First-pass versus second-pass parsing processes in a Wernicke's and a Broca's aphasic: electrophysiological evidence for a double dissociation

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.

Electrophysiological correlates of basic semantic composition in people with aphasia

The neuroanatomical correlates of basic semantic composition have been investigated in previous neuroimaging and lesion studies, but research on the electrophysiology of the involved processes is scarce. A large literature on sentence-level event-related potentials (ERPs) during semantic processing has identified at least two relevant components - the N400 and the P600. Other studies demonstrated that these components are reduced and/or delayed in people with aphasia (PWA). However, it remains to be shown if these findings generalize beyond the sentence level. Specifically, it is an open question if an alteration in ERP responses in PWA can also be observed during basic semantic composition, providing a potential future diagnostic tool. The present study aimed to elucidate the electrophysiological dynamics of basic semantic composition in a group of post-stroke PWA. We included 20 PWA and 20 age-matched controls (mean age 58 years) and measured ERP responses while they performed a plausibility judgment task on two-word phrases that were either meaningful ("anxious horse"), anomalous ("anxious wood") or had the noun replaced by a pseudoword ("anxious gufel"). The N400 effect for anomalous versus meaningful phrases was similar in both groups. In contrast, unlike the control group, PWA did not show an N400 effect between pseudoword and meaningful phrases. Moreover, both groups exhibited a parietal P600 effect towards pseudoword phrases, while PWA showed an additional P600 over frontal electrodes. Finally, PWA showed an inverse correlation between the magnitude of the N400 and P600 effects: PWA exhibiting no or even reversed N400 effects towards anomalous and pseudoword phrases showed a stronger P600 effect. These results may reflect a compensatory mechanism which allows PWA to arrive at the correct interpretation of the phrase. When compositional processing capacities are impaired in the early N400 time-window, PWA may make use of a more elaborate re-analysis process reflected in the P600.

Test-retest reliability of electroencephalographic and magnetoencephalographic measures elicited during language tasks: A literature review

Electroencephalographic (EEG) and magnetoencephalographic (MEG) recordings during language processing can provide relevant insights on neuroplasticity in clinical populations (including patients with aphasia). To use EEG and MEG in a longitudinal way, the outcome measures should be consistent across time in healthy individuals. Therefore, the current study provides a review on the test-retest reliability of EEG and MEG measures elicited during language paradigms in healthy adults. PubMed, Web of Science and Embase were searched for relevant articles based on specific eligibility criteria. In total, 11 articles were included in this literature review. The test-retest reliability of the P1, N1 and P2 is systematically considered to be satisfactory, whereas findings are more variable for event-related potentials/fields occurring later in time. The within subject consistency of EEG and MEG measures during language processing can be influenced by multiple variables such as the stimulus presentation mode, the offline reference choice and the required amount of cognitive resources during the task. To conclude, most of the available results are favourable regarding the longitudinal use of EEG and MEG measures elicited during language paradigms in healthy young individuals. In view to the use of these techniques in patients with aphasia, future research should focus on whether the same findings apply to different age groups.

Online neurostimulation of Broca's area does not interfere with syntactic predictions: A combined TMS-EEG approach to basic linguistic combination

Categorical predictions have been proposed as the key mechanism supporting the fast pace of syntactic composition in language. Accordingly, grammar-based expectations are formed-e.g., the determiner "a" triggers the prediction for a noun-and facilitate the analysis of incoming syntactic information, which is then checked against a single or few other word categories. Previous functional neuroimaging studies point towards Broca's area in the left inferior frontal gyrus (IFG) as one fundamental cortical region involved in categorical prediction during incremental language processing. Causal evidence for this hypothesis is however still missing. In this study, we combined Electroencephalography (EEG) and Transcranial Magnetic Stimulation (TMS) to test whether Broca's area is functionally relevant in predictive mechanisms for language. We transiently perturbed Broca's area during the first word in a two-word construction, while simultaneously measuring the Event-Related Potential (ERP) correlates of syntactic composition. We reasoned that if Broca's area is involved in predictive mechanisms for syntax, disruptive TMS during the first word would mitigate the difference in the ERP responses for predicted and unpredicted categories in basic two-word constructions. Contrary to this hypothesis, perturbation of Broca's area at the predictive stage did not affect the ERP correlates of basic composition. The correlation strength between the electrical field induced by TMS and the ERP responses further confirmed this pattern. We discuss the present results considering an alternative account of the role of Broca's area in syntactic composition, namely the bottom-up integration of words into constituents, and of compensatory mechanisms within the language predictive network.

Alteration of network connectivity in stroke patients with apraxia of speech after tDCS: A randomized controlled study

Objective

This study aimed to examine the changes in the functional connectivity of the cortical speech articulation network after anodal transcranial direct current stimulation (A-tDCS) over the left lip region of the primary motor cortex (M1) in subacute post-stroke patients with apraxia of speech (AoS), and the effect of A-tDCS on AoS.

Methods

A total of 24 patients with post-stroke AoS were randomized into two groups and received A-tDCS over the left lip region of M1 (tDCS group)/ sham tDCS (control group) as well as speech and language therapy two times per day for 5 days. Before and after the treatment, the AoS assessments and electroencephalogram (EEG) were evaluated. The cortical interconnections were measured using the EEG non-linear index of cross approximate entropy (C-ApEn).

Results

The analysis of EEG showed that, after the treatment, the activated connectivity was all in the left hemisphere, and not only regions in the speech articulation network but also in the dorsal lateral prefrontal cortex (DLPFC) in the domain-general network were activated in the tDCS group. In contrast, the connectivity was confined to the right hemisphere and between bilateral DLPFC and bilateral inferior frontal gyrus (IFG) in the control group. In AoS assessments, the tDCS group improved significantly more than the control group in four of the five subtests. The results of multivariate linear regression analyses showed that only the group was significantly associated with the improvement of word repetition (P = 0.002).

Conclusion

A-tDCS over the left lip region of M1 coupled with speech therapy could upregulate the connectivity of both speech-specific and domain-general networks in the left hemisphere. The improved articulation performance in patients with post-stroke AoS might be related to the enhanced connectivity of networks in the left hemisphere induced by tDCS.

Clinical trial registration

ChiCTR-TRC-14005072.

