Perceptual inferences in schizophrenia: A preliminary study on healthy participants

2015 ◽  
Vol 30 (S2) ◽  
pp. S113-S114 ◽  
Author(s):  
P. Leptourgos ◽  
C.E. Notredame ◽  
R. Jardri ◽  
S. Denève
Keyword(s):  
Visual Cues ◽  
Necker Cube ◽  
Psychotic Symptoms ◽  
Bistable Perception ◽  
Sensory Evidence ◽  
Preliminary Study ◽  
Dynamic Measures ◽  
Perceptual Systems ◽  
Healthy Participants ◽  
Inference Task

Recently, Jardri and Denève proposed that positive symptoms in schizophrenia could be generated by an imbalance between excitation and inhibition in brain networks, which leads to circular inference, an aberrant form of inference where messages (bottom up and/or top down) are counted more than once and thus, are overweighted [1]. Moreover, they postulated that psychotic symptoms are caused by a system that “expects what it senses” and as a result attributes extreme weight even to weak sensory evidences. Their hypothesis was then validated by a probabilistic inference task (in prep.). Here, we put forward a new experimental study that could validate the circular inference framework in the domain of visual perception. Initially, we restricted ourselves to healthy controls, whose tendencies for psychotic symptoms were measured using appropriate scales. We investigated the computations performed by perceptual systems when facing ambiguous sensory evidence. In those cases, perception is known to oscillate between two interpretations, a phenomenon known as bistable perception. More specifically, we asked how prior expectations and visual cues affect the dynamics of bistability. Participants looked at a Necker cube that was continuously displayed on the screen and reported their percept every time they heard a sound [2]. We manipulated sensory evidence by adding shades to the stimuli and prior expectations by giving different instructions concerning the presence of an implicit bias [3]. We showed that both prior expectations and visual cues significantly affect bistability, using both static and dynamic measures. We also found that the behavior could be well fitted by Bayesian models (“simple” Bayes, hierarchical Bayesian model with Markovian statistics). Preliminary results from patients will also be presented.

scholarly journals Circular inference in bistable perception

2019 ◽  
Author(s):  
Pantelis Leptourgos ◽  
Charles-Edouard Notredame ◽  
Marion Eck ◽  
Renaud Jardri ◽  
Sophie Denève
Keyword(s):  
Prior Knowledge ◽  
Bayesian Approach ◽  
Necker Cube ◽  
Top Down ◽  
Inference Model ◽  
Bottom Up ◽  
Bistable Perception ◽  
Sensory Evidence ◽  
The Brain ◽  
Healthy Participants

AbstractWhen facing fully ambiguous images, the brain cannot commit to a single percept and instead switches between mutually exclusive interpretations every few seconds, a phenomenon known as bistable perception. Despite years of research, there is still no consensus on whether bistability, and perception in general, is driven primarily by bottom-up or top-down mechanisms. Here, we adopted a Bayesian approach in an effort to reconcile these two theories. Fifty-five healthy participants were exposed to an adaptation of the Necker cube paradigm, in which we manipulated sensory evidence (by shadowing the cube) and prior knowledge (e.g., by varying instructions about what participants should expect to see). We found that manipulations of both sensory evidence and priors significantly affected the way participants perceived the Necker cube. However, we observed an interaction between the effect of the cue and the effect of the instructions, a finding incompatible with Bayes-optimal integration. In contrast, the data were well predicted by a circular inference model. In this model, ambiguous sensory evidence is systematically biased in the direction of current expectations, ultimately resulting in a bistable percept.

scholarly journals Effect of Visual Cues on the Resolution of Perceptual Ambiguity in Parkinson’s Disease and Normal Aging

2015 ◽  
Vol 21 (2) ◽  
pp. 146-155 ◽  
Author(s):  
Mirella Díaz-Santos ◽  
Bo Cao ◽  
Samantha A. Mauro ◽  
Arash Yazdanbakhsh ◽  
Sandy Neargarder ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Visual Cues ◽  
Necker Cube ◽  
Normal Aging ◽  
Volitional Control ◽  
Bistable Perception ◽  
Task Instructions ◽  
Passive Viewing ◽  
The Face

