Target-to-target interval, intensity, and P300 from an auditory single-stimulus task

Unsupervised Characterization of Prediction Error Markers in Unisensory and Multisensory Streams Reveal the Spatiotemporal Hierarchy of Cortical Information Processing

Elicited upon violation of regularity in stimulus presentation, mismatch negativity (MMN) reflects the brain's ability to perform automatic comparisons between consecutive stimuli and provides an electrophysiological index of sensory error detection whereas P300 is associated with cognitive processes such as updating of the working memory. To date, there has been extensive research on the roles of MMN and P300 individually, because of their potential to be used as clinical markers of consciousness and attention, respectively. Here, we intend to explore with an unsupervised and rigorous source estimation approach, the underlying cortical generators of MMN and P300, in the context of prediction error propagation along the hierarchies of brain information processing in healthy human participants. The existing methods of characterizing the two ERPs involve only approximate estimations of their amplitudes and latencies based on specific sensors of interest. Our objective is twofold: first, we introduce a novel data-driven unsupervised approach to compute latencies and amplitude of ERP components accurately on an individual-subject basis and reconfirm earlier findings. Second, we demonstrate that in multisensory environments, MMN generators seem to reflect a significant overlap of "modality-specific" and "modality-independent" information processing while P300 generators mark a shift toward completely "modality-independent" processing. Advancing earlier understanding that multisensory contexts speed up early sensory processing, our study reveals that temporal facilitation extends to even the later components of prediction error processing, using EEG experiments. Such knowledge can be of value to clinical research for characterizing the key developmental stages of lifespan aging, schizophrenia, and depression.

An auditory brain-computer interface to detect changes in sound pressure level for automatic volume control

Volume control is necessary to adjust sound levels for a comfortable audio or video listening experience. This study aims to develop an automatic volume control system based on a brain-computer interface (BCI). We thus focused on a BCI using an auditory oddball paradigm, and conducted two types of experiments. In the first experiment, the participant was asked to pay attention to a target sound where the sound level was high (70 dB) compared with the other sounds (60 dB). The brain activity measured by electroencephalogram showed large positive activity (P300) for the target sound, and classification of the target and nontarget sounds achieved an accuracy of 0.90. The second experiment adopted a two-target paradigm where a low sound level (50 dB) was introduced as the second target sound. P300 was also observed in the second experiment, and a value of 0.76 was obtained for the binary classification of the target and nontarget sounds. Further, we found that better accuracy was observed in large sound levels compared to small ones. These results suggest the possibility of using BCI for automatic volume control; however, it is necessary to improve its accuracy for application in daily life.

ERP evidence of attentional somatosensory processing and stimulus-response coupling under different hand and arm postures

We investigated (1) the effects of divided and focused attention on event-related brain potentials (ERPs) elicited by somatosensory stimulation under different response modes, (2) the effects of hand position (closely-placed vs. separated hands) and arm posture (crossed vs. uncrossed forearms) on the attentional modulation of somatosensory ERPs, and (3) changes in the coupling of stimulus- and response-related processes by somatosensory attention using a single-trial analysis of P300 latency and reaction times. Electrocutaneous stimulation was presented randomly to the thumb or middle finger of the left or right hand at random interstimulus intervals (700-900 ms). Subjects attended unilaterally or bilaterally to stimuli in order to detect target stimuli by a motor response or counting. The effects of unilaterally-focused attention were also tested under different hand and arm positions. The amplitude of N140 in the divided attention condition was intermediate between unilaterally attended and unattended stimuli in the unilaterally-focused attention condition in both the mental counting and motor response tasks. Attended infrequent (target) stimuli elicited greater P300 in the unilaterally attention condition than in the divided attention condition. P300 latency was longer in the divided attention condition than in the unilaterally-focused attention condition in the motor response task, but remained unchanged in the counting task. Closely locating the hands had no impact, whereas crossing the forearms decreased the attentional enhancement in N140 amplitude. In contrast, these two manipulations uniformly decreased P300 amplitude and increased P300 latency. The correlation between single-trial P300 latency and RT was decreased by crossed forearms, but not by divided attention or closely-placed hands. Therefore, the present results indicate that focused and divided attention differently affected middle latency and late processing, and that hand position and arm posture also differently affected attentional processes and stimulus-response coupling.

Weathering the storm of emotions: immediate and lasting effects of reinterpretation and distancing on event-related potentials and their association with habitual use of cognitive reappraisal

Reinterpretation and distancing, two cognitive reappraisal tactics, are known to effectively reduce negative feelings and event-related potentials (ERPs), such as the P300 and the late positive potential (LPP), in the short-term. Less is known about differential and lasting effects on ERPs as well as their association with habitual reappraisal. Fifty-seven participants were instructed to passively view or reappraise (reinterpretation, distancing) pictures that were repeatedly presented with the same instruction (active regulation phase). Thirty minutes later, these pictures were shown again without instruction for the assessment of lasting effects (re-exposure phase). ERPs were recorded and participants rated the intensity of negative feelings following picture presentation. Reappraisal led to an attenuation of the LPP, and both tactics decreased negative feelings during active regulation, whereby reinterpretation had a stronger impact on the subjective level. Passive re-exposure resulted in reduced negative feelings for previously reappraised pictures but had no lasting effects on ERPs. Higher habitual reappraisal was associated with higher P300 and early LPP amplitudes for emotional reactivity during the active regulation phase. During the re-exposure phase, higher habitual reappraisal was not related to ERPs. The current findings emphasize the effectiveness of both tactics in the short-term and lasting effects on the subjective experience of negative feelings. Enhanced emotional reactivity on the electrocortical level in individuals with a more frequent habitual use of reappraisal might indicate a higher preparedness to regulate.

