Activations of "motor" and other non-language structures during sentence comprehension

Receptive language and receptive-expressive discrepancy in minimally verbal autistic children and adolescents

Among the approximately one-third of autistic individuals who experience considerable challenges in acquiring spoken language and are minimally verbal (MV), relatively little is known about the range of their receptive language abilities. This study included 1579 MV autistic children and adolescents between 5 and 18 years of age drawn from the National Database for Autism Research and the SFARI Base data repository. MV autistic children and adolescents demonstrated significantly lower receptive language compared to the norms on standardized language assessment and parent report measures. Moreover, their receptive language gap widened with age. Overall, our sample demonstrated significantly better receptive than expressive language. However, at the individual level, only about 25% of MV autistic children and adolescents demonstrated significantly better receptive language relative to their minimal expressive levels. Social skills explained a significant proportion of the variance in parent-reported receptive language skills, while motor skills were the most significant predictor of greater receptive-expressive discrepancy. Findings from this study revealed the heterogeneous language profiles in MV autistic children and adolescents, underscoring the importance of individualizing interventions to match their different communication strengths and needs and integrating multiple interconnected areas to optimize their overall development of language comprehension, socialization, and general motor skills.

Reinvestigating the Neural Bases Involved in Speech Production of Stutterers: An ALE Meta-Analysis

Background: Stuttering is characterized by dysfluency and difficulty in speech production. Previous research has found abnormalities in the neural function of various brain areas during speech production tasks. However, the cognitive neural mechanism of stuttering has still not been fully determined. Method: Activation likelihood estimation analysis was performed to provide neural imaging evidence on neural bases by reanalyzing published studies. Results: Our analysis revealed overactivation in the bilateral posterior superior temporal gyrus, inferior frontal gyrus, medial frontal gyrus, precentral gyrus, postcentral gyrus, basal ganglia, and cerebellum, and deactivation in the anterior superior temporal gyrus and middle temporal gyrus among the stutterers. The overactivated regions might indicate a greater demand in feedforward planning in speech production, while the deactivated regions might indicate dysfunction in the auditory feedback system among stutterers. Conclusions: Our findings provide updated and direct evidence on the multi-level impairment (feedforward and feedback systems) of stutterers during speech production and show that the corresponding neural bases were differentiated.

Is Reduced Visual Processing the Price of Language?

We suggest a later timeline for full language capabilities in Homo sapiens, placing the emergence of language over 200,000 years after the emergence of our species. The late Paleolithic period saw several significant changes. Homo sapiens became more gracile and gradually lost significant brain volumes. Detailed realistic cave paintings disappeared completely, and iconic/symbolic ones appeared at other sites. This may indicate a shift in perceptual abilities, away from an accurate perception of the present. Language in modern humans interact with vision. One example is the McGurk effect. Studies show that artistic abilities may improve when language-related brain areas are damaged or temporarily knocked out. Language relies on many pre-existing non-linguistic functions. We suggest that an overwhelming flow of perceptual information, vision, in particular, was an obstacle to language, as is sometimes implied in autism with relative language impairment. We systematically review the recent research literature investigating the relationship between language and perception. We see homologues of language-relevant brain functions predating language. Recent findings show brain lateralization for communicative gestures in other primates without language, supporting the idea that a language-ready brain may be overwhelmed by raw perception, thus blocking overt language from evolving. We find support in converging evidence for a change in neural organization away from raw perception, thus pushing the emergence of language closer in time. A recent origin of language makes it possible to investigate the genetic origins of language.

Cerebellar tDCS does not modulate language processing performance in healthy individuals

Clinical and neuroscientific studies in healthy volunteers have established that the cerebellum contributes to language comprehension and production. Yet most evidence is correlational and the exact role of the cerebellum remains unclear. The aim of this study was to investigate the role of the right cerebellum in unimpaired language comprehension and production using non-invasive brain stimulation. In this double-blind, sham-controlled experiment, thirty-six healthy participants received anodal or sham transcranial direct current (tDCS) stimulation to the right cerebellum while performing a lexical decision, sentence comprehension, verbal fluency and a non-language control task. Active tDCS did not modulate performance in any of the tasks. Additional exploratory analyses suggest difficulty-specific performance modulation in the sentence comprehension and lexical decision task, with tDCS improving performance in easy trials of the sentence comprehension task and difficult trials in the lexical decision task. Overall, our findings provide no evidence for the involvement of the right posterior cerebellum in language processing. Further research is needed to dissociate the influence of task difficulty of the underlying cognitive processes.

Hierarchical control as a shared neurocognitive mechanism for language and music

Although comparative research has made substantial progress in clarifying the relationship between language and music as neurocognitive systems from both a theoretical and empirical perspective, there is still no consensus about which mechanisms, if any, are shared and how they bring about different neurocognitive systems. In this paper, we tackle these two questions by focusing on hierarchical control as a neurocognitive mechanism underlying syntax in language and music. We put forward the Coordinated Hierarchical Control (CHC) hypothesis: linguistic and musical syntax rely on hierarchical control, but engage this shared mechanism differently depending on the current control demand. While linguistic syntax preferably engages the abstract rule-based control circuit, musical syntax rather employs the coordination of the abstract rule-based and the more concrete motor-based control circuits. We provide evidence for our hypothesis by reviewing neuroimaging as well as neuropsychological studies on linguistic and musical syntax. The CHC hypothesis makes a set of novel testable predictions to guide future work on the relationship between language and music.