AbstractParkinson’s disease (PD) and normal aging have been associated with changes in visual perception, including reliance on external cues to guide behavior. This raises the question of the extent to which these groups use visual cues when disambiguating information. Twenty-seven individuals with PD, 23 normal control adults (NC), and 20 younger adults (YA) were presented a Necker cube in which one face was highlighted by thickening the lines defining the face. The hypothesis was that the visual cues would help PD and NC to exert better control over bistable perception. There were three conditions, including passive viewing and two volitional-control conditions (hold one percept in front; and switch: speed up the alternation between the two). In the Hold condition, the cue was either consistent or inconsistent with task instructions. Mean dominance durations (time spent on each percept) under passive viewing were comparable in PD and NC, and shorter in YA. PD and YA increased dominance durations in the Hold cue-consistent condition relative to NC, meaning that appropriate cues helped PD but not NC hold one perceptual interpretation. By contrast, in the Switch condition, NC and YA decreased dominance durations relative to PD, meaning that the use of cues helped NC but not PD in expediting the switch between percepts. Provision of low-level cues has effects on volitional control in PD that are different from in normal aging, and only under task-specific conditions does the use of such cues facilitate the resolution of perceptual ambiguity. (JINS, 2015, 21, 146–155)

scholarly journals Effect of Peony-Glycyrrhiza Decoction on Amisulpride-Induced Hyperprolactinemia in Women with Schizophrenia: A Preliminary Study

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Ping Yang ◽  
Liang Li ◽  
Dong Yang ◽  
Chaoying Wang ◽  
Hongli Peng ◽  
...  
Keyword(s):  
Placebo Group ◽  
Clinical Symptoms ◽  
Psychotic Symptoms ◽  
Group Level ◽  
Hormone Levels ◽  
Mental Symptoms ◽  
Treatment Changes ◽  
Preliminary Study

Objective. The aim of this study is to observe the effect of Peony-Glycyrrhiza Decoction (PGD) on hyperprolactinemia in women with schizophrenia induced by Amisulpride. Material and Methods. A total of 41 female schizophrenia patients receiving Amisulpride were randomly divided into placebo (n=20) and PGD groups (n=21). Maintaining the original Amisulpride dose, the two groups were given placebo and PGD, respectively. The levels of Prolactin (PRL) and other hormones were measured on the initial day and at weeks 4 and 8 after treatment. Changes of clinical symptoms in patients with hyperprolactinemia were observed. The PANSS scores were recorded to assess the psychotic symptoms. Results. Compared with placebo group, level of PRL decreased while Progesterone increased remarkably in the PGD group at weeks 4 and 8 (p<0.01), and level of Estradiol in the PGD group increased significantly at week 8 (p<0.05). There were no differences in PANSS scores and biochemical indexes between two groups at weeks 4 and 8. Conclusion. PGD can improve symptoms of hyperprolactinemia and hormone levels in women with schizophrenia caused by Amisulpride, without affecting their mental symptoms and biochemical indexes.

scholarly journals Influence of virtual reality visual feedback on the illusion of movement induced by tendon vibration of wrist in healthy participants

PLoS ONE ◽  
2020 ◽  
Vol 15 (11) ◽  
pp. e0242416
Author(s):  
Salomé Le Franc ◽  
Mathis Fleury ◽  
Mélanie Cogne ◽  
Simon Butet ◽  
Christian Barillot ◽  
...  
Keyword(s):  
Virtual Reality ◽  
Visual Feedback ◽  
Visual Cues ◽  
Static Condition ◽  
Likert Scale ◽  
Tendon Vibration ◽  
Virtual Hand ◽  
Significant Difference ◽  
Illusory Movement ◽  
Healthy Participants

Introduction Illusion of movement induced by tendon vibration is an effective approach for motor and sensory rehabilitation in case of neurological impairments. The aim of our study was to investigate which modality of visual feedback in Virtual Reality (VR) associated with tendon vibration of the wrist could induce the best illusion of movement. Methods We included 30 healthy participants in the experiment. Tendon vibration inducing illusion of movement (wrist extension, 100Hz) was applied on their wrist during 3 VR visual conditions (10 times each): a moving virtual hand corresponding to the movement that the participants could feel during the tendon vibration (Moving condition), a static virtual hand (Static condition), or no virtual hand at all (Hidden condition). After each trial, the participants had to quantify the intensity of the illusory movement on a Likert scale, the subjective degree of extension of their wrist and afterwards they answered a questionnaire. Results There was a significant difference between the 3 visual feedback conditions concerning the Likert scale ranking and the degree of wrist’s extension (p<0.001). The Moving condition induced a higher intensity of illusion of movement and a higher sensation of wrist’s extension than the Hidden condition (p<0.001 and p<0.001 respectively) than that of the Static condition (p<0.001 and p<0.001 respectively). The Hidden condition also induced a higher intensity of illusion of movement and a higher sensation of wrist’s extension than the Static condition (p<0.01 and p<0.01 respectively). The preferred condition to facilitate movement’s illusion was the Moving condition (63.3%). Conclusions This study demonstrated the importance of carefully selecting a visual feedback to improve the illusion of movement induced by tendon vibration, and the increase of illusion by adding VR visual cues congruent to the illusion of movement. Further work will consist in testing the same hypothesis with stroke patients.

scholarly journals Cueing the Necker cube: Pupil dilation reflects the viewing-from-above constraint in bistable perception

