Cortical signatures of temporal integration and arousal: a multiscale approach

Co-directors: 
Catherine Tallon-Baudry
Yves Boubenec

Committee

Maria Chait - Rapporteuse
Jean-Marc Edeline - Rapporteur 

Sander Nieuwenhuis - Examinateur
Brice Bathellier - Invite

Abstract:

Auditory processes are inherently variable and yet perception is remarkably stable. There are many sources of variability, coming both from the external world (such as variability in sounds) and the internal world (like internal states). How is the brain capable of creating a stable representation of the auditory world in light of inherent variability associated with the sounds or with the internal state? This thesis investigates temporal integration, a computational process hypothesized to tackle temporal variability in the acoustic inputs, and cortical signatures of arousal, a major driver of internal variability. In Chapter 1 I present results of a study for which we collected electrophysiology using multi-electrode arrays and laminar probes and recorded responses to natural stimuli across the auditory cortex in awake ferrets. These results reveal that temporal integration in the auditory cortex of the ferret is organized by the anatomical hierarchy and is predominantly invariant to the category and modulation rate of sounds. In Chapter 2 I assess whether different sources of internal variability, i.e. different varieties of arousal, share neural substrates. I present the results of a large semantic and neuroimaging analysis of the arousal literature and show evidence for domain-general arousal in humans. In Chapter 3 I present some preliminary results of an experiment in which we measured neural responses to natural sounds in the auditory cortex of the ferret and simultaneously collected multiple measures of arousal. We then quantify how distinct proxy for arousal differentially affects multiple aspects of neural responses. Overall, in this thesis we leveraged both large and more fine-grained neuroimaging tools to shed light on mechanisms underlying remarkable features of stable and yet adaptive perception processes.