Publications

Abstract

The meaning of a sentence can be understood, whether presented in written or spoken form. Therefore it is highly probable that brain processes supporting language comprehension are at least partly independent of sensory modality. To identify where and when in the brain language processing is independent of sensory modality, we directly compared neuromagnetic brain signals of 200 human subjects (102 males) either reading or listening to sentences. We used multiset canonical correlation analysis to align individual subject data in a way that boosts those aspects of the signal that are common to all, allowing us to capture word-by-word signal variations, consistent across subjects and at a fine temporal scale. Quantifying this consistency in activation across both reading and listening tasks revealed a mostly left hemispheric cortical network. Areas showing consistent activity patterns include not only areas previously implicated in higher-level language processing, such as left prefrontal, superior & middle temporal areas and anterior temporal lobe, but also parts of the control-network as well as subcentral and more posterior temporal-parietal areas. Activity in this supramodal sentence processing network starts in temporal areas and rapidly spreads to the other regions involved. The findings do not only indicate the involvement of a large network of brain areas in supramodal language processing, but also indicate that the linguistic information contained in the unfolding sentences modulates brain activity in a word-specific manner across subjects.

Abstract

Bodily mimicry often makes the mimickee have more positive feelings about the mimicker. Yet, little is known about the causes of mimicry’s social effects. When people mimic each other’s bodily movements face to face, they can either adopt a mirrorwise perspective (moving in the same absolute direction) or an anatomical perspective (moving in the same direction relative to their own bodies). Mirrorwise mimicry maximizes visuo-spatial similarity between the mimicker and mimickee, whereas anatomical mimicry maximizes the similarity in the states of their motor systems. To compare the social consequences of visuo-spatial and motoric similarity, we asked participants to converse with an embodied virtual agent (VIRTUO), who mimicked their head movements either mirrorwise, anatomically, or not at all. Compared to participants who were not mimicked, those who were mimicked mirrorwise tended to rate VIRTUO more positively, but those who were mimicked anatomically rated him more negatively. During face-to-face conversation, mirrorwise and anatomical mimicry have opposite social consequences. Results suggest that visuo-spatial similarity between mimicker and mimickee, not similarity in motor system activity, gives rise to the positive social effects of bodily mimicry.

Abstract

Language processing involves the ability to store and integrate pieces of
information in working memory over short periods of time. According to
the dominant view, information is maintained through sustained, elevated
neural activity. Other work has argued that short-term synaptic facilitation
can serve as a substrate of memory. Here, we propose an account where
memory is supported by intrinsic plasticity that downregulates neuronal
firing rates. Single neuron responses are dependent on experience and we
show through simulations that these adaptive changes in excitability pro-
vide memory on timescales ranging from milliseconds to seconds. On this
account, spiking activity writes information into coupled dynamic variables
that control adaptation and move at slower timescales than the membrane
potential. From these variables, information is continuously read back into
the active membrane state for processing. This neuronal memory mech-
anism does not rely on persistent activity, excitatory feedback, or synap-
tic plasticity for storage. Instead, information is maintained in adaptive
conductances that reduce firing rates and can be accessed directly with-
out cued retrieval. Memory span is systematically related to both the time
constant of adaptation and baseline levels of neuronal excitability. Inter-
ference effects within memory arise when adaptation is long-lasting. We
demonstrate that this mechanism is sensitive to context and serial order
which makes it suitable for temporal integration in sequence processing
within the language domain. We also show that it enables the binding of
linguistic features over time within dynamic memory registers. This work
provides a step towards a computational neurobiology of language.

Abstract

Speakers and listeners usually interact in larger discourses than single words or even single sentences. The goal of the present study was to identify the neural bases reflecting how the mental representation of the situation denoted in a multi-sentence discourse (situation model) is constructed and shared between speakers and listeners. An fMRI study using a variant of the ambiguous text paradigm was designed. Speakers (n=15) produced ambiguous texts in the scanner and listeners (n=27) subsequently listened to these texts in different states of ambiguity: preceded by a highly informative, intermediately informative or no title at all. Conventional BOLD activation analyses in listeners, as well as inter-subject correlation analyses between the speakers’ and the listeners’ hemodynamic time courses were performed. Critically, only the processing of disambiguated, coherent discourse with an intelligible situation model representation involved (shared) activation in bilateral lateral parietal and medial prefrontal regions. This shared spatiotemporal pattern of brain activation between the speaker and the listener suggests that the process of memory retrieval in medial prefrontal regions and the binding of retrieved information in the lateral parietal cortex constitutes a core mechanism underlying the communication of complex conceptual representations.

