Publications

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

We investigated music and language processing in a group of early bilinguals who spoke a tone language and a non-tone language (Cantonese and Dutch). We assessed online speech-music processing interactions, that is, interactions that occur when speech and music are processed simultaneously in songs, with a speeded classification task. In this task, participants judged sung pseudowords either musically (based on the direction of the musical interval) or phonologically (based on the identity of the sung vowel). We also assessed longer-term effects of linguistic experience on musical ability, that is, the influence of extensive prior experience with language when processing music. These effects were assessed with a task in which participants had to learn to identify musical intervals and with four pitch-perception tasks. Our hypothesis was that due to their experience in two different languages using lexical versus intonational tone, the early Cantonese-Dutch bilinguals would outperform the Dutch control participants. In online processing, the Cantonese-Dutch bilinguals processed speech and music more holistically than controls. This effect seems to be driven by experience with a tone language, in which integration of segmental and pitch information is fundamental. Regarding longer-term effects of linguistic experience, we found no evidence for a bilingual advantage in either the music-interval learning task or the pitch-perception tasks. Together, these results suggest that being a Cantonese-Dutch bilingual does not have any measurable longer-term effects on pitch and music processing, but does have consequences for how speech and music are processed jointly.

Abstract

We sketch four applications of Marr's levels-of-analysis methodology to the relations between logic and experimental data in the cognitive neuroscience of language and reasoning. The first part of the paper illustrates the explanatory power of computational level theories based on logic. We show that a Bayesian treatment of the suppression task in reasoning with conditionals is ruled out by EEG data, supporting instead an analysis based on defeasible logic. Further, we describe how results from an EEG study on temporal prepositions can be reanalyzed using formal semantics, addressing a potential confound. The second part of the article demonstrates the predictive power of logical theories drawing on EEG data on processing progressive constructions and on behavioral data on conditional reasoning in people with autism. Logical theories can constrain processing hypotheses all the way down to neurophysiology, and conversely neuroscience data can guide the selection of alternative computational level models of cognition.

Abstract

In using language, people not only exchange information, but also navigate their social world – for example, they can express themselves indirectly to avoid losing face. In this functional magnetic resonance imaging study, we investigated the neural correlates of interpreting face-saving indirect replies, in a situation where participants only overheard the replies as part of a conversation between two other people, as well as in a situation where the participants were directly addressed themselves. We created a fictional job interview context where indirect replies serve as a natural communicative strategy to attenuate one’s shortcomings, and asked fMRI participants to either pose scripted questions and receive answers from three putative job candidates (addressee condition) or to listen to someone else interview the same candidates (overhearer condition). In both cases, the need to evaluate the candidate ensured that participants had an active interest in comprehending the replies. Relative to direct replies, face-saving indirect replies increased activation in medial prefrontal cortex, bilateral temporo-parietal junction (TPJ), bilateral inferior frontal gyrus and bilateral middle temporal gyrus, in active overhearers and active addressees alike, with similar effect size, and comparable to findings obtained in an earlier passive listening study (Bašnáková et al., 2013). In contrast, indirectness effects in bilateral anterior insula and pregenual ACC, two regions implicated in emotional salience and empathy, were reliably stronger in addressees than in active overhearers. Our findings indicate that understanding face-saving indirect language requires additional cognitive perspective-taking and other discourse-relevant cognitive processing, to a comparable extent in active overhearers and addressees. Furthermore, they indicate that face-saving indirect language draws upon affective systems more in addressees than in overhearers, presumably because the addressee is the one being managed by a face-saving reply. In all, face-saving indirectness provides a window on the cognitive as well as affect-related neural systems involved in human communication.

Abstract

During sentence level language comprehension, semantic and syntactic unification are functionally distinct operations. Nevertheless, both recruit roughly the same brain areas (spatially overlapping networks in the left frontotemporal cortex) and happen at the same time (in the first few hundred milliseconds after word onset). We tested the hypothesis that semantic and syntactic unification are segregated by means of neuronal synchronization of the functionally relevant networks in different frequency ranges: gamma (40 Hz and up) for semantic unification and lower beta (10–20 Hz) for syntactic unification. EEG power changes were quantified as participants read either correct sentences, syntactically correct though meaningless sentences (syntactic prose), or sentences that did not contain any syntactic structure (random word lists). Other sentences contained either a semantic anomaly or a syntactic violation at a critical word in the sentence. Larger EEG gamma-band power was observed for semantically coherent than for semantically anomalous sentences. Similarly, beta-band power was larger for syntactically correct sentences than for incorrect ones. These results confirm the existence of a functional dissociation in EEG oscillatory dynamics during sentence level language comprehension that is compatible with the notion of a frequency-based segregation of syntactic and semantic unification.

