The neurocognitive basis of reading single words as seen through early latency ERPs: A model of converging pathways

Dissociating different temporal stages of emotional word processing by feature-based attention

Negative emotional content is prioritized across different stages of information processing as reflected by different components of the event-related potential (ERP). In this preregistered study (N = 40), we investigated how varying the attentional focus allows us to dissociate the involvement of specific ERP components in the processing of negative and neutral words. Participants had to discriminate the orientation of lines overlaid onto the words, the word type (adjective/noun), or the emotional content (negative/neutral). Thus, attention was either not focused on words (distraction task), non-emotional aspects, or the emotional relevance of words. Regardless of the task, there were no significant differences between negative and neutral words for the P1, N1, or P2 components. In contrast, interactions between emotion and task were observed for the early posterior negativity (EPN) and late positive potential (LPP). EPN differences were absent during the distraction task but were present in the other two tasks. LPP emotion differences were found only when attention was directed to the emotional content of words. Our study adds to the evidence that early ERP components do not reliably separate negative and neutral words. However, results show that mid-latency and late stages of emotion processing are separable by different attention tasks. The EPN represents a stage of attentional enhancement of negative words given sufficient attentional resources. Differential activations during the LPP stage are associated with more elaborative processing of the emotional meaning of words.

Getting language right: Relating individual differences in right hemisphere contributions to language learning and relearning

Language, or the diverse set of dynamic processes through which symbolic, perceptual codes are linked to meaning representations in memory, has long been assumed to be lateralized to the left hemisphere (LH). However, after over 150 years of investigation, we still lack a unifying account of when, and for whom, a particular linguistic process relies upon LH or right hemisphere (RH) computations, or both. With a focus on individual differences, this article integrates existing theories of hemispheric contributions to language and cognition into a novel proposed framework for understanding how, when, and for whom the RH contributes to linguistic processes. We use evidence from first and second language learning and language relearning following focal brain damage to highlight the critical contributions of the RH.

Attentional tuning of valent word forms

Using event-related brain potentials (ERPs), we tested the hypothesis of valent word forms (Kissler et al., 2006, Prog Brain Res) stating that the mere visual shapes of emotional words acquire valence through numerous co-occurrences with affective activation over an experienced reader's life. Thereby, associations between neuronal representations of visual word forms and affect are strengthened. If so, selective attention to a specific level of the valence of single visual words should not only pre-activate neuronal representations of that level of valence, but this activation should also spread to the associated word forms. This should improve their processing and/or affective discrimination. In a valence-detection task, N = 53 participants made speeded responses only to words of the current target level of valence (negative, neutral, or positive), which varied across separate blocks. We focused on posterior visual P1 and N170 components, two well-established ERP markers of low-level and structural word form processing, respectively. P1 increased from negative over neutral to positive words; this effect was stronger in target compared to nontarget words. N170 was larger for emotional compared to neutral target words, whereas nontarget words showed a strong reverse pattern. The P1 effect for target words and the N170 effect for nontarget words both were driven by good task performers in terms of fast hit responses. Results support the idea of valent word forms that can be tuned by selective attention to valence, which implies both, facilitated affective discrimination and processing of target words, and inhibition of the processing of nontarget words.

Attention to affect 2.0: Multiple effects of emotion and attention on event-related potentials of visual word processing in a valence-detection task

Here we continue recent work on the specific mental processes engaged in a valence-detection task. Fifty-seven participants responded to one predefined target level of valence (negative, neutral, or positive), and ignored the remaining two levels. This enables more precise fine-tuning of neuronal pathways, compared to valence categorization where attention is divided between different levels of valence. Our group recently used valence detection with emotional words. Posterior P1 and N170 effects in the event-related potential (ERP) supported the idea of valent word forms that can be tuned by selective attention to valence. Here we report findings on three distinct posterior N2 components, P300, N400, and the late positive potential (LPP). Target but not nontarget words showed an arousal effect (emotional > neutral) on left-side early posterior negativity (180-280 ms). In contrast, an arousal effect on a sharp N2 deflection in left-minus-right difference ERPs (230-270 ms), suggesting facilitation of lexical access for emotional words, was independent of target status. This also applied to increased medial parieto-occipital N2 (260-300 ms) specific to negative words, indicating attentional capture. Medial-central N400 was specifically enhanced for negative nontarget words, further supporting attentional capture. The typical LPP arousal effect was observed, being stronger and more left-lateralized in target words. An exploratory finding concerned a broad component-overarching ERP valence effect (250-650 ms). Independent of target status, ERPs were more positive for positive than negative words. Combined with our previous results, data suggest multiple loci of emotion-attention interactions in valence detection.