Abstract

Visual context facilitates perception, but how this is neurally implemented remains unclear. One example of contextual facilitation is found in reading, where letters are more easily identified when embedded in a word. Bottom-up models explain this word advantage as a post-perceptual decision bias, while top-down models propose that word contexts enhance perception itself. Here, we arbitrate between these accounts by presenting words and nonwords and probing the representational fidelity of individual letters using functional magnetic resonance imaging. In line with top-down models, we find that word contexts enhance letter representations in early visual cortex. Moreover, we observe increased coupling between letter information in visual cortex and brain activity in key areas of the reading network, suggesting these areas may be the source of the enhancement. Our results provide evidence for top-down representational enhancement in word recognition, demonstrating that word contexts can modulate perceptual processing already at the earliest visual regions.

Abstract

Recent neuroimaging evidence suggests that the frequency of entrained oscillations in auditory cortices influences the perceived duration of speech segments, impacting word perception (Kösem et al. 2018). We further tested the causal influence of neural entrainment frequency during speech processing, by manipulating entrainment with continuous transcranial alternating
current stimulation (tACS) at distinct oscillatory frequencies (3 Hz and 5.5 Hz) above the auditory cortices. Dutch participants listened to speech and were asked to report their percept of a target Dutch word, which contained a vowel with an ambiguous duration. Target words
were presented either in isolation (first experiment) or at the end of spoken sentences (second experiment). We predicted that the tACS frequency would influence neural entrainment and
therewith how speech is perceptually sampled, leading to a perceptual over- or underestimation of the vowel’s duration. Whereas results from Experiment 1 did not confirm this prediction, results from experiment 2 suggested a small effect of tACS frequency on target word
perception: Faster tACS lead to more long-vowel word percepts, in line with the previous neuroimaging findings. Importantly, the difference in word perception induced by the different tACS frequencies was significantly larger in experiment 1 vs. experiment 2, suggesting that the
impact of tACS is dependent on the sensory context. tACS may have a stronger effect on spoken word perception when the words are presented in continuous speech as compared to when they are isolated, potentially because prior (stimulus-induced) entrainment of brain oscillations
might be a prerequisite for tACS to be effective.

Abstract

Perceiving speech requires the integration of different speech cues, that is, formants. When the speech signal is split so that different cues are presented to the right and left ear (dichotic listening), comprehension requires the integration of binaural information. Based on prior electrophysiological evidence, we hypothesized that the integration of dichotically presented speech cues is enabled by interhemispheric phase synchronization between primary and secondary auditory cortex in the gamma frequency band. We tested this hypothesis by applying transcranial alternating current stimulation (TACS) bilaterally above the superior temporal lobe to induce or disrupt interhemispheric gamma-phase coupling. In contrast to initial predictions, we found that gamma TACS applied in-phase above the two hemispheres (interhemispheric lag 0°) perturbs interhemispheric integration of speech cues, possibly because the applied stimulation perturbs an inherent phase lag between the left and right auditory cortex. We also observed this disruptive effect when applying antiphasic delta TACS (interhemispheric lag 180°). We conclude that interhemispheric phase coupling plays a functional role in interhemispheric speech integration. The direction of this effect may depend on the stimulation frequency.