Evoked responses to note onsets and phrase boundaries in Mozart's K448

Understanding the neural correlates of perception of hierarchical structure in music presents a direct window into auditory organization. To examine the hypothesis that high-level and low-level structures—i.e. phrases and notes—elicit different neural responses, we collected intracranial electroencephalography (iEEG) data from eight subjects during exposure to Mozart’s K448 and directly compared Event-related potentials (ERPs) due to note onsets and those elicited by phrase boundaries. Cluster-level permutation tests revealed that note-onset-related ERPs and phrase-boundary-related ERPs were significantly different at \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$-150$$\end{document}-150, 200, and 450 ms relative to note onset and phrase markers. We also observed increased activity in frontal brain regions when processing phrase boundaries. We relate these observations to (1) a process which syntactically binds notes together hierarchically to form larger phrases; (2) positive emotions induced by successful prediction of forthcoming phrase boundaries and violations of melodic expectations at phrase boundaries.

Musical and linguistic syntactic processing in agrammatic aphasia: An ERP study

Language and music rely on complex sequences organized according to syntactic principles that are implicitly understood by enculturated listeners. Across both domains, syntactic processing involves predicting and integrating incoming elements into higher-order structures. According to the Shared Syntactic Integration Resource Hypothesis (SSIRH; Patel, 2003), musical and linguistic syntactic processing rely on shared resources for integrating incoming elements (e.g., chords, words) into unfolding sequences. One prediction of the SSIRH is that people with agrammatic aphasia (whose deficits are due to syntactic integration problems) should present with deficits in processing musical syntax. We report the first neural study to test this prediction: event-related potentials (ERPs) were measured in response to musical and linguistic syntactic violations in a group of people with agrammatic aphasia (n=7) compared to a group of healthy controls (n=14) using an acceptability judgement task. The groups were matched with respect to age, education, and extent of musical training. Violations were based on morpho-syntactic relations in sentences and harmonic relations in chord sequences. Both groups presented with a significant P600 response to syntactic violations across both domains. The aphasic participants presented with a reduced-amplitude posterior P600 compared to the healthy adults in response to linguistic, but not musical, violations. Participants with aphasia did however present with larger frontal positivities in response to violations in both domains. Intriguingly, extent of musical training was associated with larger posterior P600 responses to syntactic violations of language and music in both groups. Overall, these findings are not consistent with the predictions of the SSIRH, and instead suggest that linguistic, but not musical, syntactic processing may be selectively impaired in stroke-induced agrammatic aphasia. However, the findings also suggest a relationship between musical training and linguistic syntactic processing, which may have clinical implications for people with aphasia, and motivates more research on the relationship between these two domains.

Functional Connectivity Signatures Underlying Simultaneous Language Translation in Interpreters and Non-Interpreters of Mandarin and English: An fNIRS Study

Recent neuroimaging research has suggested that interpreters and non-interpreters elicit different brain activation patterns during simultaneous language translation. However, whether these two groups have different functional connectivity during such a task, and how the neural coupling is among brain subregions, are still not well understood. In this study, we recruited Mandarin (L1)/English (L2) interpreters and non-interpreter bilinguals, whom we asked to perform simultaneous language translation and reading tasks. Functional near-infrared spectroscopy (fNIRS) was used to collect cortical brain data for participants during each task, using 68 channels that covered the prefrontal cortex and the bilateral perisylvian regions. Our findings revealed both interpreter and non-interpreter groups recruited the right dorsolateral prefrontal hub when completing the simultaneous language translation tasks. We also found different functional connectivity between the groups. The interpreter group was characterized by information exchange between the frontal cortex and Wernicke’s area. In comparison, the non-interpreter group revealed neural coupling between the frontal cortex and Broca’s area. These findings indicate expertise modulates functional connectivity, possibly because of more developed cognitive skills associated with executive functions in interpreters.

The electrophysiology of aphasia: A scoping review

OBJECTIVE

To systematically assess the body of literature using N400 and P600 as they relate to people with aphasia. The primary aim was to reveal patterns in the literature which could be used to direct future research in the development of clinically relevant Event-Related Potentials (ERPs) for language assessment, while also identifying gaps in existing knowledge and highlight areas of further inquiry.

METHODS

A literature search was performed on studies published before May 2021. Relevant studies on aphasia and the two ERPs of interest were assessed for quality, and the relationship between aphasia and these ERPs was explored.

RESULTS

A total of 721 articles were identified, with 30 meeting inclusion criteria. Although there is significant variation in the literature, this scoping review revealed people with aphasia show reduced amplitude, delayed latency and different distribution compared to controls, and that ERPs are modulated by severity of aphasia.

CONCLUSIONS

To develop a relevant clinical tool for the management of aphasia, future research must strive to improve consistency within ERP methodology, with a greater number of diverse aphasia subtypes included in research.

SIGNIFICANCE

This scoping review reveals N400 and P600 represent promising potential biomarkers for the diagnosis and ongoing management of aphasia.

The contribution of semantics to the sentence superiority effect

When a sequence of written words is presented briefly and participants are asked to report the identity of one of the words, identification accuracy is higher when the words form a correct sentence. Here we examined the extent to which this sentence superiority effect can be modulated by semantic content. The central hypothesis guiding this study is that the sentence superiority effect is primarily a syntactic effect. We therefore predicted little or no modulation of the effect by semantics. The influence of semantic content was measured by comparing the sentence superiority effect obtained with semantically regular sentences (e.g., son amie danse bien [her friend dances well]) and semantically anomalous but syntactically correct sentences (e.g., votre sac boit gros [your bag drinks big]), with effects being measured against ungrammatical scrambled versions of the same words in both cases. We found sentence superiority effects with both types of sentences, and a significant interaction, such that the effects were greater with semantically regular sentences compared with semantically anomalous sentences. We conclude that sentence-level semantic information can constrain word identities under parallel word processing, albeit with less impact than that exerted by syntax.

Optical Mapping of Brain Activity Underlying Directionality and Its Modulation by Expertise in Mandarin/English Interpreting

Recent neuroimaging research has suggested that unequal cognitive efforts exist between interpreting from language 1 (L1) to language 2 (L2) compared with interpreting from L2 to L1. However, the neural substrates that underlie this directionality effect are not yet well understood. Whether directionality is modulated by interpreting expertise also remains unknown. In this study, we recruited two groups of Mandarin (L1)/English (L2) bilingual speakers with varying levels of interpreting expertise and asked them to perform interpreting and reading tasks. Functional near-infrared spectroscopy (fNIRS) was used to collect cortical brain data for participants during each task, using 68 channels that covered the prefrontal cortex and the bilateral perisylvian regions. The interpreting-related neuroimaging data was normalized by using both L1 and L2 reading tasks, to control the function of reading and vocalization respectively. Our findings revealed the directionality effect in both groups, with forward interpreting (from L1 to L2) produced more pronounced brain activity, when normalized for reading. We also found that directionality was modulated by interpreting expertise in both normalizations. For the group with relatively high expertise, the activated brain regions included the right Broca's area and the left premotor and supplementary motor cortex; whereas for the group with relatively low expertise, the activated brain areas covered the superior temporal gyrus, the dorsolateral prefrontal cortex (DLPFC), the Broca's area, and visual area 3 in the right hemisphere. These findings indicated that interpreting expertise modulated brain activation, possibly because of more developed cognitive skills associated with executive functions in experienced interpreters.

