomarker evaluation procedures, such as positron emission tomography or cerebrospinal fluid measurements of phospho-tau and amyloid beta, are invasive and costly, and not universally available or accessible. This review considers the functionality of the event-related potential (ERP) P300 methodology as a surrogate biomarker for predicting the procognitive potential of drugs in clinical development for neurocognitive disorders. Through the application of standardized electroencephalography (EEG) described here, ERP P300 can be reliably measured. The P300 waveform objectively measures large-scale neuronal network functioning and working memory processes. Increased ERP P300 latency has been reported throughout the literature in disorders of cognition, supporting the potential utility of ERP P300 as a biomarker in many neurological and neuropsychiatric disorders, including AD. Specifically, evidence presented here supports ERP P300 latency as a quantitative, unbiased measure for detecting changes in cognition in patients with AD dementia through the progression from mild to moderate cognitive impairment and after drug treatment.

Task Demands Differentially Affect Processing of Intrinsic and Extrinsic Object Features in Working Memory

Some argue that visual working memory operates on integrated object representations. Here, we contend that obligatory feature integration occurs with intrinsic but not extrinsic object features. Working memory for shapes and colors was assessed using a change-detection task with a central test probe, while recording event-related potentials (ERPs). Color was either an intrinsic surface feature of a shape or connected to the shape via a proximal but spatially disjunct extrinsic frame. There were two types of test: The direct test required memory for shape and color; the indirect test required only shape memory. Study-test changes of color were therefore either task-relevant or task-irrelevant. We assessed performance costs and event-related potential (ERP) effects arising from color changes. In the direct test, performance was poorer for extrinsic than intrinsic stimuli; task-relevant color changes elicited enhanced frontal negativity (N2, FN400) for both intrinsic and extrinsic stimuli. In the indirect test, performance costs and ERP effects associated with irrelevant color change were larger for intrinsic than extrinsic stimuli. This suggests intrinsic information is more readily integrated into the working-memory representation and evaluated against the test probe. Findings imply that feature integration is not obligatory under all conditions but influenced by stimulus-driven and task-related focus of attention.

Electroencephalogram and heart rate variability features as predictors of responsiveness to vagus nerve stimulation in patients with epilepsy: a systematic review

INTRODUCTION

Vagus nerve stimulation (VNS) is a mainstay treatment in people with medically refractive epilepsy with a growing interest to identify biomarkers that are predictive of VNS efficacy. In this review, we looked at electroencephalography (EEG) and heart rate variability (HRV) parameters as potential biomarkers.

METHODOLOGY

A comprehensive search of several databases limited to the English language and excluding animal studies was conducted. Data was collected from studies that specifically reviewed preoperative EEG and HRV characteristics as predictive factors of VNS outcomes.

RESULTS

Ten out of 1078 collected studies were included in this review, of which EEG characteristics were reported in seven studies; HRV parameters were reported in two studies, and one study reported both. For EEG, studies reported a lower global rate of synchronization in alpha, delta, and gamma waves as predictors of the VNS response. The P300 wave, an evoked response on EEG, had conflicting results. Two studies reported high P300 wave amplitudes in nonresponders and low amplitudes in responders, whereas another study reported high P300 wave amplitudes in responders. For HRV, one study reported high-frequency power as the only parameter to be significantly lower in responders. In contrast, two studies from the same authors showed that HRV parameters were not different between responders and nonresponders.

CONCLUSION

HRV parameters and EEG characteristics including focal seizures and P300 wave have been reported as potential biomarkers for VNS outcomes in people with medically refractive epilepsy. However, the contradictory findings imply a need for validation through clinical trials.

Effects of decorative pictures on mental processing demands and learning: An EEG and eye-tracking study

Across two experiments, the effects of presenting decorative pictures (DP) alongside texts were assessed with respect to the mental processing demands during reading, learning outcomes, and subjective task experience. DP were thought to function as so-called seductive details. Eye-tracking and the electroencephalogram (EEG) were recorded during reading. Pupil dilation and the EEG theta (4-8 Hz) and alpha (8-13 Hz) frequency band power served as measures of the mental processing demands. Texts on features and habitats of animals served as learning materials. Working memory (WM) load was manipulated as an additional factor during reading. Neither the additional WM load nor DP had significant effects on learning outcomes, albeit in both experiments the increased WM load affected the physiological measures as expected. DP with a few different motifs generally were not very seductive (Experiment 1). DP with more diverse motifs resulted in increased mental processing demands as indicated by the EEG alpha frequency band power (Experiment 2). Subjective task experience was positively affected by the DP present in Experiment 2 as indicated by higher subjective ratings of interestingness, comprehensibility, emotionality, and aesthetical pleasantness when DP were present. In sum, the study indicates that DP with diverse motifs may function as seductive details, increasing mental processing demands without detrimental effects on learning outcomes.

