Distractor P3 is associated with attentional capture by stimulus deviance

Deviant consonance and dissonance capture attention differently only when task demand is high: An ERP study with three-stimulus oddball paradigm

The current study investigated whether consonance (imperfect consonance: major third) and dissonance (minor second) would capture attention differently when they occurred as chords (combinations of two tones) that were deviant from their context. In addition, we also examined how task demand would modulate these chords' attentional capture. For this investigation, we used an auditory three-stimulus oddball paradigm in which these chords were presented as deviant stimuli (5% each) among frequent standard (80%) and infrequent target (10%) pure tones. The task difficulty was manipulated by changing pitch intervals between standard and target tones. The results showed that these chords elicited dual-peak P3a, and that consonance enhanced the late phase of P3a compared to dissonance, only when the task demand was high. These findings revealed that deviant consonance and dissonance captured attention differently; in particular, consonance captured attention more strongly than dissonance, and this effect was induced by high task demand. This attentional capture difference between the chord categories was induced through enhanced focus of attention on the pitch dimension of oddball stimuli. In addition, the deviant chords might have been processed by a mechanism similar to that which processes novel stimuli, and these chords' differences might have affected not the novelty detection process, but a process which orients attentional resources to deviant chords, which were recognized as novel stimuli.

Effect of negatively valenced words on deviant P3 during the three-stimulus oddball paradigm

Attentional bias (sensitization) for negative information was estimated using event-related brain potentials (ERP). We used a three-stimulus visual oddball paradigm that comprised a small diamond standard stimulus (66.7%), a large diamond target stimulus (16.7%), and deviant word stimuli (16.7%) written in Kanji. Furthermore, half the deviant words were negative emotional words (e.g., destruction or scream) and the others half were neutral words (e.g., structure or range). Healthy participants (N = 26) were instructed to press a button after the target appeared while ignoring the other stimuli. EEG was recorded from Fz, Cz, and Pz sites and the average of EEG that time-locked to the onset of stimuli was calculated. Results indicated that the P3 amplitude for the target at Pz was the largest among the three sites, whereas the P3 amplitude for deviant words at Cz and Pz was larger than those at Fz. Furthermore, the P3 amplitudes for negative words increased in comparison to those for neutral words. These results suggest that increased amplitudes to word stimuli are regarded as deviant P3, and changes reflect passive attentional capture elicited by negative emotional information. Implications for using ERPs for estimating attentional bias to threat information are discussed.

Use of virtual reality in improving poststroke neglect: Promising neuropsychological and neurophysiological findings from a case study

After experiencing a stroke in the right hemisphere, almost 50% of patients show unilateral spatial neglect (USN). Virtual Reality technologies offer impressive opportunities for both the rehabilitation and assessment of different cognitive deficits, including USN. A 57-year-old woman, affected by subarachnoid hemorrhage presented a severe left hemiparesis with severe cognitive and behavioral alterations, including temporal and spatial disorientation, reduction of attention and memory process, slowing ideation, USN, and depression of mood. She underwent two different rehabilitation trainings, including standard cognitive training (SCT) in addition to semi-immersive virtual training with her shadow (S-IVT_s) and SCT in addition to a Semi- immersive virtual training, without her shadow (S-IVT). The patient was assessed before and after each of the two different trainings, by using a specific psychometric battery and the event related potential, P300. Only at the end of the use of the S-IVT, we observed a significant improvement in the motor and cognitive function, with regard to USN. SCT in addition to S-IVT with Bts-Nirvana System may be a promising approach in improving attention process, spatial cognition, and mood in patients with post stroke USN, as also demonstrated by the electrophysiological parameters.

Auditory Target and Novelty Processing in Patients with Unilateral Hippocampal Sclerosis: A Current-Source Density Study

The capacity to respond to novel events is crucial for adapting to the constantly changing environment. Here, we recorded 29-channel Event Related Brain Potentials (ERPs) during an active auditory novelty oddball paradigm and used for the first time Current Source Density-transformed Event Related Brain Potentials and associated time-frequency spectra to study target and novelty processing in a group of epileptic patients with unilateral damage of the hippocampus (N = 18) and in healthy matched control participants (N = 18). Importantly, we used Voxel-Based Morphometry to ensure that our group of patients had a focal unilateral damage restricted to the hippocampus and especially its medial part. We found a clear deficit for target processing at the behavioral level. In addition, compared to controls, our group of patients presented (i) a reduction of theta event-related synchronization (ERS) for targets and (ii) a reduction and delayed P3a source accompanied by reduced theta and low-beta ERS and alpha event-related synchronization (ERD) for novel stimuli. These results suggest that the integrity of the hippocampus might be crucial for the functioning of the complex cortico-subcortical network involved in the detection of novel and target stimuli.