Nudging the N170 forward with prior stimulation-Bridging the gap between N170 and recognition potential

Evoked response potentials are often divided up into numerous components, each with their own body of literature. But is there less variety than we might suppose? In this study, we nudge one component into looking like another. Both the N170 and recognition potential (RP) are N1 components in response to familiar objects. However, the RP is often measured with a forward mask that ends at stimulus onset whereas the N170 is often measured with no masking at all. This study investigates how inter‐stimulus interval (ISI) may delay and distort the N170 into an RP by manipulating the temporal gap (ISI) between forward mask and target. The results revealed reverse relationships between the ISI on the one hand, and the N170 latency, single‐trial N1 jitter (an approximation of N1 width) and reaction time on the other hand. Importantly, we find that scalp topographies have a unique signature at the N1 peak across all conditions, from the longest gap (N170) to the shortest (RP). These findings prove that the mask‐delayed N1 is still the same N170, even under conditions that are normally associated with a different component like the RP. In general, our results suggest greater synthesis in the study of event related potential components.

Altered brain network centrality in patients with mild cognitive impairment: an fMRI study using a voxel-wise degree centrality approach

PURPOSE

Previous studies in patients with Alzheimer's disease have shown amyloid beta accumulation in the brain and abnormal brain activity, with mild cognitive impairment (MCI) in early stages of the disease. The aim of the current study was to investigate functional connectivity in patients with MCI.

METHODS

We recruited 24 subjects in total, including 12 patients with MCI (6 men and 6 women) and 12 healthy controls (HCs) (6 men and 6 women), matched for age, gender, and lifestyle factors. All subjects underwent resting-state functional magnetic resonance imaging scans and voxel-wise degree centrality (DC) was used to evaluate alterations in the strength of brain network connectivity.

RESULTS

The DC value of the left inferior temporal gyrus was lower in MCI but significantly higher in the right fusiform gyrus and the left supplementary motor area, compared with HCs. The DC value in left inferior temporal gyrus correlated positively with disease duration and negatively with Mini-Mental State Examination. ROC curve analysis of brain regions showed acceptable specificity and accuracy of DC values between MCIs and HCs in the area under the curve (right fusiform gyrus, 0.955; left supplementary motor area, 0.992; left inferior temporal gyrus, 1.000).

CONCLUSIONS

Abnormal functional connectivity in brain regions of patients with MCI may reflect the pathological process of Alzheimer's disease development and could prove useful in clinical diagnosis and treatment.

Individuals with dyslexia use a different visual sampling strategy to read text

Individuals with dyslexia present with reading-related deficits including inaccurate and/or less fluent word recognition and poor decoding abilities. Slow reading speed and worse text comprehension can occur as secondary consequences of these deficits. Reports of visual symptoms such as atypical eye movements during reading gave rise to a search for these deficits' underlying mechanisms. This study sought to replicate established behavioral deficits in reading and cognitive processing speed while investigating their underlying mechanisms in more detail by developing a comprehensive profile of eye movements specific to reading in adult dyslexia. Using a validated standardized reading assessment, our findings confirm a reading speed deficit among adults with dyslexia. We observed different eye movements in readers with dyslexia across numerous eye movement metrics including the duration of a stop (i.e., fixation), the length of jumps (i.e., saccades), and the number of times a reader's eyes expressed a jump atypical for reading. We conclude that individuals with dyslexia visually sample written information in a laborious and more effortful manner that is fundamentally different from those without dyslexia. Our findings suggest a mix of aberrant cognitive linguistic and oculomotor processes being present in adults with dyslexia.

The impact of emotional content on pseudoword recognition

The present study investigates the influence of emotional information on language processing. To this aim, we measured behavioral responses and event-related brain potentials (ERPs) during four Italian lexical decision experiments in which we used emotionally intense and neutral pseudowords—i.e., pseudowords derived from changing one letter in a word (e.g., cammelto, derived from cammello ‘camel’ vs. copezzolo, from capezzolo ‘nipple’)—as stimuli. In Experiment 1 and 2, half of the pseudowords were emotionally intense and half were neutral, and were mixed with neutral words. In Experiment 3, the list composition was manipulated, with ¼ of the pseudowords being derived from emotionally intense words and ¾ derived from neutral words. Experiment 4 was identical to Experiment 1, but ERPs were recorded. Emotionally intense pseudowords were categorized more slowly than neutral pseudowords, with the difference emerging both in the mean and at the leading edge of the response times distribution. Moreover, emotionally intense pseudowords elicited smaller N170 and N400 than neutral pseudowords. These results speak in favor of a fast and multi-level infiltration of the emotional information into the linguistic process of word recognition.

