Evolution des activations cérébrales lors de la production de parole après exérèse au niveau de la cavité orale

International audienceUsing functional MRI, acoustic data and motor oral assessment, brain correlates of speech recovery after dramatic structural changes in the vocal tract have been investigated during three tasks: orofacial movements and speech production (vowels and syllables). Eleven patients were recorded during three sessions, preoperatively and postoperatively, 1 month and 3 months after surgery (for seven of them also 9 months after surgery). Eleven healthy subjects were recorded in parallel. A "whole brain" group analysis (patients/healthy subjects) reveals a specific activation pattern for patients, in particular during vowel task, which is session-dependent. Moreover, global lower brain activation compared to healthy subjects was found for all tasks in primary, secondary and integrative sensorimotor regions. Differences are interpreted in relation with the emergence of new speech motor goals and changes in the internal models.A partir de données d'IRM fonctionnelle, acoustiques et praxiques, nous avons étudié les corrélats cérébraux de l'adaptation de la parole après une modification structurelle importante du conduit vocal lors de trois tâches : mouvements oro-faciaux silencieux, voyelles et syllabes. Onze patients ont été enregistrés lors de trois sessions, pré-opératoire et post-opératoire à 1 mois et 3 mois (pour sept d'entre eux aussi à 9 mois). Onze sujets contrôles ont été enregistrés en parallèle. Une analyse de groupe (patients/contrôles) " cerveau entier " révèle des patrons d'activation spécifiques aux patients au cours des différentes sessions en particulier pour la tâche de production de voyelles. De plus, une moindre activation cérébrale par rapport aux sujets sains a été observée pour toutes les tâches dans des régions motrices, sensorielles et d'intégration sensori-motrice. Nous interprétons ces résultats en relation avec la redéfinition des buts de parole et l'adaptation de modèles internes du système moteur périphérique

Reliability of single-subject neural activation patterns in speech production tasks

Traditional group fMRI (functional magnetic resonance imaging) analyses are not designed to detect individual differences that may be crucial to better understanding speech disorders. Single-subject research could therefore provide a richer characterization of the neural substrates of speech production in development and disease. Before this line of research can be tackled, however, it is necessary to evaluate whether healthy individuals exhibit reproducible brain activation across multiple sessions during speech production tasks. In the present study, we evaluated the reliability and discriminability of cortical functional magnetic resonance imaging data from twenty neurotypical subjects who participated in two experiments involving reading aloud mono- or bisyllabic speech stimuli. Using traditional methods like the Dice and intraclass correlation coefficients, we found that most individuals displayed moderate to high reliability, with exceptions likely due to increased head motion in the scanner. Further, this level of reliability for speech production was not directly correlated with reliable patterns in the underlying average blood oxygenation level dependent signal across the brain. Finally, we found that a novel machine-learning subject classifier could identify these individuals by their speech activation patterns with 97% accuracy from among a dataset of seventy-five subjects. These results suggest that single-subject speech research would yield valid results and that investigations into the reliability of speech activation in people with speech disorders are warranted.Accepted manuscrip

The cerebellum, internal models and prediction in 'non-motor' aspects of language: A critical review

The emergence of studies on cerebellar contributions in 'non-motor' aspects of predictive language processing has long been awaited by researchers investigating the neural foundations of language and cognition. Despite (i) progress in research implicating the cerebellum in language processing, (ii) the widely-accepted nature of the uniform, multi-modal computation that the cerebellum implements in the form of internal models, as well as (iii) the long tradition of psycholinguistic studies addressing prediction mechanisms, research directly addressing cerebellar contributions to 'non-motor' predictive language processing has only surfaced in the last five years. This paper provides the first review of this novel field, along with a critical assessment of the studies conducted so far. While encouraging, the evidence for cerebellar involvement in 'non-motor' aspects of predictive language processing remains inconclusive under further scrutiny. Future directions are finally discussed with respect to outstanding questions in this novel field of research

