Human Language Function Research Articles

Connectivity Reveals the Relationships between Human Brain Areas Associated with High-Level Linguistic Processing and Macaque Brain Areas.

Cross-species research has advanced human understanding of brain regions, with cross-species comparisons using magnetic resonance imaging technology becoming increasingly common. Currently, cross-species research on human language regions has primarily focused on traditional brain areas such as the Broca region. While some studies have indicated that human language function also involves other language regions, the corresponding relationships between these brain regions in humans and macaques remain unclear. This study calculated the strength of the connections between the high-level language processing regions in human and macaque brains, identified homologous target areas based on the structural connections of white-matter fiber bundles, and compared the connectivity profiles of both species. The results of the experiment demonstrated that macaques possess brain regions which exhibit connectivity patterns resembling those found in human high-level language processing regions. This discovery suggests that while the function of a human brain region is specialized, it still maintains a structural connectivity similar to that seen in macaques.

Turning the Spotlight to Cholinergic Pharmacotherapy of the Human Language System.

Even though language is essential in human communication, research on pharmacological therapies for language deficits in highly prevalent neurodegenerative and vascular brain diseases has received little attention. Emerging scientific evidence suggests that disruption of the cholinergic system may play an essential role in language deficits associated with Alzheimer's disease and vascular cognitive impairment, including post-stroke aphasia. Therefore, current models of cognitive processing are beginning to appraise the implications of the brain modulator acetylcholine in human language functions. Future work should be directed further to analyze the interplay between the cholinergic system and language, focusing on identifying brain regions receiving cholinergic innervation susceptible to modulation with pharmacotherapy to improve affected language domains. The evaluation of language deficits in pharmacological cholinergic trials for Alzheimer's disease and vascular cognitive impairment has thus far been limited to coarse-grained methods. More precise, fine-grained language testing is needed to refine patient selection for pharmacotherapy to detect subtle deficits in the initial phases of cognitive decline. Additionally, noninvasive biomarkers can help identify cholinergic depletion. However, despite the investigation of cholinergic treatment for language deficits in Alzheimer's disease and vascular cognitive impairment, data on its effectiveness are insufficient and controversial. In the case of post-stroke aphasia, cholinergic agents are showing promise, particularly when combined with speech-language therapy to promote trained-dependent neural plasticity. Future research should explore the potential benefits of cholinergic pharmacotherapy in language deficits and investigate optimal strategies for combining these agents with other therapeutic approaches.

Individualized Functional Subnetworks Connect Human Striatum and Frontal Cortex.

The striatum and cerebral cortex are interconnected via multiple recurrent loops that play a major role in many neuropsychiatric conditions. Primate corticostriatal connections can be precisely mapped using invasive tract-tracing. However, noninvasive human research has not mapped these connections with anatomical precision, limited in part by the practice of averaging neuroimaging data across individuals. Here we utilized highly sampled resting-state functional connectivity MRI for individual-specific precision functional mapping (PFM) of corticostriatal connections. We identified ten individual-specific subnetworks linking cortex-predominately frontal cortex-to striatum, most of which converged with nonhuman primate tract-tracing work. These included separable connections between nucleus accumbens core/shell and orbitofrontal/medial frontal gyrus; between anterior striatum and dorsomedial prefrontal cortex; between dorsal caudate and lateral prefrontal cortex; and between middle/posterior putamen and supplementary motor/primary motor cortex. Two subnetworks that did not converge with nonhuman primates were connected to cortical regions associated with human language function. Thus, precision subnetworks identify detailed, individual-specific, neurobiologically plausible corticostriatal connectivity that includes human-specific language networks.

Co-evolution of internalization and externalization in the emergence of the human lexicon

AbstractThere has been a long-standing controversy in the context of language evolution on whether the original function of human language was internal thought or external communication. However, given the fact that language clearly serves both functions, internalization and externalization must have been co-evolutionarily acted in the emergence of human language. This article proposes a theoretical hypothesis about this co-evolutionary relationship of internalization and externalization, which especially explains the emergence of the human lexicon. To discuss the evolution of language from a comprehensive perspective, this article proposes a promising model that integrates two approaches with different standpoints: generative grammar and cognitive linguistics. This paper also examines the definition and nature of the lexicon and lexical items based on this integrated model. The hypothesis presented here demonstrates that the co-evolutionary work of internalization and externalization has been involved in two processes in the development of the lexicon: the establishment of syntactic objects (lexical items) and the improvement of creativity responsible for the expansion of lexicon size. The main conclusion is that these processes have formed a positive feedback loop and provided our lexicon with complex and unique properties.

