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Visual Dysfunction in Schizophrenia: A View into the Mechanisms of Madness?

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889195152 Year: Pages: 319 DOI: 10.3389/978-2-88919-515-2 Language: English
Publisher: Frontiers Media SA
Subject: Psychology --- Science (General)
Added to DOAB on : 2015-10-30 16:33:44
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Research on visual perception in schizophrenia has a long history. However, it is only recently that it has been included in mainstream efforts to understand the cognitive neuroscience of the disorder and to assist with biomarker and treatment development (e.g., the NIMH CNTRICS and RDoC initiatives). Advances in our understanding of visual disturbances in schizophrenia can tell us about both specific computational and neurobiological abnormalities, and about the widespread computational and neurobiological abnormalities in the illness, of which visual disturbances constitute well-studied, replicable, low-level examples. Importantly, far from being a passive sensory registration process, visual perception is active, inferential, and hypothesis-generating, and therefore can provide excellent examples of breakdowns in general brain functions in schizophrenia. Despite progress made in understanding visual processing disturbances in schizophrenia, many challenges exist and many unexplored areas are in need of examination. For example, the directional relationships between perceptual and cognitive disturbances (e.g., in attention, memory, executive function, predictive coding) remain unclear in many cases, as do links with symptoms, including visual hallucinations. The effect of specific visual disturbances on multisensory integration in schizophrenia has also not been explored. In addition, few studies of vision in schizophrenia have used naturalistic stimuli, including real-world objects, and almost no studies have examined processing during interaction with objects or visual exploration, which can provide important data on functioning of the perception for action pathway. Relatedly, studies of visual processing in schizophrenia have also not been conducted within contexts that include emotional stimulation and the presence of reinforcers - characteristics of many real-world situations - and the consequences of this are likely to be an incomplete view of how and when perception is abnormal in the condition. An additional important area involves treatment of visual disturbances in schizophrenia. Two major questions regarding this are: 1) can visual processing be improved in cases where it is impaired (and by what types of interventions affecting which cognitive and neurobiological mechanisms)? and 2) what are the clinical and functional benefits of improving specific visual functions in people with schizophrenia? Other important and understudied questions concern: 1) the extent to which indices of visual functioning can serve as biomarkers such as predictors of relapse, treatment response, and/or recovery; 2) the potential role of visual functioning in diagnosing and predicting illness; 3) the extent to which some visual perception disturbances are diagnostically specific to schizophrenia; and 4) the extent to which visual disturbances are truly manifestations of disease, as opposed to aspects of normal variation that, in combination with disease, serves to modify the clinical presentation. This Frontiers Research Topic explores some of these, and other issues facing this exciting interface between vision science and schizophrenia research. We include papers that span the entire range of different Frontiers paper types, including those that are data driven (using psychophysics, electroencephalography, neuroimaging, computational and animal models, and other methods), reviews, hypotheses, theories, opinion, methods, areas of impact, and historical perspectives.

Color Vision Sensation and Perception

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889199600 Year: Pages: 91 DOI: 10.3389/978-2-88919-960-0 Language: English
Publisher: Frontiers Media SA
Subject: Science (General) --- Psychology
Added to DOAB on : 2016-01-19 14:05:46
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Color vision is considered a microcosm of the visual science. Special physiological and psychological processes make this scientific topic an intriguing and complex research field that can aggregates around molecular biologists, neurophysiologists, physicists, psychophysicists and cognitive neuroscientists. Our purpose is to present the frontier knowledge of this area of visual science, showing, in the end, the future prospects of application and basic studies of color perception.