Reliability and stability of oddball P300 amplitude in older adults: The role of stimulus sequence effects

The P300 may be an individual difference marker of neuro-cognitive function, which due to age-related cognitive decline may be particularly useful in older adults. Recently, we reported effects of the local stimulus sequence in an oddball task (i.e., the number of non-targets that preceded a target) on P300 amplitude in young and older adults. The same older adults completed a second session of the task 4-8 months after the first session. Here, we examined the effect of the stimulus sequence on the between- and within-session reliability and stability of P300 amplitude and RT, and their intertrial variability, in this sample of older adults. The sequence effects - an inverted U-shape effect of the number of standards preceding a target on parietal P300, and a linear effect on frontal P300 - were stable within and across sessions on the group level. Within individuals, P300 amplitude at frontal and parietal electrodes was generally very reliable and stable, mostly independently of sequence effects, encouraging its use as an individual difference marker of neuro-cognitive function in older adults. However, measures of the strength of the sequence effects themselves showed unacceptable reliability, speaking against their use as individual difference markers, at least in older adults.

Depression reduces neural correlates of reward salience with increasing effort over the course of the progressive ratio task

BACKGROUND

Depressive disorders have been associated with altered effort-cost decision making (ECDM) in behavioral investigations, such as a decreased willingness to expend effort for reward attainment. However, little is known about neural mechanisms implicated in altered ECDM.

METHODS

The study investigates neural correlates of reward attainment during a progressive ratio task in participants with a current depressive disorder (n = 65) and never-depressed healthy individuals (n = 44). On each trial, participants completed an increasing number of button presses to attain a fixed monetary reward, indicated by an auditory reward signal. Participants could decide to quit the task anytime (breakpoint). EEG was recorded during the task and P300 amplitudes were examined in response to the auditory signal of reward attainment.

RESULTS

There was no difference in breakpoint, as both groups completed comparable numbers of button presses. In contrast, results from mixed-effects models of trial-level ERP responses indicated depression-related effects on P300 amplitudes over the course of the task. Generally, the reward-locked P300 increased with ascending effort expenditure; however, compared to healthy participants, individuals with current depression were characterized by an attenuated trajectory of the reward-locked P300, pointing towards decreased reactivity to reward attainment with increasing effort.

LIMITATIONS

Sample size and reward magnitude were possibly not large enough to detect differences in breakpoint.

CONCLUSIONS

The results of the current study demonstrate that the investigation of reward-related P300 trajectory may represent an informative novel addition to the progressive ratio task, which could help shed light on depression-related alterations in motivation and ECDM.

Impaired selective attention in patients with severe primary monosymptomatic nocturnal enuresis: An event-related potential study

Objectives

Primary monosymptomatic nocturnal enuresis (PMNE) is a very common problem in school age children. It is thought that PMNE represents a maturational lag in the central nervous system of those children. We did this case control study to assess the selective attention and resource allocation in those children using the P300 wave of the Event-Related Potentials (ERPs) and its relation to disease severity.

Methods

Forty four patients with PMNE and twenty three healthy controls were included in this study. Patients were diagnosed according to the criteria of international children's continence society and were classified into two groups; patients with frequent wetting (≥4 episodes/week), and patients with infrequent wetting (<4 episodes/week). ERPs were recorded at Fz, Cz, and Pz locations using odd-ball paradigm. N200 and P300 peak latencies (ms), and N200/P300 peak to peak amplitudes (µV) were measured.

Results

We found significant increase of P300 and N200/P300 interpeak latencies, and significant decrease of P300 amplitudes in frequent wetting group "severe" PMNE compared to healthy controls and infrequent wetting group.

Conclusion

Abnormal selective attention and resource allocation were found in patients with severe PMNE. Measures to improve selective attention might be helpful in treatment of patients with severe PMNE.

Significance

Impaired selective attention might play a role in pathogenesis of severe PMNE and the need for the various measures to improve selective attention may be further studied as a therapeutic tool for patients with severe PMNE.

Efficacy of a Single-Task ERP Measure to Evaluate Cognitive Workload During a Novel Exergame

This study aimed to validate the efficacy of single-task event-related potential (ERP) measures of cognitive workload to be implemented in exergame-based rehabilitation. Twenty-four healthy participants took part in a novel gamified balance task where task-irrelevant auditory tones were presented in the background to generate ERPs in the participants’ electroencephalogram (EEG) as a measure of cognitive workload. For the balance task, a computer-based tilt-ball game was combined with a balance board. Participants played the game by shifting their weight to tilt the balance board, which moved a virtual ball to score goals. The game was manipulated by adjusting the size of the goalposts to set three predefined levels of game difficulty (easy, medium, and hard). The participant’s experience of game difficulty was evaluated based on the number of goals scored and their subjective reporting of perceived difficulty. Participants experienced a significant difference in the three levels of task difficulty based on the number of goals scored and perceived difficulty (p < 0.001). Post hoc analysis revealed the lowest performance for the hardest level. The mean amplitude of the N1 ERP component was used to measure the cognitive workload associated with the three difficulty levels. The N1 component’s amplitude decreased significantly (p < 0.001), with an increase in the task difficulty. Moreover, the amplitude of the N1 component for the hard level was significantly smaller compared to medium (p = 0.0003) and easy (p < 0.001) levels. These results support the efficacy of the N1 ERP component to measure cognitive workload in dynamic and real-life scenarios such as exergames and other rehabilitation exercises.