Auditory Discrimination Elicited by Nonspeech and Speech Stimuli in Children With Congenital Hearing Loss

PURPOSE

Congenital deafness not only delays auditory development but also hampers the ability to perceive nonspeech and speech signals. This study aimed to use auditory event-related potentials to explore the mismatch negativity (MMN), P3a, negative wave (Nc), and late discriminative negativity (LDN) components in children with and without hearing loss.

METHOD

Nineteen children with normal hearing (CNH) and 17 children with hearing loss (CHL) participated in this study. Two sets of pure tones (1 kHz vs. 1.1 kHz) and lexical tones (/ba2/ vs. /ba4/) were used to examine the auditory discrimination process.

RESULTS

MMN could be elicited by the pure tone and the lexical tone in both groups. The MMN latency elicited by nonspeech and speech was later in CHL than in CNH. Additionally, the MMN latency induced by speech occurred later in the left than in the right hemisphere in CNH, and the MMN amplitude elicited by speech in CHL produced a discriminative deficiency compared with that in CNH. Although the P3a latency and amplitude elicited by nonspeech in CHL and CNH were not significantly different, the Nc amplitude elicited by speech performed much lower in CHL than in CNH. Furthermore, the LDN latency elicited by nonspeech was later in CHL than in CNH, and the LDN amplitude induced by speech showed higher dominance in the right hemisphere in both CNH and CHL.

CONCLUSION

By incorporating nonspeech and speech auditory conditions, we propose using MMN, Nc, and LDN as potential indices to investigate auditory perception, memory, and discrimination.

Enhancing the feasibility of cognitive load recognition in remote learning using physiological measures and an adaptive feature recalibration convolutional neural network

The precise assessment of cognitive load during a learning phase is an important pathway to improving students’ learning efficiency and performance. Physiological measures make it possible to continuously monitor learners’ cognitive load in remote learning during the COVID-19 outbreak. However, maintaining a good balance between performance and computational cost is still a major challenge in advancing cognitive load recognition technology to real-world applications. This paper introduced an adaptive feature recalibration (AFR) convolutional neural network to overcome this challenge by capturing the most discriminative physiological features (EEG and eye-tracking). The results revealed that the optimal average classification accuracy of the feature combination obtained by the AFR method reached 95.56% with only 60 feature dimensions. Additionally, compared with the best result of the conventional correlation-based feature selection (CFS) method, the introduced AFR algorithm achieved higher accuracy and cheaper computational cost, as well as a 2.06% improvement in accuracy and a 51.21% reduction in feature dimension, which is more in line with the requirements of low delay and real-time performance in practical BCI applications.

Neural Research on Depth Perception and Stereoscopic Visual Fatigue in Virtual Reality

Virtual reality (VR) technology provides highly immersive depth perception experiences; nevertheless, stereoscopic visual fatigue (SVF) has become an important factor currently hindering the development of VR applications. However, there is scant research on the underlying neural mechanism of SVF, especially those induced by VR displays, which need further research. In this paper, a Go/NoGo paradigm based on disparity variations is proposed to induce SVF associated with depth perception, and the underlying neural mechanism of SVF in a VR environment was investigated. The effects of disparity variations as well as SVF on the temporal characteristics of visual evoked potentials (VEPs) were explored. Point-by-point permutation statistical with repeated measures ANOVA results revealed that the amplitudes and latencies of the posterior VEP component P2 were modulated by disparities, and posterior P2 amplitudes were modulated differently by SVF in different depth perception situations. Cortical source localization analysis was performed to explore the original cortex areas related to certain fatigue levels and disparities, and the results showed that posterior P2 generated from the precuneus could represent depth perception in binocular vision, and therefore could be performed to distinguish SVF induced by disparity variations. Our findings could help to extend an understanding of the neural mechanisms underlying depth perception and SVF as well as providing beneficial information for improving the visual experience in VR applications.

Mu-desynchronization, N400 and corticospinal excitability during observation of natural and anatomically unnatural finger movements

The action observation networks (AON) (or the mirror neuron system) are the neural underpinnings of visuomotor integration and play an important role in motor control. Besides, one of the main functions of the human mirror neuron system is recognition of observed actions and the prediction of its outcome through the comparison with the internal mental motor representation. Previous studies focused on the human mirror neurons (MNs) activation during object-oriented movements observation, therefore intransitive movements observation effects on MNs activity remains relatively little-studied. Moreover, the dependence of MNs activation on the biomechanical characteristics of observed movement and their biological plausibility remained highly underexplored. In this study we proposed that naturalness of observed intransitive movement can modulate the MNs activity. Event-related desynchronization (ERD) of sensorimotor electroencephalography (EEG) rhythms, N400 event-related potentials (ERPs) component and corticospinal excitability were investigated in twenty healthy volunteers during observation of simple non-transitive finger flexion that might be either biomechanically natural or unnatural when finger wriggled out toward the dorsal side of palm. We showed that both natural and unnatural movements caused mu/beta-desynchronization, which gradually increased during the flexion phase and returned to baseline while observation of extension. Desynchronization of the mu-rhythm was significantly higher during observation of the natural movements. At the same time, beta-rhythm was not found to be sensitive to the action naturalness. Also, observation of unnatural movements caused an increased amplitude of the N400 component registered in the centro-parietal regions. We suggest that the sensitivity of N400 to intransitive action observation with no explicit semantic context might imply the broader role of N400 sources within AON. Surprisingly, no changes in corticospinal excitability were found. This lack of excitability modulation by action observation could be related with dependence of the M1 activity on the observed movement phase.

