[Show abstract][Hide abstract] ABSTRACT: Unlike other aspects of language comprehension, the ability to process complex sentences develops rather late in life. Brain maturation as well as verbal working memory (vWM) expansion have been discussed as possible reasons. To determine the factors contributing to this functional development, we assessed three aspects in different age groups (5–6 years, 7–8 years, and adults): First, functional brain activity during the processing of increasingly complex sentences; second, brain structure in language-related ROIs; and third, the behavioral comprehension performance on complex sentences and the performance on an independent vWM test. At the whole-brain level, brain-functional data revealed a qualitatively similar neural network in children and adults including the left pars opercularis (PO), the left inferior parietal lobe together with the posterior superior temporal gyrus (IPL/pSTG), the supplementary motor area, and the cerebellum. While functional activation of the language-related ROIs PO and IPL/pSTG predicted sentence comprehension performance for all age groups, only adults showed a functional selectivity in these brain regions with increased activation for more complex sentences. The attunement of both the PO and IPL/pSTG towards a functional selectivity for complex sentences is predicted by region-specific gray matter reduction while that of the IPL/pSTG is additionally predicted by vWM span. Thus, both structural brain maturation and vWM expansion provide the basis for the emergence of functional selectivity in language-related brain regions leading to more efficient sentence processing during development.
[Show abstract][Hide abstract] ABSTRACT: Resting-state functional magnetic resonance imaging is a powerful technique to study the whole-brain neural connectivity that underlies cognitive systems. The present study aimed to define the changes in neural connectivity in their relation to language development. Longitudinal resting-state functional data were acquired from a cohort of preschool children at age 5 and one year later, and changes in functional connectivity were correlated with language performance in sentence comprehension. For this, degree centrality, a voxel-based network measure, was used to assess age-related differences in connectivity at the whole-brain level. Increases in connectivity with age were found selectively in a cluster within the left posterior superior temporal gyrus and sulcus (STG/STS). In order to further specify the connection changes, a secondary seed-based functional connectivity analysis on this very cluster was performed. The correlations between resting-state functional connectivity (RSFC) and language performance revealed developmental effects with age and, importantly, also dependent on the advancement in sentence comprehension ability over time. In children with greater advancement in language abilities, the behavioral improvement was positively correlated with RSFC increase between left posterior STG/STS and other regions of the language network, i.e., left and right inferior frontal cortex. The age-related changes observed in this study provide evidence for alterations in the language network as language develops and demonstrates the viability of this approach for the investigation of normal and aberrant language development.
[Show abstract][Hide abstract] ABSTRACT: Children's perception of prosodic phrasing provides a head start into the discovery of speech structure. Based on the close prosody-syntax correspondence, children can infer the underlying syntactic structure from the acoustic modulations of prosodic boundaries, typically consisting of co-occurring pitch changes, preboundary lengthening, and pausing. Previous electrophysiological studies revealed that listeners are to some degree flexible in the detection of major prosodic boundaries that are not marked with all three of the suprasegmental cues. Adults and 6-year-olds still showed the brain response for prosodic boundary perception, the Closure Positive Shift (CPS), when pauses marking boundaries were deleted. In contrast, younger children at 3 years did not show this ability yet, but required pausing to complement the other boundary cues. Following the hypothesis that German weights duration cues more heavily than pitch cues, we here examined 3-year-olds' brain responses to prosodic phrasing, testing the role of boundary-related pitch changes. Results revealed that children at this age even showed the CPS in response to pitch-neutralized boundaries with only pausing and preboundary lengthening being present. These results indicate differential roles of acoustic cues in boundary perception, with a preferential reliance on duration cues over pitch changes in 3-year-olds. This preference likely results from the characteristics of the German intonation system and furthers the discussion of cross-linguistic differences in the weighting of prosodic boundary cues.