Identification of risk factors for poor language outcome in surgical resection of glioma involving the arcuate fasciculus: an observational study.

The arcuate fasciculus is a critical component of the neural substrate of human language function. Surgical resection of glioma adjacent to the arcuate fasciculus likely damages this region. In this study, we evaluated the outcome of surgical resection of glioma adjacent to the arcuate fasciculus under the guidance of magnetic resonance imaging and diffusion tensor imaging, and we aimed to identify the risk factors for postoperative linguistic deficit. In total, 54 patients with primary glioma adjacent to the arcuate fasciculus were included in this observational study. These patients comprised 38 men and 16 women (aged 43 ± 11 years). All patients underwent surgical resenction of glioma under the guidance of magnetic resonance imaging and diffusion tensor imaging. Intraoperative images were updated when necessary for further resection. The gross total resection rate of the 54 patients increased from 38.9% to 70.4% by intraoperative magnetic resonance imaging. Preoperative language function and glioma-to-arcuate fasciculus distance were associated with poor language outcome. Multivariable logistic regression analyses showed that glioma-to-arcuate fasciculus distance was the major independent risk factor for poor outcome. The cutoff point of glioma-to-arcuate fasciculus distance for poor outcome was 3.2 mm. These findings suggest that intraoperative magnetic resonance imaging combined with diffusion tensor imaging of the arcuate fasciculus can help optimize tumor resection and result in the least damage to the arcuate fasciculus. Notably, glioma-to-arcuate fasciculus distance is a key independent risk factor for poor postoperative language outcome. This study was approved by the Ethics Committee of the Chinese PLA General Hospital, China (approval No. S2014-096-01) on October 11, 2014.

The Essentials of Brain Anatomy for Physiatrists: Magnetic Resonance Imaging Findings.

Detailed knowledge of the brain anatomy is important for the treatment of patients with brain disorders. In this study, we conducted a review of essential parts of human brain anatomy based on magnetic resonance imaging of the brain. Using T2-weighted brain magnetic resonance imaging, we explained how to recognize several structures in each brain lobe (the frontal, parietal, temporal, and occipital lobes). We depicted the boundary of each structure on brain magnetic resonance imaging and described their functions. The limbic system controls various functions such as emotion, motivation, behavior, memory, and olfaction. Broca's and Wernicke's areas and arcuate fasciculus are important structures for human language functions. Emotion, memory, and language function are one of the main functions of human. Therefore, the anatomical knowledge of the limbic system and language-related structures is important for physiatrists. We described the anatomical location and function of each substructure of the limbic system and language centers. In addition, we indicated the exact points of motor- and sensory-related neural tracts (corticospinal tract, corticoreticular pathway, medial lemniscus, and spinothalamic tract) on brain magnetic resonance imaging. We believe that our review on brain anatomy would be helpful for physiatrists to accurately identify the damage of each function from brain disorders and elucidate proper plan for rehabilitative treatment.

Linguistics and communication

AbstractThis essay begins by identifying what communication is and what linguistics is in order to establish the relationship between them. The characterization of linguistics leads to discussion of the nature of language and of the relationship between a theory of language, i. e., linguistic theory, and the object language it models. This, in turn, leads to a review of speculations on the origins of human language with a view to identifying the motivation for its creation and its primary function. After considering a host of data, it becomes clear that, contrary to some approaches, the primary function of human language is to function as a vehicle of communication. Thus, linguistics studies what for humans is their primary vehicle of communication.

Brain Functional Organization Associated With Language Lateralization.