Learning to see (better): Improving visual deficits with perceptual learning

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889196036 Year: Pages: 95 DOI: 10.3389/978-2-88919-603-6 Language: English
Publisher: Frontiers Media SA
Subject: Science (General) --- Psychology
Added to DOAB on : 2016-08-16 10:34:25
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Perceptual learning can be defined as a long lasting improvement in a perceptual skill following a systematic training, due to changes in brain plasticity at the level of sensory or perceptual areas. Its efficacy has been reported for a number of visual tasks, such as detection or discrimination of visual gratings (De Valois, 1977; Fiorentini & Berardi, 1980, 1981; Mayer, 1983), motion direction discrimination (Ball & Sekuler, 1982, 1987; Ball, Sekuler, & Machamer, 1983), orientation judgments (Fahle, 1997; Shiu & Pashler, 1992; Vogels & Orban, 1985), hyperacuity (Beard, Levi, & Reich, 1995; Bennett & Westheimer, 1991; Fahle, 1997; Fahle & Edelman, 1993; Kumar & Glaser, 1993; McKee & Westheimer, 1978; Saarinen & Levi, 1995), visual search tasks (Ahissar & Hochstein, 1996; Casco, Campana, & Gidiuli, 2001; Campana & Casco, 2003; Ellison & Walsh, 1998; Sireteanu & Rettenbach, 1995) or texture discrimination (Casco et al., 2004; Karni & Sagi, 1991, 1993). Perceptual learning is long-lasting and specific for basic stimulus features (orientation, retinal position, eye of presentation) suggesting a long-term modification at early stages of visual analysis, such as in the striate (Karni & Sagi, 1991; 1993; Saarinen & Levi, 1995; Pourtois et al., 2008) and extrastriate (Ahissar & Hochstein, 1996) visual cortex. Not confined to a basic research paradigm, perceptual learning has recently found application outside the laboratory environment, being used for clinical treatment of a series of visually impairing conditions such as amblyopia (Levi & Polat, 1996; Levi, 2005; Levi & Li, 2009, Polat et al., 2004; Zhou et al., 2006), myopia (Tan & Fong, 2008) or presbyopia (Polat, 2009). Different authors adopted different paradigms and stimuli in order to improve malfunctioning visual abilities, such as Vernier Acuity (Levi, Polat & Hu, 1997), Gratings detection (Zhou et al., 2006), oculomotor training (Rosengarth et al., 2013) and lateral interactions (Polat et al., 2004). The common result of these studies is that a specific training produces not only improvements in trained functions, but also in other, untrained and higher-level visual functions, such as visual acuity, contrast sensitivity and reading speed (Levi et al, 1997a, 1997b; Polat et al., 2004; Polat, 2009; Tan & Fong, 2008). More recently (Maniglia et al. 2011), perceptual learning with the lateral interactions paradigm has been successfully used for improving peripheral vision in normal people (by improving contrast sensitivity and reducing crowding, the interference in target discrimination due to the presence of close elements), offering fascinating new perspectives in the rehabilitation of people who suffer of central vision loss, such as maculopathy patients, partially overcoming the structural differences between fovea and periphery that limit the vision outside the fovea. One of the strongest point, and a distinguishing feature of perceptual learning, is that it does not just improve the subject’s performance, but produces changes in brain’s connectivity and efficiency, resulting in long-lasting, enduring neural changes. By tailoring the paradigms on each subject’s needs, perceptual learning could become the treatment of choice for the rehabilitation of visual functions, emerging as a simple procedure that doesn’t need expensive equipment.

The Impact of Sensory; Linguistic and Social Deprivation on Cognition

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889453542 Year: Pages: 183 DOI: 10.3389/978-2-88945-354-2 Language: English
Publisher: Frontiers Media SA
Subject: Science (General) --- Psychology
Added to DOAB on : 2018-02-27 16:16:45
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Early experience plays a crucial role in determining the trajectory of cognitive development. For example, early sensory deprivation is known to induce neural reorganization by way of adaptation to the altered sensory experience. Neville and Bavelier’s “compensatory theory’’ hypothesizes that loss of one sense may bring about a sensory enhancement in the remaining modalities. Sensory deprivation will, however, also impact the age of emergence, or the speed of acquisition of cognitive abilities that depend upon sensory inputs. Understanding how a child’s early environment shapes their cognition is not only of theoretical interest. It is essential for the development of early intervention programs that address not just the early deprivation itself, but also the cognitive sequelae of such deprivation. The articles in this e-book all address different aspects of deprivation - sensory, linguistic, and social - and explore the impacts of such deprivation on a wide range of cognitive outcomes. In reading these contributions, it is important to note that sensory, linguistic, and social deprivation are not independent factors in human experience. For example, a child born deaf into a hearing family is likely to experience delays in exposure to natural language, with subsequent limits on their linguistic competence having an effect on social interactions and inclusion: a child raised in environments where social interaction is highly limited is also likely to experience reductions in the quantity and quality of linguistic inputs. Future work will need to carefully examine the complex interactions between the sensory, linguistic and social environments of children raised in atypical or impoverished environments.

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