The hard oddball: Effects of difficult response selection on stimulus-related P3 and on response-related negative potentials

Motor cortex activation during visuomotor transformations: evoked potentials during overt and imagined movements

Despite the prevalence of visuomotor transformations in our motor skills, their mechanisms remain incompletely understood, especially when imagery actions are considered such as mentally picking up a cup or pressing a button. Here, we used a stimulus-response task to directly compare the visuomotor transformation underlying overt and imagined button presses. Electroencephalographic activity was recorded while participants responded to highlights of the target button while ignoring the second, non-target button. Movement-related potentials (MRPs) and event-related desynchronization occurred for both overt movements and motor imagery (MI), with responses present even for non-target stimuli. Consistent with the activity accumulation model where visual stimuli are evaluated and transformed into the eventual motor response, the timing of MRPs matched the response time on individual trials. Activity-accumulation patterns were observed for MI, as well. Yet, unlike overt movements, MI-related MRPs were not lateralized, which appears to be a neural marker for the distinction between generating a mental image and transforming it into an overt action. Top-down response strategies governing this hemispheric specificity should be accounted for in future research on MI, including basic studies and medical practice.

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.

A Study of Event-Related Potentials During Monaural and Bilateral Hearing in Single-Sided Deaf Cochlear Implant Users

OBJECTIVES

Single-sided deafness (SSD) is characterized by a profoundly deaf ear and normal hearing in the contralateral ear. A cochlear implant (CI) is the only method to restore functional hearing in a profoundly deaf ear. In a previous study, we identified that the cortical processing of a CI signal differs from the normal-hearing ear (NHE) when directly compared using an auditory oddball paradigm consisting of pure tones. However, exactly how the brain integrates the electrical and acoustic signal is not well investigated. This study aims to understand how the provision of the CI in combination with the NHE may improve SSD CI users' ability to discriminate and evaluate auditory stimuli.

DESIGN

Electroencephalography from 10 SSD-CI participants (4 participated in the previous pure-tone study) were recorded during a semantic acoustic oddball task, where they were required to discriminate between odd and even numbers. Stimuli were presented in four hearing conditions: directly through the CI, directly to the NHE, or in free field with the CI switched on and off. We examined task-performance (response time and accuracy) and measured N1, P2, N2N4, and P3b event-related brain potentials (ERPs) linked to the detection, discrimination, and evaluation of task relevant stimuli. Sound localization and speech in noise comprehension was also examined.

RESULTS

In direct presentation, task performance was superior during NHE compared with CI (shorter and less varied reaction times [~720 versus ~842 msec], higher target accuracy [~93 versus ~70%]) and early neural responses (N1 and P2) were enhanced for NHE suggesting greater signal saliency. However, the size of N2N4 and P3b target-standard effects did not differ significantly between NHE and CI. In free field, target accuracy was similarly high with the CI (FF-On) and without the CI (FF-Off) (~95%), with some evidence of CI interference during FF-On (more variable and slightly but significantly delayed reaction times [~737 versus ~709 msec]). Early neural responses and late effects were also greater during FF-On. Performance on sound localization and speech in noise comprehension (S CI N NHE configuration only) was significantly greater during FF-On.

CONCLUSIONS

Both behavioral and neural responses in the semantic oddball task were sensitive to CI in both direct and free-field presentations. Direct conditions revealed that participants could perform the task with the CI alone, although performance was suboptimal and early neural responses were reduced when compared with the NHE. For free-field, the addition of the CI was associated with enhanced early and late neural responses, but this did not result in improved task performance. Enhanced neural responses show that the additional input from the CI is modulating relevant perceptual and cognitive processes, but the benefit of binaural hearing on behavior may not be realized in simple oddball tasks which can be adequately performed with the NHE. Future studies interested in binaural hearing should examine performance under noisy conditions and/or use spatial cues to allow headroom for the measurement of binaural benefit.

