Disruption of Conscious Access in Schizophrenia

Berkovitch, Lucie; Dehaene, Stanislas; Gaillard, R.

doi:10.1016/j.tics.2017.08.006

Cited by 47 publications

(75 citation statements)

References 133 publications

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“…More broadly, the present results fit with several other physiopathological aspects of schizophrenia ( Berkovitch et al 2017 ). Schizophrenic patients exhibit anomalies in long-distance anatomical connectivity ( Bassett et al 2008 ; Benetti et al 2015 ; Jones et al 2006 ; Kubicki et al 2005 ; Sigmundsson et al 2001 ) and functional connectivity ( Ford et al 2002 ; Frith et al 1995 ; Lawrie et al 2002 ; Vinckier et al 2014 ) in distributed networks that are thought to underlie the broadcasting of conscious information in the global workspace ( Dehaene and Changeux 2011 ).…”

Section: Discussionsupporting

confidence: 90%

“…If the elevated threshold for conscious perception in schizophrenia was solely due to abnormal bottom-up sensory processing, one would expect subliminal and unattended processing to be abnormal too. However, first, even subtle measures of subliminal priming have repeatedly been shown to be fully preserved in schizophrenia ( Dehaene et al 2003a ; Del Cul et al 2006 ; for a review, see: Berkovitch et al 2017 ) and our results are compatible with these observations since no difference was observed for short SOAs. Second, the present results extend this logic by showed that, following the total withdrawal of spatial, temporal and executive attention, the remaining brain activity evoked by a flashed stimulus is indistinguishable between patients and controls.…”

Section: Discussionsupporting

confidence: 90%

“…This latter explanation is worth considering given the widely acknowledge modulatory effect that attention may have on early brain activation including the mismatch negativity ( Kasai et al 1999 ; Oades et al 1997 ; Sauer et al 2017 ), the P1 ( Feng et al 2012 ; Hillyard and Anllo-Vento 1998 ; Luck and Ford 1998 ; Wyart et al 2012 ), and probably the P50 in healthy controls ( Guterman et al, 1992 ) and schizophrenic patients ( Yee et al 2010 ). An additional argument suggesting that bottom-up processing may not be responsible for the patients' elevated consciousness threshold in masking experiments comes from the observation that subliminal processing can be fully preserved in schizophrenia patients, as reported in a variety of paradigms with masked words ( Dehaene et al 2003a ) or digits ( Del Cul et al 2006 ), subliminal error detection ( Charles et al 2017 ) and response inhibition ( Huddy et al 2009 ; for a review, see: Berkovitch et al 2017 ). This argument rests upon the idea that subliminal priming merely reflects the feed-forward propagation of sensory activation ( Fahrenfort et al 2008 ; Lamme and Roelfsema 2000 ).…”

Section: Introductionmentioning

confidence: 99%

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Impaired conscious access and abnormal attentional amplification in schizophrenia

Berkovitch

Cul

Maheu

et al. 2018

NeuroImage: Clinical

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Previous research suggests that the conscious perception of a masked stimulus is impaired in schizophrenia, while unconscious bottom-up processing of the same stimulus, as assessed by subliminal priming, can be preserved. Here, we test this postulated dissociation between intact bottom-up and impaired top-down processing and evaluate its brain mechanisms using high-density recordings of event-related potentials. Sixteen patients with schizophrenia and sixteen controls were exposed to peripheral digits with various degrees of visibility, under conditions of either focused attention or distraction by another task. In the distraction condition, the brain activity evoked by masked digits was drastically reduced in both groups, but early bottom-up visual activation could still be detected and did not differ between patients and controls. By contrast, under focused top-down attention, a major impairment was observed: in patients, contrary to controls, the late non-linear ignition associated with the P3 component was reduced. Interestingly, the patients showed an essentially normal attentional amplification of the P1 and N2 components. These results suggest that some but not all top-down attentional amplification processes are impaired in schizophrenia, while bottom-up processing seems to be preserved.