The Effect of Focal Damage to the Right Medial Posterior Cerebellum on Word and Sentence Comprehension and Production

Functional imaging studies of neurologically intact adults have demonstrated that the right posterior cerebellum is activated during verb generation, semantic processing, sentence processing, and verbal fluency. Studies of patients with cerebellar damage converge to show that the cerebellum supports sentence processing and verbal fluency. However, to date there are no patient studies that investigated the specific importance of the right posterior cerebellum in language processing, because: (i) case studies presented patients with lesions affecting the anterior cerebellum (with or without damage to the posterior cerebellum), and (ii) group studies combined patients with lesions to different cerebellar regions, without specifically reporting the effects of right posterior cerebellar damage. Here we investigated whether damage to the right posterior cerebellum is critical for sentence processing and verbal fluency in four patients with focal stroke damage to different parts of the right posterior cerebellum (all involving Crus II, and lobules VII and VIII). We examined detailed lesion location by going beyond common anatomical definitions of cerebellar anatomy (i.e., according to lobules or vascular territory), and employed a recently proposed functional parcellation of the cerebellum. All four patients experienced language difficulties that persisted for at least a month after stroke but three performed in the normal range within a year. In contrast, one patient with more damage to lobule IX than the other patients had profound long-lasting impairments in the comprehension and repetition of sentences, and the production of spoken sentences during picture description. Spoken and written word comprehension and visual recognition memory were also impaired, however, verbal fluency was within the normal range, together with object naming, visual perception and verbal short-term memory. This is the first study to show that focal damage to the right posterior cerebellum leads to language difficulties after stroke; and that processing impairments persisted in the case with most damage to lobule IX. We discuss these results in relation to current theories of cerebellar contribution to language processing. Overall, our study highlights the need for longitudinal studies of language function in patients with focal damage to different cerebellar regions, with functional imaging to understand the mechanisms that support recovery.

Reliance on visual feedback from ocular accommodation on motor skills in children with developmental coordination disorder and typically developing controls

Children with developmental coordination disorder (DCD) present with marked impairments in motor skills, including visual-motor integration. Oculomotor anomalies are more prevalent in children with DCD than typically developing children. Children with DCD further demonstrate altered use of visual feedback compared to typically developing controls. We investigated whether the accommodation system, a key component of the oculomotor system, contributes to visual feedback during fine and gross motor skills performance; and whether children with DCD demonstrate differences in reliance on visual feedback from accommodation. Minus dioptre lenses were used to maximally induce accommodation and impede accommodation dynamics. Children with DCD and typically developing controls performed motor skills tests assessing balance, upper limb coordination, visual-motor performance, gross and fine dexterity. Motor skills performance in controls was significantly affected by impeded accommodation in all tasks. Children with DCD demonstrated reliance on accommodation feedback in upper limb and visual-motor tasks only. Children with DCD may be less reliant on visual feedback obtained from accommodation due to adaptive mechanisms to overcome faulty information in the presence of oculomotor anomalies. These results strengthen our previous findings that accommodation anomalies contribute to motor skills impairment, and suggest that performance on these motor tasks is heavily reliant on visual feedback from accommodation.

Semantic Processing in Autism Spectrum Disorders Is Associated With the Timing of Language Acquisition: A Magnetoencephalographic Study

Individuals with autism show difficulties in using sentence context to identify the correct meaning of ambiguous words, such as homonyms. In this study, the brain basis of sentence context effects on word understanding during reading was examined in autism spectrum disorder (ASD) and typical development (TD) using magnetoencephalography. The correlates of a history of developmental language delay in ASD were also investigated. Event related field responses at early (150 ms after the onset of a final word) and N400 latencies are reported for three different types of sentence final words: dominant homonyms, subordinate homonyms, and unambiguous words. Clear evidence for semantic access was found at both early and conventional N400 latencies in both TD participants and individuals with ASD with no history of language delay. By contrast, modulation of evoked activity related to semantic access was weak and not significant at early latencies in individuals with ASD with a history of language delay. The reduced sensitivity to semantic context in individuals with ASD and language delay was accompanied by strong right hemisphere lateralization at early and N400 latencies; such strong activity was not observed in TD individuals and individuals with ASD without a history of language delay at either latency. These results provide new evidence and support for differential neural mechanisms underlying semantic processing in ASD, and indicate that delayed language acquisition in ASD is associated with different lateralization and processing of language.

Distinct Neural Networks Relate to Common and Speaker-Specific Language Priors

Effective natural communication requires listeners to incorporate not only very general linguistic principles which evolved during a lifetime but also other information like the specific individual language use of a particular interlocutor. Traditionally, research has focused on the general linguistic rules, and brain science has shown a left hemispheric fronto-temporal brain network related to this processing. The present fMRI research explores speaker-specific individual language use because it is unknown whether this processing is supported by similar or distinct neural structures. Twenty-eight participants listened to sentences of persons who used more easy or difficult language. This was done by manipulating the proportion of easy SOV vs. complex OSV sentences for each speaker. Furthermore, ambiguous probe sentences were included to test top-down influences of speaker information in the absence of syntactic structure information. We observed distinct neural processing for syntactic complexity and speaker-specific language use. Syntactic complexity correlated with left frontal and posterior temporal regions. Speaker-specific processing correlated with bilateral (right-dominant) fronto-parietal brain regions. Finally, the top-down influence of speaker information was found in frontal and striatal brain regions, suggesting a mechanism for controlled syntactic processing. These findings show distinct neural networks related to general language principles as well as speaker-specific individual language use.

Tracking competition and cognitive control during language comprehension with multi-voxel pattern analysis

To successfully comprehend a sentence that contains a homonym, readers must select the ambiguous word's context-appropriate meaning. The outcome of this process is influenced both by top-down contextual support and bottom-up, word-specific characteristics. We examined how these factors jointly affect the neural signatures of lexical ambiguity resolution. We measured the similarity between multi-voxel patterns evoked by the same homonym in two distinct linguistic contexts: once after subjects read sentences that biased interpretation toward each homonym's most frequent, dominant meaning, and again after interpretation was biased toward a weaker, subordinate meaning. We predicted that, following a subordinate-biasing context, the dominant yet inappropriate meaning would nevertheless compete for activation, manifesting in increased similarity between the neural patterns evoked by the two word meanings. In left anterior temporal lobe (ATL), degree of within-word pattern similarity was positively predicted by the association strength of each homonym's dominant meaning. Further, within-word pattern similarity in left ATL was negatively predicted by item-specific responses in a region of left ventrolateral prefrontal cortex (VLPFC) sensitive to semantic conflict. These findings have implications for psycholinguistic models of lexical ambiguity resolution, and for the role of left VLPFC function during this process. Moreover, these findings demonstrate the utility of item-level, similarity-based analyses of fMRI data for our understanding of competition between co-activated word meanings during language comprehension.

