Causal evidence for a coordinated temporal interplay within the language network.

Recent neurobiological models on language suggest that auditory sentence comprehension is supported by a coordinated temporal interplay within a left-dominant brain network, including the posterior inferior frontal gyrus (pIFG), posterior superior temporal gyrus and sulcus (pSTG/STS), and angular gyrus (AG). Here, we probed the timing and causal relevance of the interplay between these regions by means of concurrent transcranial magnetic stimulation and electroencephalography (TMS-EEG). Our TMS-EEG experiments reveal region- and time-specific causal evidence for a bidirectional information flow from left pSTG/STS to left pIFG and back during auditory sentence processing. Adapting a condition-and-perturb approach, our findings further suggest that the left pSTG/STS can be supported by the left AG in a state-dependent manner.

Evaluation standards regulate the generation and selection of novel ideas in creative behaviors: insights from individual differences in event-related potentials.

Evaluation is generally considered to occur after the generation of novel ideas to select truly creative ideas; however, evaluation may occur concurrently with the generation and regulate its efficiency. To test this hypothesis, 120 participants who held strict, moderate, or loose evaluation standards were grouped, and neural responses related to novel idea generation were compared retrospectively. The results showed that lower N400 amplitudes and greater LSP amplitudes were simultaneously elicited by objectively defined novel and usable options than by novel but unusable options among participants with moderate standards but not among participants with strict or loose standards. Evaluation standards influence the efficiency of novel idea generation; neither strict nor loose evaluation standards are conducive to fully resolving cognitive conflicts and generating novel ideas. Moreover, lower N400 amplitudes and greater LSP amplitudes were simultaneously elicited by the subjectively rated novel and usable option than by the novel but unusable option among participants with strict and moderate standards but not among participants with loose standards. Evaluation standards influence the selection among the generated ideas; participants in the strict and moderate groups made a wise choice based on the degree of conflict resolution, whereas participants in the loose group did not.

Alexithymia modulates emotion concept activation during facial expression processing.

Alexithymia is characterized by difficulties in emotional information processing. However, the underlying reasons for emotional processing deficits in alexithymia are not fully understood. The present study aimed to investigate the mechanism underlying emotional deficits in alexithymia. Using the Toronto Alexithymia Scale-20, we recruited college students with high alexithymia (n = 24) or low alexithymia (n = 24) in this study. Participants judged the emotional consistency of facial expressions and contextual sentences while recording their event-related potentials. Behaviorally, the high alexithymia group showed longer response times versus the low alexithymia group in processing facial expressions. The event-related potential results showed that the high alexithymia group had more negative-going N400 amplitudes compared with the low alexithymia group in the incongruent condition. More negative N400 amplitudes are also associated with slower responses to facial expressions. Furthermore, machine learning analyses based on N400 amplitudes could distinguish the high alexithymia group from the low alexithymia group in the incongruent condition. Overall, these findings suggest worse facial emotion perception for the high alexithymia group, potentially due to difficulty in spontaneously activating emotion concepts. Our findings have important implications for the affective science and clinical intervention of alexithymia-related affective disorders.

N400 event-related brain potential index of semantic processing and two-year clinical outcomes in persons at high risk for psychosis: A longitudinal study.

The N400 event-related brain potential (ERP) semantic priming effect reflects greater activation of contextually related versus unrelated concepts in long-term semantic memory. Deficits in this measure have been found in persons with schizophrenia and those at clinical high risk (CHR) for this disorder. In CHR patients, we previously found that these deficits predict poorer social functional outcomes after 1 year. In the present study, we tested whether these deficits predicted greater psychosis-spectrum symptom severity and functional impairment over 2 years. We measured N400 semantic priming effects at baseline in CHR patients (n = 47) who viewed prime words each followed by a related/unrelated target word at stimulus-onset asynchronies (SOAs) of 300 or 750 ms. We measured psychosis-spectrum symptoms using the Structured Interview for Prodromal Symptoms and role and social functioning with the Global Functioning: Role and Social scales, at baseline, 1 (n = 29) and 2 years (n = 25). There was a significant interaction between the N400 semantic priming effect at the 300-ms SOA and time on GF:Role scores, indicating that, contrary to expectations, smaller baseline N400 semantic priming effects were associated with more improvement in role functioning from baseline to Year 1, but baseline N400 priming effects did not predict role functioning at Year 2. N400 priming effects were not significantly associated with different trajectories in psychosis-spectrum symptoms or social functioning. Thus, CHR patients' N400 semantic priming effects did not predict clinical outcomes over 2 years, suggesting that this ERP measure may have greater value as a state or short-term prognostic neurophysiological biomarker.

