Various conflicts from ventral and dorsal streams are sequentially processed in a common system

How to do Better N400 Studies: Reproducibility, Consistency and Adherence to Research Standards in the Existing Literature

Given the complexity of ERP recording and processing pipeline, the resulting variability of methodological options, and the potential for these decisions to influence study outcomes, it is important to understand how ERP studies are conducted in practice and to what extent researchers are transparent about their data collection and analysis procedures. The review gives an overview of methodology reporting in a sample of 132 ERP papers, published between January 1980 - June 2018 in journals included in two large databases: Web of Science and PubMed. Because ERP methodology partly depends on the study design, we focused on a well-established component (the N400) in the most commonly assessed population (healthy neurotypical adults), in one of its most common modalities (visual images). The review provides insights into 73 properties of study design, data pre-processing, measurement, statistics, visualization of results, and references to supplemental information across studies within the same subfield. For each of the examined methodological decisions, the degree of consistency, clarity of reporting and deviations from the guidelines for best practice were examined. Overall, the results show that each study had a unique approach to ERP data recording, processing and analysis, and that at least some details were missing from all papers. In the review, we highlight the most common reporting omissions and deviations from established recommendations, as well as areas in which there was the least consistency. Additionally, we provide guidance for a priori selection of the N400 measurement window and electrode locations based on the results of previous studies.

Face-like configurations modulate electrophysiological mismatch responses

The human face is one of the most salient stimuli in the environment. It has been suggested that even basic face-like configurations (three dots composing a downward pointing triangle) may convey salience. Interestingly, stimulus salience can be signaled by mismatch detection phenomena, characterized by greater amplitudes of event-related potentials (ERPs) in response to relevant novel stimulation as compared to non-relevant repeated events. Here, we investigate whether basic face-like stimuli are salient enough to modulate mismatch detection phenomena. ERPs are elicited by a pair of sequentially presented visual stimuli (S1-S2), delivered at a constant 1-s interval, representing either a face-like stimulus (Upright configuration) or three neutral configurations (Inverted, Leftwards, and Rightwards configurations), that are obtained by rotating the Upright configuration along the three different axes. In pairs including a canonical face-like stimulus, we observe a more effective mismatch detection mechanism, with significantly larger N270 and P300 components when S2 is different from S1 as compared to when S2 is identical to S1. This ERP modulation, not significant in pairs excluding face-like stimuli, reveals that mismatch detection phenomena are significantly affected by basic face-like configurations. Even though further experiments are needed to ascertain whether this effect is specifically elicited by face-like configuration rather than by particular orientation changes, our findings suggest that face essential, structural attributes are salient enough to affect change detection processes.

Task relevance effect on number/shape conflict detection in the number-matching task: An ERP study

It is debatable whether the task relevance effect on a conflict occurs in the detection or in the inhibition underlying sequential matching. To explore this issue, three types of number pairs, identical (e.g., 12, 12), conserved (e.g., 12, ), and non-conserved (e.g., 12, 15) pairs, were displayed to be judged as perceptually (identical shape condition) or quantitatively (identical value condition) the same. Both error rates and RTs for the three types of number pairs showed different patterns to detect perceptual mismatch in the identical shape condition and number inequivalence in the identical value conditions. The event-related potential (ERP) results showed that increased N200 and N400 as well as decreased P300 were triggered by the conserved and non-conserved pairs in contrast to identical pairs in the identical shape condition and by the non-conserved pairs relative to the conserved and identical pairs in the identical value condition. These results showed that task-relevant mismatches were attended to and detected in both conditions. Therefore, for the task-relevance effect on a conflict, attention is selectively directed to task-relevant features rather than inhibiting task-irrelevant conflict.

Cognitive impairment in generalized anxiety disorder revealed by event-related potential N270

BACKGROUND

Cognitive function in anxiety disorders has been the subject of limited investigation, especially in generalized anxiety disorder (GAD). The purpose of this study was to investigate the cognitive function in subjects with GAD using mismatch-triggered negativity N270.

METHODS

Fifteen medication-free patients with a DSM-IV diagnosis of GAD, and 15 well-matched healthy controls performed a dual-feature delayed matching task while event-related potentials were recorded from their scalp.

RESULTS

The GAD group was characterized by the decreased N270 amplitude in the left hemisphere. The smaller N270 amplitude was associated with greater symptoms of anxiety and depression.

CONCLUSION

Since N270 is thought to index cognitive function in different domains, including attention and memory, our results suggest that individuals with GAD have an impaired cognitive function, particularly in selective attention and working memory. These cognitive deficits may have clinical significance in subjects with GAD and should be considered in treatment planning.

Visual working memory capacity does not modulate the feature-based information filtering in visual working memory

Background

The limited capacity of visual working memory (VWM) requires us to select the task relevant information and filter out the irrelevant information efficiently. Previous studies showed that the individual differences in VWM capacity dramatically influenced the way we filtered out the distracters displayed in distinct spatial-locations: low-capacity individuals were poorer at filtering them out than the high-capacity ones. However, when the target and distracting information pertain to the same object (i.e., multiple-featured object), whether the VWM capacity modulates the feature-based filtering remains unknown.

Methodology/Principal Findings

We explored this issue mainly based on one of our recent studies, in which we asked the participants to remember three colors of colored-shapes or colored-landolt-Cs while using two types of task irrelevant information. We found that the irrelevant high-discriminable information could not be filtered out during the extraction of VWM but the irrelevant fine-grained information could be. We added 8 extra participants to the original 16 participants and then split the overall 24 participants into low- and high-VWM capacity groups. We found that regardless of the VWM capacity, the irrelevant high-discriminable information was selected into VWM, whereas the irrelevant fine-grained information was filtered out. The latter finding was further corroborated in a second experiment in which the participants were required to remember one colored-landolt-C and a more strict control was exerted over the VWM capacity.

Conclusions/Significance

We conclude that VWM capacity did not modulate the feature-based filtering in VWM.

Effects of discrepancy between imagined and perceived sounds on the N2 component of the event-related potential

Two experiments were conducted to examine whether the N2 component of the event-related potential (ERP), typically elicited in a S1-S2 matching task and considered to reflect mismatch process, can still be elicited when the S1 was imagined instead of perceived and to investigate how N2 amplitude varied with the degree of S1-S2 discrepancy. Three levels of discrepancy were defined by the degree of separation between the heard (S2) and imagined (S1) sounds. It was found that the N2 was reliably elicited when the perceived S2 differed from the imagined S1, but whether N2 amplitude increased with the degree of discrepancy depended in part on the S1-S2 discriminability (as evidenced by reaction time). Specifically, the effect of increasing discrepancy was attenuated as discriminability increased from hard to easy. These results, together with the dynamic ERP topography observed within the N2 window, suggest that the N2 effect reflects two sequential but overlapping processes: automatic mismatch and controlled detection.

Detecting perceptual conflict by the feedback-related negativity in brain potentials

The feedback-related negativity (FRN) in brain potentials is typically observed for the outcome evaluation concerning one's performance or monetary reward. Using a task in which the participant guesses whether the first stimulus (S1) would have the same color as the subsequently presented second stimulus (S2), this study demonstrates that the FRN to S2, which serves as feedback to the guessing, is also sensitive to the conflict between perceptual representations of S1 and S2 in working memory. The FRN effect for the feedback concerning the correctness of one's performance is modulated by the congruency between perceptual properties of the stimuli. The anterior cingulate cortex, which generates the FRN, is thus a general conflict-monitoring device detecting both response and perceptual conflicts.