Informational Masking Effects of Similarity and Uncertainty on Early and Late Stages of Auditory Cortical Processing

PURPOSE

Understanding speech in a background of other people talking is a difficult listening situation for hearing-impaired individuals, and even for those with normal hearing. Speech-on-speech masking is known to contribute to increased perceptual difficulty over nonspeech background noise because of informational masking provided over and above the effects of energetic masking. While informational masking research has identified factors of similarity and uncertainty between target and masker that contribute to reduced behavioral performance in speech background noise, critical gaps in knowledge including the underlying neural-perceptual processes remain. By systematically manipulating aspects of acoustic similarity and uncertainty in the same auditory paradigm, the current study examined the time course and objectively quantified these informational masking effects at both early and late stages of auditory processing using auditory evoked potentials (AEPs).

METHOD

Thirty participants were included in a cross-sectional repeated measures design. Target-masker similarity was manipulated by varying the linguistic/phonetic similarity (i.e., language) of the talkers in the background. Specifically, four levels representing hypothesized increasing levels of informational masking were implemented: (1) no masker (quiet); (2) Mandarin; (3) Dutch; and (4) English. Stimulus uncertainty was manipulated by task complexity, specifically presentation of target-to-target interval (TTI) in the auditory evoked paradigm. Participants had to discriminate between English word stimuli (/bæt/ and /pæt/) presented in an oddball paradigm under each masker condition pressing buttons to either the target or standard stimulus. Responses were recorded simultaneously for P1-N1-P2 (standard waveform) and P3 (target waveform). This design allowed for simultaneous recording of multiple AEP peaks, as well as accuracy, reaction time, and d' behavioral discrimination to button press responses.

RESULTS

Several trends in AEP components were consistent with effects of increasing linguistic/phonetic similarity and stimulus uncertainty. All babble maskers significantly affected outcomes compared to quiet. In addition, the native language English masker had the largest effect on outcomes in the AEP paradigm, including reduced P3 amplitude and area, as well as decreased accuracy and d' behavioral discrimination to target word responses. AEP outcomes for the Mandarin and Dutch maskers, however, were not significantly different across any measured component. Latency outcomes for both N1 and P3 also supported an effect of stimulus uncertainty, consistent with increased processing time related to greater task complexity. An unanticipated result was the absence of the interaction of linguistic/phonetic similarity and stimulus uncertainty.

CONCLUSIONS

Observable effects of both similarity and uncertainty were evidenced at a level of the P3 more than the earlier N1 level of auditory cortical processing suggesting that higher-level active auditory processing may be more sensitive to informational masking deficits. The lack of significant interaction between similarity and uncertainty at either level of processing suggests that these informational masking factors operated independently. Speech babble maskers across languages altered AEP component measures, behavioral detection, and reaction time. Specifically, this occurred when the babble was in the native/same language as the target, while the effects of foreign language maskers did not differ. The objective results from this study provide a foundation for further investigation of how the linguistic content of target and masker and task difficulty contribute to difficulty understanding speech-in-noise.

Sequential gains and losses during gambling feedback: Differential effects in time-frequency delta and theta measures

One critical aspect of reward-feedback is the impact of local outcome history-how past experiences with choices and outcomes influences current behavior and neural activity. Yet, prior event-related potential work in this area has been contentious. This study contributes to this field by using time-frequency measures to better isolate constituent processes. Specifically, we identify how theta and delta are differentially sensitive to local outcome history. Participants completed a binary monetary choice task while we collected EEG data. Unbeknownst to them, trial outcomes were manipulated into pre-determined sequences, ranging from one to eight gains or losses in a row. Analyses were arranged by sequence establishment (first 2 trials of a sequence) and continuation (prolonged sequences of 3-8 trials). During the establishment of a sequence, delta activity to gains and losses were virtually identical on the first (change) trial, demonstrating marked divergence only on the second trial. This difference grew throughout the continuation period, as delta activity was sustained with accruing gains but declined with multiple losses. Theta activity, conversely, demonstrated a maximal loss-gain difference on the change trial but was insensitive to the establishment of a new sequence. Differential theta activity between outcomes decreased as sequences continued, with theta activity increasing over accruing gains and remaining stable over losses. Results indicate that delta-gain and theta-loss signals are relatively stable across sequential outcomes. Furthermore, theta is most sensitive to loss-gain differences on the initial change trial, while delta is more sensitive to gain-loss differences with the continuation of a sequence.