Multivariate pattern analysis of EEG reveals nuanced impact of negation on sentence processing in the N400 and later time windows.

The neurocognitive mechanism underlying negation processing remains controversial. While negation is suggested to modulate the access of word meaning, no such evidence has been observed in the event-related potential (ERP) literature on sentence processing. In the current study, we applied both univariate ERP and multivariate pattern analysis (MVPA) methods to examine the processing of sentence negation. We investigated two types of negative congruent/incongruent sentence pairs with truth-value evaluation (e.g., "A robin is a/not a bird") and without (e.g., "The woman reads a/no book"). In the N400 time window, ERPs consistently showed increased negativity for negative and incongruent conditions. MVPA, on the other hand, revealed nuanced interactions between polarity and congruency. In the later P600 time window, MVPA but not the ERPs revealed an effect of congruency, which may be functionally distinct from the N400 window. We further used cross-decoding to show that the cognitive processes underlying the N400 window for both affirmative and negative sentences are comparable, whereas in the P600 window, only for the truth sentences, negative sentences showed a distinct pattern from their affirmative counterparts. Our results thus speak for a more interactive, but nevertheless serial and biphasic, and potentially construction-specific processing account of negation. We also discuss the advantage of applying MVPA in addition to the classical univariate methods for a better understanding of the neurobiology of negation processing and language comprehension alike.

Parafoveal and foveal N400 effects in natural reading: A timeline of semantic processing from fixation-related potentials.

The depth at which parafoveal words are processed during reading is an ongoing topic of debate. Recent studies using RSVP-with-flanker paradigms have shown that implausible words within sentences elicit an N400 component while they are still in parafoveal vision, suggesting that the semantics of parafoveal words can be accessed to rapidly update the sentence representation. To study this effect in natural reading, we combined the coregistration of eye movements and EEG with the deconvolution modeling of fixation-related potentials (FRPs) to test whether semantic plausibility is processed parafoveally during Chinese sentence reading. For one target word per sentence, both its parafoveal and foveal plausibility were orthogonally manipulated using the boundary paradigm. Consistent with previous eye movement studies, we observed a delayed effect of parafoveal plausibility on fixation durations that only emerged on the foveal word. Crucially, in FRPs aligned to the pretarget fixation, a clear N400 effect emerged already based on parafoveal plausibility, with more negative voltages for implausible previews. Once participants fixated the target, we again observed an N400 effect of foveal plausibility. Interestingly, this foveal N400 was absent whenever the preview had been implausible, indicating that when a word's (im)plausibility is already processed in parafoveal vision, this information is not revised anymore upon direct fixation. Implausible words also elicited a late positive component (LPC), but exclusively when in foveal vision. Our results not only provide convergent neural and behavioral evidence for the parafoveal uptake of semantic information, but also indicate different contributions of parafoveal versus foveal information toward higher level sentence processing.

Hebbian learning can explain rhythmic neural entrainment to statistical regularities.

In many domains, learners extract recurring units from continuous sequences. For example, in unknown languages, fluent speech is perceived as a continuous signal. Learners need to extract the underlying words from this continuous signal and then memorize them. One prominent candidate mechanism is statistical learning, whereby learners track how predictive syllables (or other items) are of one another. Syllables within the same word predict each other better than syllables straddling word boundaries. But does statistical learning lead to memories of the underlying words-or just to pairwise associations among syllables? Electrophysiological results provide the strongest evidence for the memory view. Electrophysiological responses can be time-locked to statistical word boundaries (e.g., N400s) and show rhythmic activity with a periodicity of word durations. Here, I reproduce such results with a simple Hebbian network. When exposed to statistically structured syllable sequences (and when the underlying words are not excessively long), the network activation is rhythmic with the periodicity of a word duration and activation maxima on word-final syllables. This is because word-final syllables receive more excitation from earlier syllables with which they are associated than less predictable syllables that occur earlier in words. The network is also sensitive to information whose electrophysiological correlates were used to support the encoding of ordinal positions within words. Hebbian learning can thus explain rhythmic neural activity in statistical learning tasks without any memory representations of words. Learners might thus need to rely on cues beyond statistical associations to learn the words of their native language. RESEARCH HIGHLIGHTS: Statistical learning may be utilized to identify recurring units in continuous sequences (e.g., words in fluent speech) but may not generate explicit memory for words. Exposure to statistically structured sequences leads to rhythmic activity with a period of the duration of the underlying units (e.g., words). I show that a memory-less Hebbian network model can reproduce this rhythmic neural activity as well as putative encodings of ordinal positions observed in earlier research. Direct tests are needed to establish whether statistical learning leads to declarative memories for words.

