Publications

Abstract

At least three cognitive brain components are necessary in order for us to be able to produce and comprehend language: a Memory repository for the lexicon, a Unification buffer where lexical information is combined into novel structures, and a Control apparatus presiding over executive function in language. Here we describe the brain networks that support Memory and Unification in semantics. A dynamic account of their interactions is presented, in which a balance between the two components is sought at each word-processing step. We use the theory to provide an explanation of the N400 effect.

Abstract

Many children with Specific Language Impairment (SLI) show impairments in discriminating auditorily presented stimuli. The present study investigates whether these discrimination problems are speech specific or of a general auditory nature. This was studied by using a linguistic and nonlinguistic contrast that were matched for acoustic complexity in an active behavioral task and a passive ERP paradigm, known to elicit the mismatch negativity (MMN). In addition, attention skills and a variety of language skills were measured. Participants were 25 five-year-old Dutch children with SLI having receptive as well as productive language problems and 25 control children with typical speechand language development. At the behavioral level, the SLI group was impaired in discriminating the linguistic contrast as compared to the control group, while both groups were unable to distinguish the non-linguistic contrast. Moreover, the SLI group tended to have impaired attention skills which correlated with performance on most of the language tests. At the neural level, the SLI group, in contrast to the control group, did not show an MMN in response to either the linguistic or nonlinguistic contrast. The MMN data are consistent with an account that relates the symptoms in children with SLI to non-speech processing difficulties.

Abstract

The first objective of this study was to compare the brain network engaged by preference classification and the standard grammaticality classification after implicit artificial syntax acquisition by re-analyzing previously reported event-related fMRI data. The results show that preference and grammaticality classification engage virtually identical brain networks, including Broca’s region, consistent with previous behavioral findings. Moreover, the results showed that the effects related to artificial syntax in Broca’s region were essentially the same when masked with variability related to natural syntax processing in the same participants. The second objective was to explore CNTNAP2-related effects in implicit artificial syntax learning by analyzing behavioral and event-related fMRI data from a subsample. The CNTNAP2 gene has been linked to specific language impairment and is controlled by the FOXP2 transcription factor. CNTNAP2 is expressed in language related brain networks in the developing human brain and the FOXP2–CNTNAP2 pathway provides a mechanistic link between clinically distinct syndromes involving disrupted language. Finally, we discuss the implication of taking natural language to be a neurobiological system in terms of bounded recursion and suggest that the left inferior frontal region is a generic on-line sequence processor that unifies information from various sources in an incremental and recursive manner.

Abstract

During face-to-face communication, one does not only hear speech but also see a speaker's communicative hand movements. It has been shown that such hand gestures play an important role in communication where the two modalities influence each other's interpretation. A gesture typically temporally overlaps with coexpressive speech, but the gesture is often initiated before (but not after) the coexpressive speech. The present ERP study investigated what degree of asynchrony in the speech and gesture onsets are optimal for semantic integration of the concurrent gesture and speech. Videos of a person gesturing were combined with speech segments that were either semantically congruent or incongruent with the gesture. Although gesture and speech always overlapped in time, gesture and speech were presented with three different degrees of asynchrony. In the SOA 0 condition, the gesture onset and the speech onset were simultaneous. In the SOA 160 and 360 conditions, speech was delayed by 160 and 360 msec, respectively. ERPs time locked to speech onset showed a significant difference between semantically congruent versus incongruent gesture–speech combinations on the N400 for the SOA 0 and 160 conditions. No significant difference was found for the SOA 360 condition. These results imply that speech and gesture are integrated most efficiently when the differences in onsets do not exceed a certain time span because of the fact that iconic gestures need speech to be disambiguated in a way relevant to the speech context.

Abstract

Whether the brain’s speech-production system is also involved in speech comprehension is a topic of much debate. Research has focused on whether motor areas are involved in listening, but overlap between speaking and listening might occur not only at primary sensory and motor levels, but also at linguistic levels (where semantic, lexical, and syntactic processes occur). Using functional MRI adaptation during speech comprehension and production, we found that the brain areas involved in semantic, lexical, and syntactic processing are mostly the same for speaking and for listening. Effects of primary processing load (indicative of sensory and motor processes) overlapped in auditory cortex and left inferior frontal cortex, but not in motor cortex, where processing load affected activity only in speaking. These results indicate that the linguistic parts of the language system are used for both speaking and listening, but that the motor system does not seem to provide a crucial contribution to listening.

