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Cerebral Networks of Speech Motor Control: fMRI Data

This study explores the organization of speech motor control in the brain using fMRI data. It examines the cerebral networks involved in different stages of speech production and the control of syllable rate. The findings suggest the involvement of various brain regions including the supplementary motor area, insular cortex, and cerebellum.

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Cerebral Networks of Speech Motor Control: fMRI Data

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  1. Cerebral Networks of Speech Motor Control: fMRI Data H. Ackermann, K. Mathiak, I. Hertrich, W. Grodd, A. Riecker Departments of Neurology and Neuroradiology, University of Tübingen 5th International Conference on Speech Motor Control Nijmegen, June 7 – 10, 2006

  2. Cerebral Organization of Speech Motor Control: The Beginnings Petersen et al. 1988, 1989 (PET study) but see Sidtis et al. 1999

  3. Cerebral Organization of …. supplementary motor area (SMA) BL sensorimotor cortex LH insular cortex BL medial cerebellum Petersen et al. 1988, 1989,Posner & Raichle 21999 Wise et al. 1999: left anterior insula engaged in „articulatory planning“ (Dronkers 1996, but see Hillis et al. 2002)

  4. P Indefrey, WJM Levelt.The spatial and temporal signatures of word production components.Cognition 2004;92:101-144 review of 82 imaging studies on word production cerebral correlates / time course of the following successive stages of speech production: lexical selection, phonological code retrieval, syllabification, self-monitoring, phonetic / articulatory processes (Levelt, Roelofs & Meyer 1999)

  5. Indefrey & Levelt 2004

  6. Cerebral Network of Phonetic / Articulatory Processes 12 areas pertaining to the central-motor system: R/L ventral motor and sensory regions, R dorsal motor region, R SMA, R/L cerebellum, R/L thalamus, R midbrain 5 areas not pertaining to the central-motor system, e.g., orbitofrontal and occipitotemporal regions Indefrey & Levelt 2004

  7. Syllable Rate Control: fMRI Experiment I figure Riecker et al. 2005 normal subjects, overt (aloud) syllable repetitions (“pa”), 2.0 / 2.5 / 3.0 / 4.0 / 5.0 / 6.0 Hz, applied via earphones

  8. Experiment I: Signal Analysis 1. Parametric approach: 1.1. hemodynamic main effects across all repetition rates versus baseline 1.2. positive linear, negative linear and nonlinear rate / response functions Büchel & Friston 1996, 1998 2. Connectivity analyses based upon time series of hemodynamic activation

  9. Experiment I: Signal Analysis 1. Parametric approach: 1.1. hemodynamic main effects across all repetition rates versus baseline 1.2. positive linear, negative linear and nonlinear rate / response functions Büchel & Friston 1996, 1998 2. Connectivity analyses based upon time series of hemodynamic activation

  10. Overt Syllable Repetitions I Main Effects normal subjects Riecker et al. 2005

  11. Guenther et al. 2006

  12. Experiment I: Signal Analysis 1. Parametric approach: 1.1. hemodynamic main effects across all repetition rates versus baseline 1.2. positive linear, negative linear and nonlinear rate / response functions Büchel & Friston 1996, 1998 2. Connectivity analyses based upon time series of hemodynamic activation

  13. Overt Syllable Repetitions II Rate / Response Functions Riecker et al. 2005

  14. Insel links Putamen / Pallidum 6 6 4 4 2 2 0 0 1 2 3 4 5 6 1 2 3 4 5 6 Caudatum links Thalamus 6 6 4 4 2 2 0 0 3 1 2 4 5 6 2 4 5 6 1 3 Overt Syllable Repetitions III Group Averages normal subjects Riecker et al. 2005

  15. JJ Sidtis, SC Strother, DA Rottenberg. Predicting performance from functional imaging data: Methods matter.NeuroImage 2003;20:615-624 question: can functional imaging data predict performance? task: syllable repetitions as fast as possible syllable rate = (- 3.55 * right caudate) + (2.51 * left inferior frontal) + 5.60 more efficient organization at higher rates (p.c.)

  16. Rate Control / Basal Ganglia: • Brown 2003: Oscillatory nature of human basal ganglia activity • Logigian et al. 1991: Tremor oscillations may pace repetitive voluntary motor behaviour (finger flexion / extension, oral diadochokinesis) • Possible control mechanism of syllable repetitions: adjustment of inherent basal ganglia oscillations to the pacing signal

  17. Cerebellum z=-24 Cerebellum z=-57 6 6 4 4 2 2 0 1 2 3 4 5 6 0 1 2 3 4 5 6 Overt Syllable Repetitions III Group Averages normal subjects Riecker et al. 2005

  18. Syllable Rate Control: fMRI Experiment II • Hypothesis: differential contribution of basal ganglia and cerebellum to syllable rate control • Task: covert (silent) syllable repetitions, • 2.5 / 4.0 / 5.5 Hz, •   paced via earphones • Design: block design (8 blocks, R/A, 10 meas) • Analysis: categorical and parametric (rate and time effects) analysis using SPM99 Wildgruber et al. 2001