The role and use of event-related potentials in aphasia: A scoping review

Event-related potentials (ERPs) can provide important insights into underlying language processes in both unimpaired and neurologically impaired populations and may be particularly useful in aphasia. This scoping review was conducted to provide a comprehensive summary of how ERPs have been used with people with aphasia (PWA), with the goal of exploring the potential clinical application of ERPs in aphasia assessment and treatment. We identified 117 studies that met inclusionary criteria, reflecting six thematic domains of inquiry that relate to understanding both unimpaired and aphasic language processing and the use of ERPs with PWA. In these studies, a wide variety of ERP components were reported. Inconsistencies in reporting of participant characteristics and study protocols limit our ability to generalize beyond the individual studies and understand implications for clinical applicability. We discuss the potential roles of ERPs in aphasia management and make recommendations for further developing ERPs for clinical utility in PWA.

Extracting representations of cognition across neuroimaging studies improves brain decoding

Cognitive brain imaging is accumulating datasets about the neural substrate of many different mental processes. Yet, most studies are based on few subjects and have low statistical power. Analyzing data across studies could bring more statistical power; yet the current brain-imaging analytic framework cannot be used at scale as it requires casting all cognitive tasks in a unified theoretical framework. We introduce a new methodology to analyze brain responses across tasks without a joint model of the psychological processes. The method boosts statistical power in small studies with specific cognitive focus by analyzing them jointly with large studies that probe less focal mental processes. Our approach improves decoding performance for 80% of 35 widely-different functional-imaging studies. It finds commonalities across tasks in a data-driven way, via common brain representations that predict mental processes. These are brain networks tuned to psychological manipulations. They outline interpretable and plausible brain structures. The extracted networks have been made available; they can be readily reused in new neuro-imaging studies. We provide a multi-study decoding tool to adapt to new data.

Effect of Anodic Transcranial Direct Current Stimulation Combined With Speech Language Therapy on Nonfluent Poststroke Aphasia

OBJECTIVES

Transcranial direct current stimulation (tDCS) facilitates or inhibits spontaneous neuronal activity by low-intensity current. In this study, we evaluated the effects of tDCS and sham stimulation combined with speech language therapy (SLT) on nonfluent poststroke aphasia (PSA) patients.

MATERIALS AND METHODS

Patients with PSA were randomly divided into the anode tDCS (A-tDCS) group (n = 8) and sham tDCS (S-tDCS) group (n = 10). The anodes and cathodes were fixed over left inferior gyrus frontalis (L-IFG) and the deltoid muscle of the right shoulder. A-tDCS consisted of 2 mA for 20 min, while S-tDCS current started at 2 mA but automatically decreased to 0 mA after 30 sec. Stimulation was concurrent with 30 min of SLT. Stimulation + SLT sessions occurred five times a week for four weeks. The Western Aphasia Battery (WAB) was given before treatment to obtain the baseline score and once more after all sessions were completed, and the Aphasia Quotient (AQ) was calculated.

RESULTS

After tDCS treatment, the AQ mean(SD) in both groups was significantly higher than before treatment (p < 0.001) and the AQ of the A-tDCS group 72.99 (21.91) was significantly higher than that of the S-tDCS group 46.18 (19.29) (t = 2.760, p < 0.05). Upon further analysis of the WAB subscores, except for comprehension, all other items were significantly higher in the A-tDCS group than in the S-tDCS group (p < 0.05).

CONCLUSION

Our results suggest that left inferior gyrus frontalis anodic transcranial direct current stimulation is an effective adjuvant to conventional speech language therapy for patients with nonfluent PSA.

Online sentence processing impairments in agrammatic and logopenic primary progressive aphasia: Evidence from ERP

Evidence from psycholinguistic research indicates that sentence processing is impaired in Primary Progressive Aphasia (PPA), and more so in individuals with agrammatic (PPA-G) than logopenic (PPA-L) subtypes. Studies have mostly focused on offline sentence production ability, reporting impaired production of verb morphology (e.g., tense, agreement) and verb-argument structure (VAS) in PPA-G, and mixed findings in PPA-L. However, little is known about real-time sentence comprehension in PPA. The present study is the first to compare real-time semantic, morphosyntactic and VAS processing in individuals with PPA (10 with PPA-G and 9 with PPA-L), and in two groups of healthy (22 young and 19 older) individuals, using event-related potentials (ERP). Participants were instructed to listen to sentences that were either well-formed (n = 150) or contained a violation of semantics (e.g., *Owen was mentoring pumpkins at the party, n = 50), morphosyntax (e.g., *The actors was singing in the theatre, n = 50) or VAS (*Ryan was devouring on the couch, n = 50), and were required to perform a sentence acceptability judgment task while EEG was recorded. Results indicated that in the semantic task both healthy and PPA groups showed an N400 response to semantic violations, which was delayed in PPA and older (vs. younger) groups. Morphosyntactic violations elicited a P600 in both groups of healthy individuals and in PPA-L, but not in PPA-G. A similar P600 response was also found only in healthy individuals for VAS violations; whereas, abnormal ERP responses were observed in both PPA groups, with PPA-G showing no evidence of VAS violation detection and PPA-L showing a delayed and abnormally-distributed positive component that was negatively associated with offline sentence comprehension scores. These findings support characterizations of sentence processing impairments in PPA-G, by providing online evidence that VAS and morphosyntactic processing are impaired, in the face of substantially preserved semantic processing. In addition, the results indicate that on-line processing of VAS information may also be impaired in PPA-L, despite their near-normal accuracy on standardized language tests of argument structure production.