Abstract

Defeasible inferences are inferences that can be revised in the light of new information. Although defeasible inferences are pervasive in everyday communication, little is known about how and when they are processed by the brain. This study examined the electrophysiological signature of defeasible reasoning using a modified version of the suppression task. Participants were presented with conditional inferences (of the type “if p, then q; p, therefore q”) that were preceded by a congruent or a disabling context. The disabling context contained a possible exception or precondition that prevented people from drawing the conclusion. Acceptability of the conclusion was indeed lower in the disabling condition compared to the congruent condition. Further, we found a large sustained negativity at the conclusion of the disabling condition relative to the congruent condition, which started around 250 msec and was persistent throughout the entire epoch. Possible accounts for the observed effect are discussed.

Abstract

Work on animals indicates that BOLD is preferentially sensitive to local field potentials, and that it correlates most strongly with gamma band neuronal synchronization. Here we investigate how the BOLD signal in humans performing a cognitive task is related to neuronal synchronization across different frequency bands. We simultaneously recorded EEG and BOLD while subjects engaged in a visual attention task known to induce sustained changes in neuronal synchronization across a wide range of frequencies. Trial-by-trial BOLD luctuations correlated positively with trial-by-trial fluctuations in high-EEG gamma power (60–80 Hz) and negatively with alpha and beta power. Gamma power on the one hand, and alpha and beta power on the other hand, independently contributed to explaining BOLD variance. These results indicate that the BOLD-gamma coupling observed in animals can be extrapolated to humans performing a task and that neuronal dynamics underlying high- and low-frequency synchronization contribute independently to the BOLD signal.

Abstract

Speakers tend to repeat syntactic structures across sentences, a phenomenon called syntactic priming. Although it has been suggested that repeating syntactic structures should result in speeded responses, previous research has focused on effects in response tendencies. We investigated syntactic priming effects simultaneously in response tendencies and response latencies for active and passive transitive sentences in a picture description task. In Experiment 1, there were priming effects in response tendencies for passives and in response latencies for actives. However, when participants' pre-existing preference for actives was altered in Experiment 2, syntactic priming occurred for both actives and passives in response tendencies as well as in response latencies. This is the first investigation of the effects of structure frequency on both response tendencies and latencies in syntactic priming. We discuss the implications of these data for current theories of syntactic processing.

Abstract

In individuals with ASD, difficulties with language comprehension are most evident when higher-level semantic-pragmatic language processing is required, for instance when context has to be used to interpret the meaning of an utterance. Until now, it is unclear at what level of processing and for what type of context these difficulties in language comprehension occur. Therefore, in the current fMRI study, we investigated the neural correlates of the integration of contextual information during auditory language comprehension in 24 adults with ASD and 24 matched control participants. Different levels of context processing were manipulated by using spoken sentences that were correct or contained either a semantic or world knowledge anomaly. Our findings demonstrated significant differences between the groups in inferior frontal cortex that were only present for sentences with a world knowledge anomaly. Relative to the ASD group, the control group showed significantly increased activation in left inferior frontal gyrus (LIFG) for sentences with a world knowledge anomaly compared to correct sentences. This effect possibly indicates reduced integrative capacities of the ASD group. Furthermore, world knowledge anomalies elicited significantly stronger activation in right inferior frontal gyrus (RIFG) in the control group compared to the ASD group. This additional RIFG activation probably reflects revision of the situation model after new, conflicting information. The lack of recruitment of RIFG is possibly related to difficulties with exception handling in the ASD group.

