The research group Neurophonetics and Translational Neurorehabilitation is based on a cooperation between the University of Tübingen and the Rehabilitation Clinics at Hohenurach. The projects of this group focus on the neurobiology of speech communication, including clinical studies, psycholinguistic experiments, brain imaging studies, and magnetoencephalography... more Info
1. Perception of accelerated speech by blind subjects
While the normal syllable rate of speech amounts to ca. 5 syllables per second (syl/s), blind subjects can learn to comprehend accelerated synthetic speech beyond 20 syl/s. Starting with a single-case study (Hertrich et al., Neurocase 2009;15:163), two follow-up projects were supported by the German Research foundation (DFG, AC 55/9-1 and HE 1573/6-2), provided the opportunity for a larger group studies (blind in comparison to sighted subjects) using fMRI, structural MRI, and MEG in order to assess the brain activity associated with the processing of accelerated speech. Among others, blind subjects showed significant activation in primary visual cortex of the right hemisphere, in the pulvinar, and in the pre-supplementary motor area (pre-SMA) (Dietrich et al., BMC Neurosci 2013;14:74; Dietrich et al., PLoS ONE 2015;10:e0132196). In line with the finding of hemodynamic activity in visual cortex, MEG recordings could demonstrate a right-occipital signal component phase-locked to the envelope of the scoustic speech signal (Hertrich et al., Brain Lang 2013;124:9). Based on these results, a "visual strategy" of auditory speech processing of blind subjects was hypothesed, assuming that the visual cortex receives an early afferent auditory signal via a subcortical interface (pulvinar) that, subsequently, is transferred to the pre-SMA (Hertrich et al., Front Psychol 2013;4:530). This network, presumably, represents a "syllabic event recording" signal to coordinate phonological top-down representations within the left-frontal speech generation network with the syllable-prosodic rhythm of the incoming speech signal. These analyses were expanded by a training study performed with blind, visually impaired, and sighted subjects (Dietrich et al., Front Hum Neurosci 2013;7:701; Dietrich et al., PLoS ONE 2015;10:e0122863).
2. Speech and voice disorders in cerebellar patients
Lesions and other disorders of the cerebellum may cause a characteristic syndrome: the ataxic dysarthria. In cooperation with the work group Schöls, the research question was addressed whether subtypes of spino-crebellar ataxias (SCA) give rise to distinct modifications of ataxic dysarthria, depending on the regions of the cerebellum that are affected in these disorders. So far, the study included patients with Friedreich's ataxia (FA) and the types SCA3 und SCA6. Among others, FA subjects showed two dominant features comprising reduced speech rate and an voice irregularity that correlated with the extent of other motor impairments (Brendel et al., Cerebellum 2013;12:475). In case of the SCA subtypes, articulatory impairments predicted the overall severity of motor coordination (Brendel et al., J Neurol 2015;262:21).
3. The processing of presuppositions in sentence uttrances
In cooperation with the "Sonderforschungsbereich 833" of the German Research Council (Bedeutungskonstitution – Dynamik und Adaptivität sprachlicher Strukturen) an MEG study was performed (Hertrich et al., Brain Lang 2015;149:1), showing significant effects of preceding context sentences on the MEG activity during the perception of test sentences containing a presupposition. Cross-correlation analysis between the MEG signals and the speech envelope showed that the matching between the context sentence and the presupposition in the test sentences correlated with early auditory responses to syllable onsets at a latency of 70-200 ms. Additionally, non-matching gave rise to widespread suppression of alpha activity, which might be interpreted in terms of a cognitive load (e.g. searching for a referent in case of the presupposition of the definite determiner.
4. Theoretical work
a) Comparison of acoustic communication between humans an non-human primates
Spoken language is an exclusive characteristic of the human species, and the ability to speak can be considered as a pre-condition of our cumulative species-specific development of culture. Thus, "any account of what is special about the human brain must specify the neural bases of our unique trait of articulate speech – and the evolution of these remarkable skills in the first place" (Passingham 2008). In cooperation with the primate neurobiologist Steffen Hage (University of Tübingen) and the neurolinguist Wolfram Ziegler (LMU München, see cooperation partners), a two-step model of the phylogenetic development of speech motor control was introduced, that points toward a central role of the basal ganglia in this context. (Ackermann et al., Behav Brain Sci. 2014; 37:529; published together with 30 „open peer commentaries“ and an additional "authors' response").
b) The role of the supplementary motor area (SMA) for speech processing
The SMA , a mesiofrontal region anterior to the motor cortex, is composed of a posterior region that mainly serves motor control (SMA proper) and a more anterior region (pre-SMA) that is involved in mechanisms of cognitive control. Both parts of the SMA play an important role for speech processing although traditionally they have not been considered as core regions of speech and language processing. The control functions of SMA proper include initiation and timing of articulatory movements, whereas the pre-SMA serves superordinate functions such as semantic monitoring, lexikal disambiguation, and cognitive switching (Hertrich et al., Neurosci Biobehav Rev 2016;68:602).
Following these considerations, currently a projekt is set up, investigating the role of SMA proper and pre-SMA for the comprehension of accelerated speech. To these ends, the effect of virtual lesions (Theta-burst magnetic stimulation) will be investigated.