  19. Covert Syllable Repetitions: R/R-F Wildgruber et al. 2001

  20. Syllable Rate in Dysarthric SubjectsAcoustic Analyses Ackermann et al. 1995 Review: Hertrich, Ackermann. Acoustic analysis of durational ... In: Lebrun Y (ed). From the Brain to the Mouth.Dordrecht 1997, 11-47 Review: Ackermann, Mathiak, Ivry. Temporal organization of „internal speech” ... Behav Cogn Neurosci Rev 2004;3:14-22

  21. Insel links Putamen / Pallidum 6 6 4 4 2 2 0 0 1 2 3 4 5 6 1 2 3 4 5 6 Caudatum links Thalamus 6 6 4 4 2 2 0 0 3 1 2 4 5 6 2 4 5 6 1 3 Overt Syllable Repetitions III Group Averages normal subjects Riecker et al. 2005

  22. Finger Tapping Tasks Rate / Response Functions normal subjects Riecker et al. 2003

  23. Summary Part 1: Cerebral Rate Control • Convergence of clinical-behavioural findings and functional imaging data: • Striatum: normal speaking rate / hastening phenomenon - negative fMRI rate / response functions • Cerebellum: reduced syllable rate (> 3 Hz) – fMRI threshold effect at about 3 Hz for a review see Ackermann & Hertrich 2000, Ackermann et al. 2004

  24. Cerebellar Functions

  25. Experiment I: Signal Analysis 1. Parametric approach: 1.1. hemodynamic main effects across all repetition rates versus baseline 1.2. positive linear, negative linear and nonlinear rate / response functions Büchel & Friston 1996, 1998 2. Connectivity analyses based upon time series of hemodynamic activation

  26. Time course of hemodynamic activation Riecker et al. 2005

  27. Two Cerebral Networks of Speech Motor Control ??? effect size bold lines: very high correlations (>0.9) thin lines: high correlations (0.75-0.9) time (s)

  28. Syllable Rate Control: fMRI Experiment II • Hypothesis: differential contribution of basal ganglia and cerebellum to syllable rate control • Task: covert (silent) syllable repetitions, • 2.5 / 4.0 / 5.5 Hz, •   paced via earphones • Design: block design (8 blocks, R/A, 10 meas) • Analysis: categorical and parametric (rate and time effects) analysis using SPM99 Wildgruber et al. 2001 Covert production of fluent speech (highly overlearned word strings): Wildgruber et al. 1996, Ackermann et al. 1998, Riecker et al. 2000

  29. Inner / Silent / Covert Speech • internal speech = “prearticulatory, but otherwise fully parsed speech code” (Levelt 1989) • “close functional equivalence between motor imagery and motor preparation” (Jeannerod 1994) • inner speech = “window” into articulatory planning processes (preceding movement execution) • but: Sokolov 1968, 1972

  30. Covert Syllable Repetitions: R/R-F LC: -21, -60, -24 / RC: 24, -57, -24 Wildgruber et al. 2001

  31. Guenther et al. 2006: DIVA model

  32. Two Cerebral Networks of Speech Motor Control ??? effect size anterior insula / speech production: Ackermann & Riecker 2004

  33. Hemodynamic activation of intrasylvian cortex in association with • anticipation / application of painful stimuli, • spider phobia (sensitive to therapy), • swallowing & tactile stimulation of the tongue, • stress urinary incontinence (sensitive to therapy), • high-intensity emotional facial expressions, • aesthetic judgments of beauty, • olfactory functions. NeuroImage, vol 29, no 1, January 1, 2006

  34. Speech and Anterior Insula • Insular cortex part of the cerebral representation of the autonomic nervous system, e.g., cardiac functions or respiration, e.g., Harper et al. 2005 • pre-setting of laryngeal and respiratory muscles • However, no insular activation duringwhistling, Dresel et al. 2005 for a review see Ackermann & Riecker 2004

  35. Hemodynamic activation of intrasylvian cortex in association with • anticipation / application of painful stimuli, • spider phobia (sensitive to therapy), • swallowing & tactile stimulation of the tongue, • stress urinary incontinence (sensitive to therapy), • high-intensity emotional facial expressions, • aesthetic judgments of beauty, • olfactory functions. NeuroImage, vol 29, no 1, January 1, 2006

  36. Putamen / Pallidum Insel links 6 6 4 4 2 2 0 0 1 2 3 4 5 6 1 2 3 4 5 6 Caudatum links Thalamus 6 6 4 4 2 2 0 0 1 2 3 4 5 6 2 4 5 6 1 3 Part 1: Rate / Response Functions of Hemodynamic Activation effect size Part 2: Time Course of Hemodynamic Activation time (s)

  37. NEUROLOGIE Participants NEUROLOGY Dirk Wildgruber Axel Riecker Ingo Hertrich Klaus Mathiak Hermann Ackermann NEURORADIOLOGY Michael Erb Uwe Klose Wolfgang Grodd

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