The mental representation and social aspect of expressives

Despite increased focus on emotional language, research lacks for the most emotional language: Swearing. We used event-related potentials (ERPs) to investigate whether swear words have content distinct from function words, and if so, whether this content is emotional or social in nature. Stimuli included swear (e.g. shit, damn), negative but non-swear (e.g. kill, sick), open-class neutral (e.g. wood, lend), and closed-class neutral words (e.g. while, whom). Behaviourally, swears were recognised slower than valence- and arousal- matched negative words, meaning that there is more to the expressive dimension than merely a heightened emotional state. In ERPs, both swears and negative words elicited a larger positivity (250-550 ms) than open-class neutral words. Later, swears elicited a larger late positivity (550-750 ms) than negative words. We associate the earlier positivity effect with attention due to negative valence, and the later positivity effect with pragmatics due to social tabooness. Our findings suggest a view in which expressives are not merely function words or emotional words. Rather, expressives are emotionally and socially significant. Swears are more than what is indicated by valence ore arousal alone.

Event-related brain potentials related to the identification of different types of signs

The present study examined the electrophysiological activity during the processing in the identification of signs. Participants performed a sign identification task, in which real, pseudo, and fake signs were adopted as stimuli. Common mathematical operation signs (e.g. +, -, ×, and ÷), which were known to the participants were adopted as the real signs. The pseudo signs had a similar appearance to the real signs (e.g. (Equation is included in full-text article.), (Equation is included in full-text article.), ×, and ÷). The fake signs were also unknown, but had an entirely different shape from the real signs (e.g. (Equation is included in full-text article.), (Equation is included in full-text article.), (Equation is included in full-text article.), and (Equation is included in full-text article.)). The behavioral results showed inferior recognition performance for pseudo signs relative to real or fake signs. Event-related potential results showed that (a) pseudo signs evoked a more positive P200 component than did real or fake signs, suggesting that more attentional resources might be allocated to the pseudo signs relative to the real or fake signs and (b) fake signs evoked a more negative N300 component than real or pseudo signs, suggesting that more cognitive resources might be recruited in processing the visual aspects for fake signs relative to real or pseudo signs. These results suggested that the P200 component, which is associated with attentional resource allocation, and the N300, which is sensitive to visual aspects, were evoked in processing the signs.

Lexical Processing as Revealed by Lateralized Event-Related Brain Potentials

Abstract. Neurocognitive models of written-word processing from low-level perceptual up to semantic analysis include the notion of a strongly left-lateralized posterior-to-anterior stream of activation. Two left-lateralized components in the event-related brain potential (ERP), N170 and temporo-parietal PSA (posterior semantic asymmetry; peak at 300 ms), have been suggested to reflect sublexical analysis and semantic processing, respectively. However, for intermediate processing steps, such as lexical access, no posterior left-lateralized ERP signature has yet been observed under single-word reading conditions. In combination with a recognition task, lexicality and depth of processing were varied. Left-minus-right difference ERPs optimally suited to accentuate left-lateralized language processes revealed an occipito-temporal processing negativity (210–270 ms) for all stimuli except alphanumerical strings. This asymmetry showed greater sensitivity to the combined effects of attention and lexicality than other ERPs in this time range (i.e., N170, P1, and P2). It is therefore introduced as “lexical asymmetry.”

How Action Context Modulates the Action-Language Relationship: A Topographic ERP Analysis

The aim of the present study was to investigate how the context in which an action is presented could modulate the effect of action observation on language processing, an effect that is classically observed in the literature. To address this question, we recorded both behavioral (reaction times) and electrophysiological measures (event-related potentials) of participants performing a semantic decision task involving a verb describing an action that was congruent or incongruent with the action presented in a prime picture that had been observed. The prime picture presented an action performed in a usual or an unusual context. The results revealed different behavioral and topographical pattern responses according to the context in which an action is presented. Importantly, only in the usual context, the congruency between the prime picture and the verb stimulus facilitated the semantic processes, leading to shorter response times in this condition compared to the others. Moreover, the topographic analysis revealed that this facilitation was related to reduced processing times for the semantic access to the verb and for the motor preparation for the answer. Taken together, these findings demonstrate that the context of an action is crucial in the link between action and language.