Although it is well-established that human language functions are mostly lateralized to the left hemisphere of the brain, little is known about the functional mechanisms underlying such hemispheric dominance. The present study investigated intrinsic organization of the whole brain at rest, by means of functional connectivity and graph theoretical analysis, with the aim to characterize brain functional organization underlying typical and atypical language dominance. We included healthy left-handers, both those with typical left-lateralized language and those with atypical right-lateralized language. Results show that 1) differences between typical and atypical language lateralization are associated with functional connectivity within the language system, particularly with weakened connectivity between left inferior frontal gyrus and several other language-related areas; and 2) for participants with atypical language dominance, the degree of lateralization is linked with multiple functional connectivities and graph theoretical metrics of whole brain organization, including local efficiency and small-worldness. This is the first study, to our knowledge, that linked the degree of language lateralization to global topology of brain networks. These results reveal that typical and atypical language dominance mainly differ in functional connectivity within the language system, and that atypical language dominance is associated with whole-brain organization.

Investigating Stimulation Protocols for Language Mapping by Repetitive Navigated Transcranial Magnetic Stimulation.

Navigated transcranial magnetic stimulation (nTMS) is increasingly applied to map human language functions. However, studies on protocol comparisons are mostly lacking. In this study, 20 healthy volunteers (25.7 ± 3.8 years, 12 females) underwent left-hemispheric language mapping by nTMS, combined with an object-naming task, over a cortical spot with reproducible naming errors within the triangular or opercular part of the inferior frontal gyrus (trIFG, opIFG: anterior stimulation) and the angular gyrus or posterior part of the superior temporal gyrus (anG, pSTG: posterior stimulation), respectively. Various stimulation intensities [80, 100, and 120% of the resting motor threshold (rMT)], frequencies (2, 5, 10, and 20 Hz), and coil orientations (in steps of 45°) were evaluated, and the adjustments leading to the highest error rates (ERs), combined with low occurrences of errors due to muscle stimulation, were considered optimal. Regarding anterior stimulation, 100% rMT, 5 Hz, and a coil orientation of 90° or 270° in relation to the respective stimulated gyrus resulted in optimal results. For posterior stimulation, 100% rMT, 10 Hz, and coil orientations of 90° or 270° were considered optimal. Errors due to facial muscle stimulation only played a considerable role during analyses of high-intensity (120% rMT) or high-frequency stimulation (20 Hz). In conclusion, this is one of the first studies to systematically investigate different stimulation protocols for nTMS language mapping, including detailed analyses of the distribution of ERs in relation to various coil orientations considered during neuronavigated stimulation. Mapping with 100% rMT, combined with 5 Hz (anterior stimulation) or 10 Hz (posterior stimulation) and a coil orientation perpendicular to the respective stimulated gyrus can be recommended as optimal adjustments.

Setup presentation and clinical outcome analysis of treating highly language-eloquent gliomas via preoperative navigated transcranial magnetic stimulation and tractography

OBJECTIVE Awake surgery combined with intraoperative direct electrical stimulation (DES) and intraoperative neuromonitoring (IONM) is considered the gold standard for the resection of highly language-eloquent brain tumors. Different modalities, such as functional magnetic resonance imaging (fMRI) or magnetoencephalography (MEG), are commonly added as adjuncts for preoperative language mapping but have been shown to have relevant limitations. Thus, this study presents a novel multimodal setup consisting of preoperative navigated transcranial magnetic stimulation (nTMS) and nTMS-based diffusion tensor imaging fiber tracking (DTI FT) as an adjunct to awake surgery. METHODS Sixty consecutive patients (63.3% men, mean age 47.6 ± 13.3 years) suffering from highly language-eloquent left-hemispheric low- or high-grade glioma underwent preoperative nTMS language mapping and nTMS-based DTI FT, followed by awake surgery for tumor resection. Both nTMS language mapping and DTI FT data were available for resection planning and intraoperative guidance. Clinical outcome parameters, including craniotomy size, extent of resection (EOR), language deficits at different time points, Karnofsky Performance Scale (KPS) score, duration of surgery, and inpatient stay, were assessed. RESULTS According to postoperative evaluation, 28.3% of patients showed tumor residuals, whereas new surgery-related permanent language deficits occurred in 8.3% of patients. KPS scores remained unchanged (median preoperative score 90, median follow-up score 90). CONCLUSIONS This is the first study to present a clinical outcome analysis of this very modern approach, which is increasingly applied in neurooncological centers worldwide. Although human language function is a highly complex and dynamic cortico-subcortical network, the presented approach offers excellent functional and oncological outcomes in patients undergoing surgery of lesions affecting this network.

