Presentation

Search Abstracts | Symposia | Slide Sessions | Poster Sessions | Lightning Talks

Bridging verbal coordination and neural dynamics

Poster C69 in Poster Session C, Wednesday, October 25, 10:15 am - 12:00 pm CEST, Espace Vieux-Port

Isaih Mohamed¹, Leonardo Lancia^2,3, Manuel Mercier¹, Daniele Schön¹; ¹Institut de Neurosciences des Systèmes (INS), ²Laboratoire Phonétique et Phonologie (LPP), ³Laboratoire Parole et Langage (LPL)

Our use of language, which is profoundly social in nature, essentially takes place in interaction contexts and is therefore based on coordination rules that each interlocutor must respect. It is then necessary to adapt our actions in real time, particularly our verbal productions. Here, we recorded the intracranial brain activity of 16 patients with drug-resistant epilepsy while they performed a verbal coordination task with a virtual partner (VP). More precisely, patients had to repeat short sentences synchronously with the VP. Based on a model which describes the synchronisation behaviour of coupled oscillators, the VP can track the instantaneous phase of the patient's speech signal and predict it so that it can adjust in real time with the patient. Moreover, by changing the coupling strength parameters, we could modulate patients capacity to synchronise speech with the VP. This coordination task allows us to monitor the coupling between the patient and the VP in a continuous manner. From speech signals, verbal coordination was estimated by computing the variability of the phase lag (PLV) between the verbal productions of patients and VP. For each patient, a large variability of this coordination index was found across trials, indicating more or less successful coordinative behaviour. We focused on high frequency activity power (HFa, 70-125Hz) of the neural activity and showed, compared to a baseline, an increase in temporal (STG BA22) and frontal (IFG BA44) regions. While these regions showed a similar increase of HFa, looking at the relation between neural (HFa) and behavioural (PLV) data points to a differential role of the two regions. More precisely, power increases in STG BA22 was associated with positive correlations, while power increases in IFG BA44 was associated with negative ones. In other words, a poor coordinative verbal behaviour implies a greater involvement of frontal regions and a reduced involvement of auditory regions. Our results highlight different activity dynamics depending on the ability to adjust our verbal productions, and show that combining dynamically resolved behavior and neural data is a powerful avenue to better understand natural speech processing.

Topic Areas: Speech Perception, Language Production