Creativity, Comprehension, Conversation and the Hippocampal Region: New Data and Theory

Present findings indicate that hippocampal region (HR) damage impairs aspects of everyday language comprehension and production that require creativity ^___ defined as the ability to form new internal representations that satisfy relevant constraints for being useful or valuable in the real world. In two studies, seventeen people participated in extensive face-to-face interviews: sixteen normal individuals and H.M., an amnesic with cerebellar and HR damage but virtually no neocortical damage. Study 1 demonstrated deficits in H.M.'s comprehension of creative but not routine aspects of the interviews ^___ extending to the real world twelve prior demonstrations that H.M. understands routine but not novel aspects of experimentally constructed sentences, deficits that reflected his HR damage, but not his cerebellar damage, his explicit or declarative memory problems, inability to comprehend or recall the instructions, forgetting, poor visual acuity, motoric slowing, time pressure, deficits in visual scanning or attentional allocation, lack of motivation, and excessive memory load in the tasks. Study 2 demonstrated similar deficits in H.M.'s ability to produce creative but not routine aspects of conversational discourse, extending findings in five prior sentence production experiments to real-world creativity. We discuss conceptual frameworks for explaining relations between new-and-useful creativity and the HR.

An fMRI-study on semantic priming of panic-related information in depression without comorbid anxiety

Depression often involves anxiety symptoms and shows a strong comorbidity with panic disorder. However, the neural basis is unclear. The aim of the current study was to use semantic priming to investigate the neural correlates of panic and anxiety-related information processing in depression. In a lexical decision task, panic/agoraphobia-disorder-related and neutral word-pairs were presented during functional magnetic resonance imaging. Participants comprised 19 patients with major depression but without comorbid anxiety and 19 demographically matched controls. On a behavioral level, comparable significant priming effects were found for the neutral condition, while only patients showed a significant inhibition effect (slower reaction time for panic-related stimuli) for the panic condition. On a neural level, significant group differences emerged in left fronto-parietal (enhanced activation for patients) and left temporo-occipital regions (reduced activation for patients). The results showed that depressed patients recruit not only areas related to the interaction of emotion and semantic processing but also regions that are related to fear circuitry to process panic-related information. Hence, in the context of depression, there seems to be a pathological processing of panic-related information that could play an important role during the disorder and should be considered.

Cerebellar function in developmental dyslexia

Developmental dyslexia is a genetically based neurobiological syndrome, which is characterized by reading difficulty despite normal or high general intelligence. Even remediated dyslexic readers rarely achieve fast, fluent reading. Some dyslexics also have impairments in attention, short-term memory, sequencing (letters, word sounds, and motor acts), eye movements, poor balance, and general clumsiness. The presence of "cerebellar" motor and fluency symptoms led to the proposal that cerebellar dysfunction contributes to the etiology of dyslexia. Supporting this, functional imaging studies suggest that the cerebellum is part of the neural network supporting reading in typically developing readers, and reading difficulties have been reported in patients with cerebellar damage. Differences in both cerebellar asymmetry and gray matter volume are some of the most consistent structural brain findings in dyslexics compared with good readers. Furthermore, cerebellar functional activation patterns during reading and motor learning can differ in dyslexic readers. Behaviorally, some children and adults with dyslexia show poorer performance on cerebellar motor tasks, including eye movement control, postural stability, and implicit motor learning. However, many dyslexics do not have cerebellar signs, many cerebellar patients do not have reading problems, and differences in dyslexic brains are found throughout the whole reading network, and not isolated to the cerebellum. Therefore, impaired cerebellar function is probably not the primary cause of dyslexia, but rather a more fundamental neurodevelopmental abnormality leads to differences throughout the reading network.

Role of the striatum in language: Syntactic and conceptual sequencing

The basal ganglia (BG) have long been associated with cognitive control, and it is widely accepted that they also subserve an indirect, control role in language. Nevertheless, it cannot be completely ruled out that the BG may be involved in language in some domain-specific manner. The present study aimed to investigate one type of cognitive control-sequencing, a function that has long been connected with the BG-and to test whether the BG could be specifically implicated in language. Participants were required to rearrange materials sequentially based on linguistic (syntactic or conceptual) or non-linguistic (order switching) rules, or to repeat a previously ordered sequence as a control task. Functional magnetic resonance imaging (fMRI) data revealed a strongly active left-lateralized corticostriatal network, encompassing the anterior striatum, dorsolaterial and ventrolateral prefrontal cortex and presupplementary motor area, while the participants were sequencing materials using linguistic vs. non-linguistic rules. This functional network has an anatomical basis and is strikingly similar to the well-known associative loop implicated in sensorimotor sequence learning. We concluded that the anterior striatum has extended its original sequencing role and worked in concert with frontal cortical regions to subserve the function of linguistic sequencing in a domain-specific manner.

Combination Across Domains: An MEG Investigation into the Relationship between Mathematical, Pictorial, and Linguistic Processing

Debates surrounding the evolution of language often hinge upon its relationship to cognition more generally and many investigations have attempted to demark the boundary between the two. Though results from these studies suggest that language may recruit domain-general mechanisms during certain types of complex processing, the domain-generality of basic combinatorial mechanisms that lie at the core of linguistic processing is still unknown. Our previous work (Bemis and Pylkkänen, 2011, 2012) used magnetoencephalography to isolate neural activity associated with the simple composition of an adjective and a noun (“red boat”) and found increased activity during this processing localized to the left anterior temporal lobe (lATL), ventro-medial prefrontal cortex (vmPFC), and left angular gyrus (lAG). The present study explores the domain-generality of these effects and their associated combinatorial mechanisms through two parallel non-linguistic combinatorial tasks designed to be as minimal and natural as the linguistic paradigm. In the first task, we used pictures of colored shapes to elicit combinatorial conceptual processing similar to that evoked by the linguistic expressions and find increased activity again localized to the vmPFC during combinatorial processing. This result suggests that a domain-general semantic combinatorial mechanism operates during basic linguistic composition, and that activity generated by its processing localizes to the vmPFC. In the second task, we recorded neural activity as subjects performed simple addition between two small numerals. Consistent with a wide array of recent results, we find no effects related to basic addition that coincide with our linguistic effects and instead find increased activity localized to the intraparietal sulcus. This result suggests that the scope of the previously identified linguistic effects is restricted to compositional operations and does not extend generally to all tasks that are merely similar in form.