Parafoveal previews and lexical frequency in natural reading: Evidence from eye movements and fixation-related potentials

Participants' eye movements and electroencephalogram (EEG) signal were recorded as they read sentences displayed according to the gaze-contingent boundary paradigm. Two target words in each sentence were manipulated for lexical frequency (high vs. low frequency) and parafoveal preview of each target word (identical vs. string of random letters vs. string of Xs). Eye movement data revealed visual parafoveal-on-foveal (PoF) effects, as well as foveal visual and orthographic preview effects and word frequency effects. Fixation-related potentials (FRPs) showed visual and orthographic PoF effects as well as foveal visual and orthographic preview effects. Our results replicated the early preview positivity effect (Dimigen, Kliegl, & Sommer, 2012) in the X-string preview condition, and revealed different neural correlates associated with a preview comprised of a string of random letters relative to a string of Xs. The former effects seem likely to reflect difficulty associated with the integration of parafoveal and foveal information, as well as feature overlap, while the latter reflect inhibition, and potentially disruption, to processing underlying reading. Interestingly, and consistent with Kretzschmar, Schlesewsky, and Staub (2015), no frequency effect was reflected in the FRP measures. The findings provide insight into the neural correlates of parafoveal processing and written word recognition in reading and demonstrate the value of utilizing ecologically valid paradigms to study well established phenomena that occur as text is read naturally. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Compounding matters: Event-related potential evidence for early semantic access to compound words

Reading words in a native language triggers a largely obligatory cognitive process that we accept as leading to comprehension of the word - we cannot suppress our understanding of word meaning. In this study, we investigated the early stages of this comprehension process by means of event-related potentials (ERPs) to identify when this processing of meaning - that is, semantic processing - first occurs. We report that, when processing visually presented compound words, semantic access at some level occurs as early as the P100 and persists through to the N400. Specifically, we focused on the P100 ERP component, and utilized the unique features of compound words (i.e. variation in the transparency of meaning) to investigate the speed with which we gain access to information about meaning (i.e. semantic access). Twenty-two participants performed a lexical decision task including 40 English compounds, which varied with respect to their constituent semantic transparency. Compounds ranged from full constituent semantic transparency (e.g. grapeseed) to partial transparency (e.g. grapefruit) to full opacity (e.g. hogwash). Regression analyses predicted ERP components from compound constituent transparency, adjusting for word frequency. Word frequency and transparency of both the first and second constituents each uniquely predicted P100 amplitude. Transparency of the second constituent, but not word frequency, predicted later component amplitudes, including that of the N400. The findings suggest that some level of semantic access occurs as early as the P100. Overall, these results support models which emphasize simultaneous processing of form and meaning as opposed to serial or hierarchical approaches.

Visual expertise for print in schizophrenia: Analysis of the N170 component

Reading deficits have been reported for patients suffering from schizophrenia namely, specific phonological processing deficits. Phonological processing skills are crucial in the learning-to-read process as they are necessary to develop visual expertise for print, which reflects the neural specialization for print. The present study is the first to test visual expertise for print in patients suffering from schizophrenia by measuring the N170 component. Patients and pair-matched healthy control participants performed a lexical decision task, in which words and symbols were presented. As expected, larger N170 amplitudes to word than to control stimuli were observed at the left occipito-temporal site PO7 but not at the PO8. More importantly, the modulation of the N170 as a function of the stimulus and hemisphere did not vary between patients and controls. This result suggests preserved visual expertise for print processing in patients suffering from schizophrenia.

Increased Left Inferior Temporal Gyrus Was Found in Both Low Function Autism and High Function Autism

Previous neuroimaging studies of autism spectrum disorder (ASD) have focused on subjects with IQ > 70 or ASD without considering IQ levels. It remains unclear whether differences in brain anatomy in this population are associated with variations in clinical phenotype. In this study, 19 children with low functioning autism (LFA) and 19 children with high functioning autism (HFA) were compared with 27 healthy controls (HC). We found increased gray matter volume (GMV) in the left inferior temporal gyrus in subjects with both HFA and LFA and increased GMV of left middle temporal gyrus BA21 was found only in the LFA group. A significant negative correlation was found between the left inferior temporal gyrus (LITG) and the score of repetitive behavior in the HFA group.

Effects of Aging Stereotype Threat on Working Self-Concepts: An Event-Related Potentials Approach

Although the influence of stereotype threat (ST) on working self-concepts has been highlighted in recent years, its neural underpinnings are unclear. Notably, the aging ST, which largely influences older adults' cognitive ability, mental and physical health, did not receive much attention. In order to investigate these issues, electroencephalogram (EEG) data were obtained from older adults during a modified Stroop task using neutral words, positive and negative self-concept words in aging ST vs. neutral control conditions. Results showed longer reaction times (RTs) for identifying colors of words under the aging ST compared to the neutral condition. More importantly, the negative self-concept elicited more positive late P300 amplitudes and enhanced theta band activities compared to the positive self-concept or neutral words under the aging ST condition, whereas no difference was found between these self-concepts and neutral words in the control condition. Furthermore, the aging ST induced smaller theta band synchronization and enhanced alpha band synchronization compared to the control condition. Moreover, we also observed valence differences in self-concepts where the negative self-concept words reduced early P150/N170 complex relative to neutral words. These findings suggest that priming ST could activate negative self-concepts as current working self-concept, and that this influence occurred during a late neural time course.