The Impact of Vigorous Cycling Exercise on Visual Attention: A Study With the BR8 Wireless Dry EEG System

Many studies have reported that exercise can influence cognitive performance. But advancing our understanding of the interrelations between psychology and physiology in sports neuroscience requires the study of real-time brain dynamics during exercise in the field. Electroencephalography (EEG) is one of the most powerful brain imaging technologies. However, the limited portability and long preparation time of traditional wet-sensor systems largely limits their use to laboratory settings. Wireless dry-sensor systems are emerging with much greater potential for practical application in sports. Hence, in this paper, we use the BR8 wireless dry-sensor EEG system to measure P300 brain dynamics while cycling at various intensities. The preparation time was mostly less than 2 min as BR8 system’s dry sensors were able to attain the required skin-sensor interface impedance, enabling its operation without any skin preparation or application of conductive gel. Ten participants performed four sessions of a 3 min rapid serial visual presentation (RSVP) task while resting and while cycling. These four sessions were pre-CE (RSVP only), low-CE (RSVP in 40–50% of max heart rate), vigorous-CE (RSVP in 71–85% of max heart rate) and post-CE (RSVP only). The recorded brain signals demonstrate that the P300 amplitudes, observed at the Pz channel, for the target and non-target responses were significantly different in all four sessions. The results also show decreased reaction times to the visual attention task during vigorous exercise, enriching our understanding of the ways in which exercise can enhance cognitive performance. Even though only a single channel was evaluated in this study, the quality and reliability of the measurement using these dry sensor-based EEG systems is clearly demonstrated by our results. Further, the smooth implementation of the experiment with a dry system and the success of the data analysis demonstrate that wireless dry EEG devices can open avenues for real-time measurement of cognitive functions in athletes outside the laboratory.

Altered somatosensory evoked potentials associated with improved reaction time in a simple sensorimotor response task following repetitive practice

INTRODUCTION

Repetitive practice of sensorimotor tasks is widely used for neurorehabilitation; however, it is unknown how practice alters sensory processing (e.g., recognition, discrimination, and attentional allocation) and associated cognitive processing, such as decision-making. The purpose of this study was to investigate whether long-latency somatosensory evoked potentials (SEPs) reflecting sensory processing, attention, and decision-making are altered by sensorimotor learning.

METHODS

Fifteen participants performed a simple sensorimotor response task (thumb opposition in response to surface electrical stimulation), with experimental recording sessions before and after three days of practice. We then compared multiple SEP waveforms and reaction times (RTs) between pre- and postpractice trials.

RESULTS

The RT was reduced after practice of three days, and we found a significant positive correlation between ΔRT and ΔN140_lat at F3, Cz, and C3', ΔRT and ΔN250_lat at F3, and there was a significant negative correlation between ΔRT and ΔP300_amp at C3'.

CONCLUSION

The present study suggests that motor learning improves somatosensory processing and attentional allocation via neuroplasticity and that these alterations are reflected by specific SEP changes.

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.

Different Contexts in the Oddball Paradigm Induce Distinct Brain Networks in Generating the P300

Despite the P300 event-related potential (ERP) differences between distinct stimulus sequences, the effect of stimulus sequence on the brain network is still left unveiled. To uncover the corresponding effect of stimulus sequence, we thus investigated the differences of functional brain networks, when a target (T) or standard (S) stimulus was presented preceding another T as background context. Results of this study demonstrated that, when an S was first presented preceding a T (i.e., ST sequence), the P300 experiencing large amplitude was evoked by the T, along with strong network architecture. In contrast, if a T was presented in advance [i.e., target-to-target (TT) sequence], decreased P300 amplitude and attenuated network efficiency were demonstrated. Additionally, decreased activations in regions, such as inferior frontal gyrus and superior frontal gyrus were also revealed in TT sequence. Particularly, the effect of stimulus sequence on P300 network could be quantitatively measured by brain network properties, the increase in network efficiency corresponded to large P300 amplitude evoked in P300 task.

A Dual Stimuli Approach Combined with Convolutional Neural Network to Improve Information Transfer Rate of Event-Related Potential-Based Brain-Computer Interface

Increasing command generation rate of an event-related potential-based brain-robot system is challenging, because of limited information transfer rate of a brain-computer interface system. To improve the rate, we propose a dual stimuli approach that is flashing a robot image and is scanning another robot image simultaneously. Two kinds of event-related potentials, N200 and P300 potentials, evoked in this dual stimuli condition are decoded by a convolutional neural network. Compared with the traditional approaches, this proposed approach significantly improves the online information transfer rate from 23.0 or 17.8 to 39.1 bits/min at an accuracy of 91.7%. These results suggest that combining multiple types of stimuli to evoke distinguishable ERPs might be a promising direction to improve the command generation rate in the brain-computer interface.

Target probability modulates fixation-related potentials in visual search

This study investigated the influence of target probability on the neural response to target detection in free viewing visual search. Participants were asked to indicate the number of targets (one or two) among distractors in a visual search task while EEG and eye movements were co-registered. Target probability was manipulated by varying the set size of the displays between 10, 22, and 30 items. Fixation-related potentials time-locked to first target fixations revealed a pronounced P300 at the centro-parietal cortex with larger amplitudes for set sizes 22 and 30 than for set size 10. With increasing set size, more distractor fixations preceded the detection of the target, resulting in a decreased target probability and, consequently, a larger P300. For distractors, no increase of P300 amplitude with set size was observed. The findings suggest that set size specifically affects target but not distractor processing in overt serial visual search.