Odd-even oddball task: Evaluating event-related potentials during word discrimination compared to speech-token and tone discrimination

Tonal and speech token auditory oddball tasks have been commonly used to assess auditory processing in various populations; however, tasks using non-word sounds may fail to capture the higher-level ability to interpret and discriminate stimuli based on meaning, which are critical to language comprehension. As such, this study examines how neural signals associated with discrimination and evaluation-processes (P3b) from semantic stimuli compare with those elicited by tones and speech tokens. This study comprises of two experiments, both containing thirteen adults with normal hearing in both ears (PTA ≤ 20 dB HL). Scalp electroencephalography and auditory event related potentials were recorded in free field while they completed three different oddball tasks: (1) tones, (2) speech tokens and (3) odd/even numbers. Based on the findings of experiment one, experiment two was conducted to understand if the difference in responses from the three tasks was attributable to stimulus duration or other factors. Therefore, in experiment one, stimulus duration was not controlled and in experiment two, the duration of each stimulus was modified to be the same across all three tasks (∼400 ms). In both experiments, P3b peak latency was significantly different between all three tasks. P3b amplitude was sensitive to reaction time, with tasks that had a large reaction time variability resulting in the P3b amplitude to be smeared, thereby reducing the amplitude size. The findings from this study highlight the need to consider all factors of the task before attributing any effects to any additional process, such as semantic processing and mental effort. Furthermore, it highlights the need for more cautious interpretation of P3b results in auditory oddball tasks.

Electrophysiological evidence for the coexistence of expectancy fulfillment and semantic integration during the processing of binding and compound nouns

This study employed electrophysiological measures to investigate the processes of expectancy fulfillment and semantic integration during the processing of binding and compound nouns in Chinese. Sequential expectancy and cloze probability between the two constituents of a two-character noun were manipulated in two experiments, resulting in four types of target characters (i.e., the final characters of two-character nouns): (i) high-cloze, binding character (HB); (ii) high-cloze, compound character (HC); (iii) low-cloze, binding character (LB); (iv) low-cloze, compound character (LC). Participants were asked to judge as quickly and accurately as possible whether the two characters, presented sequentially, formed a real word. The two experiments varied in stimulus onset asynchrony (SOA) between the initial and the target characters: 1000 ms and 300 ms. ERPs acquired at the target characters revealed a significant semantic integration effect in both experiments whereby low-cloze target characters elicited more negative-going activities than high-cloze target characters (L > H) with both long and short SOAs. Importantly, there was a graded N400 effect (LC = LB > HC > HB) at the central region: a clearly visible positive deflection for HB relative to HC in synchrony with an equivalence in negativity for LB and LC. This graded pattern was observed with an SOA of 1000 ms but not 300 ms. These results are discussed in terms of the possible coexistence of an expectancy fulfillment mechanism indexed by the P300 that monitors incoming information for realization of expectancies based on stored mental representations and a semantic integration mechanism indexed by the N400 that incorporates incoming information into the preceding context based on semantic-pragmatic knowledge. Manifestation of this coexistence appears sensitive to SOA-modulated attention orientation.

An Investigation of the Slope Parameters of Reaction Times and P3 Latencies in the Sternberg Memory Scanning Task - A Fixed-Links Model Approach

The speed of short-term memory scanning is thought to be captured in the slope of the linear function of mean reaction times (RTs) regressed on set size in the Sternberg memory scanning task (SMST). Individual differences in the slope parameter have been hypothesized to correlate with general intelligence (g). However, this correlation can usually not be found. This present study chose a fixed-links model (FLM) approach to re-evaluate the RT slope parameter on a latent level in a sample of 102 participants aged 18 to 61 years who completed the SMST with set sizes 1, 3, and 5. The same was tried for P3 latencies to investigate whether or not both parameters measure the same cognitive processes in the SMST, and to assess the usability of both slopes to predict g. For RTs, a linear increase with set size was found. The slope of mean RTs correlated with g on a manifest level already. The FLM approach could better reveal this relationship with the correlation between the slope and g being substantially higher. For P3 latencies, we found no evidence for a linear increase, but a general increase from the smallest set size to the two larger ones. This indicates that RTs and P3 latencies do not measure the same cognitive processes in the SMST. The FLM proved suitable to investigate the association between the speed of short-term memory scanning and intelligence.