Mood Structure Analysis and Thematisation Patterns in Niyi Osundare’s “My Lord, Tell Me Where to Keep Your Bribe”

One of the theories that seek to unravel how the human language functions is the Systemic Functional Grammar (SFG). SFG achieves its uniqueness by seeking to develop a theory about language as a social process and an analytical methodology for detailed and systematic description of language patterns (Eggins, 2004). Given its suitability for the analysis of any text, SFG was used in this study for the analysis of the poem “My Lord, Tell Me Where to Keep Your Bribe”. Though SFG shows how three different strands of meanings (ideational, interpersonal and textual) are expressed in the structures of clauses, the focus of analysis was on the grammar of textual and interpersonal meanings, hence the thematic and Mood structure analyses of the poem. The thematisation patterns identified in the poem included the use of textual themes (for inter-clause cohesive purposes), interpersonal themes (for the assignment of Mood labels to clauses) and topical themes, which altogether enabled the poet bring into thematic prominence the major issues of worry to an average Nigerian who had always thought judges and the courts of law should be immune from corruption. The Mood structure analysis showed the poet’s conscious choices of the indicative Mood, with alternating options of interrogative and declarative clause types. Overall, the SFG-based analysis showed how the poet made conscious paradigmatic choices and arranged them into linear (syntagmatic) structures to make the different meanings conveyed in the poem.

Transcranial Direct Current Stimulation in Poststroke Aphasia Recovery.

Transcranial direct current stimulation (tDCS), a form of noninvasive brain stimulation originally studied for its effect on motor limb physiology,1 has been investigated for its use in the treatment of aphasia since 2008.2–3 The experimental use of tDCS for aphasia, however, began differently from those paradigms established for poststroke motor recovery, both conceptually and in method. Not only is aphasia research a relative newcomer to the field of tDCS experimentation, it has thus far been somewhat of an outlier in its limited use of tDCS autonomously. Theoretically understood to be vastly more complex than our intricate motor systems, cortical language representation has most recently been conceptualized as a dual stream, diffuse network,4–6 with language processing subcomponents evolved from nonlinguistic primates.7,8 In the dual stream model, human language functions are lateralized primarily in the left hemisphere, with Broca’s area comprising the left complement of a bilateral dorsal stream network devoted to naming and articulation. Conversely, Wernicke’s area constitutes the origin of a bilateral ventral stream in which semantic meaning is attached to components of speech sounds.6,9–21 Additional activation in homologous right hemisphere language areas seems to be determined by lexical necessity, with increased articulatory demands activated within the bilateral dorsal stream and the decoding of unfamiliar words activated in the bilateral ventral stream network.9 Complex as it may be to optimally prime the motor cortex for poststroke limb rehabilitation using tDCS, it may be considered even more challenging to modulate the cortical plexus which encodes and produces language in all of its richness. The theoretical mechanisms of brain activation during tDCS protocols suggest that tDCS primes the brain for enhanced outcomes in behavioral therapies,22 which may have led to the appeal of combining methods concurrently. The …

A contemporary framework of language processing in the human brain in the context of preoperative and intraoperative language mapping.

The emergence of advanced in vivo neuroimaging methods has redefined the understanding of brain function with a shift from traditional localizationist models to more complex and widely distributed neural networks. In human language processing, the traditional localizationist models of Wernicke and Broca have fallen out of favor for a dual-stream processing system involving complex networks organized over vast areas of the dominant hemisphere. The current review explores the cortical function and white matter connections of human language processing, as well as their relevance to surgical planning. We performed a systematic review of the literature with narrative data analysis. Although there is significant heterogeneity in the literature over the past century of exploration, modern evidence provides new insight into the true cortical function and white matter anatomy of human language. Intraoperative data and postoperative outcome studies confirm a widely distributed language network extending far beyond the traditional cortical areas of Wernicke and Broca. The anatomic distribution of language networks, based on current theories, is explored to present a modern and clinically relevant interpretation of language function. Within this framework, we present current knowledge regarding the known effects of damage to both cortical and subcortical components of these language networks. Ideally, we hope this framework will provide a common language for which to base future clinical studies in human language function.

Spatial-temporal functional mapping of language at the bedside with electrocorticography.