Inefficient speech-motor control affects predictive speech comprehension: atypical electrophysiological correlates in stuttering.

Listeners predict upcoming information during language comprehension. However, how this ability is implemented is still largely unknown. Here, we tested the hypothesis proposing that language production mechanisms have a role in prediction. We studied 2 electroencephalographic correlates of predictability during speech comprehension-pre-target alpha-beta (8-30 Hz) power decrease and the post-target N400 event-related potential effect-in a population with impaired speech-motor control, i.e. adults who stutter (AWS), compared to typically fluent adults (TFA). Participants listened to sentences that could either constrain towards a target word or not, modulating its predictability. As a complementary task, participants also performed context-driven word production. Compared to TFA, AWS not only displayed atypical neural responses in production, but, critically, they showed a different pattern also in comprehension. Specifically, while TFA showed the expected pre-target power decrease, AWS showed a power increase in frontal regions, associated with speech-motor control. In addition, the post-target N400 effect was reduced for AWS with respect to TFA. Finally, we found that production and comprehension power changes were positively correlated in TFA, but not in AWS. Overall, the results support the idea that processes and neural structures prominently devoted to speech planning also support prediction during speech comprehension.

Neural correlates of unconventional verb extensions reveal preschoolers' analogical abilities.

In the current event-related potential (ERP) study, we assessed 4-year-olds' ability to extend verbs to new action events on the basis of abstract similarities. Participants were presented with images of actions (e.g., peeling an orange) while hearing sentences containing a conventional verb (e.g., peeling), a verb sharing an abstract relation (i.e., an analogical verb, e.g., undressing), a verb sharing an object type (i.e., an object-related verb, e.g., pressing) with the action, or a pseudoverb (e.g., kebraying). The amplitude of the N400 gradually increased as a function of verb type-from conventional verbs to analogical verbs to object-related verbs to pseudoverbs. These findings suggest that accessing the meaning of a verb is easier when it shares abstract relations with the expected verb. Our results illustrate that measuring brain signals in response to analogical word extensions provides a useful tool to investigate preschools' analogical abilities.

Can irony regulate negative emotion? Evidence from behaviour and ERPs.

This study used ratings and event-related potentials (ERPs) to compare the mechanisms through which verbal irony and cognitive reappraisal mitigate negative emotion. Verbal irony is when the literal meaning of words contrasts with their intended meaning. Cognitive reappraisal is when we reconsider emotional stimuli to make them less intense. Our hypothesis was that cognitive reappraisal is a potential mechanism through which irony reduces negative emotion. Participants viewed mildly negative pictures first, then read an ironic or literal statement about it in one block, and used cognitive reappraisal of or attending to the picture in the other block. Participants then viewed the picture for a second time, before rating how negative they felt. Behaviourally, irony reduced negative feelings more than literal statements, and reappraisal reduced negative feelings more than attending, with a larger reduction from reappraisal than from irony. In ERPs, irony elicited a prolonged N400 compared to literal, indexing an initial contrast between picture and word affect and sustained processing of their combination. Cognitive reappraisal elicited a larger late positivity compared to attending at the instruction screen. No differences were found during second picture presentation. These findings suggest that irony and cognitive reappraisal can reduce negative affect in different ways.

How L2 Learners Process Different Means of Time Encoding in a Tenseless Language: An ERP Study of Mandarin.