[Show abstract][Hide abstract] ABSTRACT: Previous behavioral studies showed that it is not until around the age of seven that German children reliably use case markers for the interpretation of complex sentences. Some explanations of this late development suggested that children might have difficulties in perceptual differentiation between function words that carry case information. We tested this hypothesis by using the neurophysiological index of pre-attentive discrimination, the mismatch negativity (MMN). Our data showed that children at the age of three years are able to automatically discriminate between the two determiner forms der and den when presented out of sentential context. The determiner form der elicited a more mature MMN response in children than the form den. In adults, the MMN pattern also differed with der showing an earlier peak than den. These findings indicate that der is easier to process than den, which in turn is related to the occurrence frequency of the determiner forms in language.
Full-text · Article · Nov 2015 · Frontiers in Psychology
[Show abstract][Hide abstract] ABSTRACT: Language is thought to represent one of the most complex cognitive functions in humans. Here we break down complexity of language to its most basic syntactic computation which hierarchically binds single words together to form larger phrases and sentences. So far, the neural implementation of this basic operation has only been inferred indirectly from studies investigating more complex linguistic phenomena. In the present sub-region based functional magnetic resonance imaging (fMRI) study we directly assessed the neuroanatomical nature of this process. Our results showed that syntactic phrases—compared to word-list sequences—corresponded to increased neural activity in the ventral-anterior portion of the left pars opercularis [Brodmann Area (BA) 44], whereas the adjacently located deep frontal operculum/anterior insula (FOP/aINS), a phylogenetically older and less specialized region, was found to be equally active for both conditions. Crucially, the functional activity of syntactic binding was confined to one out of five clusters proposed by a recent fine-grained sub-anatomical parcellation for BA 44, with consistency across individuals. Neuroanatomically, the present results call for a redefinition of BA 44 as a region with internal functional specializations. Neurocomputationally, they support the idea of invariance within BA 44 in the location of activation across participants for basic syntactic building processing.
Preview · Article · Nov 2015 · Frontiers in Psychology
[Show abstract][Hide abstract] ABSTRACT: The present study explored the origins of word learning in early infancy. Using event-related potentials (ERP) we monitored the brain activity of 3-month-old infants when they were repeatedly exposed to several initially novel words paired consistently with each the same initially novel objects or inconsistently with different objects. Our results provide strong evidence that these young infants extract statistic regularities in the distribution of the co-occurrences of objects and words extremely quickly. The data suggest that this ability is based on the rapid formation of associations between the neural representations of objects and words, but that the new associations are not retained in long-term memory until the next day. The type of brain response moreover indicates that, unlike in older infants, in 3-month-olds a semantic processing stage is not involved. Their ability to combine words with meaningful information is caused by a primary learning mechanism that enables the formation of proto-words and acts as a precursor for the acquisition of genuine words.
No preview · Article · Nov 2015 · Developmental Science
[Show abstract][Hide abstract] ABSTRACT: Sentence comprehension requires the integration of both syntactic and semantic information, the acquisition of which seems to have different trajectories in the developing brain. Using functional magnetic resonance imaging, we examined the neural correlates underlying syntactic and semantic processing during auditory sentence comprehension as well as its development in preschool children by manipulating case marking and animacy hierarchy cues, respectively. A functional segregation was observed within Broca's area in the left inferior frontal gyrus for adults, where the pars opercularis was involved in syntactic processing and the pars triangularis in semantic processing. By contrast, five-year-old children sensitive to animacy hierarchy cues showed diffuse activation for semantic processing in the left inferior frontal and posterior temporal cortices. While no main effect of case marking was found in the left fronto-temporal language network, children with better syntactic skills showed greater neural responses for syntactically complex sentences, most prominently in the posterior superior temporal cortex. The current study provides both behavioral and neural evidence that five-year-old children compared to adults rely more on semantic information than on syntactic cues during sentence comprehension, but with the development of syntactic abilities, their brain activation in the left fronto-temporal network increases for syntactic processing.