Double Dissociation of Auditory Attention Span and Visual Attention in Long-Term Survivors of Childhood Cerebellar Tumor: A Deterministic Tractography Study of the Cerebellar-Frontal and the Superior Longitudinal Fasciculus Pathways

OBJECTIVE

Right cerebellar-left frontal (RC-LF) white matter integrity (WMI) has been associated with working memory. However, prior studies have employed measures of working memory that include processing speed and attention. We examined the relationships between the RC-LF WMI and processing speed, attention, and working memory to clarify the relationship of RC-LF WMI with a specific cognitive function. Right superior longitudinal fasciculus II (SLF II) WMI and visual attention were included as a negative control tract and task to demonstrate a double dissociation.

METHODS

Adult survivors of childhood brain tumors [n = 29, age: M = 22 years (SD = 5), 45% female] and demographically matched controls were recruited (n = 29). Tests of auditory attention span, working memory, and visual attention served as cognitive measures. Participants completed a 3-T MRI diffusion-weighted imaging scan. Fractional anisotropy (FA) and radial diffusivity (RD) served as WMI measures. Partial correlations between WMI and cognitive scores included controlling for type of treatment.

RESULTS

A correlational double dissociation was found. RC-LF WMI was associated with auditory attention (FA: r = .42, p = .03; RD: r = -.50, p = .01) and was not associated with visual attention (FA: r = -.11, p = .59; RD: r = -.11, p = .57). SLF II FA WMI was associated with visual attention (FA: r = .44, p = .02; RD: r = -.17, p = .40) and was not associated with auditory attention (FA: r = .24, p = .22; RD: r = -.10, p = .62).

CONCLUSIONS

The results show that RC-LF WMI is associated with auditory attention span rather than working memory per se and provides evidence for a specificity based on the correlational double dissociation.

Brain connectivity in the left frontotemporal network dynamically modulated by processing difficulty: Evidence from Chinese relative clauses

Although the connection between the left inferior frontal gyrus (LIFG) and the left superior temporal gyrus (LSTG) has been found to be essential for the comprehension of relative clause (RC) sentences, it remains unclear how the LIFG and the LSTG interact with each other, especially during the processing of Chinese RC sentences with different processing difficulty. This study thus conducted a 2 × 2 (modifying position × extraction position) factorial analyses to examine how these two factors influences regional brain activation. The results showed that, regardless of the modifying position, greater activation in the LIFG was consistently elicited in Chinese subject-extracted relative clauses (SRCs) with non-canonical word order than object-extracted relative clauses (ORCs) with canonical word order, implying that the LIFG subserving the ordering process primarily contributes to the processing of information with increased integration demands due to the non-canonical sequence. Moreover, the directional connection between the LIFG and the LSTG appeared to be modulated by different modifying positions. When the RC was at the subject-modifying position, the effective connectivity from the LIFG to the LSTG was dominantly activated for sentence comprehension; whereas when the RC was at the object-modifying position thus being more difficult, it might be the feedback mechanism from the LSTG back to the LIFG that took place in sentence processing. These findings reveal that brain activation in between the LIFG and the LSTG may be dynamically modulated by different processing difficulty and suggest the relative specialization but extensive collaboration involved in the LIFG and the LSTG for sentence comprehension.

Effects of Transcranial Direct Current Stimulation on Apraxia of Speech and Cortical Activation in Patients With Stroke: A Randomized Sham-Controlled Study

Purpose The study aims to investigate, using anodal transcranial direct current stimulation (A-tDCS), over which site, the left lip region of primary motor cortex (M1) or the Broca's area, there would be better recovery from apraxia of speech (AoS) in patients with poststroke aphasia and to examine for altered activation in speech-related areas after tDCS with nonlinear electroencephalography (EEG). Method Fifty-two patients with AoS were randomized into A-tDCS over the left M1 (A-tDCS-M1), Broca's area, and sham tDCS groups who underwent 10 sessions of tDCS and speech treatment for 5 days. The EEG nonlinear index of approximate entropy was calculated for 6 subjects in each group before and after treatment. Results After treatment, the change in speech-language performance improved more significantly in the A-tDCS-M1 group than the other 2 groups (p < .05). EEG approximate entropy indicated that both A-tDCS groups could activate the stimulated sites; the improvement in the A-tDCS-M1 group was correlated with high activation in the dorsal lateral prefrontal cortex and Broca's areas of the left hemisphere in addition to the stimulated site. Conclusion A-tDCS over the left M1 can improve the speech function in patients with poststroke aphasia and severe AoS and excite and recruit more areas in the motor speech network.

Electrophysiology of prosodic and lexical-semantic processing during sentence comprehension in aphasia

Event-related potentials (ERPs) were used to examine how individuals with aphasia and a group of age-matched controls use prosody and themattic fit information in sentences containing temporary syntactic ambiguities. Two groups of individuals with aphasia were investigated; those demonstrating relatively good sentence comprehension whose primary language difficulty is anomia (Individuals with Anomic Aphasia (IWAA)), and those who demonstrate impaired sentence comprehension whose primary diagnosis is Broca's aphasia (Individuals with Broca's Aphasia (IWBA)). The stimuli had early closure syntactic structure and contained a temporary early closure (correct)/late closure (incorrect) syntactic ambiguity. The prosody was manipulated to either be congruent or incongruent, and the temporarily ambiguous NP was also manipulated to either be a plausible or an implausible continuation for the subordinate verb (e.g., "While the band played the song/the beer pleased all the customers."). It was hypothesized that an implausible NP in sentences with incongruent prosody may provide the parser with a plausibility cue that could be used to predict syntactic structure. The results revealed that incongruent prosody paired with a plausibility cue resulted in an N400-P600 complex at the implausible NP (the beer) in both the controls and the IWAAs, yet incongruent prosody without a plausibility cue resulted in an N400-P600 at the critical verb (pleased) only in healthy controls. IWBAs did not show evidence of N400 or P600 effects at the ambiguous NP or critical verb, although they did show evidence of a delayed N400 effect at the sentence-final word in sentences with incongruent prosody. These results suggest that IWAAs have difficulty integrating prosodic cues with underlying syntactic structure when lexical-semantic information is not available to aid their parse. IWBAs have difficulty integrating both prosodic and lexical-semantic cues with syntactic structure, likely due to a processing delay.

rTMS treatments combined with speech training for a conduction aphasia patient: A case report with MRI study

RATIONALE

To date, little is known regarding the neural mechanisms of the functional recovery of language after repetitive transcranial magnetic stimulation (rTMS) in aphasia. Our aim was to investigate the mechanism that underlies rTMS and speech training in a case report.

PATIENT CONCERNS AND DIAGNOSES

We report the case of a 39-year-old woman who was initially diagnosed with conduction aphasia following a left hemisphere stroke.