The discrepant effect of acute stress on cognitive inhibition and response inhibition

This study aimed to investigate how acute stress impinges on individual's cognitive inhibition and response inhibition abilities. Electroencephalography was adopted when 35 healthy adult females performing the No Go Flanker task before and after the Trier Social Stress Test. Both inhibition processes evoked N2 and P3 components, but only the response inhibition evoked the late positive potential (LPP), indicating the response inhibition needed continuous cognitive effort to inhibit the prepotent response. The N2 and the P3 amplitudes were decreased, while the LPP amplitudes were increased under acute stress. These results suggested that acute stress caused the detrimental effect by occupying cognitive resources. Contrastingly, individuals actively regulated and made more efforts to counteract the detrimental effect of acute stress on response inhibition. Thus, acute stress impaired cognitive inhibition but did not affect response inhibition.

The Spatial-Numerical Association of Response Codes (SNARC) effect in highly math-anxious individuals: An ERP study

The Spatial-Numerical Association of Response Codes (SNARC) effect was examined in highly (HMA) and low math-anxious (LMA) individuals performing a number comparison in an ERP study. The SNARC effect consists of faster latencies when the response side is congruent with number location in the mental number line (MNL). Despite the stronger SNARC effect in the HMA group, their responses in incongruent trials were slower than in congruent trials only for the largest numerical magnitudes. Moreover, HMAs showed a less positive centroparietal P3b component in incongruent trials than in congruent ones, but only for the largest magnitudes. Since the SNARC effect arises during response selection and P3b positivity decreases with the difficulty of decision, this result suggests that HMA individuals might find it more difficult than LMAs to control the conflict between the automatically activated location of numbers in the MNL and the response side, especially in more cognitively demanding trials.

Parietal P3 and midfrontal theta prospectively predict the development of adolescent alcohol use

BACKGROUND

Subclinical adolescent alcohol use is highly prevalent and may have deleterious effects on important psychosocial and brain outcomes. Prior research has focused on identifying endophenotypes of pathological drinking, and the predictors of normative drinking remain understudied. This study investigated the incremental predictive value of two potential psychophysiological endophenotypes, P3 amplitude (an index of decision making) and midfrontal theta power (a correlate of attentional control), for prospectively predicting the expression and initiation of alcohol use emerging in adolescence.

METHODS

A large (N = 594) epidemiological sample was prospectively assessed at ages 11/14/17. Alcohol/substance use was assessed at all ages via a computerized self-report inventory. EEG was recorded at age-14 during a visual oddball task to elicit P3 and theta.

RESULTS

Reduced target-related P3 and theta at age-14 prospectively predicted drinking at age-17 independent of one another. Among alcohol-naive individuals at age-14, attenuated P3 and theta increased the odds of new-onset alcohol behaviors 3 years later. Importantly, the endophenotypes provided significant incremental predictive power of future non-clinical alcohol use beyond relevant risk factors (prior alcohol use; tobacco/illicit drug initiation; parental alcohol use disorder).

CONCLUSIONS

The current report is the first of our knowledge to demonstrate that deviations in parietal P3 and midfrontal theta prospectively predict the emergence of normative/non-pathological drinking. P3 and theta provide modest yet significant explanatory variance beyond prominent self-report and familial risk measures. Findings offer strong evidence supporting the predictive utility of P3 and theta as candidate endophenotypes for adolescent drinking.

Cochlear implants in single-sided deaf recipients: Near normal higher-order processing

OBJECTIVE

Single-sided deafness (SSD) is a condition where an individual has a severe to profound sensorineural hearing loss in one ear and normal hearing on the contralateral side. The use of cochlear implants in individuals with SSD leads to functional improvements in hearing. However, it is relatively unclear how sounds incoming via the cochlear implant (independent of the hearing ear) are processed and interpreted by higher-order processes in the brain.