Effectiveness of Fish Oil-DHA Supplementation for Cognitive Function in Thai Children: A Randomized, Doubled-Blind, Two-Dose, Placebo-Controlled Clinical Trial

The effects of fish oil (FO) or omega-3 supplementation on cognition has been the subject of several previous clinical trials. However, the effect of different doses taken chronically on cognition in children has not been well studied. In order to address this gap in our knowledge, we conducted a randomized, double-blind, placebo-controlled clinical trial. A total of one hundred and twenty healthy, cognitively normal Thai children aged 6–12 years old consumed daily low dose FO (260 mg Docosahexaenoic acid (DHA)), high dose FO (520 mg DHA), or placebo (Soybean oil) for 12 weeks. Cognitive function was assessed using a computerized cognitive battery, including the Go/NoGo, N-Back, and Digit Span tests as well as concurrent event-related potentials (ERPs), which together measured attention, processing speed, inhibition, and memory at baseline and 12 weeks. We hypothesized that compared to placebo, the two FO groups would show improved cognitive performance and shorter ERP latencies. In total, 42, 39, and 39 participants completed each of the test (FO-A, FO-B) and placebo groups (P) allocations, respectively, and were analyzed (120 in total across the three groups). No significant differences were observed between reaction times (RTs), accuracy, or error rates for all three of the cognitive tests. The ERP measurement and analysis of brain activity during the cognitive tests showed an increase in ERP amplitude. For all cognitive tests, there was a dose-response effect of FO on ERP amplitudes. These findings indicate that fish oil intake leads to a consistent improvement in attention and cognitive processing ability measured by changes in brain activity during working and long-term memory processes. This is the first study to directly quantify such an effect through simultaneous measurement of manual and mental activity during cognitive tasks following chronic FO use in children.

The reliability of P300 and the influence of age, gender and education variables in a 50 years and older normative sample

OBJECTIVES

The present study aims to investigate the effects of age, gender, and level of education on P300 in a healthy population, aged 50 years and over; and determine the reliability metrics for different conditions and measurement methods.

METHOD

Auditory and visual oddball recordings of 171 healthy adults were investigated. A fully automated preprocessing was applied to elicit ERP P300. Maximum peak amplitude, latency and mean amplitudes were measured. Data were stratified by age, gender, and education to determine group-level differences by using repeat measures of ANOVA. The internal consistency of P300 was calculated by a split-half method using odd-even segments. Test-retest reliability was assessed by calculating the intraclass correlation coefficient (ICC).

RESULTS

Maximum peak P300 amplitudes were higher in the 50-64 years age group compared to the >65 years age group; and females showed increased P300 amplitudes compared to males. P300 measures showed fair to good internal consistency and poor to good test-retest reliability.

CONCLUSION

Age and gender should be taken into account when designing ERP studies with elderly individuals. P300 showed good internal consistency in general, between gender groups and age groups. Long-term test-retest reliability was lower but acceptable. These findings can be interpreted as the strength of P300 by being an objective and reliable method independent of cultural differences. Here we underline several factors that may affect P300 measures and discuss other possible factors that should be standardized for P300 to be used in clinical settings.

Objective Detection of Tinnitus Based on Electrophysiology

Tinnitus, a common disease in the clinic, is associated with persistent pain and high costs to society. Several aspects of tinnitus, such as the pathophysiology mechanism, effective treatment, objective detection, etc., have not been elucidated. Any change in the auditory pathway can lead to tinnitus. At present, there is no clear and unified mechanism to explain tinnitus, and the hypotheses regarding its mechanism include auditory plasticity theory, cortical reorganization theory, dorsal cochlear nucleus hypothesis, etc. Current theories on the mechanism of tinnitus mainly focus on the abnormal activity of the central nervous system. Unfortunately, there is currently a lack of objective diagnostic methods for tinnitus. Developing a method that can detect tinnitus objectively is crucial, only in this way can we identify whether the patient really suffers from tinnitus in the case of cognitive impairment or medical disputes and the therapeutic effect of tinnitus. Electrophysiological investigations have prompted the development of an objective detection of tinnitus by potentials recorded in the auditory pathway. However, there is no objective indicator with sufficient sensitivity and specificity to diagnose tinnitus at present. Based on recent findings of studies with various methods, possible electrophysiological approaches to detect the presence of tinnitus have been summarized. We analyze the change of neural activity throughout the auditory pathway in tinnitus subjects and in patients with tinnitus of varying severity to find available parameters in these methods, which is helpful to further explore the feasibility of using electrophysiological methods for the objective detection of tinnitus.