Characteristics of N400 component elicited in patients who have migraine with aura

Background This study aimed to examine the N400 effect and event-related potentials (ERPs) elicited from congruent and incongruent stimuli in patients who have migraines with aura (MwA). Methods A total of 33 MwA patients and 20 healthy controls (HCs) were studied. They were balanced in age (35.12 ± 8.94 vs 34.70 ± 9.59 years, p = 0.872) and sex (69.7 vs 75.0% females, p = 0.761). ERPs were measured in response to both stimuli, where pictures were preceded with an object name that either matched or mismatched with the object. Averaged amplitudes, peaks, peak latencies, difference waves and topography were compared between MwA and HCs. Results MwA patients had significantly lower averaged amplitudes at the Fz and F4 sites during incongruent stimuli, as well as reduced peaks at the C3 and Pz sites. Topography showed a more widespread N400 effect over scalp relative to HCs. The difference ERP waveforms did not differ in the N400 effect between groups, but the P600 effect was significantly stronger in the HCs group relative to the MwA group at the Pz (6.52 ± 2.57 vs. 3.50 ± 3.15, p = 0.001) and P4 (5.86 ± 2.79 vs. 3.95 ± 3.64, p = 0.040) sites. Conclusions Picture-word matching tasks could serve as a potential new method for the investigation of semantic processing in MwA patients.

The P600, but not N400, is modulated by sustained attention

The functional significance of the two prominent language-related ERP components N400 and P600 is still under debate. It has recently been suggested that one important dimension along which the two vary, is in terms of automaticity versus attentional control, with N400 amplitudes reflecting more automatic and P600 amplitudes reflecting more controlled aspects of sentence comprehension. The availability of executive resources necessary for controlled processes depends on sustained attention, which fluctuates over time. Here, we thus tested whether P600 and N400 amplitudes depend on the level of sustained attention. We re-analyzed EEG and behavioral data from a sentence processing task by Sassenhagen & Bornkessel-Schlesewsky (2015, Cortex), which included sentences with morphosyntactic and semantic violations. Participants read sentences phrase by phrase and indicated whether a sentence contained any type of anomaly as soon as they had the relevant information. To quantify periods of high versus low sustained attention, we extracted a moving reaction time coefficient of variation over the entire course of the task. We found that the P600 amplitude was significantly larger during periods of low reaction time variability (high sustained attention) than in periods of high reaction time variability (low sustained attention). In contrast, the amplitude of the N400 was not affected by reaction time variability. These results thus suggest that the P600 component is sensitive to sustained attention while the N400 component is not, which provides independent evidence for accounts suggesting that P600 amplitudes reflect more controlled and N400 amplitudes more automatic aspects of sentence comprehension.

Semantic feedback processing mechanism of the enactment effect: Evidence from event-related potentials

The enactment effect refers to a phenomenon in which the memory performance for action phrases is enhanced by performing the described action (e.g., sharpen a pencil) compared with simply reading the action phrase. This produced effect can result in improved motor processing. This study investigated the contribution of semantic integration to the enactment effect by contrasting well-integrated phrases, such as “blow up the balloon,” with poorly integrated phrases, such as “sew the toothpick,” and analysing the N400 component of event-related potentials (ERPs). The subjects encoded action phrases with different degrees of semantic integration by either pretending to perform or reading action phrases. They then completed a phrase recognition test, while electroencephalographic signals were simultaneously recorded. The behavioural results showed that semantic integration improved memory performance under the motor encoding condition but not under the verbal encoding condition. The ERP results revealed that, regardless of whether it was an old (memorised) or new (distractor) phrase, a larger N400 component was elicited under the motor encoding condition than under the verbal encoding condition. In the motor encoding condition, poorly integrated phrases elicited a larger N400 component than well-integrated phrases; in the verbal encoding condition, this effect was not observed. The N400 effect associated with semantic processing was enhanced by semantic integration under the motor encoding condition rather than the verbal encoding condition. These results supported a deep semantic processing mechanism under the motor encoding condition, and a semantic feedback processing mechanism for the enactment effect was partially supported.

Multisensory Input Modulates P200 and L2 Sentence Comprehension: A One-Week Consolidation Phase

Multisensory input is an aid to language comprehension; however, it remains to be seen to what extent various combinations of senses may affect the P200 component and attention-related cognitive processing associated with L2 sentence comprehension along with the N400 as a later component. To this aim, we provided some multisensory input (enriched with data from three (i.e., exvolvement) and five senses (i.e., involvement)) for a list of unfamiliar words to 18 subjects. Subsequently, the words were embedded in an acceptability judgment task with 360 pragmatically correct and incorrect sentences. The task, along with the ERP recording, was conducted after a 1-week consolidation period to track any possible behavioral and electrophysiological distinctions in the retrieval of information with various sense combinations. According to the behavioral results, we found that the combination of five senses leads to more accurate and quicker responses. Based on the electrophysiological results, the combination of five senses induced a larger P200 amplitude compared to the three-sense combination. The implication is that as the sensory weight of the input increases, vocabulary retrieval is facilitated and more attention is directed to the overall comprehension of L2 sentences which leads to more accurate and quicker responses. This finding was not, however, reflected in the neural activity of the N400 component.