[Show abstract][Hide abstract] ABSTRACT: Successful communication in everyday life crucially involves the processing of auditory and visual components of speech. Viewing our interlocutor and processing visual components of speech facilitates speech processing by triggering auditory processing. Auditory phoneme processing, analyzed by event-related brain potentials (ERP), has been shown to be associated with impairments in reading and spelling (i.e. developmental dyslexia), but visual aspects of phoneme processing have not been investigated in individuals with such deficits. The present study analyzed the passive visual Mismatch Response (vMMR) in school children with and without developmental dyslexia in response to video-recorded mouth movements pronouncing syllables silently. Our results reveal that both groups of children showed processing of visual speech stimuli, but with different scalp distribution. Children without developmental dyslexia showed a vMMR with typical posterior distribution. In contrast, children with developmental dyslexia showed a vMMR with anterior distribution, which was even more pronounced in children with severe phonological deficits and very low spelling abilities. As anterior scalp distributions are typically reported for auditory speech processing, the anterior vMMR of children with developmental dyslexia might suggest an attempt to anticipate potentially upcoming auditory speech information in order to support phonological processing, which has been shown to be deficient in children with developmental dyslexia.
No preview · Article · Oct 2015 · Developmental Science
[Show abstract][Hide abstract] ABSTRACT: Literacy acquisition is highly associated with auditory processing abilities, such as auditory discrimination. The event-related potential Mismatch Response (MMR) is an indicator for cortical auditory discrimination abilities and it has been found to be reduced in individuals with reading and writing impairments and also in infants at risk for these impairments. The goal of the present study was to analyze the relationship between auditory speech discrimination in infancy and writing abilities at school age within subjects, and to determine when auditory speech discrimination differences, relevant for later writing abilities, start to develop. We analyzed the MMR registered in response to natural syllables in German children with and without writing problems at two points during development, that is, at school age and at infancy, namely at age 1 month and 5 months. We observed MMR related auditory discrimination differences between infants with and without later writing problems, starting to develop at age 5 months-an age when infants begin to establish language-specific phoneme representations. At school age, these children with and without writing problems also showed auditory discrimination differences, reflected in the MMR, confirming a relationship between writing and auditory speech processing skills. Thus, writing problems at school age are, at least, partly grounded in auditory discrimination problems developing already during the first months of life.
No preview · Article · Oct 2015 · Research in developmental disabilities
[Show abstract][Hide abstract] ABSTRACT: Prior structural imaging studies found initial evidence for the link between structural gray matter changes and the development of language performance in children. However, previous studies generally only focused on sentence comprehension. Therefore, little is known about the relationship between structural properties of brain regions relevant to sentence processing and more specific cognitive abilities underlying complex sentence comprehension. In this study, whole-brain magnetic resonance images from 59 children between 5 and 8 years were assessed. Scores on a standardized sentence comprehension test determined grammatical proficiency of our participants. A confirmatory factory analysis corroborated a grammar-relevant and a verbal working memory-relevant factor underlying the measured performance. Voxel-based morphometry of gray matter revealed that while children's ability to assign thematic roles is positively correlated with gray matter probability (GMP) in the left inferior temporal gyrus and the left inferior frontal gyrus, verbal working memory-related performance is positively correlated with GMP in the left parietal operculum extending into the posterior superior temporal gyrus. Since these areas are known to be differentially engaged in adults' complex sentence processing, our data suggest a specific correspondence between children's GMP in language-relevant brain regions and differential cognitive abilities that guide their sentence comprehension.
[Show abstract][Hide abstract] ABSTRACT: Language comes in utterances in which words are bound together according to a simple rule-based syntactic computation (merge),
which creates linguistic hierarchies of potentially infinite length—phrases and sentences. In the current functional magnetic
resonance imaging study, we compared prepositional phrases and sentences—both involving merge—to word lists—not involving
merge—to explore how this process is implemented in the brain. We found that merge activates the pars opercularis of the left
inferior frontal gyrus (IFG; Brodmann Area [BA] 44) and a smaller region in the posterior superior temporal sulcus (pSTS).
Within the IFG, sentences engaged a more anterior portion of the area (pars triangularis, BA 45)—compared with phrases—which
showed activity peak in BA 44. As prepositional phrases, in contrast to sentences, do not contain verbs, activity in BA 44
may reflect structure-building syntactic processing, while the involvement of BA 45 may reflect the encoding of propositional
meaning initiated by the verb. The pSTS appears to work together with the IFG during thematic role assignment not only at
the sentential level, but also at the phrasal level. The present results suggest that merge, the process of binding words
together into syntactic hierarchies, is primarily supported by BA 44 in the IFG.