Independent contributions of theta and delta time-frequency activity to the visual oddball P3b

A growing body of work suggests that the P300 (P3) event-related potential (ERP) component is better understood as a mixture of task-relevant processes (Polich, 2007). This converges with earlier time-frequency work suggesting that the P3b is primarily composed of centroparietal delta (0.5-3 Hz) and frontocentral theta (3-7 Hz) activity. Within this study (N = 229), we hope to re-affirm these prior ideas and expand upon them in several crucial ways, reassessing how delta and theta contribute to the visual oddball P3b through the lens of several recent decades of additional P3b research. We provide a comprehensive assessment of how theta and delta time-frequency activity contribute to several common variants of the time-domain P3b, specifically measuring the target and non-target P3b, as well as differences between targets and non-targets, target-to-target interval (TTI), and target habituation. Results replicate and extend earlier work indicating that delta and theta account for a majority of variance in both the target and non-target P3b as well as their respective amplitude differences. They also newly indicate that theta and delta activity can have unique contributions to TTI differences and target habituation effects. Results in target habituation particularly demonstrate how time-frequency analyses can disentangle nuanced changes in P3b activity, shedding new light on these complicated phenomena. Findings suggest that delta and theta measures index separable processes occurring during the P3b, and provide additional support for the idea that they index theoretical frontocentral and centroparietal P3 subcomponents.

Improving the Performance of an Auditory Brain-Computer Interface Using Virtual Sound Sources by Shortening Stimulus Onset Asynchrony

Recently, a brain-computer interface (BCI) using virtual sound sources has been proposed for estimating user intention via electroencephalogram (EEG) in an oddball task. However, its performance is still insufficient for practical use. In this study, we examine the impact that shortening the stimulus onset asynchrony (SOA) has on this auditory BCI. While very short SOA might improve its performance, sound perception and task performance become difficult, and event-related potentials (ERPs) may not be induced if the SOA is too short. Therefore, we carried out behavioral and EEG experiments to determine the optimal SOA. In the experiments, participants were instructed to direct attention to one of six virtual sounds (target direction). We used eight different SOA conditions: 200, 300, 400, 500, 600, 700, 800, and 1,100 ms. In the behavioral experiment, we recorded participant behavioral responses to target direction and evaluated recognition performance of the stimuli. In all SOA conditions, recognition accuracy was over 85%, indicating that participants could recognize the target stimuli correctly. Next, using a silent counting task in the EEG experiment, we found significant differences between target and non-target sound directions in all but the 200-ms SOA condition. When we calculated an identification accuracy using Fisher discriminant analysis (FDA), the SOA could be shortened by 400 ms without decreasing the identification accuracies. Thus, improvements in performance (evaluated by BCI utility) could be achieved. On average, higher BCI utilities were obtained in the 400 and 500-ms SOA conditions. Thus, auditory BCI performance can be optimized for both behavioral and neurophysiological responses by shortening the SOA.

Cognitive Event-Related Potentials in Patients With Adenoid Hypertrophy: A Case-Control Pilot Study

PURPOSE

Children with adenoid hypertrophy commonly have sleep-disordered breathing. Sleep-disordered breathing is associated with various neurocognitive problems. The aim of this study was to assess the cognitive function in those patients using cognitive event-related potentials.

METHODS

Twenty-three patients with moderate to severe adenoid hypertrophy were compared with 20 healthy controls. The intelligence quotient was performed for all study participants. The latencies of the N200, P300 peaks and the amplitudes of the N200/P300 components of event-related potentials were recorded. The above variables were measured at baseline for both patients and control groups and 2 months after adenoidectomy for the patient group.

RESULTS

There was no significant difference between patients and controls regarding full intelligence quotient scales. P300 latency was significantly prolonged in patient group compared with the healthy controls. Moreover, postoperative P300 latency was significantly reduced compared with the preoperative P300 latency. Postoperative P300 latency was not statistically different from healthy controls' data.

CONCLUSIONS

P300 latency delay may reflect some sort of cognitive impairment in patients with adenoid hypertrophy. This delay was reversible after adenoidectomy. Event-related potentials may help for assessment of cognitive functions in patients with adenoid hypertrophy.

Action Experience and Action Discovery in Medicated Individuals with Parkinson's Disease

Parkinson’s disease (PD) is a neurodegenerative disorder that markedly affects voluntary action. While regular dopamine treatment can help restore motor function, dopamine also influences cognitive portions of the action system. Previous studies have demonstrated that dopamine medication boosts action-effect associations, which are crucial for the discovery of new voluntary actions. In the present study, we investigated whether neural processes involved in the discovery of new actions are altered in PD participants on regular dopamine treatment, compared to healthy age-matched controls. We recorded brain electroencephalography (EEG) activity while PD patients and age-matched controls performed action discovery (AD) and action control tasks. We found that the novelty P3, a component normally present when there is uncertainty about the occurrence of the sensory effect, was enhanced in PD patients. However, AD was maintained in PD patients, and the novelty P3 demonstrated normal learning-related reductions. Crucially, we found that in PD patients the causal association between an action and its resulting sensory outcome did not modulate the amplitude of the feedback correct-related positivity (fCRP), an EEG component sensitive to the association between an action and its resulting effect. Collectively, these preliminary results suggest that the formation of long-term action-outcome representations may be maintained in PD patients on regular dopamine treatment, but the initial experience of action-effect association may be affected.