Abstract

Synesthesia provides an elegant model to investigate neural mechanisms underlying individual differences in subjective experience in humans. In grapheme–color synesthesia, written letters induce color sensations, accompanied by activation of color area V4. Competing hypotheses suggest that enhanced V4 activity during synesthesia is either induced by direct bottom-up cross-activation from grapheme processing areas within the fusiform gyrus, or indirectly via higher-order parietal areas. Synesthetes differ in the way synesthetic color is perceived: “projector” synesthetes experience color externally colocalized with a presented grapheme, whereas “associators” report an internally evoked association. Using dynamic causal modeling for fMRI, we show that V4 cross-activation during synesthesia was induced via a bottom-up pathway (within fusiform gyrus) in projector synesthetes, but via a top-down pathway (via parietal lobe) in associators. These findings show how altered coupling within the same network of active regions leads to differences in subjective experience. Our findings reconcile the two most influential cross-activation accounts of synesthesia.

Abstract

To highlight relevant information in dialogues, both wh-question context and pitch accent in answers can be used, such that focused information gains more attention and is processed more elaborately. To evaluate the relative influence of context and pitch accent on the depth of semantic processing, we measured Event-Related Potentials (ERPs) to auditorily presented wh-question-answer pairs. A semantically incongruent word in the answer occurred either in focus or non-focus position as determined by the context, and this word was either accented or unaccented. Semantic incongruency elicited different N400 effects in different conditions. The largest N400 effect was found when the question-marked focus was accented, while the other three conditions elicited smaller N400 effects. The results suggest that context and accentuation interact. Thus accented focused words were processed more deeply compared to conditions where focus and accentuation mismatched, or when the new information had no marking. In addition, there seems to be sex differences in the depth of semantic processing. For males, a significant N400 effect was observed only when the question-marked focus was accented, reduced N400 effects were found in the other dialogues. In contrast, females produced similar N400 effects in all the conditions. These results suggest that regardless of external cues, females tend to engage in more elaborate semantic processing compared to males.

Abstract

We investigated how visual and linguistic information interact in the perception of emotion. We borrowed a phenomenon from film theory which states that presentation of an as such neutral visual scene intensifies the percept of fear or suspense induced by a different channel of information, such as language. Our main aim was to investigate how neutral visual scenes can enhance responses to fearful language content in parts of the brain involved in the perception of emotion. Healthy participants’ brain activity was measured (using functional magnetic resonance imaging) while they read fearful and less fearful sentences presented with or without a neutral visual scene. The main idea is that the visual scenes intensify the fearful content of the language by subtly implying and concretizing what is described in the sentence. Activation levels in the right anterior temporal pole were selectively increased when a neutral visual scene was paired with a fearful sentence, compared to reading the sentence alone, as well as to reading of non-fearful sentences presented with the same neutral scene. We conclude that the right anterior temporal pole serves a binding function of emotional information across domains such as visual and linguistic information.

Abstract

A debated issue in the relationship between language and thought is how our linguistic abilities are involved in understanding the intentions of others (‘mentalizing’). The results of both theoretical and empirical work have been used to argue that linguistic, and more specifically, grammatical, abilities are crucial in representing the mental states of others. Here we contribute to this debate by investigating how damage to the language system influences the generation and understanding of intentional communicative behaviors. Four patients with pervasive language difficulties (severe global or agrammatic aphasia) engaged in an experimentally controlled non-verbal communication paradigm, which required signaling and understanding a communicative message. Despite their profound language problems they were able to engage in recipient design as well as intention recognition, showing similar indicators of mentalizing as have been observed in the neurologically healthy population. Our results show that aspects of the ability to communicate remain present even when core capacities of the language system are dysfunctional

Abstract

Humans imitate each other during social interaction. This imitative behavior streamlines social interaction and aids in learning to replicate actions. However, the effect of imitation on action comprehension is unclear. This study investigated whether vocal imitation of an unfamiliar accent improved spoken-language comprehension. Following a pretraining accent comprehension test, participants were assigned to one of six groups. The baseline group received no training, but participants in the other five groups listened to accented sentences, listened to and repeated accented sentences in their own accent, listened to and transcribed accented sentences, listened to and imitated accented sentences, or listened to and imitated accented sentences without being able to hear their own vocalizations. Posttraining measures showed that accent comprehension was most improved for participants who imitated the speaker’s accent. These results show that imitation may aid in streamlining interaction by improving spoken-language comprehension under adverse listening conditions.