Hertrich I, Dietrich S, Ackermann H. Cortical phase locking to accelerated speech in blind and sighted listeners prior to and after training. Brain and Language 2018;185:19-29.
Dietrich S, Hertrich I, Müller-Dahlhaus F, Ackermann H, Belardinelli P, Desideri D, Seibold VC, Ziemann U. Reduced Performance During a Sentence Repetition Task by Continuous Theta-Burst Magnetic Stimulation of the Pre-supplementary Motor Area. Frontiers in Neuroscience 2018;12:361.
Ziegler W, Ackermann H. Subcortical Contributions to Motor Speech: Phylogenetic, Developmental, Clinical. Trends in Neurosciences 2017; 40: 458-468.
Hertrich I, Dietrich S, Ackermann H. The role of the supplementary motor area for speech and language processing. Neurosci Biobehav Rev 2016;68:602-610.
Dietrich S, Hertrich I, Ackermann H. Network Modeling for Functional Magnetic Resonance Imaging (fMRI) Signals during Ultra-Fast Speech Comprehension in Late-Blind Listeners. PLoS ONE 2015;10:e0132196.
Dietrich S, Hertrich I, Kumar V, Ackermann H. Experience-Related Structural Changes of Degenerated Occipital White Matter in Late-Blind Humans – A Diffusion Tensor Imaging Study. PLoS ONE. 2015;10:e0122863.
Hertrich I, Kirsten M, Tiemann S, Beck S, Wühle A, Ackermann H, Rolke B. Context-dependent impact of presuppositions on early magnetic brain responses during speech perception. Brain Lang 2015;149:1-12.
Marien P, Ackermann H, Adamaszek M, Barwood CHS, Beaton A, Desmond J, et al. Consensus paper: Language and the cerebellum - an ongoing enigma. Cerebellum 2014;13:386-410.
Ackermann H, Hage SR, Ziegler W. Brain mechanisms of acoustic communication in humans and nonhuman primates: An evolutionary perspective. Behav Brain Sci 2014;37:529-546.
Dietrich S, Hertrich I, Ackermann H. Ultra-fast speech comprehension in blind subjects engages primary visual cortex, fusiform gyrus, and pulvinar -- a functional magnetic resonance imaging (fMRI) study. BMC Neurosci 2013;14:74.
Hertrich I, Dietrich S, Ackermann H. Tracking the speech signal: Time-locked MEG signals during perception of ultra-fast and moderately fast speech in blind and in sighted listeners. Brain Lang 2013;124:9-21.
Lidzba K, Staudt M, Zieske F, Schwilling E, Ackermann H. Prestroke/poststroke fMRI in aphasia: Perilesional hemodynamic activation and language recovery. Neurology 2012;78:289-291.
Dietrich S, Hertrich I, Riedel A, Ackermann H. Brief report: Impaired differentiation of vegetative/affective and intentional nonverbal vocalizations in a subject with Asperger Syndrome (AS). J Autism Dev Disord 2012;42:2219-2224.
Hertrich I, Dietrich S, Ackermann H. Cross-modal interactions during perception of audiovisual speech and nonspeech signals: An fMRI study. J Cogn Neurosci 2011;23:221-237.
Ackerman H, Ziegler W. Brain mechanisms underlying speech motor control. In: Hardcastle WJ, Laver J, Gibbon FE (eds). The Handbook of Phonetic Sciences, 2nd ed. Wiley-Blackwell, Malden/MA 2010:202-250.
Brendel B, Hertrich I, Erb M, Lindner A, Riecker A, Grodd W, Ackermann H. The contribution of mesiofrontal cortex to the preparation and execution of repetitive syllable productions: An fMRI study. NeuroImage 2010;50:1219-1230.
Ackermann H, Riecker A. The contribution(s) of the insula to speech production: A review of the clinical and functional imaging literature. Brain Struct Funct 2010;214:419-433.
Steinbrink C, Ackermann H, Lachmann T, Riecker A. Contribution of the anterior insula to temporal auditory processing deficits in developmental dyslexia. Hum Brain Mapp 2009;30:2401-2411.
Hertrich I, Mathiak K, Lutzenberger W, Ackermann H. Time course of early audiovisual interactions during speech and nonspeech central auditory processing: A magnetoencephalography study. J Cogn Neurosci 2009;21:259-274.
Cooperations in Tübingen
English Department, Faculty of Humanities, University of Tuebingen
Steffen R. Hage
Werner Reichardt Centre for Integrative Neuroscience and Department of Biology, University of Tuebingen
Department of Linguistics, Faculty of Humanities, University of Tuebingen
Department of Psychology, Faculty of Science, University of Tuebingen
Computational Linguistics and Phonetics, Saarland University, Saarbrücken
Centre for General Linguistics, Humbold-University Berlin
Institute of Phonetics and Speech Processing, Ludwig-Maximilians-University Munich
Department of Psychiatry and Psychotherapy, University of Freiburg
Department of Psychiatry, Psychotherapy and Psychosomatics, University Hospital, RWTH, Aachen University
Martin J. Ball
IKE / Enheten för Logopedi, Linköping University, Linköping, Sweden
Department of Linguistics, University of Maryland, College Park, MD, USA
Brain & Language Research Institute, LPL - CNRS & Universite d'Aix-Marseille, Aix-en-Provence, France