2020 ◽  
Vol 20 (4) ◽  
pp. 7 ◽  
Author(s):  
Fumiaki Sato ◽  
Bruno Laeng ◽  
Shigeki Nakauchi ◽  
Tetsuto Minami
Keyword(s):  
Necker Cube ◽  
Pupil Dilation ◽  
Bistable Perception

scholarly journals Shift toward prior knowledge confers a perceptual advantage in early psychosis and psychosis-prone healthy individuals

2015 ◽  
Vol 112 (43) ◽  
pp. 13401-13406 ◽  
Author(s):  
Christoph Teufel ◽  
Naresh Subramaniam ◽  
Veronika Dobler ◽  
Jesus Perez ◽  
Johanna Finnemann ◽  
...  
Keyword(s):  
Information Processing ◽  
Prior Knowledge ◽  
Early Psychosis ◽  
Psychotic Symptoms ◽  
Psychotic Experiences ◽  
Healthy Individuals ◽  
Top Down ◽  
Bottom Up ◽  
Psychosis Proneness ◽  
Sensory Evidence

Many neuropsychiatric illnesses are associated with psychosis, i.e., hallucinations (perceptions in the absence of causative stimuli) and delusions (irrational, often bizarre beliefs). Current models of brain function view perception as a combination of two distinct sources of information: bottom-up sensory input and top-down influences from prior knowledge. This framework may explain hallucinations and delusions. Here, we characterized the balance between visual bottom-up and top-down processing in people with early psychosis (study 1) and in psychosis-prone, healthy individuals (study 2) to elucidate the mechanisms that might contribute to the emergence of psychotic experiences. Through a specialized mental-health service, we identified unmedicated individuals who experience early psychotic symptoms but fall below the threshold for a categorical diagnosis. We observed that, in early psychosis, there was a shift in information processing favoring prior knowledge over incoming sensory evidence. In the complementary study, we capitalized on subtle variations in perception and belief in the general population that exhibit graded similarity with psychotic experiences (schizotypy). We observed that the degree of psychosis proneness in healthy individuals, and, specifically, the presence of subtle perceptual alterations, is also associated with stronger reliance on prior knowledge. Although, in the current experimental studies, this shift conferred a performance benefit, under most natural viewing situations, it may provoke anomalous perceptual experiences. Overall, we show that early psychosis and psychosis proneness both entail a basic shift in visual information processing, favoring prior knowledge over incoming sensory evidence. The studies provide complementary insights to a mechanism by which psychotic symptoms may emerge.

scholarly journals Perceptual Inferences in Schizophrenia: A preliminary study in healthy participants

2016 ◽  
Vol 16 (12) ◽  
pp. 1220
Author(s):  
Pantelis Leptourgos ◽  
Charles-Edouard Notredame ◽  
Renaud Jardri ◽  
Sophie Deneve
Keyword(s):  
Preliminary Study ◽  
Healthy Participants

scholarly journals Measuring Gaze and Arrow Cuing Effects With a Short Test Adapted to Brain Damaged Patients With Unilateral Spatial Neglect: A Preliminary Study

2021 ◽  
Vol 12 ◽  
Author(s):  
Rindra Narison ◽  
Marie de Montalembert ◽  
Andrew Bayliss ◽  
Laurence Conty
Keyword(s):  
Older Patients ◽  
Brain Lesion ◽  
Brain Lesions ◽  
Spatial Neglect ◽  
Short Version ◽  
Unilateral Spatial Neglect ◽  
Right Brain ◽  
Short Test ◽  
Preliminary Study ◽  
Healthy Participants

People with left unilateral spatial neglect (USN) following a right brain lesion show difficulty in orienting their attention toward stimuli presented on the left. However, cuing the stimuli with gaze direction or a pointing arrow can help some of them to compensate for this difficulty. In order to build a tool that helps to identify these patients, we needed a short version of the paradigm classically used to test gaze and arow cuing effects in healthy adults, adapted to the capacities of patients with severe attention deficit. Here, we tested the robustness of the cuing effects measured by such a short version in 48 young adult healthy participants, 46 older healthy participants, 10 patients with left USN following a right brain lesion (USN+), and 10 patients with right brain lesions but no USN (USN–). We observed gaze and arrow cuing effects in all populations, independently of age and presence or absence of a right brain lesion. In the neglect field, the USN+ group showed event greater cuing effect than older healthy participants and the USN– group. We showed that gaze and arrow cuing effects are powerful enough to be detected in a very short test adapted to the capacities of older patients with severe attention deficits, which increases their applicability in rehabilitation settings. We further concluded that our test is a suitable basis to develop a tool that will help neuropsychologists to identify USN patients who respond to gaze and/or arrow cuing in their neglect field.

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