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Cucca A, Manara CV, Catalan M, Liccari M, Antonutti L, Lombardo TMI, Cenacchi V, Rangan S, Mingolo S, Crisafulli C, Dore F, Murgia M, Agostini T, Manganotti P. Using illusions to understand hallucinations: differences in perceptual performances on illusory figures may underscore specific visuoperceptual impairments in Parkinson's disease. Front Neurosci 2023; 17:1256224. [PMID: 38125403 PMCID: PMC10732246 DOI: 10.3389/fnins.2023.1256224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Accepted: 11/06/2023] [Indexed: 12/23/2023] Open
Abstract
Visual hallucinations are prevalent, potentially disabling symptoms of Parkinson's Disease. Multiple impairments in bottom-up sensory processing and top-down perceptual modulation are implicated in the pathophysiology of these phenomena. In healthy individuals, visual illusions are elicited by illusory figures through parametric manipulations of geometrical configurations, contrast, color, or spatial relationships between stimuli. These illusory percepts provide insight on the physiologic processes subserving conscious and unconscious perception. In this exploratory, cross-sectional, controlled study, perceptual performance on illusory figures was assessed on 11 PD patients with hallucinations, 10 non-hallucinating PD patients, and 10 age-matched healthy individuals. In order to characterize potential neural substrates of perceptual performances, patients' brain metabolic patterns on FDG PET were also analyzed. Illusions relying on attentional modulation and global perception were attenuated in PD patients without hallucinations. This pattern was no longer recognizable in hallucinating patients. Conversely, illusory effects normally counteracted by figure to background segregation and overlapping figures recognition were enhanced in PD patients with hallucinations. FDG PET findings further suggest that perceptual differences between PD patients might be linked to abnormal top-down perceptual modulation.
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Affiliation(s)
- Alberto Cucca
- Department of Life Sciences, University of Trieste, Trieste, Italy
- Department of Neurology, New York University Grossman School of Medicine, New York, NY, United States
| | | | - Mauro Catalan
- Neurology Clinic, Department of Medicine, Surgery and Health Sciences, University of Trieste, Trieste, Italy
| | - Marco Liccari
- Neurology Clinic, Department of Medicine, Surgery and Health Sciences, University of Trieste, Trieste, Italy
| | - Lucia Antonutti
- Neurology Clinic, Department of Medicine, Surgery and Health Sciences, University of Trieste, Trieste, Italy
| | | | - Valentina Cenacchi
- Neurology Clinic, Department of Medicine, Surgery and Health Sciences, University of Trieste, Trieste, Italy
| | - Sophie Rangan
- Neurology Clinic, Department of Medicine, Surgery and Health Sciences, University of Trieste, Trieste, Italy
| | - Serena Mingolo
- Department of Life Sciences, University of Trieste, Trieste, Italy
| | - Carmelo Crisafulli
- Nuclear Medicine, Imaging Diagnostic Department University Hospital and Health Services of Trieste, Trieste, Italy
| | - Franca Dore
- Nuclear Medicine, Imaging Diagnostic Department University Hospital and Health Services of Trieste, Trieste, Italy
| | - Mauro Murgia
- Department of Life Sciences, University of Trieste, Trieste, Italy
| | - Tiziano Agostini
- Department of Life Sciences, University of Trieste, Trieste, Italy
| | - Paolo Manganotti
- Neurology Clinic, Department of Medicine, Surgery and Health Sciences, University of Trieste, Trieste, Italy
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The impact of optical impressions on dog feeding practice. Top Companion Anim Med 2022; 50:100693. [PMID: 35872114 DOI: 10.1016/j.tcam.2022.100693] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 06/28/2022] [Accepted: 07/11/2022] [Indexed: 11/20/2022]
Abstract
According to the literature, as many as 60% of domestic dogs are overweight, whereby obesity is implicated in many serious diseases and hence a reduction of body weight results in a reduced risk of disease. Approximately 32% of reduction diets are unsuccessful in helping dogs to reach their ideal body weight. The likely reasons for this high drop-out rate include, among others, the fear of increased hunger-induced distress or a loss of affection on the part of the pet towards the owner. To alleviate these apprehensions, the use of optical effects that increase the perceived food intake could be useful. To investigate this, a mixed-methods study design was applied and 100 test persons - including dog owners and non-owners - were instructed to fill up 11 separate dog bowls with the same amount of dogfood. The bowls varied in five different variables (total height, upper diameter, angulation of sidewall, volume, and colour). The influence of the shape and colour of the dog bowls in relation to the filling quantity was evaluated. Overall, the body of the inner food bowl - especially its diameter and shape - showed a significant impact on the feeder as the wider the diameter, the more the dog bowl was filled. Moreover, the flatter the sidewall was angulated, the larger the fill-up quantity. Significantly, the volume on its own did not have a significant impact on the feeder. A difference of up to 37.6% in fill quantity resulted depending on the type of dog bowl used. Furthermore, the use of inner cones confused the test persons whereas different colours and the total height of the bowl showed no impact. Dog bowls with a small upper diameter and a steep sidewall - regardless of volume and colour - were filled less by the test persons. This tendency could be useful for adapting the feeding of overweight dogs or those with an increased risk of obesity.