The cerebellum, internal models and prediction in 'non-motor' aspects of language: A critical review

The emergence of studies on cerebellar contributions in ‘non-motor’ aspects of predictive language processing has long been awaited by researchers investigating the neural foundations of language and cognition. Despite (i) progress in research implicating the cerebellum in language processing, (ii) the widely-accepted nature of the uniform, multi-modal computation that the cerebellum implements in the form of internal models, as well as (iii) the long tradition of psycholinguistic studies addressing prediction mechanisms, research directly addressing cerebellar contributions to ‘non-motor’ predictive language processing has only surfaced in the last five years. This paper provides the first review of this novel field, along with a critical assessment of the studies conducted so far. While encouraging, the evidence for cerebellar involvement in ‘non-motor’ aspects of predictive language processing remains inconclusive under further scrutiny. Future directions are finally discussed with respect to outstanding questions in this novel field of research

Reliability of single-subject neural activation patterns in speech production tasks

Speech neuroimaging research targeting individual speakers could help elucidate differences that may be crucial to understanding speech disorders. However, this research necessitates reliable brain activation across multiple speech production sessions. In the present study, we evaluated the reliability of speech-related brain activity measured by functional magnetic resonance imaging data from twenty neuro-typical subjects who participated in two experiments involving reading aloud simple speech stimuli. Using traditional methods like the Dice and intraclass correlation coefficients, we found that most individuals displayed moderate to high reliability. We also found that a novel machine-learning subject classifier could identify these individuals by their speech activation patterns with 97% accuracy from among a dataset of seventy-five subjects. These results suggest that single-subject speech research would yield valid results and that investigations into the reliability of speech activation in people with speech disorders are warranted.R01 DC002852 - NIDCD NIH HHS; R01 DC007683 - NIDCD NIH HHS; T32 DC013017 - NIDCD NIH HHSAccepted manuscrip

CENTRAL NEURAL AND BEHAVIORAL CORRELATES OF VOICE SECONDARY TO INDUCED UNILATERAL VOCAL FOLD PARALYSIS

Understanding the involvement of the central nervous system (CNS) in voice production is essential to incorporating principles of neuroplasticity into therapeutic practice for voice disorders. Early steps to attaining this goal require the identification of specific neural biomarkers of the changes occurring in the CNS from a voice disorder and its subsequent treatment. In the absence of an adequate animal vocalization model, the larynx has not been acutely and reversibly perturbed to concurrently examine the effect on both peripheral and central processing of the altered input/output. Using a unique, reversible perturbation approach, it was the purpose of this study to perturb the larynx to mimic a voice disorder and study short-term neuroplastic response. Functional magnetic resonance imaging (fMRI) was the neuroimaging tool of choice for this study due to its superior spatial and temporal resolution. The voice was perturbed by anesthetizing the right recurrent laryngeal nerve, with a solution of lidocaine hydrochloride and epinephrine to induce a temporary right vocal fold paralysis. The paralysis lasted for approximately 90 minutes and had an overt presentation similar to that of a true vocal fold paralysis. Behavioral and fMRI data were obtained at three time points- baseline, during the vocal fold paralysis and one hour after recovery. Patterns of activity on fMRI during the three time points were found to be distinct on both subjective examination and statistical analysis. The regions of interest examined had distinct trends in activity as a function of the paralysis. Interestingly, males and females responded differently to the paralysis and its subsequent recovery. Strong correlation was not observed between the behavioral measures and fMRI activity reflecting a disparity between the overt presentation and recovery of vocal fold paralysis and cortical activity as seen on fMRI. The fictive paralysis model employed in this study provided a perturbation model for phonation that allowed us to examine behavioral and central neural correlates for disordered phonation in a controlled environment. Although this data is representative of acute changes from a transient paralysis, it provides an insight into the response of the cortex to sudden perturbation at the peripheral phonatory mechanism