Increased visual task difficulty enhances attentional capture by both visual and auditory distractor stimuli

Previous studies using a three-stimulus oddball task have shown the amplitude of P3a elicited by distractor stimuli increases when perceptual discrimination between standard and target stimuli becomes difficult. This means that the attentional capture by the distractor stimuli is enhanced along with an increase in task difficulty. So far, the increase of P3a has been reported when standard, target, and distractor stimuli were presented within one sensory modality (i.e., visual or auditory). In the present study, we further investigated whether or not the increase of P3a can also be observed when the distractor stimuli are presented in a different modality from the standard and target stimuli. Twelve participants performed a three-stimulus oddball task in which they were required to discriminate between visual standard and target stimuli. As the distractor stimuli, either another visual stimulus or an auditory stimulus was presented in separate blocks. Visual distractor stimuli elicited P3a, and its amplitude increased when visual standard/target discrimination was difficult, replicating previous findings. Auditory distractor stimuli elicited P3a, and importantly, its amplitude also increased when visual standard/target discrimination was difficult. This result means that attentional capture by distractor stimuli can be enhanced even when the distractor stimuli are presented in a different modality from the standard and target stimuli. Possible mechanisms and implications are discussed in terms of the relative saliency of distractor stimuli, influences of temporal/spatial attention, and the load involved in a task.

Inhibiting prepotent responses in the elderly: Distraction and disinhibition

In this study, we aimed to examine whether older adults, relative to younger adults, suffer from generic inhibition, selective inhibition, and/or distraction deficits, as assessed by behavioral and electrophysiological measures in a go/no-go task paradigm that included manipulations of no-go stimulus type (irrelevant vs. conflict) and no-go probability. A total of 96 individuals were recruited; each of three experiments included 32 participants (16 adults above and 16 adults below 60 years of age). The older adults performed more poorly than the younger adults in our behavioral test; however, the event-related potential results showed that irrelevant and conflict no-go stimuli incurred different processes that were differentially impacted by aging, as was reflected in the N2 and P3. That is, the older adults' inhibition deficits might be due to different underlying mechanisms: disproportionate processing of irrelevant no-go stimuli, and disproportionate suppression of conflicting information when executing or withholding a response to conflict no-go stimuli. The present results therefore support the theories of age-related selective inhibition and distraction deficits.

Impaired Early Attentional Processes in Parkinson's Disease: A High-Resolution Event-Related Potentials Study

Introduction

The selection of task-relevant information requires both the focalization of attention on the task and resistance to interference from irrelevant stimuli. A previous study using the P3 component of the event-related potentials suggested that a reduced ability to resist interference could be responsible for attention disorders at early stages of Parkinson’s disease (PD), with a possible role of the dorsolateral prefrontal cortex (DLPFC).

Methods

Our objective was to better determine the origin of this impairment, by studying an earlier ERP component, the N2, and its subcomponents, as they reflect early inhibition processes and as they are known to have sources in the anterior cingulate cortex (ACC), which is involved together with the DLPFC in inhibition processes. Fifteen early-stage PD patients and 15 healthy controls (HCs) performed a three-stimulus visual oddball paradigm, consisting in detecting target inputs amongst standard stimuli, while resisting interference from distracter ones. A 128-channel electroencephalogram was recorded during this task and the generators of the N2 subcomponents were identified using standardized weighted low-resolution electromagnetic tomography (swLORETA).

Results

PD patients displayed fewer N2 generators than HCs in both the DLPFC and the ACC, for all types of stimuli. In contrast to controls, PD patients did not show any differences between their generators for different N2 subcomponents.

Conclusion

Our data suggest that impaired inhibition in PD results from dysfunction of the DLPFC and the ACC during the early stages of attentional processes.