METHODS

Scalp electroencephalography and auditory event-related potentials were recorded monaurally from nine experienced single sided cochlear implant users. Speech-in-noise and localisation tests were used to measure functional changes in hearing.

RESULTS

cochlear implant use was associated with improvement in speech-in-noise and localisation tests (compared to cochlear implant off). Significant N2 and P3b effects were observed in both cochlear implant and normal hearing ear conditions, with similar waveform morphology and scalp distribution across conditions. Delayed response times and a reduced N2 (but not P3b) effect was measured in the CI condition.

CONCLUSION

The brain is capable of using processes similar to those in normal hearing to discriminate sounds presented to the cochlear implant. There was evidence of processing difficulty in the cochlear implant condition which could be due to the relatively degraded signals produced by the cochlear implant compared to the normal hearing ear.

SIGNIFICANCE

Understanding how the brain processes sound provided by a cochlear implant highlights how cortical responses can be used to guide implantation candidacy guidelines and influence rehabilitation recommendations.

P300 latency jitter and its correlates in people with amyotrophic lateral sclerosis

OBJECTIVE

People with amyotrophic lateral sclerosis (ALS) can benefit from brain-computer interfaces (BCIs). However, users with ALS may experience significant variations in BCI performance and event-related potential (ERP) characteristics. This study investigated latency jitter and its correlates in ALS.

METHODS

Electroencephalographic (EEG) responses were recorded from six people with ALS and nine neurotypical controls. ERP amplitudes and latencies were extracted. Classifier-based latency estimation was used to calculate latency jitter. ERP components and latency jitter were compared between groups using Wilcoxon rank-sum tests. Correlations between latency jitter and each of the clinical measures, ERP features, and performance measures were investigated using Spearman and repeated measures correlations.

RESULTS

Latency jitter was significantly increased in participants with ALS and significantly negatively correlated with BCI performance in both ALS and control participants. ERP amplitudes were significantly attenuated in ALS, and significant correlations between ERP features and latency jitter were observed. There was no significant correlation between latency jitter and clinical measures.

CONCLUSIONS

Latency jitter is increased in ALS and correlates with both BCI performance and ERP features.

SIGNIFICANCE

These results highlight the associations of latency jitter with BCI performance and ERP characteristics and could inform future BCI designs for people with ALS.

Don't stop me now: Hampered retrieval of action plans following interruptions

How can we retrieve action plans in working memory (WM) after being distracted or interrupted? The present EEG study investigated this question using a WM task in which a random sequence of single numbers (1-4 and 6-9) was presented. In a given trial, participants had to decide whether the number presented in the preceding trial was odd or even. Additionally, interfering stimuli were randomly presented in 25% of all trials, requiring the participants to either ignore a colored number (distraction) or respond to it (interruption) while maintaining the previously formed action plan in WM. Our results revealed a detrimental impact of interruptions on WM performance in trials after interrupting stimuli compared to trials without a preceding interference. This was reflected in decreased task accuracy and reduced stimulus- and response-locked P3b amplitudes potentially indicating a hampered reactivation of stimulus-response links. Moreover, decreased contralateral mu suppression prior to a given response highlighted an impaired response preparation following interruptions. Distractions, on the other hand, did not negatively affect task performance but were followed by faster responses in subsequent trials compared to trials without prior interference. This result pattern was supported by stronger contralateral mu suppression indicating a facilitated response preparation. Overall, these results suggest that action representations in WM are resistant to distractions but do suffer from interruptions that disrupt or interfere with their implementation. We thus propose that the possibility of adequately preparing for an upcoming response is essential for behavioral guidance in the presence of external interference.