To investigate the feasibility and clinical utility of using passive electrocorticography (ECoG) for online spatial-temporal functional mapping (STFM) of language cortex in patients being monitored for epilepsy surgery. We developed and tested an online system that exploits ECoG's temporal resolution to display the evolution of statistically significant high gamma (70-110 Hz) responses across all recording sites activated by a discrete cognitive task. We illustrate how this spatial-temporal evolution can be used to study the function of individual recording sites engaged during different language tasks, and how this approach can be particularly useful for mapping eloquent cortex. Using electrocortical stimulation mapping (ESM) as the clinical gold standard for localizing language cortex, the average sensitivity and specificity of online STFM across 7 patients were 69.9% and 83.5%, respectively. Moreover, relative to regions of interest where discrete cortical lesions have most reliably caused language impairments in the literature, the sensitivity of STFM was significantly greater than that of ESM, while its specificity was also greater than that of ESM, though not significantly so. This study supports the feasibility and clinical utility of online STFM for mapping human language function, particularly under clinical circumstances in which time is limited and comprehensive ESM is impractical.

Erratum to: The impact of repetitive navigated transcranial magnetic stimulation coil positioning and stimulation parameters on human language function

Repetitive navigated transcranial magnetic stimulation (rTMS) in combination with object naming is able to elicit naming errors by stimulating language-related brain regions. However, stimulation results mainly depend on coil positioning and stimulation parameters, which have not been investigated since the implementation of neuronavigation to transcranial magnetic stimulation. Therefore, the following three parameters were systematically examined in the present study: coil angulation, stimulation frequency, and stimulation intensity. Five healthy, right-handed subjects underwent rTMS language mapping of Broca’s as well as Wernicke’s areas of the left hemisphere. During mapping sessions, coil angulation was changed clockwise in 45° steps, and the stimulation frequency and intensity were varied within a considerably wide range. For angulation, the anterior-posterior (ap) coil orientation was used as reference position. An angulation of 90° to ap coil orientation led to the highest rate of naming errors within Broca’s area, whereas an inhomogeneous distribution of angulations was observed during stimulation of Wernicke’s area. Therefore, ap coil orientation, which is regarded as standard in rTMS language mapping, could not be approved as the optimal position. With regard to stimulation parameters, 20 Hz and 120% of the resting motor threshold (RMT) were defined as optimal. Coil angulation, stimulation frequency, and stimulation intensity have significant impacts on language impairment during rTMS mapping. The variation of only one of these parameters already leads to a clearer disruption of language performance. Therefore, individually adapted stimulation protocols have to be determined prior to language mapping in order to improve mapping results.

Recent advances in genetic studies of stuttering

Speech and language are uniquely human-specific traits, which contributed to humans becoming the predominant species on earth. Disruptions in the human speech and language function may result in diverse disorders. These include stuttering, aphasia, articulation disorder, spasmodic dysphonia, verbal dyspraxia, dyslexia and specific language impairment. Among these disorders, stuttering is the most common speech disorder characterized by disruptions in the normal flow of speech. Twin, adoption, and family studies have suggested that genetic factors are involved in susceptibility to stuttering. For several decades, multiple genetic studies including linkage analysis were performed to connect causative gene to stuttering, and several genetic studies have revealed the association of specific gene mutation with stuttering. One notable genetic discovery came from the genetic studies in the consanguineous Pakistani families. These studies suggested that mutations in the lysosomal enzyme-targeting pathway genes (GNPTAB, GNPTG and NAPGA) are associated with non-syndromic persistent stuttering. Although these studies have revealed some clues in understanding the genetic causes of stuttering, only a small fraction of patients are affected by these genes. In this study, we summarize recent advances and future challenges in an effort to understand genetic causes underlying stuttering.

Exploring the acquisition and production of grammatical constructions through human-robot interaction with echo state networks.

One of the principal functions of human language is to allow people to coordinate joint action. This includes the description of events, requests for action, and their organization in time. A crucial component of language acquisition is learning the grammatical structures that allow the expression of such complex meaning related to physical events. The current research investigates the learning of grammatical constructions and their temporal organization in the context of human-robot physical interaction with the embodied sensorimotor humanoid platform, the iCub. We demonstrate three noteworthy phenomena. First, a recurrent network model is used in conjunction with this robotic platform to learn the mappings between grammatical forms and predicate-argument representations of meanings related to events, and the robot's execution of these events in time. Second, this learning mechanism functions in the inverse sense, i.e., in a language production mode, where rather than executing commanded actions, the robot will describe the results of human generated actions. Finally, we collect data from naïve subjects who interact with the robot via spoken language, and demonstrate significant learning and generalization results. This allows us to conclude that such a neural language learning system not only helps to characterize and understand some aspects of human language acquisition, but also that it can be useful in adaptive human-robot interaction.