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Section: Discussionsupporting

confidence: 90%

Section: Discussionsupporting

confidence: 90%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Impaired conscious access and abnormal attentional amplification in schizophrenia

Berkovitch

Cul

Maheu

et al. 2018

NeuroImage: Clinical

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“…Our finding of a relationship between hallucination proneness and an increased prior for direct gaze in a masking task is of relevance for the ongoing debate about the processing stage, at which psychosis-typical perceptual alterations take effect (Berkovitch et al, 2017). Here, our finding speaks for an involvement of early, automatic processing stages.…”

Section: Discussionsupporting

confidence: 60%

Overly strong priors for socially meaningful visual signals in psychosis proneness

Stuke

Kress

Weilnhammer

et al. 2018

Preprint

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Predictive coding accounts of psychosis state that an overweighing of high-level priors relative to sensory information may lead to the misperception of meaningful signals underlying the experience of auditory hallucinations and delusions. However, it is currently unclear whether the hypothesized overweighing of priors (1) represents a pervasive alteration that also affects the visual modality, and,(2) takes already effect at early automatic processing stages.Here, we addressed these questions by studying visual perception of socially meaningful stimuli in healthy individuals with varying degrees of psychosis proneness (n=39). In a first task, we quantified participants' prior for detecting faces in visual noise. In a second task, we measured participants' prior for detecting direct gaze stimuli that were rendered invisible by continuous flash suppression. We found that the prior for detecting faces in noise correlated with hallucination proneness (rho=0.50, p=0.001) as well as delusion proneness (rho=0.44, p=0.005). Similarly, the prior for detecting invisible direct gaze was significantly associated with hallucination proneness (rho = 0.42, p = 0.010) and trend-wise with delusion proneness (rho = 0.29, p = 0.087). Our results provide evidence for the idea that overly strong high-level priors for automatically detecting socially meaningful stimuli might constitute a generic processing alteration in psychosis.

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“…Schizophrenia is a neuropsychiatric disorder that is not only characterized by positive symptoms like hallucinations and delusions, but also by perceptual deficits such as impaired perceptual grouping and object recognition deficits (Doniger et al, 2001;Uhlhaas and Silverstein, 2005;Berkovitch et al, 2017;van de Ven et al, 2017). On the other end of the spectrum lies synesthesia, a form of altered perception in which specific stimuli (e.g., letters) automatically trigger vivid additional conscious experiences (e.g., color), described as being percept-like (Ward, 2013).…”

Section: Introductionmentioning

confidence: 99%

Perceptual phenotypes: Perceptual gains and losses in synesthesia and schizophrenia

Leeuwen

Sauer

Jurjut

et al. 2018

Preprint

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No two individuals experience the world the same way. On a spectrum of inter-individual variability, synesthetes, for instance, experience additional sensations, while schizophrenia patients suffer perceptual deficits. Is there a unifying principle explaining inter-individual variability in perception? Perceptual experience results from inferential processes whereby sensory evidence is weighted by prior knowledge about the world. Different perceptual phenotypes may then stem from different weighting of sensory evidence and prior knowledge.We tested this hypothesis by comparing visibility thresholds in a perceptual closure task across medicated schizophrenia patients (N=20), synesthetes (N=20), and controls (N=26). Participants rated the subjective visibility of illusory contours of stimuli embedded in noise while the availability of sensory evidence was manipulated parametrically. Additionally, implicit priors in synesthetes were manipulated by presenting either synesthesia-inducing or neutral stimuli.Schizophrenia patients showed increased visibility thresholds, consistent with overreliance on sensory evidence and reduced influence of prior knowledge. In contrast, synesthetes exhibited lowered thresholds exclusively for synesthesia-inducing stimuli suggesting synesthetic experiences arise through excess implicit priors. Additionally, both in synesthetes and schizophrenics explicit top-down priors lowered thresholds but did not normalize perception in either group. Our results indicate that perceptual phenotypes might be traced to automatic differences in perceptual inference which are not overcome by conscious, explicit priors.

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Disruption of Conscious Access in Schizophrenia

Cited by 47 publications

References 133 publications

Impaired conscious access and abnormal attentional amplification in schizophrenia

Impaired conscious access and abnormal attentional amplification in schizophrenia

Overly strong priors for socially meaningful visual signals in psychosis proneness

Perceptual phenotypes: Perceptual gains and losses in synesthesia and schizophrenia

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