Revisiting the relationship between the P3b and working memory updating

The P3b is an extensively studied neurophysiological phenomenon that is predominantly explained in the cognitive neuroscience literature as reflecting context updating, presumably in working memory (WM). Despite the prevalence and influence of the context updating hypothesis, direct empirical support for the role of WM updating in eliciting the P3b is still missing. The present study was designed to address the empirical gap in understanding the functional role of P3b in general, and specifically in relation to WM updating. A mass-univariate approach was used to test the unique contribution of WM updating, categorization, and stimulus probability to the P3b. The results indicated that the P3b is only modulated by the categorization process, a finding that challenges the WM updating hypothesis. Taken together these results, we suggest that the P3b reflects a WM guided target identification mechanism, which operates as part of a goal-directed learning strategy.

Target-related parietal P3 and medial frontal theta index the genetic risk for problematic substance use

Theoretical and empirical work suggests that problematic substance use (PSU) is associated with individual differences in prefrontal cortex activity. While research has strongly linked parietal P3 amplitude reduction (P3AR) to genetic risk for problematic substance use, few studies have tested whether prefrontal EEG measures are sensitive to this genetic liability. In addition to P3, oddball target detection tasks elicit medial frontal theta power, reflecting attentional allocation, and parietal delta, indexing decision making or stimulus-response link updating. Midfrontal theta and parietal delta may index neurocognitive processes relevant to PSU beyond P3AR. The present investigation examined the etiological relationship between PSU and P3, frontal theta, and parietal delta in a large twin sample (N = 754). EEG was recorded during a visual oddball task. Greater PSU was associated with reduced target P3 amplitude and midfrontal theta/parietal delta power, and increased mean reaction time and reaction time variability (RTV; indexing attentional fluctuations). P3, theta, and RTV, but not delta or mean RT, explained unique variance in PSU (R2  = 0.04). Twin biometric modeling indicated a genetic relationship between PSU and P3, theta, and RTV. Theta accounted for distinct genetic variance in PSU beyond P3 and RTV. Together, 23% of the total additive genetic variance in PSU was explained by the three endophenotypes. Results replicate P3AR as an endophenotype and provide support for additional behavioral (RTV) and neurophysiological (midfrontal theta) endophenotypes of PSU. Reduced theta and greater RTV may reflect variations in a prefrontal attentional network that confers genetic risk for substance use problems.

Item Roles Explored in a Modified P300-Based CTP Concealed Information Test

In this study, we introduced familiarity-related inducer items (expressions referring to the participant’s self-related, familiar details: “mine,” “familiar”; and expressions referring to other, unfamiliar details, e.g., “other,” “irrelevant”) to the Complex Trial Protocol version of the P300-based Concealed Information Test (CIT), at the same time using different item categories with various levels of personal importance to the participants (forenames, birthdays, favorite animals). The inclusion of inducers did not significantly improve the overall efficiency of the method as we would have expected considering that these inducers should increase awareness of the denial of the recognition of the probes (the true details of the participants), and hence the subjective saliency of the items (Lukács in J Appl Res Mem Cognit, 6:283–284, 2017a). This may be explained by the visual similarity of inducers to the probe and irrelevant items and the consequent distracting influence of inducers on probe-task performance. On the other hand, the CIT effect (probe-irrelevant P300 differences) was always lower for less personally important (low-salient) and higher for more personally important (high-salient) items.

"Hit the missing stimulus". A simultaneous EEG-fMRI study to localize the generators of endogenous ERPs in an omitted target paradigm

Event-Related Potentials (ERPs) occurring independently from any stimulus are purely endogenous (emitted potentials) and their neural generators can be unequivocally linked with cognitive processes. In the present study, the subjects performed two similar visual counting tasks: a standard two-stimulus oddball, and an omitted-target oddball task, characterized by the physical absence of the target stimulus. Our investigation aimed at localizing the neural sources of the scalp-recorded endogenous/emitted ERPs. To optimize the source localization, the high temporal resolution of electrophysiology was combined with the fine spatial information provided by the simultaneous recording of functional magnetic resonance (fMRI). Both tasks identified two endogenous ERP components in the 300 to 520 ms interval. An earlier component, pP2, showed a bilateral generator in the anterior Insula. A later P3 component (P3b) was generated bilaterally in the temporal-parietal junction, the premotor and motor area and the anterior intraparietal sulcus (this latter one only in the standard oddball). Anticipatory slow waves (beginning 900 to 500 ms pre-stimulus), also of endogenous nature, were produced by the inferior and middle frontal gyrus and the supplementary and cingulate motor areas. Our protocol disentangled pre- from post-stimulus fMRI activations and provided original clues to the psychophysiological interpretation of emitted/endogenous ERPs.