Abstract

This neuroimaging study investigated the neural infrastructure of sentence-level language production. We compared brain activation patterns, as measured with BOLD-fMRI, during production of sentences that differed in verb argument structures (intransitives, transitives, ditransitives) and the lexical status of the verb (known verbs or pseudoverbs). The experiment consisted of 30 mini-blocks of six sentences each. Each mini-block started with an example for the type of sentence to be produced in that block. On each trial in the mini-blocks, participants were first given the (pseudo-)verb followed by three geometric shapes to serve as verb arguments in the sentences. Production of sentences with known verbs yielded greater activation compared to sentences with pseudoverbs in the core language network of the left inferior frontal gyrus, the left posterior middle temporalgyrus, and a more posterior middle temporal region extending into the angular gyrus, analogous to effects observed in language comprehension. Increasing the number of verb arguments led to greater activation in an overlapping left posterior middle temporal gyrus/angular gyrus area, particularly for known verbs, as well as in the bilateral precuneus. Thus, producing sentences with more complex structures using existing verbs leads to increased activation in the language network, suggesting some reliance on memory retrieval of stored lexical–syntactic information during sentence production. This study thus provides evidence from sentence-level language production in line with functional models of the language network that have so far been mainly based on single-word production, comprehension, and language processing in aphasia.

Abstract

Catecholamine (CA) function has been widely implicated in cognitive functions that are tied to the prefrontal cortex and striatal areas. The present study investigated the effects of methylphenidate, which is a CA agonist, on the electroencephalogram (EEG) response related to semantic processing using a double-blind, placebo-controlled, randomized, crossover, within-subject design. Forty-eight healthy participants read semantically congruent or incongruent sentences after receiving 20-mg methylphenidate or a placebo while their brain activity was monitored with EEG. To probe whether the catecholaminergic modulation is task-dependent, in one condition participants had to focus on comprehending the sentences, while in the other condition, they only had to attend to the font size of the sentence. The results demonstrate that methylphenidate has a task-dependent effect on semantic processing. Compared to placebo, when semantic processing was task-irrelevant, methylphenidate enhanced the detection of semantic incongruence as indexed by a larger N400 amplitude in the incongruent sentences; when semantic processing was task-relevant, methylphenidate induced a larger N400 amplitude in the semantically congruent condition, which was followed by a larger late positive complex effect. These results suggest that CA-related neurotransmitters influence language processing, possibly through the projections between the prefrontal cortex and the striatum, which contain many CA receptors.

Abstract

Speech-in-speech perception can be challenging because the processing of competing acoustic and linguistic information leads to informational masking. Here, a method is proposed to isolate the linguistic component of informational masking while keeping the distractor's acoustic information unchanged. Participants performed a dichotic listening cocktail-party task before and after training on 4-band noise-vocoded sentences that became intelligible through the training. Distracting noise-vocoded speech interfered more with target speech comprehension after training (i.e., when intelligible) than before training (i.e., when unintelligible) at −3 dB SNR. These findings confirm that linguistic and acoustic information have distinct masking effects during speech-in‐speech comprehension

Abstract

One of the most daunting tasks of a listener is to map a
continuous auditory stream onto known speech sound
categories and lexical items. A major issue with this mapping
problem is the variability in the acoustic realizations of sound
categories, both within and across speakers. Past research has
suggested listeners may use visual information (e.g., lipreading)
to calibrate these speech categories to the current
speaker. Previous studies have focused on audiovisual
recalibration of consonant categories. The present study
explores whether vowel categorization, which is known to show
less sharply defined category boundaries, also benefit from
visual cues.
Participants were exposed to videos of a speaker
pronouncing one out of two vowels, paired with audio that was
ambiguous between the two vowels. After exposure, it was
found that participants had recalibrated their vowel categories.
In addition, individual variability in audiovisual recalibration is
discussed. It is suggested that listeners’ category sharpness may
be related to the weight they assign to visual information in
audiovisual speech perception. Specifically, listeners with less
sharp categories assign more weight to visual information
during audiovisual speech recognition.