Sequential Processing and the Matching-Stimulus Interval Effect in ERP Components: An Exploration of the Mechanism Using Multiple Regression

In oddball tasks, increasing the time between stimuli within a particular condition (target-to-target interval, TTI; nontarget-to-nontarget interval, NNI) systematically enhances N1, P2, and P300 event-related potential (ERP) component amplitudes. This study examined the mechanism underpinning these effects in ERP components recorded from 28 adults who completed a conventional three-tone oddball task. Bivariate correlations, partial correlations and multiple regression explored component changes due to preceding ERP component amplitudes and intervals found within the stimulus series, rather than constraining the task with experimentally constructed intervals, which has been adequately explored in prior studies. Multiple regression showed that for targets, N1 and TTI predicted N2, TTI predicted P3a and P3b, and Processing Negativity (PN), P3b, and TTI predicted reaction time. For rare nontargets, P1 predicted N1, NNI predicted N2, and N1 predicted Slow Wave (SW). Findings show that the mechanism is operating on separate stages of stimulus-processing, suggestive of either increased activation within a number of stimulus-specific pathways, or very long component generator recovery cycles. These results demonstrate the extent to which matching-stimulus intervals influence ERP component amplitudes and behavior in a three-tone oddball task, and should be taken into account when designing similar studies.

Electrophysiology of Memory-Updating Differs with Age

In oddball tasks, the P3 component of the event-related potential systematically varies with the time between target stimuli—the target-to-target interval (TTI). Longer TTIs result in larger P3 amplitudes and shorter latencies, and this pattern of results has been linked with working memory-updating processes. Given that working memory and the P3 have both been shown to diminish with age, the current study aimed to determine whether the linear relationship between P3 and TTI is compromised in healthy aging by comparing TTI effects on P3 amplitudes and latencies, and reaction time (RT), in young and older adults. Older adults were found to have an overall reduction in P3 amplitudes, longer latencies, an anterior shift in topography, a trend toward slower RTs, and a flatter linear relationship between P3 and TTI than young adults. Results suggest that the ability to maintain templates in working memory required for stimulus categorization decreases with age, and that as a result, neural compensatory mechanisms are employed.

One-year developmental stability and covariance among oddball, novelty, go/no-go, and flanker event-related potentials in adolescence: A monozygotic twin study

ERP measures may index genetic risk for psychopathology before disorder onset in adolescence, but little is known about their developmental rank-order stability during this period of significant brain maturation. We studied ERP stability in 48 pairs of identical twins (age 14-16 years) tested 1 year apart. Trial-averaged voltage waveforms were extracted from electroencephalographic recordings from oddball/novelty, go/no-go, and flanker tasks, and 16 amplitude measures were examined. Members of twin pairs were highly similar, whether based on ERP amplitude measures (intraclass correlation [ICC] median = .64, range = .44-.86) or three factor scores (all ICCs ≥ .69) derived from them. Stability was high overall, with 69% of the 16 individual measures generating stability coefficients exceeding .70 and all factor scores showing stability above .75. Measures from 10 difference waveforms calculated from paired conditions within tasks were also examined, and were associated with lower twin similarity (ICC median = .52, .38-.64) and developmental stability (only 30% exceeding .70). In a supplemental analysis, we found significant developmental stability for error-related negativity (range = .45-.55) and positivity (.56-.70) measures when average waveforms were based on one or more trials, and that these values were equivalent to those derived from averages using the current field recommendation, which requires six or more trials. Overall, we conclude that the studied brain measures are largely stable over 1 year of mid- to late adolescence, likely reflecting familial etiologic influences on brain functions pertaining to cognitive control and salience recognition.

Increasing N200 Potentials Via Visual Stimulus Depicting Humanoid Robot Behavior

Achieving recognizable visual event-related potentials plays an important role in improving the success rate in telepresence control of a humanoid robot via N200 or P300 potentials. The aim of this research is to intensively investigate ways to induce N200 potentials with obvious features by flashing robot images (images with meaningful information) and by flashing pictures containing only solid color squares (pictures with incomprehensible information). Comparative studies have shown that robot images evoke N200 potentials with recognizable negative peaks at approximately 260[Formula: see text]ms in the frontal and central areas. The negative peak amplitudes increase, on average, from [Formula: see text]V, induced by flashing the squares, to [Formula: see text]V, induced by flashing the robot images. The data analyses support that the N200 potentials induced by the robot image stimuli exhibit recognizable features. Compared with the square stimuli, the robot image stimuli increase the average accuracy rate by 9.92%, from 83.33% to 93.25%, and the average information transfer rate by 24.56[Formula: see text]bits/min, from 72.18[Formula: see text]bits/min to 96.74 bits/min, in a single repetition. This finding implies that the robot images might provide the subjects with more information to understand the visual stimuli meanings and help them more effectively concentrate on their mental activities.

Stimulus-to-matching-stimulus interval influences N1, P2, and P3b in an equiprobable Go/NoGo task

Previous research has shown that as the stimulus-to-matching-stimulus interval (including the target-to-target interval, TTI, and nontarget-to-nontarget interval, NNI) increases, the amplitude of the P300 ERP component increases systematically. Here, we extended previous P300 research and explored TTI and NNI effects on the various ERP components elicited in an auditory equiprobable Go/NoGo task. We also examined whether a similar mechanism was underpinning interval effects in early ERP components (e.g., N1). Thirty participants completed a specially-designed variable-ISI equiprobable task whilst their EEG activity was recorded. Component amplitudes were extracted using temporal PCA with unrestricted Varimax rotation. As expected, N1, P2, and P3b amplitudes increased as TTI and NNI increased, however, Processing Negativity (PN) and Slow Wave (SW) did not show the same systematic change with interval increments. To determine the origin of interval effects in sequential processing, a multiple regression analysis was conducted on each ERP component including stimulus type, interval, and all preceding components as predictors. These analyses showed that matching-stimulus interval predicted N1, P3b, and weakly predicted P2, but not PN or SW; SW was determined by P3b only. These results suggest that N1, P3b, and to some extent, P2, are affected by a similar temporal mechanism. However, the dissimilar pattern of results obtained for sequential ERP components indicates that matching-stimulus intervals are not affecting all aspects of stimulus processing. This argues against a global mechanism, such as a pathway-specific refractory effect, and suggests that stimulus processing is occurring in parallel pathways, some of which are not affected by temporal manipulations of matching-stimulus interval.