Abstract

Previous studies suggest that linguistic material can modulate visual perception, but it is unclear at which level of processing these interactions occur. Here we aim to dissociate between two competing models of language–perception interactions: a feed-forward and a feedback model. We capitalized on the fact that the models make different predictions on the role of feedback. We presented unmasked (aware) or masked (unaware) words implying motion (e.g. “rise,” “fall”), directly preceding an upward or downward visual motion stimulus. Crucially, masking leaves intact feed-forward information processing from low- to high-level regions, whereas it abolishes subsequent feedback. Under this condition, participants remained faster and more accurate when the direction implied by the motion word was congruent with the direction of the visual motion stimulus. This suggests that language–perception interactions are driven by the feed-forward convergence of linguistic and perceptual information at higher-level conceptual and decision stages.

Abstract

Previous studies have shown that language can modulate visual perception, by biasing and/
or enhancing perceptual performance. However, it is still debated where in the brain visual and
linguistic information are integrated, and whether the effects of language on perception are
automatic and persist even in the absence of awareness of the linguistic material. Here, we aimed
to explore the automaticity of language-perception interactions and the neural loci of these
interactions in an fMRI study. Participants engaged in a visual motion discrimination task (upward
or downward moving dots). Before each trial, a word prime was briefly presented that implied
upward or downward motion (e.g., “rise”, “fall”). These word primes strongly influenced behavior:
congruent motion words sped up reaction times and improved performance relative to incongruent
motion words. Neural congruency effects were only observed in the left middle temporal gyrus,
showing higher activity for congruent compared to incongruent conditions. This suggests that higherlevel
conceptual areas rather than sensory areas are the locus of language-perception interactions.
When motion words were rendered unaware by means of masking, they still affected visual motion
perception, suggesting that language-perception interactions may rely on automatic feed-forward
integration of perceptual and semantic material in language areas of the brain.

Abstract

Perception does not function as an isolated module but is tightly linked with other cognitive functions. Several studies have demonstrated an influence of language on motion perception, but it remains debated at which level of processing this modulation takes place. Some studies argue for an interaction in perceptual areas, but it is also possible that the interaction is mediated by "language areas" that integrate linguistic and visual information. Here, we investigated whether language-perception interactions were specific to the language-dominant left hemisphere by comparing the effects of language on visual material presented in the right (RVF) and left visual fields (LVF). Furthermore, we determined the neural locus of the interaction using fMRI. Participants performed a visual motion detection task. On each trial, the visual motion stimulus was presented in either the LVF or in the RVF, preceded by a centrally presented word (e.g., "rise"). The word could be congruent, incongruent, or neutral with regard to the direction of the visual motion stimulus that was presented subsequently. Participants were faster and more accurate when the direction implied by the motion word was congruent with the direction of the visual motion stimulus. Interestingly, the speed benefit was present only for motion stimuli that were presented in the RVF. We observed a neural counterpart of the behavioral facilitation effects in the left middle temporal gyrus, an area involved in semantic processing of verbal material. Together, our results suggest that semantic information about motion retrieved in language regions may automatically modulate perceptual decisions about motion.

Abstract

This study aims to test a prediction of recent
theoretical frameworks in speech motor control: if speech production targets are specified in auditory
terms, people with better auditory acuity should have more precise speech targets.
To investigate this, we had participants perform speech perception and production tasks in a counterbalanced order. To assess speech perception acuity, we used an adaptive speech discrimination
task. To assess variability in speech production, participants performed a pseudo-word reading task; formant values were measured for each recording.
We predicted that speech production variability to correlate inversely with discrimination performance.
The results suggest that people do vary in their production and perceptual abilities, and that better discriminators have more distinctive vowel production targets, confirming our prediction. This
study highlights the importance of individual
differences in the study of speech motor control, and sheds light on speech production-perception interaction.

Abstract

Models of speech production explain event-related suppression of the auditory cortical
response as reflecting a comparison between auditory predictions and feedback. The present MEG
study was designed to test two predictions from this framework: 1) whether the reduced auditory
response varies as a function of the mismatch between prediction and feedback; 2) whether individual
variation in this response is predictive of speech-motor adaptation.
Participants alternated between online imitation and listening tasks. In the imitation task, participants
began each trial producing the same vowel (/e/) and subsequently listened to and imitated auditorilypresented
vowels varying in acoustic distance from /e/.
Results replicated suppression, with a smaller M100 during speaking than listening. Although we did
not find unequivocal support for the first prediction, participants with less M100 suppression were
better at the imitation task. These results are consistent with the enhancement of M100 serving as an
error signal to drive subsequent speech-motor adaptation.