The cerebellum and cognition: evidence from functional imaging studies

Evidence for a role of the human cerebellum in cognitive functions comes from anatomical, clinical and neuroimaging data. Functional neuroimaging reveals cerebellar activation during a variety of cognitive tasks, including language, visual-spatial, executive, and working memory processes. It is important to note that overt movement is not a prerequisite for cerebellar activation: the cerebellum is engaged during conditions which either control for motor output or do not involve motor responses. Resting-state functional connectivity data reveal that, in addition to networks underlying motor control, the cerebellum is part of "cognitive" networks with prefrontal and parietal association cortices. Consistent with these findings, regional differences in activation patterns within the cerebellum are evident depending on the task demands, suggesting that the cerebellum can be broadly divided into functional regions based on the patterns of anatomical connectivity between different regions of the cerebellum and sensorimotor and association areas of the cerebral cortex. However, the distinct contribution of the cerebellum to cognitive tasks is not clear. Here, the functional neuroimaging evidence for cerebellar involvement in cognitive functions is reviewed and related to hypotheses as to why the cerebellum is active during such tasks. Identifying the precise role of the cerebellum in cognition-as well as the mechanism by which the cerebellum modulates performance during a wide range of tasks-remains a challenge for future investigations.

How the emotional content of discourse affects language comprehension

Emotion effects on cognition have often been reported. However, only few studies investigated emotional effects on subsequent language processing, and in most cases these effects were induced by non-linguistic stimuli such as films, faces, or pictures. Here, we investigated how a paragraph of positive, negative, or neutral emotional valence affects the processing of a subsequent emotionally neutral sentence, which contained either semantic, syntactic, or no violation, respectively, by means of event-related brain potentials (ERPs). Behavioral data revealed strong effects of emotion; error rates and reaction times increased significantly in sentences preceded by a positive paragraph relative to negative and neutral ones. In ERPs, the N400 to semantic violations was not affected by emotion. In the syntactic experiment, however, clear emotion effects were observed on ERPs. The left anterior negativity (LAN) to syntactic violations, which was not visible in the neutral condition, was present in the negative and positive conditions. This is interpreted as reflecting modulatory effects of prior emotions on syntactic processing, which is discussed in the light of three alternative or complementary explanations based on emotion-induced cognitive styles, working memory, and arousal models. The present effects of emotion on the LAN are especially remarkable considering that syntactic processing has often been regarded as encapsulated and autonomous.

Ambiguity's aftermath: how age differences in resolving lexical ambiguity affect subsequent comprehension

When ambiguity resolution is difficult, younger adults recruit selection-related neural resources that older adults do not. To elucidate the nature of those resources and the consequences of their recruitment for subsequent comprehension, we embedded noun/verb homographs and matched unambiguous words in syntactically well-specified but semantically neutral sentences. Target words were followed by a prepositional phrase whose head noun was plausible for only one meaning of the homograph. Replicating past findings, younger but not older adults elicited sustained frontal negativity to homographs compared to unambiguous words. On the subsequent head nouns, younger adults showed plausibility effects in all conditions, attesting to successful meaning selection through suppression. In contrast, older adults showed smaller plausibility effects following ambiguous words and failed to show plausibility effects when the context picked out the homograph's non-dominant meaning (i.e., they did not suppress the contextually-irrelevant dominant meaning). Meaning suppression processes, reflected in the frontal negativity, thus become less available with age, with consequences for subsequent comprehension.

The influence of emotional associations on the neural correlates of semantic priming

Emotions influence our everyday life in several ways. With the present study, we wanted to examine the impact of emotional information on neural correlates of semantic priming, a well-established technique to investigate semantic processing. Stimuli were presented with a short SOA of 200 ms as subjects performed a lexical decision task during fMRI measurement. Seven experimental conditions were compared: positive/negative/neutral related, positive/negative/neutral unrelated, nonwords (all words were nouns). Behavioral data revealed a valence specific semantic priming effect (i.e., unrelated > related) only for neutral and positive related word pairs. On a neural level, the comparison of emotional over neutral relations showed activation in left anterior medial frontal cortex, superior frontal gyrus, and posterior cingulate. Interactions for the different relations were located in left anterior part of the medial frontal cortex, cingulate regions, and right hippocampus (positive > neutral + negative) and left posterior part of medial frontal cortex (negative > neutral + positive). The results showed that emotional information have an influence on semantic association processes. While positive and neutral information seem to share a semantic network, negative relations might induce compensatory mechanisms that inhibit the spread of activation between related concepts. The neural correlates highlighted a distributed neural network, primarily involving attention, memory and emotion related processing areas in medial fronto-parietal cortices. The differentiation between anterior (positive) and posterior part (negative) of the medial frontal cortex was linked to the type of affective manipulation with more cognitive demands being involved in the automatic processing of negative information.

Differential age effects on lexical ambiguity resolution mechanisms

Multiple neurocognitive subsystems are involved in resolving lexical ambiguity under different circumstances. We examined how processing in these subsystems changes with normal aging by comparing ERP responses to homographs and unambiguous words completing congruent sentences (with both semantic and syntactic contextual information) or syntactic prose (syntactic information only). Like young adults in prior work, older adults elicited more negative N400s to homographs in congruent sentences, suggesting mismatch between the context and residual activation of the contextually irrelevant sense. However, the frontal negativity seen in young adults to homographs in syntactically well-defined but semantically neutral contexts was absent in older adults as a group, suggesting a decline in recruiting additional neural resources to aid difficult semantic selection. A subset of older adults with high verbal fluency maintained a young-like effect pattern.

