Benefit of Action Naming Over Object Naming for Visualization of Subcortical Language Pathways in Navigated Transcranial Magnetic Stimulation-Based Diffusion Tensor Imaging-Fiber Tracking

Visualization of functionally significant subcortical white matter fibers is needed in neurosurgical procedures in order to avoid damage to the language network during resection. In an effort to achieve this, positive cortical points revealed during preoperative language mapping with navigated transcranial magnetic stimulation (nTMS) can be employed as regions of interest (ROIs) for diffusion tensor imaging (DTI) fiber tracking. However, the effect that the use of different language tasks has on nTMS mapping and subsequent DTI-fiber tracking remains unexplored. The visualization of ventral stream tracts with an assumed lexico-semantic role may especially benefit from ROIs delivered by the lexico-semantically demanding verb task, Action Naming. In a first step, bihemispheric nTMS language mapping was administered in 18 healthy participants using the standard task Object Naming and the novel task Action Naming to trigger verbs in a small sentence context. Cortical areas in which nTMS induced language errors were identified as language-positive cortical sites. In a second step, nTMS-based DTI-fiber tracking was conducted using solely these language-positive points as ROIs. The ability of the two tasks’ ROIs to visualize the dorsal tracts Arcuate Fascicle and Superior Longitudinal Fascicle, the ventral tracts Inferior Longitudinal Fascicle, Uncinate Fascicle, and Inferior Fronto-Occipital Fascicle, the speech-articulatory Cortico-Nuclear Tract, and interhemispheric commissural fibers was compared in both hemispheres. In the left hemisphere, ROIs of Action Naming led to a significantly higher fraction of overall visualized tracts, specifically in the ventral stream’s Inferior Fronto-Occipital and Inferior Longitudinal Fascicle. No difference was found between tracking with Action Naming vs. Object Naming seeds for dorsal stream tracts, neither for the speech-articulatory tract nor the inter-hemispheric connections. While the two tasks appeared equally demanding for phonological-articulatory processes, ROI seeding through the task Action Naming seemed to better visualize lexico-semantic tracts in the ventral stream. This distinction was not evident in the right hemisphere. However, the distribution of tracts exposed was, overall, mirrored relative to those in the left hemisphere network. In presurgical practice, mapping and tracking of language pathways may profit from these findings and should consider inclusion of the Action Naming task, particularly for lesions in ventral subcortical regions.

Do Cues Facilitate Retrieval of Verbs in Persons with Bilingual Aphasia?

Word retrieval difficulty is commonly seen in persons with aphasia. The cues would repair word retrieval difficulty. The effect of cues during verb retrieval was gauged via Action Naming Test (ANT) in Kannada and English languages in persons with aphasia (PWAs). A total of eight persons with bilingual Aphasia (Broca's, conduction, and isolation type) were recruited for the study. The participants were expected to have a minimum quantum of verbal output were considered for the study. Specifically, the study used phonemic, semantic, and verbal contextual cues to assess verb retrieval abilities. The result of the study manifested that all participants of the study were able to perform better with phonemic cues followed by semantic and verbal contextual cues in both Kannada and English languages.

Bihemispheric Navigated Transcranial Magnetic Stimulation Mapping for Action Naming Compared to Object Naming in Sentence Context

Preoperative language mapping with navigated transcranial magnetic stimulation (nTMS) is currently based on the disruption of performance during object naming. The resulting cortical language maps, however, lack accuracy when compared to intraoperative mapping. The question arises whether nTMS results can be improved, when another language task is considered, involving verb retrieval in sentence context. Twenty healthy German speakers were tested with object naming and a novel action naming task during nTMS language mapping. Error rates and categories in both hemispheres were compared. Action naming showed a significantly higher error rate than object naming in both hemispheres. Error category comparison revealed that this discrepancy stems from more lexico-semantic errors during action naming, indicating lexico-semantic retrieval of the verb being more affected than noun retrieval. In an area-wise comparison, higher error rates surfaced in multiple right-hemisphere areas, but only trends in the left ventral postcentral gyrus and middle superior temporal gyrus. Hesitation errors contributed significantly to the error count, but did not dull the mapping results. Inclusion of action naming coupled with a detailed error analysis may be favorable for nTMS mapping and ultimately improve accuracy in preoperative planning. Moreover, the results stress the recruitment of both left- and right-hemispheric areas during naming.