[Show abstract][Hide abstract] ABSTRACT: Complex human behavior is hierarchically organized. Whether or not syntax plays a role in this organization is currently under debate. The present ERP study uses piano performance to isolate syntactic operations in action planning and to demonstrate their priority over nonsyntactic levels of movement selection. Expert pianists were asked to execute chord progressions on a mute keyboard by copying the posture of a performing model hand shown in sequences of photos. We manipulated the final chord of each sequence in terms of Syntax (congruent/incongruent keys) and Manner (conventional/unconventional fingering), as well as the strength of its predictability by varying the length of the Context (five-chord/two-chord progressions). The production of syntactically incongruent compared to congruent chords showed a response delay that was larger in the long compared to the short context. This behavioral effect was accompanied by a centroparietal negativity in the long but not in the short context, suggesting that a syntax-based motor plan was prepared ahead. Conversely, the execution of the unconventional manner was not delayed as a function of Context and elicited an opposite electrophysiological pattern (a posterior positivity). The current data support the hypothesis that motor plans operate at the level of musical syntax and are incrementally translated to lower levels of movement selection.
[Show abstract][Hide abstract] ABSTRACT: One main incentive for supplying hearing impaired children with a cochlear implant is the prospect of oral language acquisition. Only scarce knowledge exists, however, of what congenitally deaf children actually perceive, when receiving their first auditory input and specifically what speech-relevant features they are able to extract from the new modality. We therefore presented congenitally deaf infants and young children implanted before the age of 4 with an oddball paradigm of long and short vowel variants of the syllable /ba/. We measured the EEG in regular intervals to study their discriminative ability starting with the first activation of the implant up to 8 months later. We were thus able to time-track the emerging ability to differentiate one of the most basic linguistic features that bears semantic differentiation and helps in word segmentation and semantic discrimination, namely vowel length. Results show that already 2 months after the first auditory input, but not directly after implant activation, these early implanted children differentiate between long and short syllables. Surprisingly, after only 4 months of hearing experience, the ERPs have reached the same properties as those of the normal hearing control group, demonstrating the plasticity of the brain with respect to the new modality. We thus show that a simple but linguistically highly relevant feature such as vowel length reaches age-appropriate electrophysiological levels as fast as 4 months after the first acoustic stimulation, providing good ground for further language acquisition.
No preview · Article · Sep 2015 · Journal of Cognitive Neuroscience
[Show abstract][Hide abstract] ABSTRACT: The development of language comprehension abilities in childhood is closely related to the maturation of the brain, especially the ability to process syntactically complex sentences. Recent studies proposed that the fronto-temporal connection within left perisylvian regions, supporting the processing of syntactically complex sentences, is still immature at preschool age. In the current study, resting state functional magnetic resonance imaging data were acquired from typically developing 5-year-old children and adults to shed further light on the brain functional development. Children additionally performed a behavioral syntactic comprehension test outside the scanner. The amplitude of low-frequency fluctuations was analyzed in order to identify the functional correlation networks of language-relevant brain regions. Results showed an intrahemispheric correlation between left inferior frontal gyrus (IFG) and left posterior superior temporal sulcus (pSTS) in adults, whereas an interhemispheric correlation between left IFG and its right-hemispheric homologue was predominant in children. Correlation analysis between resting-state functional connectivity and sentence processing performance in 5-year-olds revealed that local connectivity within the left IFG is associated with competence of processing syntactically simple canonical sentences, while long-range connectivity between IFG and pSTS in left hemisphere is associated with competence of processing syntactically relatively more complex non-canonical sentences. The present developmental data suggest that a selective left fronto-temporal connectivity network for processing complex syntax is already in functional connection at the age of 5 years when measured in a non-task situation. The correlational findings provide new insight into the relationship between intrinsic functional connectivity and syntactic language abilities in preschool children.