INTERVENTIONS

The rTMS location comprised the left Broca area, and a frequency of 5 Hz for 20 min/d for 10 days during a 2-week period was used. She had received speech rehabilitation training 1 month after stroke. Functional magnetic resonance imaging (fMRI) and diffusion tensor imaging were used to investigate the functional and microstructural changes before and after rTMS treatment.

OUTCOMES

The results demonstrated that the Western Aphasia Battery scores significantly improved for language ability at 2 weeks post-treatment, and the gains were steadily increased at 2.5 months post-treatment. The fMRI results indicated a more focused activation pattern and showed significant activation in the left dominant hemisphere relative to the right hemisphere, especially in the perilesional areas, post-treatment during 2 language tasks compared with pretreatment. Moreover, the fractional anisotropy increased in the left superior temporal gyrus, which comprises an important area that is involved in language processing.

LESSONS

Our findings suggest that rTMS combined with speech training improved the speech-language ability of this chronic conduction aphasia patient and enhanced the cerebral functional and microstructural reorganization.

Can tDCS enhance item-specific effects and generalization after linguistically motivated aphasia therapy for verbs?

BACKGROUND

Aphasia therapy focusing on abstract properties of language promotes both item-specific effects and generalization to untreated materials. Neuromodulation with transcranial Direct Current Stimulation (tDCS) has been shown to enhance item-specific improvement, but its potential to enhance generalization has not been systematically investigated. Here, we test the efficacy of ACTION (a linguistically motivated protocol) and tDCS in producing item-specific and generalized improvement in aphasia.

METHOD

Nine individuals with post-stroke aphasia participated in this study. Participants were pre-tested with a diagnostic language battery and a cognitive screening. Experimental tasks were administered over multiple baselines. Production of infinitives, of finite verbs and of full sentences were assessed before and after each treatment phase. Nonword repetition was used as a control measure. Each subject was treated in two phases. Ten daily 1-h treatment sessions were provided per phase, in a double-blind, cross-over design. Linguistically-motivated language therapy focusing on verb inflection and sentence construction was provided in both phases. Each session began with 20 min of real or sham tDCS. Stimulation site was determined individually, based on MRI scans.

RESULTS

Group data showed improved production of treated and untreated verbs, attesting the efficacy of behavioral treatment, and its potential to yield generalization. Each individual showed significant item-specific improvement. Generalization occurred in the first phase of treatment for all subjects, and in the second phase for two subjects. Stimulation effects at the group level were significant for treated and untreated verbs altogether, but a ceiling effect for Sham cannot be excluded, as scores between real tDCS and Sham differed only before treatment.

CONCLUSION

Our data demonstrate the efficacy of ACTION and suggest that tDCS may enhance both item-specific effects and generalization.

Can rhythmic auditory cuing remediate language-related deficits in Parkinson's disease?

Neurodegenerative changes of the basal ganglia in idiopathic Parkinson's disease (IPD) lead to motor deficits as well as general cognitive decline. Given these impairments, the question arises as to whether motor and nonmotor deficits can be ameliorated similarly. We reason that a domain-general sensorimotor circuit involved in temporal processing may support the remediation of such deficits. Following findings that auditory cuing benefits gait kinematics, we explored whether reported language-processing deficits in IPD can also be remediated via auditory cuing. During continuous EEG measurement, an individual diagnosed with IPD heard two types of temporally predictable but metrically different auditory beat-based cues: a march, which metrically aligned with the speech accent structure, a waltz that did not metrically align, or no cue before listening to naturally spoken sentences that were either grammatically well formed or were semantically or syntactically incorrect. Results confirmed that only the cuing with a march led to improved computation of syntactic and semantic information. We infer that a marching rhythm may lead to a stronger engagement of the cerebello-thalamo-cortical circuit that compensates dysfunctional striato-cortical timing. Reinforcing temporal realignment, in turn, may lead to the timely processing of linguistic information embedded in the temporally variable speech signal.

Autobiographically Significant Concepts: More Episodic than Semantic in Nature? An Electrophysiological Investigation of Overlapping Types of Memory

A common assertion is that semantic memory emerges from episodic memory, shedding the distinctive contexts associated with episodes over time and/or repeated instances. Some semantic concepts, however, may retain their episodic origins or acquire episodic information during life experiences. The current study examined this hypothesis by investigating the ERP correlates of autobiographically significant (AS) concepts, that is, semantic concepts that are associated with vivid episodic memories. We inferred the contribution of semantic and episodic memory to AS concepts using the amplitudes of the N400 and late positive component, respectively. We compared famous names that easily brought to mind episodic memories (high AS names) against equally famous names that did not bring such recollections to mind (low AS names) on a semantic task (fame judgment) and an episodic task (recognition memory). Compared with low AS names, high AS names were associated with increased amplitude of the late positive component in both tasks. Moreover, in the recognition task, this effect of AS was highly correlated with recognition confidence. In contrast, the N400 component did not differentiate the high versus low AS names but, instead, was related to the amount of general knowledge participants had regarding each name. These results suggest that semantic concepts high in AS, such as famous names, have an episodic component and are associated with similar brain processes to those that are engaged by episodic memory. Studying AS concepts may provide unique insights into how episodic and semantic memory interact.

Bilateral Repetitive Transcranial Magnetic Stimulation for Auditory Hallucinations in Patients with Schizophrenia: A Randomized Controlled, Cross-over Study

Objective

A randomized double-blind cross-over trial was conducted in patients with persistent auditory hallucinations (AHs) to investigate whether bilateral repetitive transcranial magnetic stimulation (rTMS) at the temporoparietal area or Broca's area is more effective at high- or low-frequencies compared to a sham condition.

Methods

Twenty three patients with persistent AHs who remained stable on the same medication for 2 months were enrolled. They were randomized to one of four conditions: low-frequency (1 Hz)-rTMS to the temporoparietal area (L-TP), high-frequency (20 Hz)-rTMS to the temporoparietal area (H-TP), high-frequency (20 Hz)-rTMS to Broca's area (H-B), or sham.

Results

All the four rTMS conditions resulted in significant decrease in the scores under the auditory hallucination rating scale and hallucination change scale over time. However, there were no significant treatment effects or interaction between time and treatment, suggesting no superior effects of the new paradigms over the sham condition.

Conclusion

Our findings suggest that bilateral rTMS at the temporoparietal area or Broca's area with high- or low-frequency does not produce superior effects in reducing AHs compared to sham stimulation.