Interplay between morphology and frequency in lexical access: the case of the base frequency effect

A major issue in lexical processing concerns storage and access of lexical items. Here we make use of the base frequency effect to examine this. Specifically, reaction time to morphologically complex words (words made up of base and suffix, e.g., agree+able) typically reflects frequency of the base element (i.e., total frequency of all words in which agree appears) rather than surface word frequency (i.e., frequency of agreeable itself). We term these complex words decomposable. However, a class of words termed whole-word do not show such sensitivity to base frequency (e.g., serenity). Using an event-related MRI design, we exploited the fact that processing low-frequency words increases BOLD activity relative to high frequency ones, and examined effects of base frequency on brain activity for decomposable and whole-word items. Morphologically complex words, half high and half low base frequency, were compared to match high and low frequency simple monomorphemic words using a lexical decision task. Morphologically complex words increased activation in the left inferior frontal and left superior temporal cortices versus simple words. The only area to mirror the behavioral distinction between the decomposable and the whole-word types was the thalamus. Surprisingly, most frequency-sensitive areas failed to show base frequency effects. This variety of responses to frequency and word type across brain areas supports an integrative view of multiple variables during lexical access, rather than a dichotomy between memory-based access and on-line computation. Lexical access appears best captured as interplay of several neural processes with different sensitivities to various linguistic factors including frequency and morphological complexity.

Syntactic reconstruction and reanalysis, semantic dead ends, and prefrontal cortex

The left inferior frontal gyrus (LIFG) is crucially has been found to be involved in syntactic processing of various kinds. This study investigates the cortical effects of two types of syntactic processes: (i) Reconstruction in ellipsis (recovery of left-out material given by context, More people have been to Paris than [...] to Oslo), using pseudo-elliptical structures ('dead ends') as control (More people have been to Paris than I have). (ii) Reanalysis in the face of structural ambiguity in syntactic 'garden paths', where the parser initially assigns an incorrect structure and is forced to reanalyze. Reanalysis and reconstruction require additional syntactic processing and were predicted to increase activation in areas otherwise involved in structural computation: LIFG (BA 44,45), premotor BA 6, and posterior temporal BA 21,22. This was borne out. The results showed an interaction effect of the types of construction in all three areas reflecting syntactic processing.

A computational neural model of goal-directed utterance selection

It is generally agreed that much of human communication is motivated by extra-linguistic goals: we often make utterances in order to get others to do something, or to make them support our cause, or adopt our point of view, etc. However, thus far a computational foundation for this view on language use has been lacking. In this paper we propose such a foundation using Markov Decision Processes. We borrow computational components from the field of action selection and motor control, where a neurobiological basis of these components has been established. In particular, we make use of internal models (i.e., next-state transition functions defined on current state action pairs). The internal model is coupled with reinforcement learning of a value function that is used to assess the desirability of any state that utterances (as well as certain non-verbal actions) can bring about. This cognitive architecture is tested in a number of multi-agent game simulations. In these computational experiments an agent learns to predict the context-dependent effects of utterances by interacting with other agents that are already competent speakers. We show that the cognitive architecture can account for acquiring the capability of deciding when to speak in order to achieve a certain goal (instead of performing a non-verbal action or simply doing nothing), whom to address and what to say.

Co-localization of stroop and syntactic ambiguity resolution in Broca's area: implications for the neural basis of sentence processing

For over a century, a link between left prefrontal cortex and language processing has been accepted, yet the precise characterization of this link remains elusive. Recent advances in both the study of sentence processing and the neuroscientific study of frontal lobe function suggest an intriguing possibility: The demands to resolve competition between incompatible characterizations of a linguistic stimulus may recruit top-down cognitive control processes mediated by prefrontal cortex. We use functional magnetic resonance imaging to test the hypothesis that individuals use shared prefrontal neural circuitry during two very different tasks-color identification under Stroop conflict and sentence comprehension under conditions of syntactic ambiguity-both of which putatively rely on cognitive control processes. We report the first demonstration of within-subject overlap in neural responses to syntactic and nonsyntactic conflict. These findings serve to clarify the role of Broca's area in, and the neural and psychological organization of, the language processing system.

The effect of presentation paradigm on syntactic processing: An event-related fMRI study

An event-related fMRI study was conducted to investigate the effect of two different sentence presentation paradigms-rapid serial visual presentation (RSVP) and whole sentence presentation-on syntactic processing. During scanning, sentences were presented using one of the two presentation paradigms and were followed by a short delay and a probe to verify sentence comprehension. The delay was included in an attempt to separate sentence-related activity from probe-related activity. The behavioral data showed a main effect of syntactic complexity for reaction time and accuracy, and accuracy revealed an interaction between complexity and the presentation paradigm employed-RSVP produced many more errors for syntactically complex sentences than did whole sentence presentation. The imaging data revealed a syntactic complexity effect during the sentence phase in left BA 44 and during the probe phase in left BA 44 and the left posterior MTG. In addition, timecourse analysis revealed that these two regions also showed an interaction between complexity and presentation paradigm such that there was no complexity effect during RSVP but a significant effect during whole sentence presentation. In addition to finding that these two presentation paradigms differentially affected syntactic processing, there were main effects within the visual pathway (V1/V2 vs. V5) and the hippocampus that revealed significant differences in activation between the paradigms.