In the past, research on the cognitive neural mechanism of second language (L2) learners' processing time information has focused on Indo-European languages. It has also focused on the temporal category expressed by morphological changes. However, there has been a lack of research on L2 learners' various time coding means, especially for Mandarin, which lacks morphological changes. Using event-related potentials (ERPs), we investigated the cognitive neural mechanism of L2 learners with native Indonesian background in processing two time coding means (time adverbs and aspect markers) in Chinese. Indonesian has time adverb encoding time information similar to that of Chinese, but there are no aspect markers similar to Chinese in Indonesian. We measured ERPs time locked to the time adverb " (cengjing)" and the aspect marker "verb + (verb + guo)" in two different conditions, i.e., a control condition (the correct sentence) and a temporal information violation. The experimental results showed that the native speaker group induced the biphasic N400-P600 effect under the condition of time adverb violation, and induced P600 under the condition of the aspect marker "verb + (verb + guo)" violation. Indonesian L2 learners of Chinese only elicited P600 for the violation of time adverbs, and there was no statistically significant N400 similar to that of Chinese native speakers. In the case of aspect marker violation, we observed no significant ERPs component for the Indonesian L2 learners of Chinese. Both groups of subjects induced elicited a widely distributed and sustained negativity on the post-critical words after "verb + (verb + guo)" and "(cengjing)". This showed that the neural mechanism of Indonesian L2 learners of Chinese processing Chinese time coding differs from that of Chinese native speakers.

Contextual incongruency triggers memory reinstatement and the disruption of neural stability.

Schemas, or internal representation models of the environment, are thought to be central in organising our everyday life behaviour by giving stability and predictiveness to the structure of the world. However, when an element from an unfolding event mismatches the schema-derived expectations, the coherent narrative is interrupted and an update to the current event model representation is required. Here, we asked whether the perceived incongruence of an item from an unfolding event and its impact on memory relied on the disruption of neural stability patterns preceded by the neural reactivation of the memory representations of the just-encoded event. Our study includes data from two different experiments whereby human participants (N = 33, 26 females and N = 18, 16 females, respectively) encoded images of objects preceded by trial-unique sequences of events depicting daily routine. We found that neural stability patterns gradually increased throughout the ongoing exposure to a schema-consistent episode, which was corroborated by the re-analysis of data from two other experiments, and that the brain stability pattern was interrupted when the encoding of an object of the event was incongruent with the ongoing schema. We found that the decrease in neural stability for low-congruence items was seen at ∼1000 ms from object encoding onset and that it was preceded by an enhanced N400 ERP and an increased degree of neural reactivation of the just-encoded episode. Current results offer new insights into the neural mechanisms and their temporal orchestration that are engaged during online encoding of schema-consistent episodic narratives and the detection of incongruencies.

Single-trial ERP Quantification Using Neural Networks.

Traditional approaches to quantify components in event-related potentials (ERPs) are based on averaging EEG responses. However, this method ignores the trial-to-trial variability in the component's latency, resulting in a smeared version of the component and underestimates of its amplitude. Different techniques to quantify ERP components in single trials have therefore been described in literature. In this study, two approaches based on neural networks are proposed and their performance was compared with other techniques using simulated data and two experimental datasets. On the simulated dataset, the neural networks outperformed other techniques for most signal-to-noise ratios and resulted in better estimates of the topography and shape of the ERP component. In the first experimental dataset, the highest correlation values between the estimated latencies of the P300 component and the reaction times were obtained using the neural networks. In the second dataset, the single-trial latency estimation techniques showed an amplitude reduction of the N400 effect with age and ascertained this effect could not be attributed to differences in latency variability. These results illustrate the applicability and the added value of neural networks for the quantification of ERP components in individual trials. A limitation, however, is that simulated data is needed to train the neural networks, which can be difficult when the ERP components to be found are not known a priori. Nevertheless, the neural networks-based approaches offer more information on the variability of the timing of the component and result in better estimates of the shape and topography of ERP components.

Separating the role of perceptual and conceptual fluency on masked word priming using event-related potentials.