Abstract

An important part of understanding speech motor control consists of capturing the
interaction between speech production and speech perception. This study tests a
prediction of theoretical frameworks that have tried to account for these interactions: if
speech production targets are specified in auditory terms, individuals with better
auditory acuity should have more precise speech targets, evidenced by decreased
within-phoneme variability and increased between-phoneme distance. A study was
carried out consisting of perception and production tasks in counterbalanced order.
Auditory acuity was assessed using an adaptive speech discrimination task, while
production variability was determined using a pseudo-word reading task. Analyses of
the production data were carried out to quantify average within-phoneme variability as
well as average between-phoneme contrasts. Results show that individuals not only
vary in their production and perceptual abilities, but that better discriminators have
more distinctive vowel production targets (that is, targets with less within-phoneme
variability and greater between-phoneme distances), confirming the initial hypothesis.
This association between speech production and perception did not depend on local
phoneme density in vowel space. This study suggests that better auditory acuity leads
to more precise speech production targets, which may be a consequence of auditory
feedback affecting speech production over time.

Abstract

Acceptability judgments are no longer acceptable as the holy grail for testing the nature of linguistic representations. Experimental and quantitative methods should be used to test theoretical claims in psycholinguistics. These methods should include not only behavior, but also the more recent possibilities to probe the neural codes for language-relevant representation

Abstract

In this paper a general cognitive architecture of spoken language processing is specified. This is followed by an account of how this cognitive architecture is instantiated in the human brain. Both the spatial aspects of the networks for language are discussed, as well as the temporal dynamics and the underlying neurophysiology. A distinction is proposed between networks for coding/decoding linguistic information and additional networks for getting from coded meaning to speaker meaning, i.e. for making the inferences that enable the listener to understand the intentions of the speaker

Abstract

Reading is a cultural invention that needs to recruit cortical infrastructure that was not designed for it (cultural recycling of cortical maps). In the case of reading both visual cortex and networks for speech processing are recruited. Here I discuss current views on the neurobiological underpinnings of spoken language that deviate in a number of ways from the classical Wernicke-Lichtheim-Geschwind model. More areas than Broca’s and Wernicke’s region are involved in language. Moreover, a division along the axis of language production and language comprehension does not seem to be warranted. Instead, for central aspects of language processing neural infrastructure is shared between production and comprehension. Arguments are presented in favor of a dynamic network view, in which the functionality of a region is co-determined by the network of regions in which it is embedded at particular moments in time. Finally, core regions of language processing need to interact with other networks (e.g. the attentional networks and the ToM network) to establish full functionality of language and communication. The consequences of this architecture for reading are discussed.

Abstract

Perspective is a crucial feature for communicating about events. Yet it is unclear how linguistically encoded perspective relates to cognitive perspective taking. Here, we tested the effect of perspective taking with short literary stories. Participants listened to stories with 1st or 3rd person pronouns referring to the protagonist, while undergoing fMRI. When comparing action events with 1st and 3rd person pronouns, we found no evidence for a neural dissociation depending on the pronoun. A split sample approach based on the self-reported experience of perspective taking revealed 3 comprehension preferences. One group showed a strong 1st person preference, another a strong 3rd person preference, while a third group engaged in 1st and 3rd person perspective taking simultaneously. Comparing brain activations of the groups revealed different neural networks. Our results suggest that comprehension is perspective dependent, but not on the perspective suggested by the text, but on the reader’s (situational) preference

Abstract

Experiments have shown that compared to fictional texts, readers read factual texts faster and have better memory for described situations. Reading fictional texts on the other hand seems to improve memory for exact wordings and expressions. Most of these studies used a ‘newspaper’ versus ‘literature’ comparison. In the present study, we investigated the effect of reader’s expectation to whether information is true or fictional with a subtler manipulation by labelling short stories as either based on true or fictional events. In addition, we tested whether narrative perspective or individual preference in perspective taking affects reading true or fictional stories differently. In an online experiment, participants (final N=1742) read one story which was introduced as based on true events or as fictional (factor fictionality). The story could be narrated in either 1st or 3rd person perspective (factor perspective). We measured immersion in and appreciation of the story, perspective taking, as well as memory for events. We found no evidence that knowing a story is fictional or based on true events influences reading behavior or experiential aspects of reading. We suggest that it is not whether a story is true or fictional, but rather expectations towards certain reading situations (e.g. reading newspaper or literature) which affect behavior by activating appropriate reading goals. Results further confirm that narrative perspective partially influences perspective taking and experiential aspects of reading

