PriorDynamics · The neural dynamics of perceptual priors in audition

The neural dynamics of perceptual priors in audition

Seeing and hearing the world around us is so effortless that we rarely notice how noisy and ambiguous the information is that our eyes and ears convey. How do we manage to rapidly generate a truthful representation of our sensory environment given such uncertainty? Helmholtz’s study of optical illusions led to the crucial insight that resolving perceptual ambiguities involves prior knowledge, possibly derived from past sensory experience that allows observers to unconsciously infer stimulus properties in a fast and efficient manner. A great amount of research has been devoted to uncovering the mechanisms by which prior information influences perceptual decisions, mostly in the visual modality. However, what is discovered for vision may or may not be a generic mechanism for perception, even though it is often presented as such. Here, we investigate how the auditory system uses information from the recent past to overcome signal noise and ambiguity. Combining novel behavioural methods with advanced neuroimaging techniques, we aim to determine the neural mechanisms that underlie the propagation and update of prior auditory information in healthy human participants. Specifically, we test the hypothesis that sensory predictions involve neural oscillations at alpha rhythm that mediate the propagation of perceptual priors. The first part of this research project investigates the neural structures underlying such oscillatory mechanism. To this end, we adapt a new time-resolved sampling technique used to examine rhythmic fluctuations in perceptual performance for functional magnetic resonance imaging (fMRI) to explore if cortical and subcortical auditory activations exhibit rhythmic modulations that correlate with oscillations in auditory detection behaviour. The second part of this project examines whether the resolution of perceptual ambiguities by prior contextual information involves similar oscillatory mechanisms. For this purpose, we combine the time-resolved sampling technique with a classic paradigm for inducing ambiguous pitch shifts. The results will shed light on a potentially crucial and yet unknown core process of perception, useful in every interaction we have with the world. This research project is a joint effort by the École Normale Supérieure in Paris, France, and Chukyo University in Nagoya, Japan.

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