Abstract

The genetic determinants of cerebral asymmetries are unknown. Sex differences in asymmetry of the planum temporale, that overlaps Wernicke’s classical language area, have been inconsistently reported. Meta-analysis of previous studies has suggested that publication bias established this sex difference in the literature. Using probabilistic definitions of cortical regions we screened over the cerebral cortex for sexual dimorphisms of asymmetry in 2337 healthy subjects, and found the planum temporale to show the strongest sex-linked asymmetry of all regions, which was supported by two further datasets, and also by analysis with the Freesurfer package that performs automated parcellation of cerebral cortical regions. We performed a genome-wide association scan meta-analysis of planum temporale asymmetry in a pooled sample of 3095 subjects, followed by a candidate-driven approach which measured a significant enrichment of association in genes of the ´steroid hormone receptor activity´ and 'steroid metabolic process' pathways. Variants in the genes and pathways identified may affect the role of the planum temporale in language cognition.

Abstract

Recipients process information from speech and co-speech gestures, but it is currently unknown how this processing is influenced by the presence of other important social cues, especially gaze direction, a marker of communicative intent. Such cues may modulate neural activity in regions associated either with the processing of ostensive cues, such as eye gaze, or with the processing of semantic information, provided by speech and gesture.
Participants were scanned (fMRI) while taking part in triadic communication involving two recipients and a speaker. The speaker uttered sentences that
were and were not accompanied by complementary iconic gestures. Crucially, the speaker alternated her gaze direction, thus creating two recipient roles: addressed (direct gaze) vs unaddressed (averted gaze) recipient. The comprehension of Speech&Gesture relative to SpeechOnly utterances recruited middle occipital, middle temporal and inferior frontal gyri, bilaterally. The calcarine sulcus and posterior cingulate cortex were sensitive to differences between direct and averted gaze. Most importantly, Speech&Gesture utterances, but not SpeechOnly utterances, produced additional activity in the right middle temporal gyrus when participants were addressed. Marking communicative intent with gaze direction modulates the processing of speech–gesture utterances in cerebral areas typically associated with the semantic processing of multi-modal communicative acts.

Abstract

Instrumental music and language are both syntactic systems, employing complex, hierarchically-structured sequences built using implicit structural norms. This organization allows listeners to understand the role of individual words or tones in the context of an unfolding sentence or melody. Previous studies suggest that the brain mechanisms of syntactic processing may be partly shared between music and language. However, functional neuroimaging evidence for anatomical overlap of brain activity involved in linguistic and musical syntactic processing has been lacking. In the present study we used functional magnetic resonance imaging (fMRI) in conjunction with an interference paradigm based on sung sentences. We show that the processing demands of musical syntax (harmony) and language syntax interact in Broca’s area in the left inferior frontal gyrus (without leading to music and language main effects). A language main effect in Broca’s area only emerged in the complex music harmony condition, suggesting that (with our stimuli and tasks) a language effect only becomes visible under conditions of increased demands on shared neural resources. In contrast to previous studies, our design allows us to rule out that the observed neural interaction is due to: (1) general attention mechanisms, as a psychoacoustic auditory anomaly behaved unlike the harmonic manipulation, (2) error processing, as the language and the music stimuli contained no structural errors. The current results thus suggest that two different cognitive domains—music and language—might draw on the same high level syntactic integration resources in Broca’s area.

Abstract

This study investigated the brain regions for the comprehension of implied emotion in sentences. Participants read negative sentences without negative words, for example, “The boy fell asleep and never woke up again,” and their neutral counterparts “The boy stood up and grabbed his bag.” This kind of negative sentence allows us to examine implied emotion derived at the sentence level, without associative emotion coming from word retrieval. We found that implied emotion in sentences, relative to neutral sentences, led to activation in some emotion-related areas, including the medial prefrontal cortex, the amygdala, and the insula, as well as certain language-related areas, including the inferior frontal gyrus, which has been implicated in combinatorial processing. These results suggest that the emotional network involved in implied emotion is intricately related to the network for combinatorial processing in language, supporting the view that sentence meaning is more than simply concatenating the meanings of its lexical building blocks.

Abstract

In everyday human communication, we often express our communicative intentions by manually pointing out referents in the material world around us to an addressee, often in tight synchronization with referential speech. This study investigated whether and how the kinematic form of index finger pointing gestures is shaped by the gesturer's communicative intentions and how this is modulated by the presence of concurrently produced speech. Furthermore, we explored the neural mechanisms underpinning the planning of communicative pointing gestures and speech. Two experiments were carried out in which participants pointed at referents for an addressee while the informativeness of their gestures and speech was varied. Kinematic and electrophysiological data were recorded online. It was found that participants prolonged the duration of the stroke and poststroke hold phase of their gesture to be more communicative, in particular when the gesture was carrying the main informational burden in their multimodal utterance. Frontal and P300 effects in the ERPs suggested the importance of intentional and modality-independent attentional mechanisms during the planning phase of informative pointing gestures. These findings contribute to a better understanding of the complex interplay between action, attention, intention, and language in the production of pointing gestures, a communicative act core to human interaction.