Abstract

The use of virtual reality (VR) as a methodological tool is becoming increasingly popular in behavioral research as its flexibility allows for a wide range of applications. This new method has not been as widely accepted in the field of psycholinguistics, however, possibly due to the assumption that language processing during human-computer interactions does not accurately reflect human-human interactions. Yet at the same time there is a growing need to study human-human language interactions in a tightly controlled context, which has not been possible using existing methods. VR, however, offers experimental control over parameters that cannot be (as finely) controlled in the real world. As such, in this study we aim to show that human-computer language interaction is comparable to human-human language interaction in virtual reality. In the current study we compare participants’ language behavior in a syntactic priming task with human versus computer partners: we used a human partner, a human-like avatar with human-like facial expressions and verbal behavior, and a computer-like avatar which had this humanness removed. As predicted, our study shows comparable priming effects between the human and human-like avatar suggesting that participants attributed human-like agency to the human-like avatar. Indeed, when interacting with the computer-like avatar, the priming effect was significantly decreased. This suggests that when interacting with a human-like avatar, sentence processing is comparable to interacting with a human partner. Our study therefore shows that VR is a valid platform for conducting language research and studying dialogue interactions in an ecologically valid manner.

Abstract

Syntactic priming, the phenomenon in which participants adopt the linguistic behaviour of their partner, is widely used in psycholinguistics to investigate syntactic operations. Although the phenomenon of syntactic priming is well documented, the memory system that supports the retention of this syntactic information long enough to influence future utterances, is not as widely investigated. We aim to shed light on this issue by assessing patients with Korsakoff's amnesia on an active-passive syntactic priming task and compare their performance to controls matched in age, education, and premorbid intelligence. Patients with Korsakoff's syndrome display deficits in all subdomains of declarative memory, yet their nondeclarative memory remains intact, making them an ideal patient group to determine which memory system supports syntactic priming. In line with the hypothesis that syntactic priming relies on nondeclarative memory, the patient group shows strong priming tendencies (12.6% passive structure repetition). Our healthy control group did not show a priming tendency, presumably due to cognitive interference between declarative and nondeclarative memory. We discuss the results in relation to amnesia, aging, and compensatory mechanisms.

Abstract

In everyday communication speakers often refer in speech and/or gesture to objects in their immediate environment, thereby shifting their addressee's attention to an intended referent. The neurobiological infrastructure involved in the comprehension of such basic multimodal communicative acts remains unclear. In an event-related fMRI study, we presented participants with pictures of a speaker and two objects while they concurrently listened to her speech. In each picture, one of the objects was singled out, either through the speaker's index-finger pointing gesture or through a visual cue that made the object perceptually more salient in the absence of gesture. A mismatch (compared to a match) between speech and the object singled out by the speaker's pointing gesture led to enhanced activation in left IFG and bilateral pMTG, showing the importance of these areas in conceptual matching between speech and referent. Moreover, a match (compared to a mismatch) between speech and the object made salient through a visual cue led to enhanced activation in the mentalizing system, arguably reflecting an attempt to converge on a jointly attended referent in the absence of pointing. These findings shed new light on the neurobiological underpinnings of the core communicative process of comprehending a speaker's multimodal referential act and stress the power of pointing as an important natural device to link speech to objects.

Abstract

The brain’s remarkable capacity for language requires bidirectional interactions between functionally specialized brain regions. We used magnetoencephalography to investigate interregional interactions in the brain network for language while 102 participants were reading sentences. Using Granger causality analysis, we identified inferior frontal cortex and anterior temporal regions to receive widespread input and middle temporal regions to send widespread output. This fits well with the notion that these regions play a central role in language processing. Characterization of the functional topology of this network, using data-driven matrix factorization, which allowed for partitioning into a set of subnetworks, revealed directed connections at distinct frequencies of interaction. Connections originating from temporal regions peaked at alpha frequency, whereas connections originating from frontal and parietal regions peaked at beta frequency. These findings indicate that the information flow between language-relevant brain areas, which is required for linguistic processing, may depend on the contributions of distinct brain rhythms