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.

Gender effects on auditory P300: A systematic review

The evidence suggests that gender-related effects could influence the electrophysiological P300 parameters and stand as an additional source of variation for both clinical and non-clinical subjects. The aim of this paper is to characterize gender-related differences in P300 potential as elicited with simple auditory paradigms. This knowledge (1) is important for the practical assessment of P300 potential in normal and clinical populations, and (2) can provide an insight into the understanding of gender differences in pathophysiology, particularly those with differential risk or prevalence in males and females. With this review it is shown that a limited number of studies encounter possible gender effects on parameters of auditory P300, and the findings need to be read with caution due to methodological limitations of the studies. Nevertheless, evidence supports that the P300 amplitude could be significantly modulated by gender, with greater amplitude in females relative to males. Noteworthy, gender has a minimal effect on the P300 latency, and it is often comparable between males and females. Furthermore, the effect of gender on P300 could be modulated by hormonal background, anatomy and some methodological aspects.

Methylphenidate selectively modulates one sub-component of the no-go P3 in pediatric ADHD medication responders

Methylphenidate (MPH) has been shown to modulate the amplitude of the no-go P3 component of the event-related potential (ERP; Øgrim, Aasen, & Brunner, 2016). Using group independent component analysis, the no-go P3 from a cued go/no-go task has been separated into two sub-components (Brunner et al., 2013). This study investigated whether sub-components of the no-go P3 could be identified in children with ADHD, and how MPH modulates their amplitudes. ERPs were registered twice (on/off MPH) in 57 children with ADHD classified as medication responders in a four-week medication trial. Two no-go P3 sub-components were identified. In the MPH session, the amplitude of one sub-component, the IC P3no-go_early (mean latency 378 ms, with a central distribution), was significantly larger than at baseline, whereas the other sub-component, the IC P3no-go_late (mean latency 428 ms, with a centro-frontal distribution), was not significantly affected. These results add to the literature documenting that the no-go P3 consists of two overlapping phenomena with different functional correlates.

Theta- and delta-band EEG network dynamics during a novelty oddball task

While the P3 component during target detection and novelty processing has been widely studied, less is known about its underlying network dynamics. A recent cognitive model suggests that frontal-parietal and frontal-temporal interregional connectivity are related to attention/action selection and target-related memory updating during the P3, respectively, but empirical work testing this model is lacking. Other work suggests the importance of theta- and delta-band connectivity between the medial frontal cortex and distributed cortical regions during attention, stimulus detection, and response selection processes, and similar dynamics may underlie P3-related network connectivity. The present study evaluated the functional connectivity elicited during a visual task, which combined oddball target and novelty stimuli, in a sample of 231 same-sex twins. It was hypothesized that both target and novel conditions would involve theta frontoparietal connectivity and medial frontal theta power, but that target stimuli would elicit the strongest frontotemporal connectivity. EEG time-frequency analysis revealed greater theta-band frontoparietal connectivity and medial frontal power during both target and novel conditions compared to standards, which may index conflict/uncertainty resolution processes. Theta-band frontotemporal connectivity was maximal during the target condition, potentially reflecting context updating or stimulus-response activation. Delta-band frontocentral-parietal connectivity was also strongest following targets, which may be sensitive to response-related demands. These results suggest the existence of functional networks related to P3 that are differentially engaged by target oddballs and novel distractors. Compared to simple P3 amplitude, network measures may provide a more nuanced view of the neural dynamics during target detection/novelty processing in normative and pathological populations.