Abstract

Research in psycholinguistics and in the cognitive neuroscience of language has suggested that semantic and syntactic integration are associated with different neurophysiologic correlates, such as the N400 and the P600 in the ERPs. However, only a handful of studies have investigated the neural basis of the syntax–semantics interface, and even fewer experiments have dealt with the cases in which semantic composition can proceed independently of the syntax. Here we looked into one such case—complement coercion—using ERPs. We compared sentences such as, “The journalist wrote the article” with “The journalist began the article.” The second sentence seems to involve a silent semantic element, which is expressed in the first sentence by the head of the VP “wrote the article.” The second type of construction may therefore require the reader to infer or recover from memory a richer event sense of the VP “began the article,” such as began writing the article, and to integrate that into a semantic representation of the sentence. This operation is referred to as “complement coercion.” Consistently with earlier reading time, eye tracking, and MEG studies, we found traces of such additional computations in the ERPs: Coercion gives rise to a long-lasting negative shift, which differs at least in duration from a standard N400 effect. Issues regarding the nature of the computation involved are discussed in the light of a neurocognitive model of language processing and a formal semantic analysis of coercion.

Abstract

There is growing evidence suggesting that synchronization changes in the oscillatory neuronal dynamics in the EEG or MEG reflect the transient coupling and uncoupling of functional networks related to different aspects of language comprehension. In this work, we examine how sentence-level syntactic unification operations are reflected in the oscillatory dynamics of the MEG. Participants read sentences that were either correct, contained a word category violation, or were constituted of random word sequences devoid of syntactic structure. A time-frequency analysis of MEG power changes revealed three types of effects. The first type of effect was related to the detection of a (word category) violation in a syntactically structured sentence, and was found in the alpha and gamma frequency bands. A second type of effect was maximally sensitive to the syntactic manipulations: A linear increase in beta power across the sentence was present for correct sentences, was disrupted upon the occurrence of a word category violation, and was absent in syntactically unstructured random word sequences. We therefore relate this effect to syntactic unification operations. Thirdly, we observed a linear increase in theta power across the sentence for all syntactically structured sentences. The effects are tentatively related to the building of a working memory trace of the linguistic input. In conclusion, the data seem to suggest that syntactic unification is reflected by neuronal synchronization in the lower-beta frequency band.

Abstract

An MEG experiment was carried out in order to compare the processing of lexical-tonal and intonational contrasts, based on the tonal dialect of Roermond (the Netherlands). A set of words with identical phoneme sequences but distinct pitch contours, which represented different lexical meanings or discourse meanings (statement vs. question), were presented to native speakers as well as to a control group of speakers of Standard Dutch, a non-tone language. The stimuli were arranged in a mismatch paradigm, under three experimental conditions: in the first condition (lexical), the pitch contour differences between standard and deviant stimuli reflected differences between lexical meanings; in the second condition (intonational), the stimuli differed in their discourse meaning; in the third condition (combined), they differed both in their lexical and discourse meaning. In all three conditions, native as well as non-native responses showed a clear MMNm (magnetic mismatch negativity) in a time window from 150 to 250 ms after the divergence point of standard and deviant pitch contours. In the lexical condition, a stronger response was found over the left temporal cortex of native as well as non-native speakers. In the intonational condition, the same activation pattern was observed in the control group, but not in the group of native speakers, who showed a right-hemisphere dominance instead. Finally, in the combined (lexical and intonational) condition, brain reactions appeared to represent the summation of the patterns found in the other two conditions. In sum, the lateralization of pitch processing is condition-dependent in the native group only, which suggests that language experience determines how processes should be distributed over both temporal cortices, according to the functions available in the grammar.

