Visual masking deficits in schizophrenia: a view into the genetics of the disease through an endophenotype.

Schizophrenia is a severe psychiatric disorder determined by a complex mixture of genetic and environmental factors. To better understand the contributions of human genetic variations to schizophrenia, we performed a genome-wide association study (GWAS) of a highly sensitive endophenotype. In this visual masking endophenotype, two vertical bars, slightly shifted in the horizontal direction, are briefly presented (vernier offset).

Neural Compensation Mechanisms of Siblings of Schizophrenia Patients as Revealed by High-Density EEG.

Visual backward masking (VBM) deficits are candidate endophenotypes of schizophrenia indexing genetic liability of the disorder. In VBM, a target is followed by a mask that deteriorates target perception. Schizophrenia patients and, to a lesser extent, their unaffected relatives show strong and reproducible VBM deficits.

No evidence for a common factor underlying visual abilities in healthy older people.

The world's population is aging at an increasing rate. Even in the absence of neurodegenerative disorders, healthy aging affects perception and cognition. In the context of cognition, common factors are well established.

Schizophrenia patients using atypical medication perform better in visual tasks than patients using typical medication.

Schizophrenia (SCZ) patients show deficits in many domains, including cognition and perception. However, results are often mixed. One reason for mixed results may be differences in medication.

Is the perception of illusions abnormal in schizophrenia?

There seems to be no common factor for visual perception, i.e., performance in visual tasks correlates only weakly with each other.

Electrophysiological correlates of visual backward masking in patients with first episode psychosis.

Visual backward masking is strongly impaired in patients with schizophrenia. Masking deficits have been proposed as potential endophenotypes of schizophrenia. Masking performance deficits manifest as strongly reduced amplitudes in the electroencephalogram (EEG).

Statistical Learning Impairments as a Consequence of Stroke.

Statistical learning is the implicit learning of the contingencies between sequential stimuli, typically from mere exposure. It is present from infancy onward, and plays a role in functions from language learning to selective attention. Despite these observations, there are few data on whether statistical learning capacity changes with age or after brain injury.

Sex-related differences in vision are heterogeneous.

Despite well-established sex differences for cognition, audition, and somatosensation, few studies have investigated whether there are also sex differences in visual perception. We report the results of fifteen perceptual measures (such as visual acuity, visual backward masking, contrast detection threshold or motion detection) for a cohort of over 800 participants. On six of the fifteen tests, males significantly outperformed females.

Rethinking Body Ownership in Schizophrenia: Experimental and Meta-analytical Approaches Show no Evidence for Deficits.

Schizophrenia is a severe psychiatric disorder, in which patients experience an abnormal sense of self. While deficits in sensorimotor self-representation (agency) are well documented in schizophrenia, less is known about other aspects of bodily self-representation (body ownership). Here, we tested a large cohort (N = 59) of chronic schizophrenia patients and matched controls (N = 30) on a well-established body illusion paradigm, the Full Body Illusion (FBI).

Local versus global and retinotopic versus non-retinotopic motion processing in schizophrenia patients.

Schizophrenia impairs cognitive functions as much as perception. For example, patients perceive global motion in random dot kinematograms less strongly, because, as it is argued, the integration of the dots into a single Gestalt is complex and therefore deteriorated. Similarly, the perception of apparent motion is impaired, because filling-in of the illusory trajectory requires complex processing.

Does chronic nicotine consumption influence visual backward masking in schizophrenia and schizotypy?

Nicotine consumption is higher for people within the schizophrenia spectrum compared to controls. This observation supports the self-medication hypothesis, that nicotine relieves symptoms in, for example, schizophrenia patients. We tested whether performance in an endophenotype of schizophrenia (visual backward masking, VBM) is modulated by nicotine consumption in i) smoking and non-smoking schizophrenia patients, their first-degree relatives, and age-matched controls, ii) non-smoking and smoking university students, and iii) non-smoking, early and late onset nicotine smokers.

Crowding, grouping, and gain control in schizophrenia.

Visual paradigms are versatile tools to investigate the pathophysiology of schizophrenia. Contextual modulation refers to a class of paradigms where a target is flanked by neighbouring elements, which either deteriorate or facilitate target perception. It is often proposed that contextual modulation is weakened in schizophrenia compared to controls, with facilitating contexts being less facilitating and deteriorating contexts being less deteriorating.

Priming and statistical learning in right brain damaged patients.

We investigated how right hemisphere lesions affected location priming and statistical learning in four groups of participants: young controls, older controls, and right brain damaged patients with or without spatial neglect. Using a version of the Maljkovic and Nakayama's (1994) priming task, but with all the targets presented at the mid-line, we biased the transition probability for targets to repeat their spatial location. The decrease in response time with spatial repetition allowed us to quantify priming, and the modulation of priming strength as a function of repeat probability allowed us to assess for statistical learning.

Statistical learning as a tool for rehabilitation in spatial neglect.

We propose that neglect includes a disorder of representational updating. Representational updating refers to our ability to build mental models and adapt those models to changing experience. This updating ability depends on the processes of priming, working memory, and statistical learning.

Spatial probability cuing and right hemisphere damage.

In this experiment we studied statistical learning, inter-trial priming, and visual attention. We assessed healthy controls and right brain damaged (RBD) patients with and without neglect, on a simple visual discrimination task designed to measure priming effects and probability learning. All participants showed a preserved priming effect for item color.