Masked word repetition increases "old" responses on an episodic recognition test (Jacoby & Whitehouse, 1989). This effect is commonly attributed to perceptual fluency; that is, unconscious perception of the prime speeds reading of the target and this fluency leads to elevated familiarity. Two experiments directly tested the claim that perceptual fluency is responsible for word priming effects. Experiment 1 held prime-target meaning constant and altered the physical characteristics of match primes (e.g., "RIGHT" primes "RIGHT") by including both lowercase (e.g, "right") and mixed case primes (e.g., "rIgHt"). If word priming effects are due to perceptual fluency, then lowering the perceptual overlap between the prime and target should decrease or eliminate word priming effects. Instead, all three conditions showed robust priming effects in the behavioral and ERP (i.e., N400) measures. Experiment 2 equated the prime-target perceptual features and lowered the conceptual overlap by using orthographically similar nonwords as primes (e.g., "JIGHT" primes "RIGHT"). Removing prime-target conceptual overlap eliminated behavioral evidence of priming and N400 ERP differences correlated with priming. The evidence suggests that word priming effects on episodic recognition memory are more likely a product of conceptual fluency than perceptual fluency.

Time flows vertically in Chinese.

Speakers of Mandarin Chinese are thought to conceptualise time along the vertical axis-as evidence for metaphor embodiment-but the extant behavioural evidence remains unclear. Here, we used electrophysiology to test space-time conceptual relationships implicitly in native speakers of Chinese. We employed a modified arrow flanker task, in which the central arrow in a set of three was replaced by a spatial word (e.g., -'up'), a spatiotemporal metaphor (e. g., -'last month', literally 'up month') or a non-spatial temporal expression (e.g., -'last year', literally 'gone year'). N400 modulations of event-related brain potentials served to measure the level of perceived congruency between semantic word content and arrow direction. Critically, we tested whether N400 modulations expected for spatial words and spatial temporal metaphors would generalise to non-spatial temporal expressions. In addition to the predicted N400 effects, we found a congruency effect of a similar magnitude for non-spatial temporal metaphors. On the basis of direct brain measurements indexing semantic processing, and in the absence of contrastive behavioural patterns, we demonstrate that native speakers of Chinese conceptualise time along the vertical axis, and thus have embodied spatiotemporal metaphors.

Event-Related Potential (ERP) evidence for fluency and disfluency effects on recognition memory.

Masked priming is used in recognition memory studies to alter fluency and create familiarity. Primes are flashed briefly before target words that are considered for a recognition judgment. Matching primes are hypothesized to produce greater familiarity by increasing the perceptual fluency of the target word. Experiment 1 tested this claim by contrasting match primes (i.e., "RIGHT" primes "RIGHT"), semantic primes (e.g., "LEFT" primes "RIGHT"), and orthographically similar (OS) primes (e.g., "SIGHT" primes "RIGHT") while recording event-related potentials (ERPs). Relative to match primes, OS primes elicited fewer "old" responses and more negative ERPs during the interval associated with familiarity (300-500 ms). This result was replicated when control primes consisting of unrelated words (Experiment 2) or symbols (Experiment 3) were inserted into the sequence. The behavioral and ERP evidence suggest that word primes are perceived as a unit and the prime word activation will affect target fluency and recognition judgments. When the prime matches the target, fluency is increased and more familiarity experiences are created. When the primes are words that do not match the target, fluency is decreased (disfluency) and fewer familiarity experiences result. This evidence suggests that the effects of disfluency on recognition should be carefully considered.

Emotional autobiographical memory retrieval in time domain.

Autobiographical memory (AM) is an important psychological phenomenon that has significance for self-development and mental health. The psychological mechanisms of emotional AM retrieval and their association with individual emotional symptoms remain largely unclear in the literature. For this purpose, the current study provided cue words to elicit emotional AMs. Event-related potentials (ERPs) associated with the retrieval process of AMs were recorded and analyzed. We found that the ERP component N400 was sensitive to both emotional valence and retrieval state, such that its amplitude was larger for negative compared to positive AMs, and larger responses for unrecalled compared to recalled AMs. Further, the N400 amplitude in the positive recalled condition was correlated with individual difference in depression (measured by the Beck Depression Inventory). Another ERP component, the late positive potential (LPP), was also sensitive to emotional valence, such that its amplitude was larger (i.e., more positive-going) for positive compared to negative cues. No significant effect was observed on the early ERP components P1, N1, or P2. The current findings bring new understanding on the difference between positive and negative AMs retrieval in the time domain. Also, the importance of this difference to the individual level of depression is worth noting.