Localization of electrophysiological responses to semantic and syntactic anomalies in language comprehension with MEG

Syntactically and semantically anomalous words encountered during sentence comprehension are known to elicit dissociable electrophysiological responses, which are thought to reflect distinct aspects of language processing. However, the sources of these responses have not been well characterized. We used beamforming analysis of magnetoencephalography (MEG) data to map generators of electrophysiological responses to linguistic anomalies. Anomalous words occurred in the context of a sentence acceptability judgement task conducted in both visual and auditory modalities. Time-frequency analysis revealed that both kinds of violations elicited event-related synchronization (ERS) in the delta-theta frequency range (1-5 Hz), and desynchronization (ERD) in the alpha-beta range (8-30 Hz). In addition, these responses were differentially modulated by violation type and presentation modality. 1-5 Hz responses were consistently localized within medial prefrontal cortex and did not vary significantly across violation types, but were stronger for visual presentation. In contrast, 8-30 Hz ERD occurred in different regions for different violation types. For semantic violations the distribution was predominantly in the bilateral occipital cortex and left temporal and inferior frontal regions, and these effects did not differ for visual and auditory presentation. In contrast, syntactic responses were strongly affected by presentation modality. Under visual presentation, syntactic violations elicited bilateral 8-30 Hz ERD extending into dorsal parietal and frontal regions, whereas effects were much weaker and mostly statistically insignificant in the auditory modality. These results suggest that delta-theta ERS reflects generalized increases in working memory demands related to linguistic anomaly detection, while alpha-beta ERD reflects specific activation of cortical regions involved in distinct aspects of linguistic processing, such as semantic vs. phonological short-term memory. Beamforming analysis of time-domain average signals (ERFs) revealed an N400m effect for semantic anomalies in both modalities, localized to left superior temporal and posterior frontal regions, and a later P600-like effect for syntactic anomalies in both modalities, widespread over bilateral frontal, posterior temporal, and parietal regions. These results indicate that time-domain averaged responses and induced oscillatory responses have distinct properties, including localization and modality dependence, and likely reflect dissociable and complementary aspects of neural activity related to language comprehension and additional task-related processes.

The strategy and motivational influences on the beneficial effect of neurostimulation: a tDCS and fNIRS study

Working memory (WM) capacity falls along a spectrum with some people demonstrating higher and others lower WM capacity. Efforts to improve WM include applying transcranial direct current stimulation (tDCS), in which small amounts of current modulate the activity of underlying neurons and enhance cognitive function. However, not everyone benefits equally from a given tDCS protocol. Recent findings revealed tDCS-related WM benefits for individuals with higher working memory (WM) capacity. Here, we test two hypotheses regarding those with low WM capacity to see if they too would benefit under more optimal conditions. We tested whether supplying a WM strategy (Experiment 1) or providing greater extrinsic motivation through incentives (Experiment 2) would restore tDCS benefit to the low WM capacity group. We also employed functional near infrared spectroscopy to monitor tDCS-induced changes in neural activity. Experiment 1 demonstrated that supplying a WM strategy improved the high WM capacity participants' accuracy and the amount of oxygenated blood levels following anodal tDCS, but it did not restore tDCS-linked WM benefits to the low WM capacity group. Experiment 2 demonstrated that financial motivation enhanced performance in both low and high WM capacity groups, especially after anodal tDCS. Here, only the low WM capacity participants showed a generalized increase in oxygenated blood flow across both low and high motivation conditions. These results indicate that ensuring that participants' incentives are high may expand cognitive benefits associated with tDCS. This finding is relevant for translational work using tDCS in clinical populations, in which motivation can be a concern.

Feasibility of event-related potential methodology to evaluate changes in cortical processing after rehabilitation in children with cerebral palsy: a pilot study

This study examined the feasibility of using event-related potentials (ERPs) to measure changes in cortical processing following an established rehabilitative intervention (constraint-induced movement therapy, CIMT) for children with cerebral palsy (CP). Sixteen participants with a diagnosis of hemiparetic CP, with a median age of 6 years, were assessed pre and immediately post CIMT and at 6-month follow-up, using a picture-word match/mismatch discrimination task and standard neurobehavioral measures. Intervention effects were evident in improved performance on behavioral tests of sensory and motor function and the increased mean ERP amplitude of the N400 match/mismatch response on the side ipsilateral to the lesion. These effects were maintained 6 months after the intervention. No such changes were observed on the side contralateral to the lesion. This research suggests that ERPs can measure rehabilitation-induced changes in neural function in children with CP.

Generating predictions: lesion evidence on the role of left inferior frontal cortex in rapid syntactic analysis

A well-documented phenomenon in event-related electroencephalography (EEG) and magnetoencephalography (MEG) studies on language processing is that syntactic violations of different types elicit negativities as early as 100 msec after the violation point. Recently, these responses have been associated with activations in or very close to sensory cortices, suggesting the involvement of basic sensory mechanisms in the detection of syntactic violations. The present study investigated whether intact auditory cortices and adjacent temporal regions are sufficient to generate early syntactic negativities in the auditory event-related potential (ERP). We tested ten clinically non-aphasic patients with left inferior frontal lesions, but intact temporal cortices in a passive auditory ERP paradigm that had reliably elicited early negativities in response to violations of subject-verb agreement and word category in the past. Subject-verb agreement violations failed to elicit early grammaticality effects in these patients, whereas a group of ten age-matched controls showed a reliable early negativity. This finding supports the idea that sensory aspects of syntactic analysis as reflected in early syntactic negativities critically depend on top-down predictions generated by the left inferior frontal cortex. In contrast, word category violations elicited a small, marginally significant early negativity both in controls and patients, suggesting an additional involvement of temporal regions in early phrase structure processing. In an additional auditory oddball experiment patients showed a regular P300, but no N2b component in response to deviant tones, indicating that their deficit in generating sensory predictions extends beyond the language domain.