Visual evoked potentials to change in coloration of a moving bar

In our previous study we found that it takes less time to detect coloration change in a moving object compared to coloration change in a stationary one (Kreegipuu etal., 2006). Here, we replicated the experiment, but in addition to reaction times (RTs) we measured visual evoked potentials (VEPs), to see whether this effect of motion is revealed at the cortical level of information processing. We asked our subjects to detect changes in coloration of stationary (0(°)/s) and moving bars (4.4 and 17.6(°)/s). Psychophysical results replicate the findings from the previous study showing decreased RTs to coloration changes with increase of velocity of the color changing stimulus. The effect of velocity on VEPs was opposite to the one found on RTs. Except for component N1, the amplitudes of VEPs elicited by the coloration change of faster moving objects were reduced than those elicited by the coloration change of slower moving or stationary objects. The only significant effect of velocity on latency of peaks was found for P2 in frontal region. The results are discussed in the light of change-to-change interval and the two methods reflecting different processing mechanisms.

Can event-related potentials serve as neural markers for wins, losses, and near-wins in a gambling task? A principal components analysis

Originally, the feedback related negativity (FRN) event-related potential (ERP) component was considered to be a robust neural correlate of non-reward/punishment processing, with greater negative deflections observed following unfavourable outcomes. More recently, it has been suggested that this component is better conceptualised as a positive deflection following rewarding outcomes. The current study sought to elucidate the nature of the FRN, as well as another component associated with incentive-value processing, the P3b, through application of a spatiotemporal principal components analysis (PCA). Seventeen healthy controls played a computer electronic gaming machine (EGM) task and received feedback on credits won or lost on each trial, and ERPs were recorded. The distribution of reward/non-reward outcomes closely matched that of a real EGM, with frequent losses, and infrequent wins and near-wins. The PCA revealed that feedback elicited both a frontally maximal negative deflection to losses, and a positive deflection to wins (which was also sensitive to reward magnitude), implying that the neural generator/s of the FRN are differentially activated following these outcomes. As expected, greater P3b amplitudes were found for wins compared to losses. Interestingly, near-wins elicited significantly smaller FRN amplitudes than losses (with no differences in P3b amplitude), and may contribute to the maintenance of gambling behaviours on EGMs. The results of the current study are integrated into a response profile of healthy controls to outcomes of varying incentive value. This may provide a foundation for the future examination of individuals who exhibit abnormalities in reward/punishment processing, such as problem gamblers.

Sensory-based and higher-order operations contribute to abnormal emotional prosody processing in schizophrenia: an electrophysiological investigation

BACKGROUND

Schizophrenia is characterized by deficits in emotional prosody (EP) perception. However, it is not clear which stages of processing prosody are abnormal and whether the presence of semantic content contributes to the abnormality. This study aimed to examine event-related potential (ERP) correlates of EP processing in 15 chronic schizophrenia individuals and 15 healthy controls.

METHOD

A total of 114 sentences with neutral semantic content [sentences with semantic content (SSC) condition] were generated by a female speaker (38 with happy, 38 with angry, and 38 with neutral intonation). The same sentences were synthesized and presented in the 'pure prosody' sentences (PPS) condition where semantic content was unintelligible.

RESULTS

Group differences were observed for N100 and P200 amplitude: patients were characterized by more negative N100 for SSC, and more positive P200 for angry and happy SSC and happy PPS. Correlations were found between delusions and P200 amplitude for happy SSC and PPS. Higher error rates in the recognition of EP were also observed in schizophrenia: higher error rates in neutral SSC were associated with reduced N100, and higher error rates in angry SSC were associated with reduced P200.

CONCLUSIONS

These results indicate that abnormalities in prosody processing occur at the three stages of EP processing, and are enhanced in SSC. Correlations between P200 amplitude for happy prosody and delusions suggest a role that abnormalities in the processing of emotionally salient acoustic cues may play in schizophrenia symptomatology. Correlations between ERP and behavioral data point to a relationship between early sensory abnormalities and prosody recognition in schizophrenia.

Neuroscientific measures of covert behavior

In radical behaviorism, the difference between overt and covert responses does not depend on properties of the behavior but on the sensitivity of the measurement tools employed by the experimenter. Current neuroscientific research utilizes technologies that allow measurement of variables that are undetected by the tools typically used by behavior analysts. Data from a specific neuroscientific technique, event-related potential (ERP), suggest that emission of otherwise covert responses can be indexed and that such covert responses are sensitive to stimulus control and selection by consequences. The P3 ERP effect is proposed as indicative of emission. Moreover, ERP results in semantic priming experiments suggest that operants are sensitive to changes in stimulus control even when they are not emitted (latent responses). Changes in response strength of latent responses as a function of stimulus control can in fact be measured by reaction time data and an ERP dependent variable called the N400 effect. If the interpretations provided in this paper are accurate, an index of covertly emitted operants (P3 effect) constitutes experimental evidence suggesting the validity of a Skinnerian radical behaviorist perspective on behavior. Moreover, in a Skinnerian paradigm, measured fluctuations in the response strength of latent operants as a function of environmental changes (N400 effect) would validate Palmer's (2009) concept of the repertoire.