Abstract

The suitability of the Artificial Grammar Learning (AGL) paradigm to capture relevant aspects of the acquisition of linguistic structures has been empirically tested in a number of EEG studies. Some have shown a syntax-related P600 component, but it has not been ruled out that the AGL P600 effect is a response to surface features (e.g., subsequence familiarity) rather than the underlying syntax structure. Therefore, in this study, we controlled for the surface characteristics of the test sequences (associative chunk strength) and recorded the EEG before (baseline preference classification) and
after (preference and grammaticality classification) exposure to a grammar. A typical, centroparietal P600 effect was elicited by grammatical violations after exposure, suggesting that the AGL P600 effect signals a response to structural irregularities. Moreover, preference and grammaticality classification showed a qualitatively similar ERP profile, strengthening the idea that the implicit structural mere
exposure paradigm in combination with preference classification is a suitable alternative to the traditional grammaticality classification test.

Abstract

Listeners interpret utterances by integrating information from multiple sources including word level semantics and world knowledge. When the semantics of an expression is inconsistent with his or her knowledge about the world, the listener may have to search through the conceptual space for alternative possible world scenarios that can make the expression more acceptable. Such cognitive exploration requires considerable computational resources and might depend on motivational factors. This study explores whether and how oxytocin, a neuropeptide known to influence socialmotivation by reducing social anxiety and enhancing affiliative tendencies, can modulate the integration of world knowledge and sentence meanings. The study used a betweenparticipant double-blind randomized placebo-controlled design. Semantic integration, indexed with magnetoencephalography through the N400m marker, was quantified while 45 healthymale participants listened to sentences that were either congruent or incongruent with facts of the world, after receiving intranasally delivered oxytocin or placebo. Compared with congruent sentences, world knowledge incongruent sentences elicited a stronger N400m signal from the left inferior frontal and anterior temporal regions and medial pFC (the N400m effect) in the placebo group. Oxytocin administration significantly attenuated the N400meffect at both sensor and cortical source levels throughout the experiment, in a state-like manner. Additional electrophysiological markers suggest that the absence of the N400m effect in the oxytocin group is unlikely due to the lack of early sensory or semantic processing or a general downregulation of attention. These findings suggest that oxytocin drives listeners to resolve challenges of semantic integration, possibly by promoting the cognitive exploration of alternative possible world scenarios.

Abstract

A central assumption in the perceptual attunement literature holds that exposure to a speech sound contrast leads to improvement in native speech sound processing. However, whether the amount of exposure matters for this process has not been put to a direct test. We elucidated indicators of frequency-dependent perceptual attunement by comparing 5–8-month-old Dutch infants’ discrimination of tokens containing a highly frequent [hɪt-he:t] and a highly infrequent [hʏt-hø:t] native vowel contrast as well as a non-native [hɛt-hæt] vowel contrast in a behavioral visual habituation paradigm (Experiment 1). Infants discriminated both native contrasts similarly well, but did not discriminate the non-native contrast. We sought further evidence for subtle differences in the processing of the two native contrasts using near-infrared spectroscopy and a within-participant design (Experiment 2). The neuroimaging data did not provide additional evidence that responses to native contrasts are modulated by frequency of exposure. These results suggest that even large differences in exposure to a native contrast may not directly translate to behavioral and neural indicators of perceptual attunement, raising the possibility that frequency of exposure does not influence improvements in discriminating native contrasts.

Abstract

Non-adjacent dependencies are challenging for the language learning machinery and are acquired later than adjacent dependencies. In this transcranial magnetic stimulation (TMS) study, we show that participants successfully discriminated between grammatical and non-grammatical sequences after having implicitly acquired an artificial language with crossed non-adjacent dependencies. Subsequent to transcranial magnetic stimulation of Broca’s region, discrimination was impaired compared to when a language-irrelevant control region (vertex) was stimulated. These results support the view that Broca’s region is engaged in structured sequence processing and extend previous functional neuroimaging results on artificial grammar learning (AGL) in two directions: first, the results establish that Broca’s region is a causal component in the processing of non-adjacent dependencies, and second, they show that implicit processing of non-adjacent dependencies engages Broca’s region. Since patients with lesions in Broca’s region do not always show grammatical processing difficulties, the result that Broca’s region is causally linked to processing of non-adjacent dependencies is a step towards clarification of the exact nature of syntactic deficits caused by lesions or perturbation to Broca’s region. Our findings are consistent with previous results and support a role for Broca’s region in general structured sequence processing, rather than a specific role for the processing of hierarchically organized sentence structure.