Abstract

Language in high-functioning autism is characterized by pragmatic and semantic deficits, and people with autism have a reduced tendency to integrate information. Because the left and right inferior frontal (LIF and RIF) regions are implicated with integration of speaker information, world knowledge, and semantic knowledge, we hypothesized that abnormal functioning of the LIF and RIF regions might contribute to pragmatic and semantic language deficits in autism. Brain activation of sixteen 12- to 18-year-old, high-functioning autistic participants was measured with functional magnetic resonance imaging during sentence comprehension and compared with that of twenty-six matched controls. The content of the pragmatic sentence was congruent or incongruent with respect to the speaker characteristics (male/female, child/adult, and upper class/lower class). The semantic- and world-knowledge sentences were congruent or incongruent with respect to semantic expectancies and factual expectancies about the world, respectively. In the semanticknowledge and world-knowledge condition, activation of the LIF region did not differ between groups. In sentences that required integration of speaker information, the autism group showed abnormally reduced activation of the LIF region. The results suggest that people with autism may recruit the LIF region in a different manner in tasks that demand integration of social information.

Abstract

In order to investigate conflicts between semantics and syntax, we recorded ERPs, while participants read Dutch sentences. Sentences containing conflicts between syntax and semantics (Fred eats in a sandwich…/ Fred eats a restaurant…) elicited an N400. These results show that conflicts between syntax and semantics not necessarily lead to P600 effects and are in line with the processing competition account. According to this parallel account the syntactic and semantic processing streams are fully interactive and information from one level can influence the processing at another level. The relative strength of the cues of the processing streams determines which level is affected most strongly by the conflict. The processing competition account maintains the distinction between the N400 as index for semantic processing and the P600 as index for structural processing.

Abstract

We know a great deal about the neurophysiological mechanisms supporting instrumental actions, i.e. actions designed to alter the physical state of the environment. In contrast, little is known about our ability to select communicative actions, i.e. actions directly designed to modify the mental state of another agent. We have recently provided novel empirical evidence for a mechanism in which a communicator selects his actions on the basis of a prediction of the communicative intentions that an addressee is most likely to attribute to those actions. The main novelty of those finding was that this prediction of intention recognition is cerebrally implemented within the intention recognition system of the communicator, is modulated by the ambiguity in meaning of the communicative acts, and not by their sensorimotor complexity. The characteristics of this predictive mechanism support the notion that human communicative abilities are distinct from both sensorimotor and linguistic processes.

Abstract

Several studies have demonstrated that people with ASD and intact language skills still have problems processing linguistic information in context. Given this evidence for reduced sensitivity to linguistic context, the question arises how contextual information is actually processed by people with ASD. In this study, we used event-related brain potentials (ERPs) to examine context sensitivity in high-functioning adults with autistic disorder (HFA) and Asperger syndrome at two levels: at the level of sentence processing and at the level of solving reasoning problems. We found that sentence context as well as reasoning context had an immediate ERP effect in adults with Asperger syndrome, as in matched controls. Both groups showed a typical N400 effect and a late positive component for the sentence conditions, and a sustained negativity for the reasoning conditions. In contrast, the HFA group demonstrated neither an N400 effect nor a sustained negativity. However, the HFA group showed a late positive component which was larger for semantically anomalous sentences than congruent sentences. Because sentence context had a modulating effect in a later phase, semantic integration is perhaps less automatic in HFA, and presumably more elaborate processes are needed to arrive at a sentence interpretation.

Abstract

Human communication is often thought about in terms of transmitted messages in a conventional code like a language. But communication requires a specialized interactive intelligence. Senders have to be able to perform recipient design, while receivers need to be able to do intention recognition, knowing that recipient design has taken place. To study this interactive intelligence in the lab, we developed a new task that taps directly into the underlying abilities to communicate in the absence of a conventional code. We show that subjects are remarkably successful communicators under these conditions, especially when senders get feedback from receivers. Signaling is accomplished by the manner in which an instrumental action is performed, such that instrumentally dysfunctional components of an action are used to convey communicative intentions. The findings have important implications for the nature of the human communicative infrastructure, and the task opens up a line of experimentation on human communication.