Mapping Verb Retrieval With nTMS: The Role of Transitivity

Navigated Transcranial Magnetic Stimulation (nTMS) is used to understand the cortical organization of language in preparation for the surgical removal of a brain tumor. Action naming with finite verbs can be employed for that purpose, providing additional information to object naming. However, little research has focused on the properties of the verbs that are used in action naming tasks, such as their status as transitive (taking an object; e.g., to read) or intransitive (not taking an object; e.g., to wink). Previous neuroimaging data show higher activation for transitive compared to intransitive verbs in posterior perisylvian regions bilaterally. In the present study, we employed nTMS and production of finite verbs to investigate the cortical underpinnings of transitivity. Twenty neurologically healthy native speakers of German participated in the study. They underwent language mapping in both hemispheres with nTMS. The action naming task with finite verbs consisted of transitive (e.g., The man reads the book) and intransitive verbs (e.g., The woman winks) and was controlled for relevant psycholinguistic variables. Errors were classified in four different error categories (i.e., non-linguistic errors, grammatical errors, lexico-semantic errors and, errors at the sound level) and were analyzed quantitatively. We found more nTMS-positive points in the left hemisphere, particularly in the left parietal lobe for the production of transitive compared to intransitive verbs. These positive points most commonly corresponded to lexico-semantic errors. Our findings are in line with previous aphasia and neuroimaging studies, suggesting that a more widespread network is used for the production of verbs with a larger number of arguments (i.e., transitives). The higher number of lexico-semantic errors with transitive compared to intransitive verbs in the left parietal lobe supports previous claims for the role of left posterior areas in the retrieval of argument structure information.

Language impairment in motor neuron disease phenotypes different from classical amyotrophic lateral sclerosis: a review

BackgroundUp to 35-40% of patients with amyotrophic lateral sclerosis (ALS) present with language deficits falling within the spectrum of frontotemporal degeneration (FTD). It is currently debated whether frontotemporal involvement occurs or not in motor neuron disease (MND) phenotypes that differ from classical ALS (i.e., both non-ALS MNDs and non-classical ALS endo-phenotypes) - this stance being supported by the notion of a common pathology underlying MNDs. To investigate whether language dysfunctions also occur in patients with different-from-classical-ALS MNDs can; a) help determine whether the MND-FTD continuum could be broadened at a neuropsychological level; b) convey relevant entailments to cognitive diagnostics in these populations.AimsThe present study thus aimed at reviewing evidence regarding language impairment in different-from-classical-ALS MND patients. Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were consulted to implement and report the present review. Studies were included if a) language was quantitatively assessed b) in patients diagnosed with different-from-classical-ALS MND phenotypes. Studies assessing demented patients only were excluded. From an original N=1117 contributions, N=20 group studies were finally included. Secondary outcomes were taken into account for qualitatively assessing potential biases in generalizing results.Main contributionStudies were divided into those assessing predominant-upper vs. - lower MND patients (UMND/LMND). Language dysfunctions appeared to be more prevalent and severe in UMND patients. Language screeners were able to detect language deficits in both groups. Lexical-semantic deficits appeared to be highly prevalent in both groups and a selective difficulty in action-vs. object-naming was systematically detected. Morpho-syntactic deficits were seldom reported in both groups. Phonological deficits and central dysgraphic features were found in UMND patients only.ConclusionPatients with different-from-classical-ALS MND phenotypes display language deficits similar to those of classical ALS patients (as far as both prevalence and type are concerned) and thus could be validly included in the MND-FTD continuum at a neuropsychological level. A greater cortical involvement might account for language deficits being more severe in UMND patients. Consistently with guidelines for cognitive assessment in ALS patients, action-naming tasks might represent a valid and sensitive tool for assessing language in UMND/LMND patients too.