Abstract

A fundamental property of language is that it can be used to refer to entities in the extra-linguistic physical context of a conversation in order to establish a joint focus of attention on a referent. Typological and psycholinguistic work across a wide range of languages has put forward at least two different theoretical views on demonstrative reference. Here we contrasted and tested these two accounts by investigating the electrophysiological brain activity underlying the construction of indexical meaning in comprehension. In two EEG experiments, participants watched pictures of a speaker who referred to one of two objects using speech and an index-finger pointing gesture. In contrast with separately collected native speakers’ linguistic intuitions, N400 effects showed a preference for a proximal demonstrative when speaker and addressee were in a face-to-face orientation and all possible referents were located in the shared space between them, irrespective of the physical proximity of the referent to the speaker. These findings reject egocentric proximity-based accounts of demonstrative reference, support a sociocentric approach to deixis, suggest that interlocutors construe a shared space during conversation, and imply that the psychological proximity of a referent may be more important than its physical proximity.

Abstract

Comprehension of pointing gestures is fundamental to human communication. However, the neural mechanisms
that subserve the integration of pointing gestures and speech in visual contexts in comprehension
are unclear. Here we present the results of an fMRI study in which participants watched images of an
actor pointing at an object while they listened to her referential speech. The use of a mismatch paradigm
revealed that the semantic unication of pointing gesture and speech in a triadic context recruits left
inferior frontal gyrus. Complementing previous ndings, this suggests that left inferior frontal gyrus
semantically integrates information across modalities and semiotic domains.

Abstract

Emotions are often expressed metaphorically, and both emotion and metaphor are ways through which abstract meaning can be grounded in language. Here we investigate specifically whether motion-related verbs when used metaphorically are differentially sensitive to a preceding emotional context, as compared to when they are used in a literal manner. Participants read stories that ended with ambiguous action/motion sentences (e.g., he got it), in which the action/motion could be interpreted metaphorically (he understood the idea) or literally (he caught the ball) depending on the preceding story. Orthogonal to the metaphorical manipulation, the stories were high or low in emotional content. The results showed that emotional context modulated the neural response in visual motion areas to the metaphorical interpretation of the sentences, but not to their literal interpretations. In addition, literal interpretations of the target sentences led to stronger activation in the visual motion areas as compared to metaphorical readings of the sentences. We interpret our results as suggesting that emotional context specifically modulates mental simulation during metaphor processing

Abstract

In this study, we explore the possibility to predict the semantic category of words from brain signals in a free word generation task. Participants produced single words from different semantic categories in a modified semantic fluency task. A Bayesian logistic regression classifier was trained to predict the semantic category of words from single-trial MEG data. Significant classification accuracies were achieved using sensor-level MEG time series at the time interval of conceptual preparation. Semantic category prediction was also possible using source-reconstructed time series, based on minimum norm estimates of cortical activity. Brain regions that contributed most to classification on the source level were identified. These were the left inferior frontal gyrus, left middle frontal gyrus, and left posterior middle temporal gyrus. Additionally, the temporal dynamics of brain activity underlying the semantic preparation during word generation was explored. These results provide important insights about central aspects of language production

Abstract

Diffusion tensor imaging (DTI) and a longitudinal language learning approach were applied to investigate the relationship between the achieved second language (L2) proficiency during L2 learning and the reorganization of structural connectivity between core language areas. Language proficiency tests and DTI scans were obtained from German students before and after they completed an intensive 6-week course of the Dutch language. In the initial learning stage, with increasing L2 proficiency, the hemispheric dominance of the BA6-temporal pathway (mainly along the arcuate fasciculus) shifted from the left to the right hemisphere. With further increased proficiency, however, lateralization dominance was again found in the left BA6-temporal pathway. This result is consistent with reports in the literature that imply a stronger involvement of the right hemisphere in L2-processing especially for less proficient L2-speakers. This is the first time that a L2-proficiency-dependent laterality shift in structural connectivity of language pathways during L2 acquisition has been observed to shift from left to right, and back to left hemisphere dominance with increasing L2-proficiency. We additionally find that changes in fractional anisotropy values after the course are related to the time elapsed between the two scans. The results suggest that structural connectivity in (at least part of) the perisylvian language network may be subject to fast dynamic changes following language learning