Wave-ering: An ERP study of syntactic and semantic context effects on ambiguity resolution for noun/verb homographs

Two event-related potential experiments investigated the effects of syntactic and semantic context information on the processing of noun/verb (NV) homographs (e.g., park). Experiment 1 embedded NV-homographs and matched unambiguous words in contexts that provided only syntactic cues or both syntactic and semantic constraints. Replicating prior work, when only syntactic information was available NV-homographs elicited sustained frontal negativity relative to unambiguous words. Semantic constraints eliminated this frontal ambiguity effect. Semantic constraints also reduced N400 amplitudes, but less so for homographs than unambiguous words. Experiment 2 showed that this reduced N400 facilitation was limited to cases in which the semantic context picks out a nondominant meaning, likely reflecting the semantic mismatch between the context and residual, automatic activation of the contextually-inappropriate dominant sense. Overall, the findings suggest that ambiguity resolution in context involves the interplay between multiple neural networks, some involving more automatic semantic processing mechanisms and others involving top-down control mechanisms.

Say it with flowers! An fMRI study of object mediated communication

Human communicational interaction can be mediated by a host of expressive means from words in a natural language to gestures and material symbols. Given the proper contextual setting even an everyday object can gain a mediating function in a communicational situation. In this study we used event-related fMRI to study the brain activity caused by everyday material objects when they are perceived as signals. We found that comprehension of material signals activates bilaterally areas of the ventral stream and pars triangularis of the inferior frontal cortex, that is, areas traditionally associated with verbal language and semantics. In addition, we found that right-hemisphere inferior frontal cortex is recruited as a function of the increasing unconventionality of communicative objects. Together these findings support an interpretation of the traditional language areas as playing a more general role across modalities in relation to communicational mediation of social semantic meaning.

Mnesic imbalance: a cognitive theory about autism spectrum disorders

Autism is characterized by impairments in social interaction, communicative capacity and behavioral flexibility. Some cognitive theories can be useful for finding a relationship between these irregularities and the biological mechanisms that may give rise to this disorder. Among such theories are mentalizing deficit, weak central coherence and executive dysfunction, but none of them has been able to explain all three diagnostic symptoms of autism. These cognitive disorders may be related among themselves by faulty learning, since several research studies have shown that the brains of autistic individuals have abnormalities in the cerebellum, which plays a role in procedural learning. In keeping with this view, one may postulate the possibility that declarative memory replaces faulty procedural memory in some of its functions, which implies making conscious efforts in order to perform actions that are normally automatic. This may disturb cognitive development, resulting in autism symptoms. Furthermore, this mnesic imbalance is probably involved in all autism spectrum disorders. In the present work, this theory is expounded, including preliminary supporting evidence.

Cortical-striatal-cortical neural circuits, reiteration, and the “narrow faculty of language”

Neural circuits linking local operations in the cortex and the basal ganglia confer reiterative capacities, expressed in seemingly unrelated human traits such as speech, syntax, adaptive actions to changing circumstances, dancing, and music. Reiteration allows the formation of a potentially unbounded number of sentences from a finite set of syntactic processes, obviating the need for the hypothetical “Narrow Faculty of Language.”

Neuroanatomical distinctions within the semantic system during sentence comprehension: evidence from functional magnetic resonance imaging

To make sense of a sentence, we must compute morphosyntactic and semantic-thematic relationships between its verbs and arguments and evaluate the resulting propositional meaning against any preceding context and our real-world knowledge. Recent electrophysiological studies suggest that, in comparison with non-violated verbs (e.g. "...at breakfast the boys would eat..."), animacy semantic-thematically violated verbs (e.g. "...at breakfast the eggs would eat...") and morphosyntactically violated verbs (e.g. "...at breakfast the boys would eats...") evoke a similar neural response. This response is distinct from that evoked by verbs that only violate real-world knowledge (e.g. "...at breakfast the boys would plant..."). Here we used fMRI to examine the neuroanatomical regions engaged in response to these three violations. Real-world violations, relative to other sentence types, led to increased activity within the left anterior inferior frontal cortex, reflecting participants' increased and prolonged efforts to retrieve semantic knowledge about the likelihood of events occurring in the real world. In contrast, animacy semantic-thematic violations of the actions depicted by the central verbs engaged a frontal/inferior parietal/basal ganglia network known to mediate the execution and comprehension of goal-directed action. We suggest that the recruitment of this network reflected a semantic-thematic combinatorial process that involved an attempt to determine whether the actions described by the verbs could be executed by their NP Agents. Intriguingly, this network was also activated to morphosyntactic violations between the verbs and their subject NP arguments. Our findings support the pattern of electrophysiological findings in suggesting (a) that a clear division within the semantic system plays out during sentence comprehension, and (b) that semantic-thematic and syntactic violations of verbs within simple active sentences are treated similarly by the brain.

Semantic adaptation and competition during word comprehension

Word comprehension engages the left ventrolateral prefrontal (lVLPFC) and posterior lateral-temporal cortices (PLTC). The contributions of these brain regions to comprehension remain controversial. We hypothesized that the PLTC activates meanings, whereas the lVLPFC resolves competition between representations. To test this hypothesis, we used functional magnetic resonance imaging (fMRI) to assess the independent effects of adaptation and competition on neural activity. Participants judged the relatedness of word pairs. Some consecutive pairs contained a common ambiguous word. The same or different meanings of this word were primed (e.g., SUMMER-FAN, CEILING-FAN; ADMIRER-FAN, CEILING-FAN). Based on the logic of fMRI adaptation, trials with more semantic overlap should produce more adaptation (less activation) in regions that activate meaning. In contrast, trials with more semantic ambiguity should produce more activation in regions that resolve competition. We observed a double dissociation between activity in the PLTC and lVLPFC. LPLTC activity depended on the amount of semantic overlap, irrespective of the amount of semantic ambiguity. In contrast, lVLPFC activity depended on the amount of semantic ambiguity. Moreover, across participants the size of the competition effect as measured by errors was correlated with the size of the competition effect in the lVLPFC. We conclude that the lVLPFC is an executive mechanism within language processing.