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Boswell AM, Kohler PJ, McCarthy JD, Caplovitz GP. Perceived group size is determined by the centroids of the component elements. J Vis 2021; 21:1. [PMID: 34851391 PMCID: PMC8648053 DOI: 10.1167/jov.21.13.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
To accomplish the deceptively simple task of perceiving the size of objects in the visual scene, the visual system combines information about the retinal size of the object with several other cues, including perceived distance, relative size, and prior knowledge. When local component elements are perceptually grouped to form objects, the task is further complicated because a grouped object does not have a continuous contour from which retinal size can be estimated. Here, we investigate how the visual system solves this problem and makes it possible for observers to judge the size of perceptually grouped objects. We systematically vary the shape and orientation of the component elements in a two-alternative forced-choice task and find that the perceived size of the array of component objects can be almost perfectly predicted from the distance between the centroids of the component elements and the center of the array. This is true whether the global contour forms a circle or a square. When elements were positioned such that the centroids along the global contour were at different distances from the center, perceived size was based on the average distance. These results indicate that perceived size does not depend on the size of individual elements, and that smooth contours formed by the outer edges of the component elements are not used to estimate size. The current study adds to a growing literature highlighting the importance of centroids in visual perception and may have implications for how size is estimated for ensembles of different objects.
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Affiliation(s)
| | - Peter J Kohler
- Department of Psychology, York University, Toronto, Ontario, Canada.,Centre for Vision Research, York University, Toronto, Ontario, Canada.,
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Ronja N, Kölle P. [Obesity in dogs - A review of underlying reasons]. TIERAERZTLICHE PRAXIS AUSGABE KLEINTIERE HEIMTIERE 2021; 49:284-293. [PMID: 34425607 DOI: 10.1055/a-1548-2293] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Obesity does not merely represent a human problem but is also recognized as an immense health threat in domestic animals. However, this disease is frequently not recognized by the pet owner. Current studies assume that up to 60 % of domestic dogs are overweight or significantly obese with various reasons existing for this development. Not only the feeding management contributes to the development of obesity but also genetics, age and gender as well as specific primary diseases add to the individual's weight gain. Addtionally, medical treatment and the owner-pet-relationship may increase the risk for obesity. In order to treat obesity in a qualified manner or ideally to prevent this from developing in the first place, a profound knowledge concerning the underlying causes is essential. The present article provides a review of the most important impact factors thus adding to the body of information allowing for the acquisition of such expertise.