Abstract

A number of recent studies have hypothesized that monitoring in speech production may occur via domain-general mechanisms responsible for the detection of response conflict. Outside of language, two ERP components have consistently been elicited in conflict-inducing tasks (e.g., the flanker task): the stimulus-locked N2 on correct trials, and the response-locked error-related negativity (ERN). The present investigation used these electrophysiological markers to test whether a common response conflict monitor is responsible for monitoring in speech and non-speech tasks. Electroencephalography (EEG) was recorded while participants performed a tongue twister (TT) task and a manual version of the flanker task. In the TT task, people rapidly read sequences of four nonwords arranged in TT and non-TT patterns three times. In the flanker task, people responded with a left/right button press to a center-facing arrow, and conflict was manipulated by the congruency of the flanking arrows. Behavioral results showed typical effects of both tasks, with increased error rates and slower speech onset times for TT relative to non-TT trials and for incongruent relative to congruent flanker trials. In the flanker task, stimulus-locked EEG analyses replicated previous results, with a larger N2 for incongruent relative to congruent trials, and a response-locked ERN. In the TT task, stimulus-locked analyses revealed broad, frontally-distributed differences beginning around 50 ms and lasting until just before speech initiation, with TT trials more negative than non-TT trials; response-locked analyses revealed an ERN. Correlation across these measures showed some correlations within a task, but little evidence of systematic cross-task correlation. Although the present results do not speak against conflict signals from the production system serving as cues to self-monitoring, they are not consistent with signatures of response conflict being mediated by a single, domain-general conflict monitor

Abstract

Even though language allows us to say exactly what we mean, we often use language to say things indirectly, in a way that depends on the specific communicative context. For example, we can use an apparently straightforward sentence like "It is hard to give a good presentation" to convey deeper meanings, like "Your talk was a mess!" One of the big puzzles in language science is how listeners work out what speakers really mean, which is a skill absolutely central to communication. However, most neuroimaging studies of language comprehension have focused on the arguably much simpler, context-independent process of understanding direct utterances. To examine the neural systems involved in getting at contextually constrained indirect meaning, we used functional magnetic resonance imaging as people listened to indirect replies in spoken dialog. Relative to direct control utterances, indirect replies engaged dorsomedial prefrontal cortex, right temporo-parietal junction and insula, as well as bilateral inferior frontal gyrus and right medial temporal gyrus. This suggests that listeners take the speaker's perspective on both cognitive (theory of mind) and affective (empathy-like) levels. In line with classic pragmatic theories, our results also indicate that currently popular "simulationist" accounts of language comprehension fail to explain how listeners understand the speaker's intended message.

Abstract

Heschl's gyrus (HG) is a core region of the auditory cortex whose morphology is highly variable across individuals. This variability has been linked to sound perception ability in both speech and music domains. Previous studies show that variations in morphological features of HG, such as cortical surface area and thickness, are heritable. To identify genetic variants that affect HG morphology, we conducted a genome-wide association scan (GWAS) meta-analysis in 3054 healthy individuals using HG surface area and thickness as quantitative traits. None of the single nucleotide polymorphisms (SNPs) showed association P values that would survive correction for multiple testing over the genome. The most significant association was found between right HG area and SNP rs72932726 close to gene DCBLD2 (3q12.1; P=2.77x10(-7)). This SNP was also associated with other regions involved in speech processing. The SNP rs333332 within gene KALRN (3q21.2; P=2.27x10(-6)) and rs143000161 near gene COBLL1 (2q24.3; P=2.40x10(-6)) were associated with the area and thickness of left HG, respectively. Both genes are involved in the development of the nervous system. The SNP rs7062395 close to the X-linked deafness gene POU3F4 was associated with right HG thickness (Xq21.1; P=2.38x10(-6)). This is the first molecular genetic analysis of variability in HG morphology

Abstract

Language and action systems are highly interlinked. A critical piece of evidence is that speech and its accompanying gestures are tightly synchronized. Five experiments were conducted to test 2 hypotheses about the synchronization of speech and gesture. According to the interactive view, there is continuous information exchange between the gesture and speech systems, during both their planning and execution phases. According to the ballistic view, information exchange occurs only during the planning phases of gesture and speech, but the 2 systems become independent once their execution has been initiated. In all experiments, participants were required to point to and/or name a light that had just lit up. Virtual reality and motion tracking technologies were used to disrupt their gesture or speech execution. Participants delayed their speech onset when their gesture was disrupted. They did so even when their gesture was disrupted at its late phase and even when they received only the kinesthetic feedback of their gesture. Also, participants prolonged their gestures when their speech was disrupted. These findings support the interactive view and add new constraints on models of speech and gesture production

Abstract

There are increasing reports that individual variation in behavioral and neurophysiological measures of infant speech processing predicts later language outcomes, and specifically concurrent or subsequent vocabulary size. If such findings are held up under scrutiny, they could both illuminate theoretical models of language development and contribute to the prediction of communicative disorders. A qualitative, systematic review of this emergent literature illustrated the variety of approaches that have been used and highlighted some conceptual problems regarding the measurements. A quantitative analysis of the same data established that the bivariate relation was significant, with correlations of similar strength to those found for well-established nonlinguistic predictors of language. Further exploration of infant speech perception predictors, particularly from a methodological perspective, is recommended.

