Description du projet
Tracer les voies du cerveau lors de la perception subjective
Notre perception visuelle du monde est le résultat non seulement des images réelles perçues par nos yeux, mais aussi de nos attentes quant à ce que nous sommes susceptibles de voir. Dans les cas où les signaux sensoriels sont faibles ou absents, de fortes attentes peuvent même nous amener à voir des choses qui n’existent pas — des hallucinations. Le mécanisme cérébral qui est responsable de ces états reste inconnu. En utilisant des attentes visuelles fortes pour provoquer des hallucinations chez des participants humains en bonne santé, le projet EXPECTPERCEPT, financé par l’UE, étudiera les mécanismes neuronaux qui sous‑tendent la perception subjective. Le projet vise à fournir des résultats qui amélioreront notre compréhension des troubles cliniques caractérisés par des aberrations de la perception, telles que la psychose.
Objectif
The way we perceive the world is strongly influenced by our expectations about what we are likely to see at any given moment. In certain situations – namely when sensory signals are very weak or noisy and expectations are very strong – expectations can even induce hallucinations: seeing an expected stimulus despite its absence. However, the neural mechanisms by which the brain integrates sensory inputs and expectations, and thereby generates the contents of perception, have yet to be established. Previous work, including my own, has demonstrated that processing in the visual cortex is strongly modulated by prior expectations. However, perhaps surprisingly, previous studies have not yet explained how these modulations relate to subjective perception, leading to a lacuna in our knowledge of how the brain supports perception.
Here, I propose to study the neural mechanisms underlying subjective perception by using strong visual expectations to induce hallucinations in healthy human participants. I hypothesise that, upon presentation of a predictive cue (e.g. a siren), memory systems pre-activate templates of expected stimuli (an ambulance) in the deep layers of visual cortex, leading to biased processing of sensory inputs from the very moment they arrive. I will test this proposal by addressing three complimentary questions: 1) How do expectations filter perception? 2) What is the computational architecture underlying perceptual inference? 3) What is the neural source of expectations? I will combine psychophysical tasks probing participants’ perception with neuroimaging tools with exquisite spatial (high-field fMRI) and temporal (MEG) resolution to address these questions. The overarching aim of my research is to provide a mechanistic account of subjective perception. Ultimately, these insights may improve our understanding of clinical disorders characterised by aberrations in perception, such as psychosis.
Champ scientifique
Programme(s)
Thème(s)
Régime de financement
ERC-STG - Starting GrantInstitution d’accueil
WC1E 6BT London
Royaume-Uni