Electrophysiological responses to argument structure violations in healthy adults and individuals with agrammatic aphasia

Sentence comprehension requires processing of argument structure information associated with verbs, i.e. the number and type of arguments that they select. Many individuals with agrammatic aphasia show impaired production of verbs with greater argument structure density. The extent to which these participants also show argument structure deficits during comprehension, however, is unclear. Some studies find normal access to verb arguments, whereas others report impaired ability. The present study investigated verb argument structure processing in agrammatic aphasia by examining event-related potentials associated with argument structure violations in healthy young and older adults as well as aphasic individuals. A semantic violation condition was included to investigate possible differences in sensitivity to semantic and argument structure information during sentence processing. Results for the healthy control participants showed a negativity followed by a positive shift (N400-P600) in the argument structure violation condition, as found in previous ERP studies (Friederici & Frisch, 2000; Frisch, Hahne, & Friederici, 2004). In contrast, individuals with agrammatic aphasia showed a P600, but no N400, response to argument structure mismatches. Additionally, compared to the control groups, the agrammatic participants showed an attenuated, but relatively preserved, N400 response to semantic violations. These data show that agrammatic individuals do not demonstrate normal real-time sensitivity to verb argument structure requirements during sentence processing.

Changes in N400 topography following intensive speech language therapy for individuals with aphasia

Our goal was to characterize the effects of intensive aphasia therapy on the N400, an electrophysiological index of lexical-semantic processing. Immediately before and after 4 weeks of intensive speech-language therapy, people with aphasia performed a task in which they had to determine whether spoken words were a 'match' or a 'mismatch' to pictures of objects. Pre-therapy, people with aphasia exhibited an N400 mismatch effect that started over right hemisphere electrodes. Post-therapy, gains were seen in clinical measures of language ability, and the onset of the N400 was left-lateralized. No changes in the scalp distribution of the N400 were observed in healthy controls tested twice over the same 4 week interval. Since the distribution of the N400 after aphasia therapy differed from that of healthy controls, we conclude that it reflects the engagement of compensatory neural mechanisms for language processing rather than a return to a "normal" pattern of brain activation.

Comprehension

Comprehension is the aspect of cognition in which information is retrieved and consciously integrated. It occurs between the input of perception and memory, and the output of language and executive functioning. This article focuses on disorders of comprehension of linguistic information and semantic knowledge. Comprehension of speech begins with the interpretation of acoustic-phonetic input as word forms. These concepts to which the word forms are semantically associated must then be retrieved, in parallel with interpretation of word order and grammatical marking, to achieve comprehension of discourse. Neural systems for semantic memory are closely related to those for lexical processing. Disorders of language comprehension and semantic knowledge for concrete entities give insight into the relationship of these processes to neural systems.

Neurofunctional (re)organization underlying narrative discourse processing in aging: evidence from fNIRS

Relatively few studies have analyzed the mechanisms underlying the cognitive changes that affect language in the elderly, and fewer have done so for narrative discourse. The goal of this study was to explore the neurofunctional changes associated with aging for different components of narrative discourse. Functional near-infrared spectroscopy (fNIRS) and behavioral data on 10 younger adults and 10 healthy elderly participants were collected. Ten younger adults in a non-proficient second language condition were included to explore the possibility that the age-related neurofunctional reorganization partly expresses demanding resource allocation. Results show within- and across-hemispheric differences in the neurofunctional pattern of activation in the older participants with reference to the younger ones, partially shared with the low-proficiency young adults, providing support for the recognized mechanisms underlying neural reserve and compensation. fNIRS was shown to be appropriate for studying the age-related neurofunctional reorganization of complex cognitive abilities.

Syntactic processing in bilinguals: an fNIRS study

The study of the neural basis of syntactic processing has greatly benefited from neuroimaging techniques. Research on syntactic processing in bilinguals has used a variety of techniques, including mainly functional magnetic resonance imaging (fMRI) and event-related potentials (ERP). This paper reports on a functional near-infrared spectroscopy (fNIRS) study on syntactic processing in highly proficient young adult speakers of Portuguese (mother tongue) (L1) and French (second language) (L2). They made a syntactic judgment of visually presented sentences, which either did or did not contain noun-verb agreement violations. The results showed that syntactic processing in both languages resulted in significant activation in anterior frontal regions of the left hemisphere and in the temporal superior posterior areas of the right hemisphere, with a more prominent activation for L2 in some areas. These findings corroborate previously reported neuroimaging evidence, showing the suitability of fNIRS for the study of syntactic processing in the bilingual brain.

How Shakespeare tempests the brain: neuroimaging insights

Shakespeare made extensive use of the functional shift (FS), a rhetorical device involving a change in the grammatical status of words, e.g., using nouns as verbs. Previous work using event-related brain potentials showed how FS triggers a surprise effect inviting mental re-evaluation, seemingly independent of semantic processing. Here, we used functional magnetic resonance imaging to investigate brain activation in participants making judgements on the semantic relationship between sentences -some containing a Shakespearean FS- and subsequently presented words. Behavioural performance in the semantic decision task was high and unaffected by sentence type. However, neuroimaging results showed that sentences featuring FS elicited significant activation beyond regions classically activated by typical language tasks, including the left caudate nucleus, the right inferior frontal gyrus and the right inferior temporal gyrus. These findings show how Shakespeare's grammatical exploration forces the listener to take a more active role in integrating the meaning of what is said.

On the early left-anterior negativity (ELAN) in syntax studies

Within the framework of Friederici's (2002) neurocognitive model of sentence processing, the early left anterior negativity (ELAN) in event-related potentials (ERPs) has been claimed to be a brain marker of syntactic first-pass parsing. As ELAN components seem to be exclusively elicited by word category violations (phrase structure violations), they have been taken as strong empirical support for syntax-first models of sentence processing and have gained considerable impact on psycholinguistic theory in a variety of domains. The present article reviews relevant ELAN studies and raises a number of serious issues concerning the reliability and validity of the findings. We also discuss how baseline problems and contextual factors can contribute to early ERP effects in studies examining word category violations. We conclude that--despite the apparent wealth of ELAN data--the functional significance of these findings remains largely unclear. The present paper does not claim to have falsified the existence of ELANs or syntax-related early frontal negativities. However, by separating facts from myths, the paper attempts to make a constructive contribution to how future ERP research in the area of syntax processing may better advance our understanding of online sentence comprehension.

Improved picture naming in aphasia patients treated with cathodal tDCS to inhibit the right Broca's homologue area

PURPOSE

Previous reports have suggested that noninvasive cortical stimulation could influence speech production in patients with chronic stroke. Here, we evaluated the hypothesis that cathodal transcranial DC stimulation (ctDCS), a technique that decreases excitability of stimulated cortical sites, applied over a healthy right Broca's homologue area could improve picture naming in patients with post-stroke aphasia.

