Odyssee : Presentation

GENERAL PRESENTATION OF THE PROJECT

ODYSSEE aims at better understanding and characterizing the cortical oscillatory dynamics underlying speech perception using magnetoencephalography (MEG).

One of the first step in speech processing is to parse the continuous acoustic stream into smaller units that will then be mapped onto internal linguistic representations. In this regard, the (quasi-)rhythmicity of speech is fundamental as it allows the listener’s cognitive system to make predictions about the incoming signal, thus helping speech segmentation and comprehension. Neurocognitive models of speech perception assign a key functional role to ongoing neural oscillations in the tracking of speech rhythm. By aligning to speech at multiple timescales, brain oscillatory activity in the gamma (~25-40 Hz), theta (~4-7 Hz) and delta (~1-3 Hz) frequency bands would segment the acoustic stream into phoneme-, syllable- and word-sized packets, respectively. EEG/MEG studies have shown coupling between theta-band oscillations in the auditory cortex and the slow modulations (2-8 Hz) in speech amplitude envelope which reflect syllabic rhythm and are crucial for speech intelligibility.

The ODYSSEE project aims at characterizing the MEG cortical oscillatory dynamics during the perception of speech at different syllabic rates in adultes and typically developing children We particularly examine how neural oscillations in auditory but also motor cortex align to the speech signal when it naturally produced at a normal or fast rate, and when it is artificially accelerated.

---

Three main objectives:

• Investigate the neurocognitive mechanisms underlying adaptation to natural fast speech in children and adults.


• Identify the brain oscillatory signature of natural speech perception at different rates using MEG.


• Better understand the functional organization of speech perception in the mature but also the developing brain.