On Why Targets Evoke P3 Components in Prediction Tasks: Drawing an Analogy between Prediction and Matching Tasks

P3 is the most conspicuous component in recordings of stimulus-evoked EEG potentials from the human scalp, occurring whenever some task has to be performed with the stimuli. The process underlying P3 has been assumed to be the updating of expectancies. More recently, P3 has been related to decision processing and to activation of established stimulus-response associations (S/R-link hypothesis). However, so far this latter approach has not provided a conception about how to explain the occurrence of P3 with predicted stimuli, although P3 was originally discovered in a prediction task. The present article proposes such a conception. We assume that the internal responses right or wrong both become associatively linked to each predicted target and that one of these two response alternatives gets activated as a function of match or mismatch of the target to the preceding prediction. This seems similar to comparison tasks where responses depend on the matching of the target stimulus with a preceding first stimulus (S1). Based on this idea, this study compared the effects of frequencies of first events (predictions or S1) on target-evoked P3s in prediction and comparison tasks. Indeed, frequencies not only of targets but also of first events had similar effects across tasks on target-evoked P3s. These results support the notion that P3 evoked by predicted stimuli reflects activation of appropriate internal “match” or “mismatch” responses, which is compatible with S/R-link hypothesis.

Neural cascade of conflict processing: Not just time-on-task

In visual conflict tasks (e.g., Stroop or flanker), response times (RTs) are generally longer on incongruent trials relative to congruent ones. Two event-related-potential (ERP) components classically associated with the processing of stimulus conflict are the fronto-central, incongruency-related negativity (N_inc) and the posterior late-positive complex (LPC), which are derived from the ERP difference waves for incongruent minus congruent trials. It has been questioned, however, whether these effects, or other neural measures of incongruency (e.g., fMRI responses in the anterior cingulate), reflect true conflict processing, or whether such effects derive mainly from differential time-on-task. To address this question, we leveraged high-temporal-resolution ERP measures of brain activity during two behavioral tasks. The first task, a modified Erikson flanker paradigm (with congruent and incongruent trials), was used to evoke the classic RT and ERP effects associated with conflict. The second was a non-conflict control task in which, participants visually discriminated a single stimulus (with easy and hard discrimination conditions). Behaviorally, the parameters were titrated to yield similar RT effects of conflict and difficulty (27ms). Neurally, both within-task contrasts showed an initial fronto-central negative-polarity wave (N2-latency effect), but they then diverged. In the difficulty difference wave, the initial negativity led directly into the posterior LPC, whereas in the incongruency contrast the initial negativity was followed a by a second fronto-central negative peak (N_inc), which was then followed by a considerably longer-latency LPC. These results provide clear evidence that the longer processing for incongruent stimulus inputs do not just reflect time-on-task or difficulty, but include a true conflict-processing component.

Effects of response delays and of unknown stimulus-response mappings on the oddball effect on P3

P3b is a prominent component of human event-related EEG potentials. P3b has been related to consciousness, encoding into memory, and updating of strategic schemata, among others, yet evidence has also been provided for its close relationship with deciding how to respond to the presented stimuli. P3b is large with rarely occurring stimuli and small with frequent ones. Here, we investigate the extent to which this oddball effect depends on selecting and executing responses. Participants pressed one of two keys in response to one of two letters, one of which was presented rarely and one frequently. Information about letter-key mapping was provided by a second stimulus. In different blocks, this mapping stimulus was either constant across trials or varied randomly, and either preceded or followed the letter. The oddball effect was reduced when responses were delayed (by waiting for the constant mapping stimulus following the letter) and was further reduced when responses could not be assigned to the letters (because letters were followed by varying mapping stimuli). This evidence suggests that P3b is closely related to decision processes, possibly reflecting reactivation of stimulus-response links.

The relevance of the irrelevant: Attention and task-set adaptation in prematurely born adults

OBJECTIVE

To investigate attention and task-set adaptation in a preterm born very low birth weight (PT/VLBW) population by means of event-related potential components from an adapted cued go/no-go task.

METHODS

P3 components after target and non-target cues, as well as target, no-go and non-target imperative stimuli were compared in 30 PT/VLBW young adults and 33 term-born controls. Changes in P3 amplitudes as a function of time-on-task were also investigated.