[Show abstract][Hide abstract] ABSTRACT: Neuroimaging and transcranial magnetic stimulation provide insights into the neuronal mechanisms underlying speech disfluencies in chronic persistent stuttering. In the present paper, the goal is not to provide an exhaustive review of existing literature, but rather to highlight robust findings. We, therefore, conducted a meta-analysis of diffusion tensor imaging studies which have recently implicated disrupted white matter connectivity in stuttering. A reduction of fractional anisotropy in persistent stuttering has been reported at several different loci. Our meta-analysis revealed consistent deficits in the left dorsal stream and in the interhemispheric connections between the sensorimotor cortices. In addition, recent fMRI meta-analyses link stuttering to reduced left fronto-parieto-temporal activation while greater fluency is associated with boosted co-activations of right fronto-parieto-temporal areas. However, the physiological foundation of these irregularities is not accessible with MRI. Complementary, transcranial magnetic stimulation (TMS) reveals local excitatory and inhibitory regulation of cortical dynamics. Applied to a speech motor area, TMS revealed reduced speech-planning-related neuronal dynamics at the level of the primary motor cortex in stuttering. Together, this review provides a focused view of the neurobiology of stuttering to date and may guide the rational design of future research. This future needs to account for the perpetual dynamic interactions between auditory, somatosensory, and speech motor circuits that shape fluent speech.
Full-text · Article · Sep 2015 · Current Neurology and Neuroscience Reports
[Show abstract][Hide abstract] ABSTRACT: Developmental dyslexia, a severe impairment of literacy acquisition, is known to have a neurological basis and a strong genetic background. However, effects of individual genetic variations on dyslexia-associated deficits are only moderate and call for the assessment of the genotype's impact on mediating neuro-endophenotypes by the imaging genetics approach. Using voxel-based morphometry (VBM) in German participants with and without dyslexia, we investigated gray matter changes and their association with impaired phonological processing, such as reduced verbal working memory. These endophenotypical alterations were, together with dyslexia-associated genetic variations, examined on their suitability as potential predictors of dyslexia. We identified two gray matter clusters in the left posterior temporal cortex related to verbal working memory capacity. Regional cluster differences correlated with genetic risk variants in TNFRSF1B. High-genetic-risk participants exhibit a structural predominance of auditory-association areas relative to auditory-sensory areas, which may partly compensate for deficient early auditory-sensory processing stages of verbal working memory. The reverse regional predominance observed in low-genetic-risk participants may in turn reflect reliance on these early auditory-sensory processing stages. Logistic regression analysis further supported that regional gray matter differences and genetic risk interact in the prediction of individuals' diagnostic status: With increasing genetic risk, the working-memory related structural predominance of auditory-association areas relative to auditory-sensory areas classifies participants with dyslexia versus control participants. Focusing on phonological deficits in dyslexia, our findings suggest endophenotypical changes in the left posterior temporal cortex could comprise novel pathomechanisms for verbal working memory-related processes translating TNFRSF1B genotype into the dyslexia phenotype.
[Show abstract][Hide abstract] ABSTRACT: In a recent Opinion article, Bornkessel-Schlesewsky et al.  make the interesting proposal that the basic computational mechanisms necessary for language processing are implemented in the nonhuman primate brain. According to the authors, neural differences between human and nonhu-man primates are quantitative but not qualitative in nature. Both species share a ventral stream underlying auditory object recognition and combination, and a dorsal stream underlying sequence processing. The cross-stream interaction is assumed to be crucial for human language to emerge. The observed cross-species differences in language are based on the prefrontal cortex (PFC) that allows the integration of information from both streams only in humans. We agree with Bornkessel-Schlesewsky et al. that language , in common with other cognitive functions, is grounded on basic physiological principles . We furthermore acknowledge that the nonhuman primate prefrontal cortex supports symbolic manipulation abilities that can be seen as precursors to the syntactically guided structuring of signs in humans . However, we emphasize that some important data not discussed by Bornkessel-Schlesewsky et al. strongly support the view that there are clear qualitative , and not merely quantitative, differences between the species with respect to both the intrinsic functional connectivity of frontal and temporal cortices, and their direct structural connection via a dorsal white matter fiber tract. Moreover, we should point out that the exact nature of the claimed interaction between streams postulated by the authors awaits specification at both the functional and structural levels, and remains to be proven empirically.
Full-text · Article · Jun 2015 · Trends in Cognitive Sciences