Abstract

Multivariate pattern analysis is a technique that allows the decoding of conceptual information such as the semantic category of a perceived object from neuroimaging data. Impressive single-trial classification results have been reported in studies that used fMRI. Here, we investigate the possibility to identify conceptual representations from event-related EEG based on the presentation of an object in different modalities: its spoken name, its visual representation and its written name. We used Bayesian logistic regression with a multivariate Laplace prior for classification. Marked differences in classification performance were observed for the tested modalities. Highest accuracies (89% correctly classified trials) were attained when classifying object drawings. In auditory and orthographical modalities, results were lower though still significant for some subjects. The employed classification method allowed for a precise temporal localization of the features that contributed to the performance of the classifier for three modalities. These findings could help to further understand the mechanisms underlying conceptual representations. The study also provides a first step towards the use of concept decoding in the context of real-time brain-computer interface applications.

Abstract

In a recent fMRI study we showed that left posterior middle temporal gyrus (LpMTG) subserves the retrieval of a word's lexical-syntactic properties from the mental lexicon (long-term memory), while left posterior inferior frontal gyrus (LpIFG) is involved in unifying (on-line integration of) this information into a sentence structure (Snijders et al., 2009). In addition, the right IFG, right MTG, and the right striatum were involved in the unification process. Here we report results from a psychophysical interactions (PPI) analysis in which we investigated the effective connectivity between LpIFG and LpMTG during unification, and how the right hemisphere areas and the striatum are functionally connected to the unification network. LpIFG and LpMTG both showed enhanced connectivity during the unification process with a region slightly superior to our previously reported LpMTG. Right IFG better predicted right temporal activity when unification processes were more strongly engaged, just as LpIFG better predicted left temporal activity. Furthermore, the striatum showed enhanced coupling to LpIFG and LpMTG during unification. We conclude that bilateral inferior frontal and posterior temporal regions are functionally connected during sentence-level unification. Cortico-subcortical connectivity patterns suggest cooperation between inferior frontal and striatal regions in performing unification operations on lexical-syntactic representations retrieved from LpMTG.

Abstract

Background: In synaesthesia, sensations in a particular modality cause additional experiences in a second, unstimulated modality (e.g., letters elicit colour). Understanding how synaesthesia is mediated in the brain can help to understand normal processes of perceptual awareness and multisensory integration. In several neuroimaging studies, enhanced brain activity for grapheme-colour synaesthesia has been found in ventral-occipital areas that are also involved in real colour processing. Our question was whether the neural correlates of synaesthetically induced colour and real colour experience are truly shared. Methodology/Principal Findings: First, in a free viewing functional magnetic resonance imaging (fMRI) experiment, we located main effects of synaesthesia in left superior parietal lobule and in colour related areas. In the left superior parietal lobe, individual differences between synaesthetes (projector-associator distinction) also influenced brain activity, confirming the importance of the left superior parietal lobe for synaesthesia. Next, we applied a repetition suppression paradigm in fMRI, in which a decrease in the BOLD (blood-oxygenated-level-dependent) response is generally observed for repeated stimuli. We hypothesized that synaesthetically induced colours would lead to a reduction in BOLD response for subsequently presented real colours, if the neural correlates were overlapping. We did find BOLD suppression effects induced by synaesthesia, but not within the colour areas. Conclusions/Significance: Because synaesthetically induced colours were not able to suppress BOLD effects for real colour, we conclude that the neural correlates of synaesthetic colour experience and real colour experience are not fully shared. We propose that synaesthetic colour experiences are mediated by higher-order visual pathways that lie beyond the scope of classical, ventral-occipital visual areas. Feedback from these areas, in which the left parietal cortex is likely to play an important role, may induce V4 activation and the percept of synaesthetic colour.

Abstract

According to theories of embodied cognition, understanding a verb like throw involves unconsciously simulating the action of throwing, using areas of the brain that support motor planning. If understanding action words involves mentally simulating one’s own actions, then the neurocognitive representation of word meanings should differ for people with different kinds of bodies, who perform actions in systematically different ways. In a test of the body-specificity hypothesis, we used functional magnetic resonance imaging to compare premotor activity correlated with action verb understanding in right- and left-handers. Righthanders preferentially activated the left premotor cortex during lexical decisions on manual-action verbs (compared with nonmanual-action verbs), whereas left-handers preferentially activated right premotor areas. This finding helps refine theories of embodied semantics, suggesting that implicit mental simulation during language processing is body specific: Right- and lefthanders, who perform actions differently, use correspondingly different areas of the brain for representing action verb meanings.