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Affiliation(s)
- Nitsch Ronja
- Medizinische Kleintierklinik, Tierärztliche Fakultät der Ludwig-Maximilians-Universität München
| | - Petra Kölle
- Medizinische Kleintierklinik, Tierärztliche Fakultät der Ludwig-Maximilians-Universität München
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Gori S, Molteni M, Facoetti A. Visual Illusions: An Interesting Tool to Investigate Developmental Dyslexia and Autism Spectrum Disorder. Front Hum Neurosci 2016; 10:175. [PMID: 27199702 PMCID: PMC4842763 DOI: 10.3389/fnhum.2016.00175] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2014] [Accepted: 04/06/2016] [Indexed: 11/13/2022] Open
Abstract
A visual illusion refers to a percept that is different in some aspect from the physical stimulus. Illusions are a powerful non-invasive tool for understanding the neurobiology of vision, telling us, indirectly, how the brain processes visual stimuli. There are some neurodevelopmental disorders characterized by visual deficits. Surprisingly, just a few studies investigated illusory perception in clinical populations. Our aim is to review the literature supporting a possible role for visual illusions in helping us understand the visual deficits in developmental dyslexia and autism spectrum disorder. Future studies could develop new tools - based on visual illusions - to identify an early risk for neurodevelopmental disorders.
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Affiliation(s)
- Simone Gori
- Department of Human and Social Sciences, University of BergamoBergamo, Italy
- Child Psychopathology Unit, Scientific Institute, IRCCS Eugenio MedeaBosisio Parini, Italy
| | - Massimo Molteni
- Child Psychopathology Unit, Scientific Institute, IRCCS Eugenio MedeaBosisio Parini, Italy
| | - Andrea Facoetti
- Child Psychopathology Unit, Scientific Institute, IRCCS Eugenio MedeaBosisio Parini, Italy
- Developmental and Cognitive Neuroscience Lab, Department of General Psychology, University of PadovaPadua, Italy
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Knol H, Huys R, Sarrazin JC, Jirsa VK. Quantifying the Ebbinghaus figure effect: target size, context size, and target-context distance determine the presence and direction of the illusion. Front Psychol 2015; 6:1679. [PMID: 26583002 PMCID: PMC4631937 DOI: 10.3389/fpsyg.2015.01679] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Accepted: 10/19/2015] [Indexed: 11/13/2022] Open
Abstract
Over the last 20 years, visual illusions, like the Ebbinghaus figure, have become widespread to investigate functional segregation of the visual system. This segregation reveals itself, so it is claimed, in the insensitivity of movement to optical illusions. This claim, however, faces contradictory results (and interpretations) in the literature. These contradictions may be due to methodological weaknesses in, and differences across studies, some of which may hide a lack of perceptual illusion effects. Indeed, despite the long history of research with the Ebbinghaus figure, standardized configurations to predict the illusion effect are missing. Here, we present a complete geometrical description of the Ebbinghaus figure with three target sizes compatible with Fitts' task. Each trial consisted of a stimulus and an isolated probe. The probe was controlled by the participant's response through a staircase procedure. The participant was asked whether the probe or target appeared bigger. The factors target size, context size, target-context distance, and a control condition resulted in a 3 × 3 × 3+3 factorial design. The results indicate that the illusion magnitude, the perceptual distinctiveness, and the response time depend on the context size, distance, and especially, target size. In 33% of the factor combinations there was no illusion effect. The illusion magnitude ranged from zero to (exceptionally) 10% of the target size. The small (or absent) illusion effects on perception and its possible influence on motor tasks might have been overlooked or misinterpreted in previous studies. Our results provide a basis for the application of the Ebbinghaus figure in psychophysical and motor control studies.
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Affiliation(s)
- Hester Knol
- Institut de Neurosciences des Systèmes, Aix-Marseille Université Marseille, France ; Institut de la Santé et de la Recherche Médical, UMR_S 1106 Marseille, France ; Systems Control and Flight Dynamics Department, Office National d'Etudes et de Recherches Aérospatiales (ONERA) Salon de Provence, France
| | - Raoul Huys
- Centre National de la Recherche Scientifique Paris, France ; Centre de Recherche Cerveau & Cognition - UMR5549, Université Toulouse III - Paul Sabatier Toulouse, France
| | - Jean-Christophe Sarrazin
- Systems Control and Flight Dynamics Department, Office National d'Etudes et de Recherches Aérospatiales (ONERA) Salon de Provence, France
| | - Viktor K Jirsa
- Institut de Neurosciences des Systèmes, Aix-Marseille Université Marseille, France ; Institut de la Santé et de la Recherche Médical, UMR_S 1106 Marseille, France ; Centre National de la Recherche Scientifique Paris, France
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