Abstract

Numerous experiments show that space and musical pitch are
closely linked in people's minds. However, the exact nature of
space-pitch associations and their neuronal underpinnings are
not well understood. In an fMRI experiment we investigated
different types of spatial representations that may underlie
musical pitch. Participants judged stimuli that varied in
spatial height in both the visual and tactile modalities, as well
as auditory stimuli that varied in pitch height. In order to
distinguish between unimodal and multimodal spatial bases of
musical pitch, we examined whether pitch activations were
present in modality-specific (visual or tactile) versus
multimodal (visual and tactile) regions active during spatial
height processing. Judgments of musical pitch were found to
activate unimodal visual areas, suggesting that space-pitch
associations may involve modality-specific spatial
representations, supporting a key assumption of embodied
theories of metaphorical mental representation.

Abstract

The left and right sides of the human brain are specialized for different kinds of information processing, and much of our cognition is lateralized to an extent towards one side or the other. Handedness is a reflection of nervous system lateralization. Roughly ten percent of people are mixed- or left-handed, and they show an elevated rate of reductions or reversals of some cerebral functional asymmetries compared to right-handers. Brain anatomical correlates of left-handedness have also been suggested. However, the relationships of left-handedness to brain structure and function remain far from clear. We carried out a comprehensive analysis of cortical surface area differences between 106 left-handed subjects and 1960 right-handed subjects, measured using an automated method of regional parcellation (FreeSurfer, Destrieux atlas). This is the largest study sample that has so far been used in relation to this issue. No individual cortical region showed an association with left-handedness that survived statistical correction for multiple testing, although there was a nominally significant association with the surface area of a previously implicated region: the left precentral sulcus. Identifying brain structural correlates of handedness may prove useful for genetic studies of cerebral asymmetries, as well as providing new avenues for the study of relations between handedness, cerebral lateralization and cognition.

Abstract

Functional and anatomical asymmetries are prevalent features of the human brain, linked to gender, handedness, and cognition. However, little is known about the neurodevelopmental processes involved. In zebrafish, asymmetries arise in the diencephalon before extending within the central nervous system. We aimed to identify genes involved in the development of subtle, left-right volumetric asymmetries of human subcortical structures using large datasets. We first tested the feasibility of measuring left-right volume differences in such large-scale samples, as assessed by two automated methods of subcortical segmentation (FSL|FIRST and FreeSurfer), using data from 235 subjects who had undergone MRI twice. We tested the agreement between the first and second scan, and the agreement between the segmentation methods, for measures of bilateral volumes of six subcortical structures and the hippocampus, and their volumetric asymmetries. We also tested whether there were biases introduced by left-right differences in the regional atlases used by the methods, by analyzing left-right flipped images. While many bilateral volumes were measured well (scan-rescan r = 0.6-0.8), most asymmetries, with the exception of the caudate nucleus, showed lower repeatabilites. We meta-analyzed genome-wide association scan results for caudate nucleus asymmetry in a combined sample of 3,028 adult subjects but did not detect associations at genome-wide significance (P < 5 × 10-8). There was no enrichment of genetic association in genes involved in left-right patterning of the viscera. Our results provide important information for researchers who are currently aiming to carry out large-scale genome-wide studies of subcortical and hippocampal volumes, and their asymmetries

Abstract

Current views on the neurobiological underpinnings of language are discussed 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. Three different accounts of the role of Broca's area in language are discussed. 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.

Abstract

A hallmark of human language is that we combine lexical building blocks retrieved from memory in endless new ways. This combinatorial aspect of language is referred to as unification. Here we focus on the neurobiological infrastructure for syntactic and semantic unification. Unification is characterized by a high-speed temporal profile including both prediction and integration of retrieved lexical elements. A meta-analysis of numerous neuroimaging studies reveals a clear dorsal/ventral gradient in both left inferior frontal cortex and left posterior temporal cortex, with dorsal foci for syntactic processing and ventral foci for semantic processing. In addition to core areas for unification, further networks need to be recruited to realize language-driven communication to its full extent. One example is the theory of mind network, which allows listeners and readers to infer the intended message (speaker meaning) from the coded meaning of the linguistic utterance. This indicates that sensorimotor simulation cannot handle all of language processing.

Abstract

The use of virtual reality (VR) as a methodological tool is
becoming increasingly popular in behavioural research due
to its seemingly limitless possibilities. This new method has
not been used frequently in the field of psycholinguistics,
however, possibly due to the assumption that humancomputer
interaction does not accurately reflect human-human
interaction. In the current study we compare participants’
language behaviour in a syntactic priming task with human
versus avatar partners. Our study shows comparable priming
effects between human and avatar partners (Human: 12.3%;
Avatar: 12.6% for passive sentences) suggesting that VR is a
valid platform for conducting language research and studying
dialogue interactions.

