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The Neurobiology of Rhythm: effects of Musical expertise on natural speech comprehension

Periodic Reporting for period 1 - NERHYMUS (The Neurobiology of Rhythm: effects of Musical expertise on natural speech comprehension)

Reporting period: 2018-04-01 to 2020-03-31

Previous research investigated rhythm perception in music or speech with different experimental approaches. However, these investigations did not study whether effects of rhythm processing in the one domain (e.g. music) transfer to another domain (e.g. speech/language). This potential transfer effects could inform therapy and educational practices related to language disorders, such as developmental language disorder (DLD). The evolution of rhythm in the human brain suggests that there is a brain network, which processes rhythm irrespective of whether the human is listening to music or speech. This brain network is called the rhythm network; specifically the supplementary motor area (SMA) seems relevant for beat processing in music or speech. The current research tested the hypothesis that regular rhythms, following a meter, engage the SMA. Additionally, the project tested whether musicians, trained on rhythmicity, perceive rhythmically regular speech more efficiently than non-musicians. Preliminary analyses confirm this hypothesis when participants listen to regular rhythms in spoken poems. Further data acquisition and analyses will shed light onto the role of musical expertise and whether musical training enhances rhythm perception in speech.
"During the fellowship period the following work has been completed:
1. Planned experimental paradigm and completed ethics application for the main experiment.
2. Selected appropriate texts (poems and stories), recorded the stimuli, and extracted audio features from these stimuli.
3. Acquired knowledge on audio signal processing techniques and applied this knowledge in the current project.
4. Completed Certified User (CU) training for MRI and TMS. EEG training focused on the combined EEG-TMS methodology.
5. Acquired knowledge on targeting TMS sites with Neuronavigation technology and applied this knowledge in the current experiment.
6. Programmed the experimental loop and implemented it for specific laboratory hardware restrictions.
7. Preparation for the experiment was completed: a) Setting up EEG paradigm, b) Piloting and optimising parameters, c) Organising procedures, d)Training student interns and volunteers on the setup and running of the experiment.
8. Prepared behavioural experiment: a) trained an Erasmus+ trainee and a master student from the collaborator’s lab in theory, experimental design, paradigm, and analysis methods, b) supervised the master student who programmed the behavioural experiment, and c) supervised the Erasmus+ trainee during piloting and running the first few sessions of the behavioural experiment.
9. Collected behavioural data – work not completed because of a cyber-attack at Maastricht University in December 2019 and the COVID-19 crisis.
10. Acquired MRI data to define the TMS target regions individually for each participant.
11. Acquired EEG data for three TMS conditions in three separate sessions for 10 control participants and 2 musicians.
12. Analysed EEG data using the multivariate Temporal Response Function analysis to correlate beat-related audio features to EEG data.
13. Disseminated the new approach of modelling EEG data at the annual meeting of the Society for the Neurobiology of Language.
14. Published a commentary on neural oscillations in speech and language.
15. Presented talks and workshops in local and international schools, student events, expert, and general public audience.
16. Organised Pint of Science festival in Maastricht in 2019.
17. Completed teaching requirements as part of academic training at Maastricht University (10%).

Main results
The project’s main objective was to investigate whether musical rhythm expertise affects speech rhythm in speech comprehension. To this end, we combined computational analysis of stimulus features with neurophysiological, continuous EEG data analysis using cutting-edge analysis methods (multivariate Temporal Response Function). Even though both behavioural and EEG data collection is not yet complete, we have developed all necessary analysis tools to correlate the rhythmic quantities in the audio signal with EEG data.
Based on the preliminary analysis of 9 non-musician datasets, findings suggest that down-regulating activity of the supplementary motor area (SMA) with TMS affects processing of regular rhythm in poems. More datasets in both the musician and non-musician populations will reveal whether this effect is significant and whether musicianship interacts with this TMS-induced effect.
With regard to the behavioural results, based on 15 datasets, we found that the high number of peaks on different frequencies of the speech signal correlates with the perception of rhythmic regularity on a behavioural level. Including more datasets in the analysis, and especially increasing the amount of musician datasets will reveal if the results are robust and affected by musicianship.

Journal publications
Kandylaki, K.D. & Kotz S.A. (2020). Distinct cortical rhythms in speech and language processing and some more: a commentary on Meyer, Sun, & Martin (2019). Language, Cognition, and Neuroscience.

Invited talks
Kandylaki, K. D. (2019, October). Rhythm: from music to speech to the brain. Music and Language Meeting, Athens, Greece.
Kandylaki, K. D. (2018, December). How to ""go natural"" in the neurobiology of language. Neurolinguistics Colloquium, Philipps-University Marburg, Germany.
Conference talks
Kandylaki, K. D. (2019, October). Why and how to employ ecologically valid tests in the neurobiology of language. 28th Meeting of the Hellenic Society for Neuroscience (HSfN), Heraklion Crete.
Kandylaki, K. D. (2018, June). Exploring the neurobiology of language with naturalistic experimental paradigms. 7th biannual conference on Language Disorders in Greek, Athens.
Conference posters
Kandylaki, K. D., Lykartsis, A., Lampe, K., Kotz, S. A. (2019, August). Modelling EEG responses with the audio signal: a methodological investigation. Annual Meeting of the Society for the Neurobiology of Language, Helsinki."
The current progress of the research outcomes is not informative enough in order to estimate the precise impact in society. However, this research is rich in potential impact to the clinical field and to the field of education and child development. Preliminary results point to the critical role of the SMA in rhythm processing and beat extraction in particular. This role of the SMA is found in speech comprehension when modelled with audio features related to the beat in the audio signal. After completing data analysis for the planned number of participants, the results will be communicated to clinical and educational experts to improve practices that involve rhythm perception in music and language. Additionally, the findings will be publicly communicated in the local and international crowds that the fellow has already established connections to with her past outreach activities, e.g. local schools.