title: Spontaneous Activity Patterns in Primary Visual Cortex Predispose to Visual Hallucinations.
abstract: According to theoretical frameworks casting perception as inference, vision results from the integration of bottom-up visual input with top-down expectations. Under conditions of strongly degraded sensory input, this may occasionally result in false perceptions in the absence of a sensory signal, also termed "hallucinations." Here, we investigated whether spontaneous prestimulus activity patterns in sensory circuits, which may embody a participant's prior expectations, predispose the observer toward false perceptions. Specifically, we used fMRI to investigate whether the representational content of prestimulus activity in early visual cortex is linked to subsequent perception during a challenging detection task. Human participants were asked to detect oriented gratings of a particular orientation that were embedded in noise. We found two characteristics of prestimulus activity that predisposed participants to hallucinations: overall lower prestimulus activity and a bias in the prestimulus activity patterns toward the to-be-detected (expected) grating. These results suggest that perceptual hallucinations may be due to an imprecise and biased state of sensory circuits preceding sensory evidence collection.
  
  
  CONCLUSIONS
  When sensory stimulation is strongly degraded, we occasionally misperceive a stimulus when only noise is present: a perceptual hallucination. Using fMRI in healthy participants, we investigated whether the state of early visual cortex preceding stimulus onset predisposes an observer to hallucinations. We found two characteristics of prestimulus activity that predisposed participants to hallucinations: overall lower prestimulus activity and a bias in the prestimulus activity patterns toward the expected grating. These results suggest that perceptual hallucinations are due to an imprecise and biased state of sensory circuits preceding sensation.
authors.affiliation: Laboratoire de Sciences Cognitives et Psycholinguistique, Département d'Études Cognitives, École Normale Supérieure, PSL Research University, 75005 Paris, France, and.
authors.forename: Auréliane
authors.initials: A
authors.lastname: Pajani
authors.affiliation: Radboud University, Donders Institute for Brain, Cognition and Behaviour, 6525 EN Nijmegen, the Netherlands.
authors.forename: Peter
authors.identifier: http://orcid.org/0000-0001-5153-4959
authors.initials: P
authors.lastname: Kok
authors.affiliation: Laboratoire de Sciences Cognitives et Psycholinguistique, Département d'Études Cognitives, École Normale Supérieure, PSL Research University, 75005 Paris, France, and.
authors.forename: Sid
authors.initials: S
authors.lastname: Kouider
authors.affiliation: Radboud University, Donders Institute for Brain, Cognition and Behaviour, 6525 EN Nijmegen, the Netherlands floris.delange@donders.ru.nl.
authors.forename: Floris P
authors.identifier: http://orcid.org/0000-0002-6730-1452
authors.initials: FP
authors.lastname: de Lange
mesh_terms: D000200:Action Potentials; D000328:Adult; D059031:Anticipation, Psychological; D003657:Decision Making; D005260:Female; D006212:Hallucinations / Q000503:physiopathology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D059906:Neuroimaging; D010364:Pattern Recognition, Visual / Q000502:physiology*; D010775:Photic Stimulation; D011597:Psychomotor Performance / Q000502:physiology; D059629:Signal-To-Noise Ratio; D065855:Spatial Processing; D014793:Visual Cortex / Q000503:physiopathology*; D055815:Young Adult
keywords: expectation; fMRI; hallucination; perception; spontaneous fluctuations