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Analysis of cortical activity for the development of brain-computer interfaces for speech

on the June 11, 2021
4 PM

Thesis defense of Philémon ROUSSEL (in English)

On Friday, June 11 2021, Philémon ROUSSEL will defend his thesis "Analysis of cortical activity for the development of brain-computer interfaces for speech".

This thesis has been directed by Blaise YVERT.

Due to the presence of non-French speakers in the jury, the defense will be held in English.

Abstract :

Brain-computer interfaces for speech have the potential to restore the ability to speak in people with severe paralysis. Such a system would decode features of what the user wants to say from their brain activity and synthesize the associated sounds in real time. This thesis aims to contribute to the development of brain-computer interfaces and to the understanding of cortical activity underlying speech.
First, we highlighted a phenomenon of acoustic contamination of electrophysiological signals during speech. Our analyses revealed that this phenomenon was present in several recordings from different laboratories around the world and that it could have an important impact on speech decoding studies by biasing the obtained performances.
Understanding the differences between overt and covert speech is important to know if the models currently developed on overt speech would be easily applicable to paralyzed people. Using an intracortical recording, we showed that the dynamics of the activity of a population of neurons in Broca's area were different during overt and covert speech. Moreover, we found that the spiking activity recorded during the pronunciation of sentences allowed to discriminate these sentences. The similarity of spike trains appeared to be correlated with the phonological similarity of the sentences. Using the same recording, we showed that the low frequency component of local field potentials was modulated by overt speech and to a lesser extent by covert speech.
Finally, we tested, in a non-paralyzed participant, a protocol allowing to build a covert speech decoder from electrophysiological activity. Our offline analyses showed that it was possible to decode acoustic features of imagined phonemes with performances statistically superior to chance. We also performed a preliminary test of real-time, closed-loop decoding in the same participant.

Key words:

Electrophysiology, Speech, Broca's area, Neural decoding

Members of the jury :

  • Tetiana AKSENOVA (CEA) - Examiner
  • Stéphan CHABARDES (CHUGA) - Examiner
  • Anne-Lise GIRADU (Université de Genève) - Examiner
  • Franck GUENTHER (Boston University) - Examiner
  • Benjamin MORILLON (Aix-Marseille Université) - Reviewer
  • Wilson TRUCCOLO (Brown University) - Reviewer
  • Blaise YVERT (Grenoble Institut des Neurosciences) - Thesis director

Practical informations / Places

Lieu

Conference room of the André Rassat building (Chimie E - Campus)
Updated on June 11, 2021

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