Electrophysiological Evidence for Early and Interactive Symbol Access and Rule Processing in Retrieving and Combining Language Constructions

The human brain stores an immense repertoire of linguistic symbols (morphemes, words) and combines them into a virtually unlimited set of well-formed strings (phrases, sentences) that serve as efficient communicative tools. Communication is hampered, however, if strings include meaningless items (e.g., "pseudomorphemes"), or if the rules for combining string elements are violated. Prior research suggests that, when participants attentively process sentences in a linguistic task, syntactic processing can occur quite early, but lexicosemantic processing, or any interaction involving this factor, is manifest later in time (ca. 400 msec or later). In contrast, recent evidence from passive speech perception paradigms suggests early processing of both combinatorial (morphosyntactic) and storage-related (lexicosemantic) properties. A crucial question is whether these parallel processes might also interact early in processing. Using ERPs in an orthogonal design, we presented spoken word strings to participants while they were distracted from incoming speech to obtain information about automatic language processing mechanisms unaffected by task-related strategies. Stimuli were either (1) well-formed miniconstructions (short pronoun-verb sentences), (2) "unstored" strings containing a pseudomorpheme, (3) "ill-combined" strings violating subject-verb agreement rules, or (4) double violations including both types of errors. We found that by 70-210 msec after the onset of the phrase-final syllable that disambiguated the strings, interactions of lexicosemantic and morphosyntactic deviance were evident in the ERPs. These results argue against serial processing of lexical storage, morphosyntactic combination and their interaction, and in favor of early, simultaneous, and interactive processing of symbols and their combinatorial structures.

Responsivity to dyslexia training indexed by the N170 amplitude of the brain potential elicited by word reading

The present study examined training effects in dyslexic children on reading fluency and the amplitude of N170, a negative brain-potential component elicited by letter and symbol strings. A group of 18 children with dyslexia in 3rd grade (9.05±0.46years old) was tested before and after following a letter-speech sound mapping training. A group of 20 third-grade typical readers (8.78±0.35years old) performed a single time on the same brain potential task. The training was differentially effective in speeding up reading fluency in the dyslexic children. In some children, training had a beneficial effect on reading fluency ('improvers') while a training effect was absent in others ('non-improvers'). Improvers at pre-training showed larger N170 amplitude to words compared to non-improvers. N170 amplitude decreased following training in improvers but not in non-improvers. But the N170 amplitude pattern in improvers continued to differ from the N170 amplitude pattern across hemispheres seen in typical readers. Finally, we observed a positive relation between the decrease in N170 amplitude and gains in reading fluency. Collectively, the results that emerged from the present study indicate the sensitivity of N170 amplitude to reading fluency and its potential as a predictor of reading fluency acquisition.

N170 Changes Show Identifiable Chinese Characters Compete Primarily with Faces Rather than Houses

Character processing is a crucial cognitive skill that is highly emphasized and industriously cultivated in contemporary society. In the present study, using a competition paradigm, we examined the electrophysiological correlates of different relationships between Chinese characters and faces and between Chinese characters and houses during early visual processing. We observed that identifiable Chinese characters compete primarily with faces rather than houses at an early visual processing stage, with a significantly reduced N170 for faces but not for houses, when they were viewed concurrently with identifiable characters relative to when they were viewed concurrently with unidentifiable characters. Consistent with our previous study, there was a significant increase in N170 after characters have been learned, indicating a modulatory effect of Chinese character identification level on N170 amplitude. Furthermore, we found an enlarged N170 in response to faces compared to houses, indicating that the neural mechanisms for processing faces and houses are different at an early visual processing stage.

Combining Different Tools for EEG Analysis to Study the Distributed Character of Language Processing

Recent studies on language processing indicate that language cognition is better understood if assumed to be supported by a distributed intelligent processing system enrolling neurons located all over the cortex, in contrast to reductionism that proposes to localize cognitive functions to specific cortical structures. Here, brain activity was recorded using electroencephalogram while volunteers were listening or reading small texts and had to select pictures that translate meaning of these texts. Several techniques for EEG analysis were used to show this distributed character of neuronal enrollment associated with the comprehension of oral and written descriptive texts. Low Resolution Tomography identified the many different sets (s_i) of neurons activated in several distinct cortical areas by text understanding. Linear correlation was used to calculate the information H(e_i) provided by each electrode of the 10/20 system about the identified s_i. H(e_i) Principal Component Analysis (PCA) was used to study the temporal and spatial activation of these sources s_i. This analysis evidenced 4 different patterns of H(e_i) covariation that are generated by neurons located at different cortical locations. These results clearly show that the distributed character of language processing is clearly evidenced by combining available EEG technologies.