Abstract

The left-hemisphere dominance for language is a core example of the functional specialization of the cerebral hemispheres. The degree of left-hemisphere dominance for language depends on hand preference: Whereas the majority of right-handers show left-hemispheric language lateralization, this number is reduced in left-handers. Here, we assessed whether handedness analogously has an influence upon lateralization in the visual system. Using functional magnetic resonance imaging, we localized 4 more or less specialized extrastriate areas in left- and right-handers, namely fusiform face area (FFA), extrastriate body area (EBA), fusiform body area (FBA), and human motion area (human middle temporal [hMT]). We found that lateralization of FFA and EBA depends on handedness: These areas were right lateralized in right-handers but not in left-handers. A similar tendency was observed in FBA but not in hMT. We conclude that the relationship between handedness and hemispheric lateralization extends to functionally lateralized parts of visual cortex, indicating a general coupling between cerebral lateralization and handedness. Our findings indicate that hemispheric specialization is not fixed but can vary considerably across individuals even in areas engaged relatively early in the visual system.

Abstract

Although language is an effective vehicle for communication, it is unclear how linguistic and communicative abilities relate to each other. Some researchers have argued that communicative message generation involves perspective taking (mentalizing), and—crucially—that mentalizing depends on language. We employed a verbal communication paradigm to directly test whether the generation of a communicative action relies on mentalizing and whether the cerebral bases of communicative message generation are distinct from parts of cortex sensitive to linguistic variables. We found that dorsomedial prefrontal cortex, a brain area consistently associated with mentalizing, was sensitive to the communicative intent of utterances, irrespective of linguistic difficulty. In contrast, left inferior frontal cortex, an area known to be involved in language, was sensitive to the linguistic demands of utterances, but not to communicative intent. These findings show that communicative and linguistic abilities rely on cerebrally (and computationally) distinct mechanisms

Abstract

Here we review evidence from cognitive neuroscience for a tight relation between language and action in the brain. We focus on two types of relation between language and action. First, we investigate whether the perception of speech and speech sounds leads to activation of parts of the cortical motor system also involved in speech production. Second, we evaluate whether understanding action-related language involves the activation of parts of the motor system. We conclude that whereas there is considerable evidence that understanding language can involve parts of our motor cortex, this relation is best thought of as inherently flexible. As we explain, the exact nature of the input as well as the intention with which language is perceived influences whether and how motor cortex plays a role in language processing.

Abstract

According to embodied theories of language, people understand a verb like throw, at least in part, by mentally simulating throwing. This implicit simulation is often assumed to be similar or identical to motor imagery. Here we used fMRI totest whether implicit simulations of actions during language understanding involve the same cortical motor regions as explicit motor imagery Healthy participants were presented with verbs related to hand actions (e.g., to throw) and nonmanual actions (e.g., to kneel). They either read these verbs (lexical decision task) or actively imagined performing the actions named by the verbs (imagery task). Primary motor cortex showd effector-specific activation during imagery, but not during lexical decision. Parts of premotor cortex distinguished manual from nonmanual actions during both lexical decision and imagery, but there was no overlap or correlation between regions activated during the two tasks. These dissociations suggest that implicit simulation and explicit imagery cued by action verbs may involve different types of motor representations and that the construct of “mental simulation” should be distinguished from “mental imagery” in embodied theories of language.

Abstract

We performed a resting-state functional connectivity study to investigate directly the functional correlations within the perisylvian language networks by seeding from 3 subregions of Broca's complex (pars opercularis, pars triangularis, and pars orbitalis) and their right hemisphere homologues. A clear topographical functional connectivity pattern in the left middle frontal, parietal, and temporal areas was revealed for the 3 left seeds. This is the first demonstration that a functional connectivity topology can be observed in the perisylvian language networks. The results support the assumption of the functional division for phonology, syntax, and semantics of Broca's complex as proposed by the memory, unification, and control (MUC) model and indicated a topographical functional organization in the perisylvian language networks, which suggests a possible division of labor for phonological, syntactic, and semantic function in the left frontal, parietal, and temporal areas.