The dissociation between early and late selection in older adults

Older adults exhibit a reduced ability to ignore task-irrelevant stimuli; however, it remains to be determined where along the information processing stream the most salient age-associated changes occur. In the current study, ERPs provided an opportunity to determine whether age-related differences in processing task-irrelevant stimuli were uniform across information processing stages or disproportionately affected either early or late selection. ERPs were measured in young and old adults during a color-selective attention task in which participants responded to target letters in a specified color (attend condition) while ignoring letters in a different color (ignore condition). Old participants were matched to two groups of young participants on the basis of neuropsychological test performance: one using age-appropriate norms and the other using test scores not adjusted for age. There were no age-associated differences in the magnitude of early selection (attend-ignore), as indexed by the size of the anterior selection positivity and posterior selection negativity. During late selection, as indexed by P3b amplitude, both groups of young participants generated neural responses to target letters under the attend versus ignore conditions that were highly differentiated. In striking contrast, old participants generated a P3b to target letters with no reliable differences between conditions. Individuals who were slow to initiate early selection appeared to be less successful at executing late selection. Despite relative preservation of the operations of early selection, processing delays may lead older participants to allocate excessive resources to task-irrelevant stimuli during late selection.

P3a from white noise

P3a and P3b event-related brain potentials (ERPs) were elicited with an auditory three-stimulus (target, distracter, and standard) discrimination task in which subjects responded only to the target. Distracter stimuli consisted of white noise or novel sounds with stimulus characteristics perceptually matched. Target/standard discrimination difficulty was manipulated by varying target/standard pitch differences to produce relatively easy, medium, and hard tasks. Error rate and response time increased with increases in task difficulty. P3a was larger for the white noise compared to novel sounds, maximum over the central/parietal recording sites, and did not differ in size across difficulty levels. P3b was unaffected by distracter type, decreased as task difficulty increased, and maximum over the parietal recording sites. The findings indicate that P3a from white noise is robust and should be useful for applied studies as it removes stimulus novelty variability. Theoretical perspectives are discussed.

Role of basal ganglia circuits in resisting interference by distracters: a swLORETA study

Background

The selection of task-relevant information requires both the focalization of attention on the task and resistance to interference from irrelevant stimuli. Both mechanisms rely on a dorsal frontoparietal network, while focalization additionally involves a ventral frontoparietal network. The role of subcortical structures in attention is less clear, despite the fact that the striatum interacts significantly with the frontal cortex via frontostriatal loops. One means of investigating the basal ganglia's contributions to attention is to examine the features of P300 components (i.e. amplitude, latency, and generators) in patients with basal ganglia damage (such as in Parkinson's disease (PD), in which attention is often impaired). Three-stimulus oddball paradigms can be used to study distracter-elicited and target-elicited P300 subcomponents.

Methodology/Principal Findings

In order to compare distracter- and target-elicited P300 components, high-density (128-channel) electroencephalograms were recorded during a three-stimulus visual oddball paradigm in 15 patients with early PD and 15 matched healthy controls. For each subject, the P300 sources were localized using standardized weighted low-resolution electromagnetic tomography (swLORETA). Comparative analyses (one-sample and two-sample t-tests) were performed using SPM5® software. The swLORETA analyses showed that PD patients displayed fewer dorsolateral prefrontal (DLPF) distracter-P300 generators but no significant differences in target-elicited P300 sources; this suggests dysfunction of the DLPF cortex when the executive frontostriatal loop is disrupted by basal ganglia damage.

Conclusions/Significance

Our results suggest that the cortical attention frontoparietal networks (mainly the dorsal one) are modulated by the basal ganglia. Disruption of this network in PD impairs resistance to distracters, which results in attention disorders.

Electrophysiological evidence for impaired attentional engagement with phonologically acceptable misspellings in developmental dyslexia

Event-related potential (ERP) studies of word recognition have provided fundamental insights into the time-course and stages of visual and auditory word form processing in reading. Here, we used ERPs to track the time-course of phonological processing in dyslexic adults and matched controls. Participants engaged in semantic judgments of visually presented high-cloze probability sentences ending either with (a) their best completion word, (b) a homophone of the best completion, (c) a pseudohomophone of the best completion, or (d) an unrelated word, to examine the interplay of phonological and orthographic processing in reading and the stage(s) of processing affected in developmental dyslexia. Early ERP peaks (N1, P2, N2) were modulated in amplitude similarly in the two groups of participants. However, dyslexic readers failed to show the P3a modulation seen in control participants for unexpected homophones and pseudohomophones (i.e., sentence completions that are acceptable phonologically but are misspelt). Furthermore, P3a amplitudes significantly correlated with reaction times in each experimental condition. Our results showed no sign of a deficit in accessing phonological representations during reading, since sentence primes yielded phonological priming effects that did not differ between participant groups in the early phases of processing. On the other hand, we report new evidence for a deficient attentional engagement with orthographically unexpected but phonologically expected words in dyslexia, irrespective of task focus on orthography or phonology. In our view, this result is consistent with deficiency in reading occurring from the point at which attention is oriented to phonological analysis, which may underlie broader difficulties in sublexical decoding.