Abstract

The CNTNAP2 gene encodes a cell-adhesion molecule that influences the properties of neural networks and the morphology and density of neurons and glial cells. Previous studies have shown association of CNTNAP2 variants with language-related phenotypes in health and disease. Here, we report associations of a common CNTNAP2 polymorphism (rs7794745) with variation in grey matter in a region in the dorsal visual stream. We tried to replicate an earlier study on 314 subjects by Tan and colleagues (2010), but now in a substantially larger group of more than 1700 subjects. Carriers of the T allele showed reduced grey matter volume in left superior occipital gyrus, while we did not replicate associations with grey matter volume in other regions identified by Tan et al (2010). Our work illustrates the importance of independent replication in neuroimaging genetic studies of language-related candidate genes.

Abstract

Language comprehension involves two basic operations: the retrieval of lexical information (such as phonologic, syntactic, and semantic information) from long-term memory, and the unification of this information into a coherent representation of the overall utterance. Neuroimaging studies using hemo¬dynamic measures such as PET and fMRI have provided detailed information on which areas of the brain are involved in these language-related memory and unification operations. However, much less is known about the dynamics of the brain's language network. This chapter presents a literature review of the oscillatory neuronal dynamics of EEG and MEG data that can be observed during language comprehen¬sion tasks. From a detailed review of this (rapidly growing) literature the following picture emerges: memory retrieval operations are mostly accompanied by increased neuronal synchronization in the theta frequency range (4-7 Hz). Unification operations, in contrast, induce high-frequency neuronal synchro¬nization in the beta (12-30 Hz) and gamma (above 30 Hz) frequency bands. A desynchronization in the (upper) alpha frequency band is found for those studies that use secondary tasks, and seems to correspond with attentional processes, and with the behavioral consequences of the language comprehension process. We conclude that it is possible to capture the dynamics of the brain's language network by a careful analysis of the event-related changes in power and coherence of EEG and MEG data in a wide range of frequencies, in combination with subtle experimental manipulations in a range of language comprehension tasks. It appears then that neuronal synchrony is a mechanism by which the brain integrates the different types of information about language (such as phonological, orthographic, semantic, and syntactic infor¬mation) represented in different brain areas.

Abstract

The human brain supports acquisition mechanisms that extract structural regularities implicitly from experience without the induction of an explicit model. It has been argued that the capacity to generalize to new input is based on the acquisition of abstract representations, which reflect underlying structural regularities in the input ensemble. In this study, we explored the outcome of this acquisition mechanism, and to this end, we investigated the neural correlates of artificial syntactic classification using event-related functional magnetic resonance imaging. The participants engaged once a day during an 8-day period in a short-term memory acquisition task in which consonant-strings generated from an artificial grammar were presented in a sequential fashion without performance feedback. They performed reliably above chance on the grammaticality classification tasks on days 1 and 8 which correlated with a corticostriatal processing network, including frontal, cingulate, inferior parietal, and middle occipital/occipitotemporal regions as well as the caudate nucleus. Part of the left inferior frontal region (BA 45) was specifically related to syntactic violations and showed no sensitivity to local substring familiarity. In addition, the head of the caudate nucleus correlated positively with syntactic correctness on day 8 but not day 1, suggesting that this region contributes to an increase in cognitive processing fluency.

Abstract

We explore the nature of the oscillatory dynamics in the EEG of subjects reading sentences that contain a semantic violation. More specifically, we examine whether increases in theta (≈3–7 Hz) and gamma (around 40 Hz) band power occur in response to sentences that were either semantically correct or contained a semantically incongruent word (semantic violation). ERP results indicated a classical N400 effect. A wavelet-based time-frequency analysis revealed a theta band power increase during an interval of 300–800 ms after critical word onset, at temporal electrodes bilaterally for both sentence conditions, and over midfrontal areas for the semantic violations only. In the gamma frequency band, a predominantly frontal power increase was observed during the processing of correct sentences. This effect was absent following semantic violations. These results provide a characterization of the oscillatory brain dynamics, and notably of both theta and gamma oscillations, that occur during language comprehension.