METHODS

Ten right-handed patients with post-stroke aphasia were enrolled in this double blind, counterbalanced sham-controlled, crossover study. Each patient received an intervention of ctDCS (2 mA for 20 min) and of sham tDCS (2 mA for 1 min) daily for 5 consecutive days in a randomized crossover manner with a minimum interval of one week between interventions, over a healthy right Broca's homologue area using a left supraorbital anode and simultaneous daily sessions of conventional word-retrieval training. The primary endpoint measure of this study was a standardized, validated Korean version of the Boston Naming Test, which is a measure of picture naming skills.

RESULTS

ctDCS was not found to have any adverse effects. Furthermore, significantly improved picture naming (p = 0.02) was observed at 1 hour following the last (5th) ctDCS treatment session, but no changes were observed after sham tDCS.

CONCLUSION

These results demonstrate that cathodal tDCS over the right healthy Broca's homologue area with a left supraorbital anodal location can improve picture naming task performance in post-stroke aphasia.

The role of Broca's area in regular past-tense morphology: an event-related potential study

It has been suggested that damage to anterior regions of the left hemisphere results in a dissociation in the perception and lexical activation of past-tense forms. Specifically, in a lexical-decision task in which past-tense primes immediately precede present-tense targets, such patients demonstrate significant priming for irregular verbs (spoke-speak), but, unlike control participants, fail to do so for regular verbs (looked-look). Here, this behavioral dissociation was first confirmed in a group of eleven patients with damage to the pars opercularis (BA 44) and pars triangularis (BA 45) of the left inferior frontal gyrus (i.e., Broca's area). Two conditions containing word-onset orthographic-phonological overlap (bead-bee, barge-bar) demonstrated that the disrupted regular-verb priming was accompanied by, and covaried with, disrupted ortho-phonological priming, regardless of whether prime stimuli contained the regular inflectional rhyme pattern. Further, the dissociation between impaired regular-verb and preserved irregular-verb priming was shown to be continuous rather than categorical; priming for weak-irregular verbs (spent-spend) was intermediate in size between that of regular verbs and strong verbs. Such continuous dissociations grounded in ortho-phonological relationships between present- and past-tense forms are predicted by single-system, connectionist approaches to inflectional morphology and not predicted by current dual-system, rule-based models. Event-related potential data demonstrated that N400 priming effects were intact for both regular and irregular verbs, suggesting that the absence of significant regular-verb priming in the response time data did not result from a disruption of lexical access, and may have stemmed instead from post-lexical events such as covert articulation, segmentation strategies, and/or cognitive control.

Are left fronto-temporal brain areas a prerequisite for normal music-syntactic processing?

An increasing number of neuroimaging studies in music cognition research suggest that "language areas" are involved in the processing of musical syntax, but none of these studies clarified whether these areas are a prerequisite for normal syntax processing in music. The present electrophysiological experiment tested whether patients with lesions in Broca's area (N=6) or in the left anterior temporal lobe (N=7) exhibit deficits in the processing of structure in music compared to matched healthy controls (N=13). A chord sequence paradigm was applied, and the amplitude and scalp topography of the Early Right Anterior Negativity (ERAN) was examined, an electrophysiological marker of musical syntax processing that correlates with activity in Broca's area and its right hemisphere homotope. Left inferior frontal gyrus (IFG) (but not anterior superior temporal gyrus - aSTG) patients with lesions older than 4 years showed an ERAN with abnormal scalp distribution, and subtle behavioural deficits in detecting music-syntactic irregularities. In one IFG patient tested 7 months post-stroke, the ERAN was extinguished and the behavioural performance remained at chance level. These combined results suggest that the left IFG, known to be crucial for syntax processing in language, plays also a functional role in the processing of musical syntax. Hence, the present findings are consistent with the notion that Broca's area supports the processing of syntax in a rather domain-general way.

Non-native phonemes in adult word learning: evidence from the N400m

Newborns are equipped with a large phonemic inventory that becomes tuned to one's native language early in life. We review and add new data about how learning of a non-native phoneme can be accomplished in adults and how the efficiency of word learning can be assessed by neurophysiological measures. For this purpose, we studied the acquisition of the voiceless, bilabial fricative /Phi/ via a statistical-learning paradigm. Phonemes were embedded in minimal pairs of pseudowords, differing only with respect to the fricative (/aPhio/ versus /afo/). During learning, pseudowords were combined with pictures of objects with some combinations of pseudowords and pictures occurring more frequently than others. Behavioural data and the N400m component, as an index of lexical activation/semantic access, showed that participants had learned to associate the pseudowords with the pictures. However, they could not discriminate within the minimal pairs. Importantly, before learning, the novel words with the sound /Phi/ showed smaller N400 amplitudes than those with native phonemes, evidencing their non-word status. Learning abolished this difference indicating that /Phi/ had become integrated into the native category /f/, instead of establishing a novel category. Our data and review demonstrate that native phonemic categories are powerful attractors hampering the mastery of non-native contrasts.

Sentence integration processes: an ERP study of Chinese sentence comprehension with relative clauses

In an event-related potentials (ERPs) study, we examined the comprehension of different types of Chinese (Mandarin) relative clauses (object vs. subject-extracted) to test the universality and language specificity of sentence comprehension processes. Because Chinese lacks morphosyntactic cues to sentence constituent relations, it allows a test of the possibility that semantic-contextual processes dominate the extraction of clausal relations, in contrast to the structure-dependent processing in English and many other languages. ERP results at the RC embedded verbs showed a P600 effect for the subject-extraction type, reflecting a processing of phrasal reconfiguration, and an N400 effect for the object-extraction type, reflecting a processing of meaning reinterpretation. A central-frontal sustained negativity was produced by the RC head noun of object-extraction, suggesting a combined effect of meaning derivation and referents establishment. LORETA (Low Resolution Electrical Tomography) source localization showed activation of posterior dominance (e.g., BA 22/39/19/41/42) supporting the integration of structure mapping (P600) and meaning derivation (N400) in a developing sentential representation, consistent with the memory unification and control model (Hagoort, 2005). More left-lateralized anterior regions of a frontal-temporal network (e.g., BA 47/38) became active later in the sentence (a sustained central-frontal negativity), when the thematic-role specification for multiple referents may have required additional cognitive and memory resources. Our findings suggest that Chinese sentence reading recruits a neural network that is sensitive to the sequential/hierarchical organization of linguistic inputs in a manner that resembles to the structure-dependent cognitive processes in other languages, reflecting a universal property of language processing. The ERP data shows that early lexical processes are important in the integration process, but also challenges the view that Chinese text reading depends primarily on semantic-contextual processing in the derivation of meaning representation.