Attachment affects social information processing: Specific electrophysiological effects of maternal stimuli

Attachment is critical to each individual. It affects the cognitive-affective processing of social information. The present study examines how attachment affects the processing of social information, specifically maternal information. We assessed the behavioral and electrophysiological responses to maternal information (compared to non-specific others) in a Go/No-go Association Task (GNAT) with 22 participants. The results illustrated that attachment affected maternal information processing during three sequential stages of information processing. First, attachment affected visual perception, reflected by enhanced P100 and N170 elicited by maternal information as compared to others information. Second, compared to others, mother obtained more attentional resources, reflected by faster behavioral response to maternal information and larger P200 and P300. Finally, mother was evaluated positively, reflected by shorter P300 latency in a mother + good condition as compared to a mother + bad condition. These findings indicated that the processing of attachment-relevant information is neurologically differentiated from other types of social information from an early stage of perceptual processing to late high-level processing.

Ideophones in Japanese modulate the P2 and late positive complex responses

Sound-symbolism, or the direct link between sound and meaning, is typologically and behaviorally attested across languages. However, neuroimaging research has mostly focused on artificial non-words or individual segments, which do not represent sound-symbolism in natural language. We used EEG to compare Japanese ideophones, which are phonologically distinctive sound-symbolic lexical words, and arbitrary adverbs during a sentence reading task. Ideophones elicit a larger visual P2 response than arbitrary adverbs, as well as a sustained late positive complex. Our results and previous literature suggest that the larger P2 may indicate the integration of sound and sensory information by association in response to the distinctive phonology of ideophones. The late positive complex may reflect the facilitated lexical retrieval of arbitrary words in comparison to ideophones. This account provides new evidence that ideophones exhibit similar cross-modal correspondences to those which have been proposed for non-words and individual sounds.

The processing difference between person names and common nouns in sentence contexts: an ERP study

Person names and common nouns differ in how they are stored in the mental lexicon. Using event-related potentials, this study compared the integration of names and nouns into sentence contexts. Both person names and common nouns were highly related in meaning and either congruent or incongruent within the previous contexts. Name incongruence elicited an N400 effect, suggesting that people were able to rapidly retrieve the semantic meaning of names from long-term memory even when this process was mediated by person identification. Conversely, participants showed a "good enough" processing of the nouns due to their low specificity level and, thus, rich semantic associations, leading to a P600 effect. These distinctive ERP effects provide clear evidence for the distinctive semantic representations of these word categories by showing that the activation of a name's meaning is mediated by a single connection between identity-specific information and person identity, whereas multiple connections exist between nouns and their meanings.

Oscillatory brain dynamics associated with the automatic processing of emotion in words

This study examines the automaticity of processing the emotional aspects of words, and characterizes the oscillatory brain dynamics that accompany this automatic processing. Participants read emotionally negative, neutral and positive nouns while performing a color detection task in which only perceptual-level analysis was required. Event-related potentials and time frequency representations were computed from the concurrently measured EEG. Negative words elicited a larger P2 and a larger late positivity than positive and neutral words, indicating deeper semantic/evaluative processing of negative words. In addition, sustained alpha power suppressions were found for the emotional compared to neutral words, in the time range from 500 to 1000ms post-stimulus. These results suggest that sustained attention was allocated to the emotional words, whereas the attention allocated to the neutral words was released after an initial analysis. This seems to hold even when the emotional content of the words is task-irrelevant.

Experience-dependent hemispheric specialization of letters and numbers is revealed in early visual processing

Recent fMRI research has demonstrated that letters and numbers are preferentially processed in distinct regions and hemispheres in the visual cortex. In particular, the left visual cortex preferentially processes letters compared with numbers, whereas the right visual cortex preferentially processes numbers compared with letters. Because letters and numbers are cultural inventions and are otherwise physically arbitrary, such a double dissociation is strong evidence for experiential effects on neural architecture. Here, we use the high temporal resolution of ERPs to investigate the temporal dynamics of the neural dissociation between letters and numbers. We show that the divergence between ERP traces to letters and numbers emerges very early in processing. Letters evoked greater N1 waves (latencies 140-170 msec) than did numbers over left occipital channels, whereas numbers evoked greater N1s than letters over the right, suggesting letters and numbers are preferentially processed in opposite hemispheres early in visual encoding. Moreover, strings of letters, but not single letters, elicited greater P2 ERP waves (starting around 250 msec) than numbers did over the left hemisphere, suggesting that the visual cortex is tuned to selectively process combinations of letters, but not numbers, further along in the visual processing stream. Additionally, the processing of both of these culturally defined stimulus types differentiated from similar but unfamiliar visual stimulus forms (false fonts) even earlier in the processing stream (the P1 at 100 msec). These findings imply major cortical specialization processes within the visual system driven by experience with reading and mathematics.