Abstract

When faced with the noun phrase (NP) versus sentence (S) coordination ambiguity as in, for example, The thief shot the jeweller and the cop hellip, readers prefer the reading with NP-coordination (e.g., "The thief shot the jeweller and the cop yesterday") over one with two conjoined sentences (e.g., "The thief shot the jeweller and the cop panicked"). A corpus study is presented showing that NP-coordinations are produced far more often than S-coordinations, which in frequency-based accounts of parsing might be taken to explain the NP-coordination preference. In addition, we describe an eye-tracking experiment investigating S-coordinated sentences such as Jasper sanded the board and the carpenter laughed, where the poor thematic fit between carpenter and sanded argues against NP-coordination. Our results indicate that information regarding poor thematic fit was used rapidly, but not without leaving some residual processing difficulty. This is compatible with claims that thematic information can reduce but not completely eliminate garden-path effects.

Abstract

This study investigates functional interpretations of left
anterior negativities (LANs), a language-related electroencephalogram effect that has been found for syntactic and morphological violations. We focus on three possible interpretations of LANs caused by the replacement of irregular affixes with regular affixes: misapplication of morphological rules, mismatch of the presented form with analogy-based expectations, and mismatch of the presented form with stored representations. Event-related brain potentials were recorded during the visual presentation of existing and novel Dutch compounds. Existing compounds contained correct or replaced interfixes (dame + s + salons > damessalons vs. *dame + n + salons > *damensalons ‘‘women’s hairdresser salons’’), whereas novel Dutch compounds contained interfixes that were either supported or not supported by analogy to similar existing compounds
(kruidenkelken vs. ?kruidskelken ‘‘herb chalices’’); earlier studies had shown that interfixes are selected by analogy instead of rules. All compounds were presented with correct or incorrect regular plural suffixes (damessalons vs. *damessalonnen). Replacing suffixes or interfixes in existing compounds both led to increased (L)ANs between 400 and 700 msec without any evidence for different scalp distributions for interfixes and suffixes. There was no evidence for a negativity when manipulating the analogical support for interfixes in novel compounds. Together with earlier studies, these results suggest that LANs had been caused by the mismatch of the presented forms with stored forms. We discuss these findings with respect to the single/dual-route debate of morphology and LANs found for the misapplication of syntactic rules.

Abstract

The recognition of a word makes available its semantic and
syntactic properties. Using electrophysiological recordings, we
investigated whether one set of these properties is available
earlier than the other set. Dutch participants saw nouns on a
computer screen and performed push-button responses: In
one task, grammatical gender determined response hand
(left/right) and semantic category determined response execution
(go/no-go). In the other task, response hand depended
on semantic category, whereas response execution depended
on gender. During the latter task, response preparation occurred
on no-go trials, as measured by the lateralized
readiness potential: Semantic information was used for
response preparation before gender information inhibited
this process. Furthermore, an inhibition-related N2 effect
occurred earlier for inhibition by semantics than for inhibition
by gender. In summary, electrophysiological measures
of both response preparation and inhibition indicated that
the semantic word property was available earlier than the
syntactic word property when participants read single
words.

Abstract

An event-related brain potential experiment was carried out to investigate the temporal relationship
between lexical selection and the semantic integration in auditory sentence processing. Participants were
presented with spoken sentences that ended with a word that was either semantically congruent or
anomalous. Information about the moment in which a sentence-final word could uniquely be identified,
its isolation point (IP), was compared with the onset of the elicited N400 congruity effect, reflecting
semantic integration processing. The results revealed that the onset of the N400 effect occurred prior to
the IP of the sentence-final words. Moreover, the factor early or late IP did not affect the onset of the
N400. These findings indicate that lexical selection and semantic integration are cascading processes, in
that semantic integration processing can start before the acoustic information allows the selection of a
unique candidate and seems to be attempted in parallel for multiple candidates that are still compatible
with the bottom–up acoustic input.