Comparing P300 modulations: target-to-target interval versus infrequent nontarget-to-nontarget interval in a three-stimulus task

This study examined temporal determinants of the P300 component of the ERP in a three-stimulus visual oddball task. Frequent standards, with equiprobable targets and infrequent nontargets, were utilized. We tested whether the infrequent nontarget-to-nontarget interval (infrequent NNI) influences P300 amplitudes and latencies analogously to the target-to-target interval (TTI). EEG was recorded from 27 participants, and response time and P300 effects of TTIs and infrequent NNIs were assessed. Increases in TTI augmented target P300 amplitudes and decreased latencies and response times. However, this modulation of P300 amplitude was weak for manipulations of infrequent NNI. P300 latencies increased initially before decreasing across infrequent NNI levels. Together, these findings support the notion that the P300 has an underlying temporal mechanism that is modulated by motivationally significant events. Theoretical implications are discussed.

Neural events leading to and associated with detection of sounds under high processing load

The neural events that lead to successful or failed detection of suprathreshold sounds are not well established. In this experiment, event-related potentials (ERPs) and functional magnetic resonance imaging (fMRI) were recorded while participants performed two tasks: a primary difficult duration judgment task on a sequence of tones presented to one ear, and a secondary target detection task on an auditory oddball stream presented to the other ear. The paradigm was designed to elicit competition and variability in detection of auditory targets despite identical input. Successful detection of auditory targets was associated mainly with greater fMRI activity in superior parietal cortex and thalamus. In the ERPs, successful detection was linked with a larger fronto-central negativity at 200-400 ms, and a later centro-posterior positivity. Failure to detect targets was associated with greater fMRI signal in the default mode network, a significantly smaller electrical fronto-central negativity and no late positivity. These findings demonstrate that variability in auditory detection is related to modulation of activity in multimodal parietal and frontal networks active ∼ 200 ms after target onset. Results are consistent with a limited capacity and late selection view of attention.

Listen, You are Writing! Speeding up Online Spelling with a Dynamic Auditory BCI

Representing an intuitive spelling interface for brain-computer interfaces (BCI) in the auditory domain is not straight-forward. In consequence, all existing approaches based on event-related potentials (ERP) rely at least partially on a visual representation of the interface. This online study introduces an auditory spelling interface that eliminates the necessity for such a visualization. In up to two sessions, a group of healthy subjects (N = 21) was asked to use a text entry application, utilizing the spatial cues of the AMUSE paradigm (Auditory Multi-class Spatial ERP). The speller relies on the auditory sense both for stimulation and the core feedback. Without prior BCI experience, 76% of the participants were able to write a full sentence during the first session. By exploiting the advantages of a newly introduced dynamic stopping method, a maximum writing speed of 1.41 char/min (7.55 bits/min) could be reached during the second session (average: 0.94 char/min, 5.26 bits/min). For the first time, the presented work shows that an auditory BCI can reach performances similar to state-of-the-art visual BCIs based on covert attention. These results represent an important step toward a purely auditory BCI.

Pupillary responses and event-related potentials as indices of the orienting reflex

This study examined skin conductance responses, the late positive complex of the event-related potential, and pupillary dilation responses as autonomic and central correlates of the orienting reflex (OR) in the context of indifferent and significant stimuli. In particular, we aimed to clarify the inconsistencies surrounding the pupillary dilation response as an OR index. An auditory dishabituation paradigm was employed, and physiological measures were recorded from 24 participants. Response decrement to a repeated stimulus, response recovery to a change stimulus, and subsequent dishabituation were assessed. Findings confirmed expectations that the skin conductance response and the late positive complex are indices of the OR. The pupillary dilation response, however, demonstrated an unexpected sensitivity to stimulus novelty only, while the prestimulus measure of tonic pupil diameter showed the significance effect that was expected of the phasic measure. Together, these findings argue against the suggestion that the pupillary dilation response is an OR index. The diverse results obtained from this experiment contribute to our understanding of the OR, and provide impetus for further research with a variety of paradigm manipulations.

Music training and working memory: an ERP study

While previous research has suggested that music training is associated with improvements in various cognitive and linguistic skills, the mechanisms mediating or underlying these associations are mostly unknown. Here, we addressed the hypothesis that previous music training is related to improved working memory. Using event-related potentials (ERPs) and a standardized test of working memory, we investigated both neural and behavioral aspects of working memory in college-aged, non-professional musicians and non-musicians. Behaviorally, musicians outperformed non-musicians on standardized subtests of visual, phonological, and executive memory. ERPs were recorded in standard auditory and visual oddball paradigms (participants responded to infrequent deviant stimuli embedded in lists of standard stimuli). Electrophysiologically, musicians demonstrated faster updating of working memory (shorter latency P300s) in both the auditory and visual domains and musicians allocated more neural resources to auditory stimuli (larger amplitude P300), showing increased sensitivity to the auditory standard/deviant difference and less effortful updating of auditory working memory. These findings demonstrate that long-term music training is related to improvements in working memory, in both the auditory and visual domains and in terms of both behavioral and ERP measures.