RESULTS

The PT/VLBW group had larger P3 amplitudes to non-target cues and non-targets compared with controls. There were no significant group differences in the P3s to target or no-go stimuli. Moreover, the amplitude of the P3 to non-target cues and non-targets decreased significantly over time in the control group but not in the PT/VLBW group.

CONCLUSIONS

PT/VLBW young adults allocate more attention to behaviorally irrelevant information than term-born controls, and persist in attending to this information over time.

SIGNIFICANCE

This is the first study to investigate ERP components in an adult population born preterm with very low birth weight.

Benefits of Instructed Responding in Manual Assembly Tasks: An ERP Approach

The majority of neuroergonomics studies are focused mainly on investigating the interaction between operators and automated systems. Far less attention has been dedicated to the investigation of brain processes in more traditional workplaces, such as manual assembly, which are still ubiquitous in industry. The present study investigates whether assembly workers’ attention can be enhanced if they are instructed with which hand to initiate the assembly operation, as opposed to the case when they can commence the operation with whichever hand they prefer. For this aim, we replicated a specific workplace, where 17 participants in the study simulated a manual assembly operation of the rubber hoses that are used in vehicle hydraulic brake systems, while wearing wireless electroencephalography (EEG). The specific EEG feature of interest for this study was the P300 components’ amplitude of the event-related potential (ERP), as it has previously been shown that it is positively related to human attention. The behavioral attention-related modality of reaction times (RTs) was also recorded. Participants were presented with two distinct tasks during the simulated operation, which were counterbalanced across participants. In the first task, digits were used as indicators for the operation initiation (Numbers task), where participants could freely choose with which hand they would commence the action upon seeing the digit. In the second task, participants were presented with arrows, which served as instructed operation initiators (Arrows task), and they were instructed to start each operation with the hand that corresponded to the arrow direction. The results of this study showed that the P300 amplitude was significantly higher in the instructed condition. Interestingly, the RTs did not differ across any task conditions. This, together with the other findings of this study, suggests that attention levels can be increased using instructed responses without compromising work performance or operators’ well-being, paving the way for future applications in manual assembly task design.

Modulation of ERP components by task instructions in a cued go/no-go task

The present study investigated how components of ERPs are modulated when participants optimize speed versus accuracy in a cued go/no-go task. Using a crossover design, 35 participants received instructions to complete the task prioritizing response speed in half of the task, and accurate responding in the other half of the task. Analysis was performed on the contingent negative variation (CNV), P3go, and P3no-go and the corresponding independent components (IC), as identified by group independent component analysis. After speed instructions, the IC CNV(late), P3go(anterior), P3no-go(early), and P3no-go(late) all had larger amplitudes than after accuracy instructions. Furthermore, both the IC P3go(posterior) and IC P3go(anterior) had shorter latencies after speed than after accuracy instructions. The results demonstrate that components derived from the CNV and P3 components are facilitated when participants optimize response speed. These findings indicate that these ERP components reflect executive processes enabling adjustment of behavior to changing demands.

Biased odds for heads or tails: Outcome-evoked P3 depends on frequencies of guesses

Events that had to be predicted evoke large P3 components of the event-related EEG potential. There is conflicting evidence whether these P3s are moderated by participants' preceding guesses. In the present study, participants made one prediction frequently and the other rarely because one stimulus was presented frequently and the other rarely. Thereby, effects on stimulus-evoked P3s of both guess frequency and stimulus frequency could be tested. Indeed, P3s were not only larger with rare than frequent stimuli but also larger after rare than frequent guesses. This result pattern may have additionally been affected by expectancies for payoff. In any case, the modification of outcome-evoked P3 by what had been guessed may reflect that each of the four guess-stimulus combinations is encoded as a separate event category. In terms of the stimulus-response link hypothesis of P3b, it is suggested that P3s are evoked by these events because internal responses (right or wrong) are associated to each of these event categories and need to be reactivated with rare guess-stimulus combinations.