Use of swLORETA to localize the cortical sources of target- and distracter-elicited P300 components

OBJECTIVE

Cognitive event-related potentials (especially P300) have long been used to explore attentional processes. The aim of this study was to identify the cortical areas involved in P300 generation during a selective attention task.

METHODS

128 channel electroencephalograms were recorded in 15 healthy controls performing a three-stimulus visual oddball paradigm, in order to identify distracter- and target-elicited P300 components. For each subject, the P300 sources were localized using standardized weighted low-resolution electromagnetic tomography (swLORETA). One sample and paired T-tests were performed using SPM5®.

RESULTS

Common sources for both P300 components were observed within a large frontoparietal network, including the frontal eye field and dorsal parietal cortex (i.e. the attentional dorsal frontoparietal network). More inferior parietal areas, prefrontal and cingulate cortices (i.e. the attentional ventral frontoparietal network) were also involved in the generation of target-elicited P300.

CONCLUSIONS

These results suggest that distracter- and target-elicited P300 are both generated by the dorsal frontoparietal network. Moreover, target processing recruits a specific ventral network.

SIGNIFICANCE

Our data agree with the literature reports using other methods and should help to improve our knowledge of the cerebral networks underlying attentional processes.

Unexpected action effects elicit deviance-related brain potentials and cause behavioral delay

To examine how people deal with perceivable consequences of their voluntary actions, we recorded event-related potentials (ERPs) during a self-paced, two-choice random generation task. Sixteen participants were asked to press one of two buttons randomly at a regular but self-selected interval of once per 1-2 s. Each button press produced either a 1000-Hz or 2000-Hz tone, but participants were told that the tones were irrelevant to the task. The button-tone combinations were initially fixed, but in subsequent blocks, a button press infrequently produced the tone associated with the opposite button (p=.15). This cognitively mismatched tone elicited N2, P3, and late positive potential (or positive slow wave) of the ERP and delayed the timing of the next button press. These results suggest that action effects are difficult to ignore and that an action effect that is different from a performer's expectation may cause task disruption.

Neural correlates of inference-driven attention in perceptual and symbolic tasks: An event-related potential study

The inferential system anticipates the external environment by building up internal representations of its regularities. To that purpose, two sources of information are especially important and attract attentional resources: expected and unexpected events, which are useful for checking the accuracy of internal representations. In the present study, we investigated the behavioural properties and the neural mechanisms underlying the strategic allocation of attention triggered by those events. To that end, event-related potentials (ERPs) were recorded during the performance of two tasks requiring detection of predictable and unpredictable response events embedded in a visuospatial or numeric sequence. The behavioural results in the two tasks mirror each other, suggesting the recruitment of similar attentional allocation processes between the two domains. The ERPs showed partially similar effects. In both tasks, a P3a-like component signalled the capture of attention by events clashing with previous expectations, whilst a P3b-like component marked the focusing of attention on predicted events and its redistribution among all possible response events occurring after the detection of an unexpected event.

Difficulty of Discrimination Modulates Attentional Capture by Regulating Attentional Focus

Attentional capture for distractors is enhanced by increasing the difficulty of discrimination between the standard and the target in the three-stimulus oddball paradigm. In this study, we investigated the cognitive mechanism of this modulation of attentional capture. Event-related brain potentials were recorded from participants while they performed a visual three-stimulus oddball paradigm (frequent standard, rare target, and rare distractor). The discrimination difficulty between standard and target was manipulated in the central location. Distractor stimuli were presented in the central or surrounding locations. The P3a component was elicited by distractor stimuli and was used as a measure of attentional capture. The results revealed that discrimination difficulty had opposite effects on the P3a response between central and surrounding locations. With an increase in the difficulty of discrimination, the P3a response was enhanced when distractor stimuli were presented in the central location. In contrast, the P3a response was reduced when distractor stimuli were presented in a surrounding location. This finding suggests that spatial attention was focused by the difficulty of discrimination, and deviant processing was increased within its focus but decreased outside its focus. Therefore, attentional capture for deviant distractors is modulated by top–down controlled attentional focus.