Age-related effects on event-related brain potentials in a congruence/incongruence judgment color-word Stroop task

We examined the event-related brain potentials elicited by color-word stimuli in a Stroop task in which healthy participants (young and old) had to judge whether the meaning and the color of the stimulus were congruent or incongruent. The Stroop effect occurred in both age groups, with longer reaction times in the older group than in the young group for both types of stimuli, but no difference in the number of errors made by either group. Although the N2 and P3b latencies were longer in the older than in the younger group, there were no differences between groups in the latencies of earlier event-related potential components, and therefore the age-related processing slowing is not generalized. The frontal P150 amplitude was larger, and the parietal P3b amplitude was smaller, in the older than in the younger group. Furthermore, the P3b amplitude was maximal at frontal locations in older participants and at parietal locations in young participants. The age-related increase in perceptual resources and the posterior-to-anterior shift in older adults support adaptive reorganization of the neural networks involved in the processing of this Stroop-type task.

Lexical access and evoked traveling alpha waves

Retrieval from semantic memory is usually considered within a time window around 300-600ms. Here we suggest that lexical access already occurs at around 100ms. This interpretation is based on the finding that semantically rich and frequent words exhibit a significantly shorter topographical latency difference between the site with the shortest P1 latency (leading site) and that with the longest P1 latency (trailing site). This latency difference can be described in terms of an evoked traveling alpha wave as was already shown in earlier studies.

Integrating the meaning of person names into discourse context: an event-related potential study

The meaning of person names is determined by their associated information. This study used event related potentials to investigate the time course of integrating the newly constructed meaning of person names into discourse context. The meaning of person names was built by two-sentence descriptions of the names. Then we manipulated the congruence of person names relative to discourse context in a way that the meaning of person names either matched or did not match the previous context. ERPs elicited by the names were compared between the congruent and the incongruent conditions. We found that the incongruent names elicited a larger N400 as well as a larger P600 compared to the congruent names. The results suggest that the meaning of unknown names can be effectively constructed from short linguistic descriptions and that the established meaning can be rapidly retrieved and integrated into contexts.

Stages of Processing in Associative Recognition: Evidence from Behavior, EEG, and Classification

In this study, we investigated the stages of information processing in associative recognition. We recorded EEG data while participants performed an associative recognition task that involved manipulations of word length, associative fan, and probe type, which were hypothesized to affect the perceptual encoding, retrieval, and decision stages of the recognition task, respectively. Analyses of the behavioral and EEG data, supplemented with classification of the EEG data using machine-learning techniques, provided evidence that generally supported the sequence of stages assumed by a computational model developed in the Adaptive Control of Thought-Rational cognitive architecture. However, the results suggested a more complex relationship between memory retrieval and decision-making than assumed by the model. Implications of the results for modeling associative recognition are discussed. The study illustrates how a classifier approach, in combination with focused manipulations, can be used to investigate the timing of processing stages.

Using in vivo probabilistic tractography to reveal two segregated dorsal 'language-cognitive' pathways in the human brain

Primate studies have recently identified the dorsal stream as constituting multiple dissociable pathways associated with a range of specialized cognitive functions. To elucidate the nature and number of dorsal pathways in the human brain, the current study utilized in vivo probabilistic tractography to map the structural connectivity associated with subdivisions of the left supramarginal gyrus (SMG). The left SMG is a prominent region within the dorsal stream, which has recently been parcellated into five structurally-distinct regions which possess a dorsal-ventral (and rostral-caudal) organisation, postulated to reflect areas of functional specialisation. The connectivity patterns reveal a dissociation of the arcuate fasciculus into at least two segregated pathways connecting frontal-parietal-temporal regions. Specifically, the connectivity of the inferior SMG, implicated as an acoustic-motor speech interface, is carried by an inner/ventro-dorsal arc of fibres, whilst the pathways of the posterior superior SMG, implicated in object use and cognitive control, forms a parallel outer/dorso-dorsal crescent.

ERP evidence on the interaction between information structure and emotional salience of words

Both emotional words and words focused by information structure can capture attention. This study examined the interplay between emotional salience and information structure in modulating attentional resources in the service of integrating emotional words into sentence context. Event-related potentials (ERPs) to affectively negative, neutral, and positive words, which were either focused or nonfocused in question-answer pairs, were evaluated during sentence comprehension. The results revealed an early negative effect (90-200 ms), a P2 effect, as well as an effect in the N400 time window, for both emotional salience and information structure. Moreover, an interaction between emotional salience and information structure occurred within the N400 time window over right posterior electrodes, showing that information structure influences the semantic integration only for neutral words, but not for emotional words. This might reflect the fact that the linguistic salience of emotional words can override the effect of information structure on the integration of words into context. The interaction provides evidence for attention-emotion interactions at a later stage of processing. In addition, the absence of interaction in the early time window suggests that the processing of emotional information is highly automatic and independent of context. The results suggest independent attention capture systems of emotional salience and information structure at the early stage but an interaction between them at a later stage, during the semantic integration of words.