Abstract

In human face-to-face communication, language comprehension is a multi-modal, situated activity. However, little is known about how we combine information from different modalities during comprehension, and how perceived communicative intentions, often signaled through visual signals, influence this process. We explored this question by simulating a multi-party communication context in which a speaker alternated her gaze between two recipients. Participants viewed speech-only or speech + gesture object-related messages when being addressed (direct gaze) or unaddressed (gaze averted to other participant). They were then asked to choose which of two object images matched the speaker’s preceding message. Unaddressed recipients responded significantly more slowly than addressees for speech-only utterances. However, perceiving the same speech accompanied by gestures sped unaddressed recipients up to a level identical to that of addressees. That is, when unaddressed recipients’ speech processing suffers, gestures can enhance the comprehension of a speaker’s message. We discuss our findings with respect to two hypotheses attempting to account for how social eye gaze may modulate multi-modal language comprehension.

Abstract

Most words that infants hear occur within fluent speech. To compile a vocabulary, infants therefore need to segment words from speech contexts. This study is the first to investigate whether infants (here: 10-month-olds) can recognize words when both initial exposure and test presentation are in continuous speech. Electrophysiological evidence attests that this indeed occurs: An increased extended negativity (word recognition effect) appears for familiarized target words relative to control words. This response proved constant at the individual level: Only infants who showed this negativity at test had shown such a response, within six repetitions after first occurrence, during familiarization.

Abstract

Morphology is the aspect of language concerned with the internal structure of words. In the past decades, a large body of masked priming (behavioral and neuroimaging) data has suggested that the visual word recognition system automatically decomposes any morphologically complex word into a stem and its constituent morphemes. Yet the reliance of morphology on other reading processes (e.g., orthography and semantics), as well as its underlying neuronal mechanisms are yet to be determined. In the current magnetoencephalography study, we addressed morphology from the perspective of the unification framework, that is, by applying the Hold/Release paradigm, morphological unification was simulated via the assembly of internal morphemic units into a whole word. Trials representing real words were divided into words with a transparent (true) or a nontransparent (pseudo) morphological relationship. Morphological unification of truly suffixed words was faster and more accurate and additionally enhanced induced oscillations in the narrow gamma band (60–85 Hz, 260–440 ms) in the left posterior occipitotemporal junction. This neural signature could not be explained by a mere automatic lexical processing (i.e., stem perception), but more likely it related to a semantic access step during the morphological unification process. By demonstrating the validity of unification at the morphological level, this study contributes to the vast empirical evidence on unification across other language processes. Furthermore, we point out that morphological unification relies on the retrieval of lexical semantic associations via induced gamma band oscillations in a cerebral hub region for visual word form processing.

Abstract

We report on an fMRI syntactic priming experiment in which we measure brain activity for participants who communicate with another participant outside the scanner. We investigated whether syntactic processing during overt language production and comprehension is influenced by having a (shared) goal to communicate. Although theory suggests this is true, the nature of this influence remains unclear. Two hypotheses are tested: i. syntactic priming effects (fMRI and RT) are stronger for participants in the communicative context than for participants doing the same experiment in a non-communicative context, and ii. syntactic priming magnitude (RT) is correlated with the syntactic priming magnitude of the speaker’s communicative partner. Results showed that across conditions, participants were faster to produce sentences with repeated syntax, relative to novel syntax. This behavioral result converged with the fMRI data: we found repetition suppression effects in the left insula extending into left inferior frontal gyrus (BA 47/45), left middle temporal gyrus (BA 21), left inferior parietal cortex (BA 40), left precentral gyrus (BA 6), bilateral precuneus (BA 7), bilateral supplementary motor cortex (BA 32/8) and right insula (BA 47). We did not find support for the first hypothesis: having a communicative intention does not increase the magnitude of syntactic priming effects (either in the brain or in behavior) per se. We did find support for the second hypothesis: if speaker A is strongly/weakly primed by speaker B, then speaker B is primed by speaker A to a similar extent. We conclude that syntactic processing is influenced by being in a communicative context, and that the nature of this influence is bi-directional: speakers are influenced by each other.

Abstract

Speakers sometimes repeat syntactic structures across sentences, a phenomenon called syntactic priming. We investigated the influence of verb-bound syntactic preferences on syntactic priming effects in response choices and response latencies for German ditransitive sentences. In the response choices we found inverse preference effects: There were stronger syntactic priming effects for primes in the less preferred structure, given the syntactic preference of the prime verb. In the response latencies we found positive preference effects: There were stronger syntactic priming effects for primes in the more preferred structure, given the syntactic preference of the prime verb. These findings provide further support for the idea that syntactic processing is lexically guided.