Effects of Design Aesthetics on the Perceived Value of a Product

Design aesthetics play a crucial role in product design. Stakeholders expect to develop highly valuable premium products by improving the design aesthetics of products. Nevertheless, the question of how to evaluate the value of design aesthetics has not been fully addressed. In this study, the effects of design aesthetics on the evaluation of the value of a product were investigated through a strictly controlled experiment in which the neural responses of the participants were measured. Forty participants completed the design aesthetics experiment in a laboratory setting. Images of products were divided into two categories: those representing high– and low–design-aesthetic stimuli. Both types of images were labeled with the same price. Overall, the images representing high design aesthetics elicited smaller N100 and lower P200 amplitudes than did the images representing low design aesthetics. This finding indicates that low design aesthetics attracted more attention than high design aesthetics did and that high design aesthetics triggered positive emotions. Low–design-aesthetic products elicited a larger N400 amplitude. This finding reveals the inconsistency between labeled and expected prices. The present study indicates that the N400 component can be used as an indicator for measuring the perceived value of a product in a future product design study. Our study provides event-related potential indicators that can be easily applied in decision making for measuring the perceived value of a product’s design.

Parafoveal words can modulate sentence meaning: Electrophysiological evidence from an RSVP-with-flanker task

During natural reading, readers also take up some visual information from not-yet-fixated words to the right of the current fixation and it is well-established that this parafoveal preview facilitates the subsequent foveal processing of the word. However, the extraction and integration of word meaning from the parafoveal word and its possible influence on the semantic sentence context are controversial. In the current study, we recorded event-related potentials (ERPs) in the RSVP-with-flankers paradigm to test whether and how updates of sentential meaning that are based only on parafoveal information influence the subsequent foveal processing. Using Chinese sentences, the sentence congruency of parafoveal and foveal target words were orthogonally manipulated. In contrast to previous research, we also controlled for potentially confounding effects of parafoveal-to-foveal repetition priming (identity preview effects) on the N400. Crucially, we found that the classic effect of foveal congruency on the N400 component only appeared when the word in preview had been congruent with sentence meaning; in contrast, there was no N400 when the preview word had been incongruent. These results indicate that sentence meaning rapidly adapts to parafoveal preview, which already changes the context for the then fixated word. We also show that a correct parafoveal preview generally attenuates the N400 once a word is fixated, regardless of congruency. Taken together, our findings underline the highly generative and adaptive framework of language comprehension.

Development of the N400 for Word Learning in the First 2 Years of Life: A Systematic Review

The N400 ERP component is a direct neural index of word meaning. Studies show that the N400 component is already present in early infancy, albeit often delayed. Many researchers capitalize on this finding, using the N400 component to better understand how early language acquisition unfolds. However, variability in how researchers quantify the N400 makes it difficult to set clear predictions or build theory. Not much is known about how the N400 component develops in the first 2 years of life in terms of its latency and topographical distributions, nor do we know how task parameters affect its appearance. In the current paper we carry out a systematic review, comparing over 30 studies that report the N400 component as a proxy of semantic processing elicited in infants between 0 and 24 months old who listened to linguistic stimuli. Our main finding is that there is large heterogeneity across semantic-priming studies in reported characteristics of the N400, both with respect to latency and to distributions. With age, the onset of the N400 insignificantly decreases, while its offset slightly increases. We also examined whether the N400 appears different for recently-acquired novel words vs. existing words: both situations reveal heterogeneity across studies. Finally, we inspected whether the N400 was modulated differently with studies using a between-subject design. In infants with more proficient language skills the N400 was more often present or showed itself here with earlier latency, compared to their peers; but no consistent patterns were observed for distribution characteristics of the N400. One limitation of the current review is that we compared studies that widely differed in choice of EEG recordings, pre-processing steps and quantification of the N400, all of which could affect the characteristics of the infant N400. The field is still missing research that systematically tests development of the N400 using the same paradigm across infancy.

Predicting the N400 ERP component using the Sentence Gestalt model trained on a large scale corpus

The N400 component of the event-related brain potential is widely used to investigate language and meaning processing. However, despite much research, the component's functional basis remains actively debated. Recent work showed that the update of the predictive representation of sentence meaning (semantic update, or SU) generated by the Sentence Gestalt model (Mcclelland1 et al. 1989) consistently displayed a similar pattern to the N400 amplitude in a series of conditions known to modulate this event-related potential. These results led Rabovsky et al. (2018) to suggest that the N400 might reflect change in a probabilistic representation of meaning corresponding to an implicit semantic prediction error. However, a limitation of this work is that the model was trained on a small artificial training corpus and thus could not be presented with the same naturalistic stimuli presented in empirical experiments. In the present study, we overcome this limitation and directly model the amplitude of the N400 elicited during naturalistic sentence processing by using as predictor the SU generated by a Sentence Gestalt model trained on a large corpus of texts. The results reported in this paper corroborate the hypothesis that the N400 component reflects the change in a probabilistic representation of meaning after every word presentation. Further analyses demonstrate that the SU of the Sentence Gestalt model and the amplitude of the N400 are influenced similarly by the stochastic and positional properties of the linguistic input.

The N400 ERP component reflects a learning signal during language comprehension

The functional significance of the N400 ERP component is still actively debated. Based on neural network modeling it was recently proposed that the N400 component can be interpreted as the change in a probabilistic representation corresponding to an internal temporal-difference prediction error at the level of meaning that drives adaptation in language processing. These computational modeling results imply that increased N400 amplitudes should correspond to greater adaptation. To investigate this model derived hypothesis, the current study manipulated expectancy in a sentence reading task, which influenced N400 amplitudes, and critically also later implicit memory for the manipulated word: reaction times in a perceptual identification task were significantly faster for previously unexpected words. Additionally, it could be demonstrated that this adaptation seems to specifically depend on the process underlying N400 amplitudes, as participants with larger N400 differences also exhibited a larger implicit memory benefit. These findings support the interpretation of the N400 as an implicit learning signal in language processing.