The role of the cerebellum in schizophrenia: an update of clinical, cognitive, and functional evidences

The role of the cerebellum in schizophrenia has been highlighted by Andreasen's hypothesis of "cognitive dysmetria," which suggests a general dyscoordination of sensorimotor and mental processes. Studies in schizophrenic patients have brought observations supporting a cerebellar impairment: high prevalence of neurological soft signs, dyscoordination, abnormal posture and propioception, impaired eyeblink conditioning, impaired adaptation of the vestibular-ocular reflex or procedural learning tests, and lastly functional neuroimaging studies correlating poor cognitive performances with abnormal cerebellar activations. Despite those compelling evidences, there has been, to our knowledge, no recent review on the clinical, cognitive, and functional literature supporting the role of the cerebellum in schizophrenia. We conducted a Medline research focusing on cerebellar dysfunctions in schizophrenia. Emphasis was given to recent literature (after 1998). The picture arising from this review is heterogeneous. While in some domains, the role of the cerebellum seems clearly defined (ie, neurological soft signs, posture, or equilibrium), in other domains, the cerebellar contribution to schizophrenia seems limited or indirect (ie, cognition) if present at all (ie, affectivity). Functional models of the cerebellum are proposed as a background for interpreting these results.

The cerebellum and language: the story so far

BACKGROUND

The cerebellum was traditionally considered to be exclusively involved in the coordination of voluntary movement, gait, posture, balance and motor speech. However, this view was challenged by recent neuroanatomical, neuroimaging and clinical findings, providing preliminary evidence of a cerebellar contribution to linguistic functioning.

AIM

To discuss the role of the cerebellum in a variety of linguistic functions and to explore the underlying mechanisms.

METHODS

A literature search was conducted via electronic databases. Exclusion criteria were: disorders following congenital cerebellar lesions, motor speech disorders, cognitive deficits outside the language sphere, neuropsychiatric disorders and insufficient information on the cerebellar role in language. Abstracts were not included. In addition, only adult subjects were taken into consideration.

RESULTS

A variety of linguistic disorders were found to occur following acquired cerebellar lesions: (1) impaired phonological and semantic fluency; (2) agrammatism (at morphological and sentence level); (3) naming and word finding difficulties; (4) cerebellar-induced aphasia; (5) reading difficulties; (6) writing problems, and (7) higher-level language deficits, including disturbed listening comprehension, impaired language proficiency and metalinguistic ability. Several hypotheses have been suggested to explain the nature of the cerebellar contribution to language. However, findings are not univocal.

CONCLUSION

The cerebellum appears to be involved in a variety of linguistic functions. However, the precise nature of this contribution is not clear yet. Linguistic, neuroimaging, neuroanatomical and neuropsychological studies should be combined in order to disentangle the specific contribution of the cerebellum to linguistic processing.

Effect of syntactic similarity on cortical activation during second language processing: a comparison of English and Japanese among native Korean trilinguals

In this study of native Korean trilinguals we examined the effect of syntactic similarity between first (L1) and second (L2) languages on cortical activation during the processing of Japanese and English, which are, respectively, very similar to and different from Korean. Subjects had equivalent proficiency in Japanese and English. They performed auditory sentence comprehension tasks in Korean, Japanese, and English during functional MRI (fMRI). The bilateral superior temporal cortex was activated during the comprehension of three languages. The pars triangularis of the left inferior frontal gyrus (IFG) was additionally activated for L2 processing. Furthermore, the right cerebellum, the pars opercularis of the left IFG, and the posteriomedial part of the superior frontal gyrus were activated during the English tasks only. We observed significantly greater activation in the pars opercularis of the left IFG, the right cerebellum, and the right superior temporal cortex during the English than Japanese task; activation in these regions did not differ significantly between Korean and Japanese. Differential activation of the pars opercularis of the left IFG and the right cerebellum likely reflects syntactic distance and differential activation in the right superior temporal cortex may reflect the prosodic distance between English from Korean and Japanese. Furthermore, in the pars oparcularis of the left IFG and the right cerebellum, significant negative correlation between the activation and duration of exposure was observed for English, but not for Japanese. Our research supports the notion that linguistic similarity between L1 and L2 affects the cortical processing of second language.

Lexical ambiguity in sentence comprehension

An event-related fMRI paradigm was used to investigate brain activity during the reading of sentences containing either a lexically ambiguous word or an unambiguous control word. Higher levels of activation occurred during the reading of sentences containing a lexical ambiguity. Furthermore, the activated cortical network differed, depending on: (1) whether the sentence contained a balanced (i.e., both meanings equally likely) or a biased (i.e., one meaning more likely than other meanings) ambiguous word; and, (2) the working memory capacity of the individual as assessed by reading span. The findings suggest that encountering a lexical ambiguity is dealt with by activating multiple meanings utilizing processes involving both hemispheres. When an early interpretation of a biased ambiguous word is later disambiguated to the subordinate meaning, the superior frontal cortex activates in response to the coherence break and the right inferior frontal gyrus and the insula activate, possibly to suppress the incorrect interpretation. Negative correlations between reading span scores and activation in the right hemisphere for both types of ambiguous words suggest that readers with lower spans are more likely to involve show right hemisphere involvement in the processing of the ambiguity. A positive correlation between reading span scores and insula activation appearing only for biased sentences disambiguated to the subordinate meaning indicates that individuals with higher spans were more likely to initially maintain both meanings and as a result had to suppress the unintended dominant meaning.

Semantic ambiguity processing in sentence context: Evidence from event-related fMRI

Lexical semantic ambiguity is the phenomenon when a word has multiple meanings (e.g. 'bank'). The aim of this event-related functional MRI study was to identify those brain areas, which are involved in contextually driven ambiguity resolution. Ambiguous words were selected which have a most frequent, dominant, and less frequent, subordinate meaning. These words were presented in two types of sentences: (1) a sentence congruent with the dominant interpretation and (2) a sentence congruent with the subordinate interpretation. Sentences without ambiguous words served as a control condition. The ambiguous words always occurred early in the sentences and were biased towards one particular meaning by the final word(s) of the sentence; the event at the end of the sentences was modeled. The results indicate that a bilaterally distributed network supports semantic ambiguity comprehension: left (BA 45/44) and right (BA 47) inferior frontal gyri and left (BA 20/37) and right inferior/middle temporal gyri (BA 20). The pattern of activation is most consistent with a scenario in which initially a frequency-based probabilistic choice is made between the alternative meanings, and the meaning is updated when this interpretation does not fit into the final disambiguating context. The neural pattern is consistent with the results of other neuroimaging experiments which manipulated various aspects of integrative and context processing task demands. The presence of a bilateral network is also in line with the lesion and divided visual field literature, but contrary to earlier claims, the two hemispheres appear to play similar roles during semantic ambiguity resolution.