Visual Verbal Information Processing under Conditions of Reading and Categorization in Schizotypy: An Event-Related Brain Potential Study.

BACKGROUND: Some individuals exhibit symptoms that resemble schizophrenia, but these manifestations are less in the degree to those seen in schizophrenia. Such a latent personality construct has been called schizotypy. It is known that schizotypal personality traits have an impact on cognitive control and semantic processing. The present study aimed to examine whether visual verbal information processing is modulated by enhancement of top-down processes applied to different words within one phrase in subjects with schizotypal personality traits. The tasks employed were based on differences in the involvement of cognitive control in visual verbal information processing and hypothesized that subjects with schizotypal traits would demonstrate failure in top-down modulation of word processing within a phrase. METHODS: Forty-eight healthy undergraduate students were enrolled in the study. Participants were screened for schizotypy with the Schizotypal Personality Questionnaire. Word combinations consisting of an attribute and a noun were used as stimuli. Participants were asked to categorize one word in a phrase and to passively read the other word in the pair. To obtain neurophysiological data during task performance, the event-related brain potential N400 was measured. RESULTS: In the low schizotypy scores group, an increased N400 amplitude was revealed for both attributes and nouns during passive reading compared to categorization. This effect was not observed in the high schizotypy scores group; therefore, word processing was modulated weakly by the experimental task in subjects with schizotypal personality traits. CONCLUSIONS: Changes observed in schizotypy can be regarded as a failure in top-down modulation of word processing within a phrase.

The Levels of Auditory Processing during Emotional Perception in Children with Autism.

BACKGROUND: The perception of basic emotional sounds, such as crying and laughter is associated with effective interpersonal communication. Difficulties with the perception and analysis of sounds that complicate understanding emotions at an early development age may contribute to communication deficits. METHODS: This study focused on auditory nonverbal emotional perception including emotional vocalizations with opposite valences (crying and laughter) and neutral sound (phoneme "Pᴂ"). We conducted event-related potential analysis and compared peak alpha frequencies (PAFs) for different conditions in children with autism spectrum disorder (ASD) and typically developing (TD) children aged 4 to 6 years old (N = 25 for each group). RESULTS: Children with ASD had a higher amplitude of P100 and lower amplitude of N200 for all types of sounds and higher P270 in response to neutral phoneme. During the perception of emotional sounds, children with ASD demonstrated a single P270 electroencephalography (EEG) component instead of a P200-P300 complex specific to TD children. However, the most significant differences were associated with a response to emotional valences of stimuli. The EEG differences between crying and laughter were expressed as a lower amplitude of N400 and higher PAF for crying compared to laughter and were found only in TD children. CONCLUSIONS: Children with ASD have shown not just abnormal acoustical perception but altered emotional analysis of affective sounds as well.

The default-interventionist model underlies premise typicality weakening the premise diversity effect during category-based induction: Event-related potentials evidence.

The diversity effect during category-based induction (CBI) means that the more diverse the evidence, the higher will be the conclusion's inductive strength. However, it is influenced by the premise typicality. Three competitive cognitive processing models account for this influence: (1) The pre-emptive conflict resolution model assumes that only premise typicality activates; (2) the parallel-competitive model assumes that premise typicality and diversity activate in parallel; and (3) the default-interventionist model assumes that a default response of premise diversity first activates and is subsequently followed by premise typicality, or premise typicality activates first, followed by premise diversity. The timing of premise typicality affecting the diversity effect during CBI was measured using event-related potentials to determine which cognitive model best explains this influence. Similar to previous studies, non-diverse premise inductive tasks involving two typical premise categories were compared with diverse premise inductive tasks involving a typical and an atypical category. The results showed that non-diverse conditions had higher "correct" response proportions, greater inductive strength, higher "definitely" response proportions, and shorter reaction times than diverse conditions, showing that premise typicality weakens the diversity effect. Moreover, the diverse premises elicited larger P2, smaller FN400, and greater frontal post-N400-positivity amplitudes than non-diverse premises, suggesting that premise diversity was facilitated during a relatively early time window and revised by premise typicality in a later window. These results support the default-interventionist in nature during thinking and reasoning.