Abstract

An ability to decode semantic information from fMRI spatial patterns has been demonstrated in previous studies mostly for 1 specific input modality. In this study, we aimed to decode semantic category independent of the modality in which an object was presented. Using a searchlight method, we were able to predict the stimulus category from the data while participants performed a semantic categorization task with 4 stimulus modalities (spoken and written names, photographs, and natural sounds). Significant classification performance was achieved in all 4 modalities. Modality-independent decoding was implemented by training and testing the searchlight method across modalities. This allowed the localization of those brain regions, which correctly discriminated between the categories, independent of stimulus modality. The analysis revealed large clusters of voxels in the left inferior temporal cortex and in frontal regions. These voxels also allowed category discrimination in a free recall session where subjects recalled the objects in the absence of external stimuli. The results show that semantic information can be decoded from the fMRI signal independently of the input modality and have clear implications for understanding the functional mechanisms of semantic memory.

Abstract

How can we understand each other during communicative interactions? An influential suggestion holds that communicators are primed by each other’s behaviors, with associative mechanisms automatically coordinating the production of communicative signals and the comprehension of their meanings. An alternative suggestion posits that mutual understanding requires shared conceptualizations of a signal’s use, i.e., “conceptual pacts” that are abstracted away from specific experiences. Both accounts predict coherent neural dynamics across communicators, aligned either to the occurrence of a signal or to the dynamics of conceptual pacts. Using coherence spectral-density analysis of cerebral activity simultaneously measured in pairs of communicators, this study shows that establishing mutual understanding of novel signals synchronizes cerebral dynamics across communicators’ right temporal lobes. This interpersonal cerebral coherence occurred only within pairs with a shared communicative history, and at temporal scales independent from signals’ occurrences. These findings favor the notion that meaning emerges from shared conceptualizations of a signal’s use.

Abstract

Despite the ambiguity inherent in human communication, people are remarkably efficient in establishing mutual understanding. Studying how people communicate in novel settings provides a window into the mechanisms supporting the human competence to rapidly generate and understand novel shared symbols, a fundamental property of human communication. Previous work indicates that the right posterior superior temporal sulcus (pSTS) is involved when people understand the intended meaning of novel communicative actions. Here, we set out to test whether normal functioning of this cerebral structure is required for understanding novel communicative actions using inhibitory low-frequency repetitive transcranial magnetic stimulation (rTMS). A factorial experimental design contrasted two tightly matched stimulation sites (right pSTS vs. left MT+, i.e. a contiguous homotopic task-relevant region) and tasks (a communicative task vs. a visual tracking task that used the same sequences of stimuli). Overall task performance was not affected by rTMS, whereas changes in task performance over time were disrupted according to TMS site and task combinations. Namely, rTMS over pSTS led to a diminished ability to improve action understanding on the basis of recent communicative history, while rTMS over MT+ perturbed improvement in visual tracking over trials. These findings qualify the contributions of the right pSTS to human communicative abilities, showing that this region might be necessary for incorporating previous knowledge, accumulated during interactions with a communicative partner, to constrain the inferential process that leads to action understanding.

Abstract

To investigate the neural underpinnings of word decoding, and how it changes as a function of repeated exposure, we trained Dutch participants repeatedly over the course of a month of training to articulate a set of novel disyllabic input strings written in Greek script to avoid the use of familiar orthographic representations. The syllables in the input were phonotactically legal combinations but non-existent in the Dutch language, allowing us to assess their role in novel word decoding. Not only trained disyllabic pseudowords were tested but also pseudowords with recombined patterns of syllables to uncover the emergence of syllabic representations. We showed that with extensive training, articulation became faster and more accurate for the trained pseudowords. On the neural level, the initial stage of decoding was reflected by increased activity in visual attention areas of occipito-temporal and occipito-parietal cortices, and in motor coordination areas of the precentral gyrus and the inferior frontal gyrus. After one month of training, memory representations for holistic information (whole word unit) were established in areas encompassing the angular gyrus, the precuneus and the middle temporal gyrus. Syllabic representations also emerged through repeated training of disyllabic pseudowords, such that reading recombined syllables of the trained pseudowords showed similar brain activation to trained pseudowords and were articulated faster than novel combinations of letter strings used in the trained pseudowords.

Abstract

In this fMRI study we investigate the neural correlates of information structure integration during sentence comprehension in Dutch. We looked into how prosodic cues (pitch accents) that signal the information status of constituents to the listener (new information) are combined with other types of information during the unification process. The difficulty of unifying the prosodic cues into overall sentence meaning was manipulated by constructing sentences in which the pitch accent did (focus-accent agreement), and sentences in which the pitch accent did not (focus-accent disagreement) match the expectations for focus constituents of the sentence. In case of a mismatch, the load on unification processes increases. Our results show two anatomically distinct effects of focus-accent disagreement, one located in the posterior left inferior frontal gyrus (LIFG, BA6/44), and one in the more anterior-ventral LIFG (BA 47/45). Our results confirm that information structure is taken into account during unification, and imply an important role for the LIFG in unification processes, in line with previous fMRI studies.