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CNRS, Brain and Cognition Research Centre, Toulouse
We investigate rhythmic processes in the brain, with a focus on the auditory system.
Here are some recent highlights from our research. You can click on the images to get to the corresponding article.
We found that attention to sensory information alternates regularly with other, possibly "internal" processes, at a rate of ~0.07 Hz.
These slow fluctuations in "attentional modes" seemed to reflect interactions between sensory brain regions and those associated with attentional control.
We used Magnetoencephalography (MEG) to discover "entrainment echoes" in the cerebellum. These echoes are rhythmic responses that are first produced by a rhythmic stimulus but then persist when the stimulus has stopped.
The cerebellum was the only brain region with such echoes, and they were only visible after intelligible (but not unintelligible) speech. During the echo (but not during the stimulus itself), the cerebellum drove activity in the left inferior frontal gyrus (IFG).
As the stimulus rhythm induced temporal expectations and these had to be updated after stimulus offset, we suggest that cerebellar entrainment echoes reflect the updating of temporal predictions, relayed to cortical regions.
We found that neural responses to irrelevant but not to relevant auditory targets depend on the preceding phase of neural oscillations. This is a critical difference to the visual system, where the phasic modulation of perception is amplified (rather than abolished) by attention.
Oscillatory mechanisms in audition therefore seem to depend on the degree of possible information loss during the oscillation’s low excitability phase, revealing a mechanism to cope with the rapid sensory dynamics that audition is normally exposed to.
Other ongoing research is dedicated to:
Modulating speech perception with transcranial alternating current stimulation (tACS).
Testing for "true" (endogenous) oscillations in rhythmic brain responses
Developing methods to test for phasic effects in perception and neural responses
Revealing a tonotopical organisation of auditory brain rhythms
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