Investigating Constituent Order Change With Elicited Pantomime: A Functional Account of SVO Emergence

One of the most basic functions of human language is to convey who did what to whom. In the world's languages, the order of these three constituents (subject [S], verb [V], and object [O]) is uneven, with SOV and SVO being most common. Recent experiments using experimentally elicited pantomime provide a possible explanation of the prevalence of SOV, but extant explanations for the prevalence of SVO could benefit from further empirical support. Here, we test whether SVO might emerge because (a) SOV is not well suited for describing reversible events (a woman pushing a boy) and (b) pressures to be efficient and mention subjects before objects conspire to rule out many other alternatives. We tested this by asking participants to describe reversible and non-reversible events in pantomime, and we instructed some participants to be consistent in the form of their gestures and to teach them to the experimenter. These manipulations led to the emergence of SVO in speakers of both English (SVO) and Turkish (SOV).

Independent contribution of individual white matter pathways to language function in pediatric epilepsy patients

Background and purposePatients with epilepsy and malformations of cortical development (MCDs) are at high risk for language and other cognitive impairment. Specific impairments, however, are not well correlated with the extent and locale of dysplastic cortex; such findings highlight the relevance of aberrant cortico-cortical interactions, or connectivity, to the clinical phenotype. The goal of this study was to determine the independent contribution of well-described white matter pathways to language function in a cohort of pediatric patients with epilepsy.Materials and methodsPatients were retrospectively identified from an existing database of pediatric epilepsy patients with the following inclusion criteria: 1. diagnosis of MCDs, 2. DTI performed at 3 T, and 3. language characterized by a pediatric neurologist. Diffusion Toolkit and Trackvis (http://www.trackvis.org) were used for segmentation and analysis of the following tracts: corpus callosum, corticospinal tracts, inferior longitudinal fasciculi (ILFs), inferior fronto-occipital fasciculi (IFOFs), uncinate fasciculi (UFs), and arcuate fasciculi (AFs). Mean diffusivity (MD) and fractional anisotropy (FA) were calculated for each tract. Wilcoxon rank sum test (corrected for multiple comparisons) was used to assess potential differences in tract parameters between language-impaired and language-intact patients. In a separate analysis, a machine learning algorithm (random forest approach) was applied to measure the independent contribution of the measured diffusion parameters for each tract to the clinical phenotype (language impairment). In other words, the importance of each tract parameter was measured after adjusting for the contribution of all other tracts.ResultsThirty-three MCD patients were included (age range: 3–18 years). Twenty-one patients had intact language, twelve had language impairment. All tracts were identified bilaterally in all patients except for the AF, which was not identified on the right in 10 subjects and not identified on the left in 11 subjects. MD and/or FA within the left AF, UF, ILF, and IFOF differed between language-intact and language-impaired groups. However, only parameters related to the left uncinate, inferior fronto-occipital, and arcuate fasciculi were independently associated with the clinical phenotype.ConclusionsScalar metrics derived from the left uncinate, inferior fronto-occipital, and arcuate fasciculi were independently associated with language function. These results support the importance of these pathways in human language function in patients with MCDs.

An exploration into the properties and functions of Graffiti

This paper discusses the linguistic properties and functions of wall writings (graffiti) made in Kenyan Universities. The paper starts with an introduction by giving the definition of graffiti and a background to its study. The paper also takes a look at the some of the common features of graffiti as forms of linguistic communication. This paper was guided by Hallidayian framework of studying linguistic function. It describes the motivations behind the authors of wall literature and identifies a number of linguistic functions of graffiti some of which are unique to this linguistics phenomenon and others which are marked in such settings. It concludes that a deeper study may unravel other fundamental properties and functions of human language. Key Words : Graffiti, Wall writings, Latrinalia, lingusitic functions