Diagnostic functional MRI: illustrated clinical applications and decision-making

Functional magnetic resonance imaging (fMRI) has become a popular research tool, yet its use for diagnostic purposes and actual treatment planning has remained less widespread. The literature yields rather sparse evidence-based data on clinical fMRI applications and accordant decision-making. Notwithstanding, blood oxygenation level dependent (BOLD)- and arterial spin labeling (ASL)-fMRI can be judiciously combined with perfusion measurements, electroencephalographic (EEG) recordings, diffusion-weighted imaging (DWI), and fiber tractographies to assist clinical decisions. In this article we provide an overview of clinical fMRI applications based on illustrative examples. Assessment of cochlear implant candidates by fMRI is covered in some detail, and distinct reference is made to particular challenges imposed by brain tumors, other space-occupying lesions, cortical dysplasias, seizure disorders, and vascular malformations. Specific strategies, merits, and pitfalls of analyzing and interpreting diagnostic fMRI studies in individual patients are highlighted.

Divergence of fine and gross motor skills in prelingually deaf children: implications for cochlear implantation

OBJECTIVE

The objective of this study was to assess relations between fine and gross motor development and spoken language processing skills in pediatric cochlear implant users.

STUDY DESIGN

The authors conducted a retrospective analysis of longitudinal data.

METHODS

Prelingually deaf children who received a cochlear implant before age 5 and had no known developmental delay or cognitive impairment were included in the study. Fine and gross motor development were assessed before implantation using the Vineland Adaptive Behavioral Scales, a standardized parental report of adaptive behavior. Fine and gross motor scores reflected a given child's motor functioning with respect to a normative sample of typically developing, normal-hearing children. Relations between these preimplant scores and postimplant spoken language outcomes were assessed.

RESULTS

In general, gross motor scores were found to be positively related to chronologic age, whereas the opposite trend was observed for fine motor scores. Fine motor scores were more strongly correlated with postimplant expressive and receptive language scores than gross motor scores.

CONCLUSIONS

Our findings suggest a disassociation between fine and gross motor development in prelingually deaf children: fine motor skills, in contrast to gross motor skills, tend to be delayed as the prelingually deaf children get older. These findings provide new knowledge about the links between motor and spoken language development and suggest that auditory deprivation may lead to atypical development of certain motor and language skills that share common cortical processing resources.

The roles of sequencing and verbal working memory in sentence comprehension deficits in Parkinson's disease

Studies of sentence comprehension deficits in Parkinson's disease (PD) patients suggest that language processing involves circuits connecting subcortical and cortical regions. Anatomically segregated neural circuits appear to support different cognitive and motor functions. To investigate which functions are implicated in PD comprehension deficits, we tested comprehension, verbal working memory span, and cognitive set-switching in a non-linguistic task in 41 PD patients; we also obtained speech measurements reflecting motor sequencing processes that may be involved in articulatory rehearsal within working memory. Comprehension of sentences with center-embedded or final relative clauses was impaired when they could not be understood from lexical semantic content alone. Overall comprehension error rates correlated strongly with impaired set-switching and significantly with reduced working memory span and speech motor sequencing deficits. Correlations with comprehension of different sentence structures indicate that these impairments do not represent a single deficit; rather, PD comprehension deficits appear to arise from several independent mechanisms. Deficits in cognitive set-switching or underlying inhibitory processes may compromise the ability to process relative clauses. Deficits in verbal working memory appear to impair comprehension of long-distance dependencies. Speech sequencing correlated with neither set-switching nor verbal working memory span, consistent with their being supported by independent, segregated cortico-subcortical circuits.

Processing lexical semantic and syntactic information in first and second language: fMRI evidence from German and Russian

We introduce two experiments that explored syntactic and semantic processing of spoken sentences by native and non-native speakers. In the first experiment, the neural substrates corresponding to detection of syntactic and semantic violations were determined in native speakers of two typologically different languages using functional magnetic resonance imaging (fMRI). The results show that the underlying neural response of participants to stimuli across different native languages is quite similar. In the second experiment, we investigated how non-native speakers of a language process the same stimuli presented in the first experiment. First, the results show a more similar pattern of increased activation between native and non-native speakers in response to semantic violations than to syntactic violations. Second, the non-native speakers were observed to employ specific portions of the frontotemporal language network differently from those employed by native speakers. These regions included the inferior frontal gyrus (IFG), superior temporal gyrus (STG), and subcortical structures of the basal ganglia.

Neural correlates of syntactic ambiguity in sentence comprehension for low and high span readers

Syntactically ambiguous sentences have been found to be difficult to process, in particular, for individuals with low working memory capacity. The current study used fMRI to investigate the neural basis of this effect in the processing of written sentences. Participants with high and low working memory capacity read sentences with either a short or long region of temporary syntactic ambiguity while being scanned. A distributed left-dominant network in the peri-sylvian region was identified to support sentence processing in the critical region of the sentence. Within this network, only the superior portion of Broca's area (BA 44) and a parietal region showed an activation increase as a function of the length of the syntactically ambiguous region in the sentence. Furthermore, it was only the BA 44 region that exhibited an interaction of working memory span, length of the syntactic ambiguity, and sentence complexity. In this area, the activation increase for syntactically more complex sentences became only significant under longer regions of ambiguity, and for low span readers only. This finding suggests that neural activity in BA 44 increases during sentence comprehension when processing demands increase, be it due to syntactic processing demands or by an interaction with the individually available working memory capacity.