Dynamic neural processing of linguistic cues related to death

Behavioral studies suggest that humans evolve the capacity to cope with anxiety induced by the awareness of death's inevitability. However, the neurocognitive processes that underlie online death-related thoughts remain unclear. Our recent functional MRI study found that the processing of linguistic cues related to death was characterized by decreased neural activity in human insular cortex. The current study further investigated the time course of neural processing of death-related linguistic cues. We recorded event-related potentials (ERP) to death-related, life-related, negative-valence, and neutral-valence words in a modified Stroop task that required color naming of words. We found that the amplitude of an early frontal/central negativity at 84-120 ms (N1) decreased to death-related words but increased to life-related words relative to neutral-valence words. The N1 effect associated with death-related and life-related words was correlated respectively with individuals' pessimistic and optimistic attitudes toward life. Death-related words also increased the amplitude of a frontal/central positivity at 124-300 ms (P2) and of a frontal/central positivity at 300-500 ms (P3). However, the P2 and P3 modulations were observed for both death-related and negative-valence words but not for life-related words. The ERP results suggest an early inverse coding of linguistic cues related to life and death, which is followed by negative emotional responses to death-related information.

Core disgust and moral disgust are related to distinct spatiotemporal patterns of neural processing: an event-related potential study

Core disgust is thought to rely more on sensory and perceptual processes, whereas moral disgust is thought to rely more on social evaluation processes. However, little is known about the neurocognitive mechanisms underlying these two types of disgust. We recorded event-related potentials (ERPs) from participants while they performed a lexical decision task in which core- and moral-disgust words were intermixed with neutral words and pseudowords. Lexical judgment was faster for coredisgust words and slower for moral-disgust words, relative to the neutral words. Core-disgust words, relative to neutral words, elicited a larger early posterior negative (EPN), a larger N320, a smaller N400, and a larger late positive component (LPC), whereas moral disgust words elicited a smaller N320 and a larger N400 than neutral words. These results suggest that the N320 and N400 components are particularly sensitive to the neurocognitive processes that overlap in processing both core and moral disgust, whereas the EPN and LPC may reflect process that are particularly sensitive to core disgust.

Congenital unilateral deafness affects cerebral organization of reading

It is known that early sensory deprivation modifies brain functional structure and connectivity. The aim of the present study was to investigate the neuro-functional organization of reading in a patient with profound congenital unilateral deafness. Using event-related potentials (ERPs), we compared cortical networks supporting the processing of written words in patient RA (completely deaf in the right ear since birth) and in a group of control volunteers. We found that congenital unilateral hearing deprivation modifies neural mechanisms of word reading. Indeed, while written word processing was left-lateralized in controls, we found a strong right lateralization of the fusiform and inferior occipital gyri activation in RA. This finding goes in the same direction of recent proposals that the ventral occipito-temporal activity in word reading seem to lateralize to the same hemisphere as the one involved in spoken language processing.

Combined ERP/fMRI evidence for early word recognition effects in the posterior inferior temporal gyrus

Two brain regions with established roles in reading are the posterior middle temporal gyrus and the posterior fusiform gyrus (FG). Lesion studies have also suggested that the region located between them, the posterior inferior temporal gyrus (pITG), plays a central role in word recognition. However, these lesion results could reflect disconnection effects since neuroimaging studies have not reported consistent lexicality effects in pITG. Here we tested whether these reported pITG lesion effects are due to disconnection effects or not using parallel Event-related Potentials (ERP)/functional magnetic resonance imaging (fMRI) studies. We predicted that the Recognition Potential (RP), a left-lateralized ERP negativity that peaks at about 200-250 msec, might be the electrophysiological correlate of pITG activity and that conditions that evoke the RP (perceptual degradation) might therefore also evoke pITG activity. In Experiment 1, twenty-three participants performed a lexical decision task (temporally flanked by supraliminal masks) while having high-density 129-channel ERP data collected. In Experiment 2, a separate group of fifteen participants underwent the same task while having fMRI data collected in a 3T scanner. Examination of the ERP data suggested that a canonical RP effect was produced. The strongest corresponding effect in the fMRI data was in the vicinity of the pITG. In addition, results indicated stimulus-dependent functional connectivity between pITG and a region of the posterior FG near the Visual Word Form Area (VWFA) during word compared to nonword processing. These results provide convergent spatiotemporal evidence that the pITG contributes to early lexical access through interaction with the VWFA.