[Visuospatial context processing in untreated schizophrenic patients and relation to disorganization syndrome]

Neurocognitive impairment on motor imagery associated with positive symptoms in patients with first-episode schizophrenia: evidence from event-related brain potentials

Motor imagery provides direct insight into an anatomically interconnected system involved in the integration of sensory information with motor actions, a process that is associated with positive symptoms in schizophrenia (SCZ). However, very little is known about the electrophysiological processing of motor imagery in first episode SCZ. In the current study, we used a visual hand mental rotation (MR) paradigm to manipulate the processing of motor imagery while event-related brain potentials (ERPs) were recorded in 42 SCZ participants and 40 healthy controls (HC). The 400-600 ms window was measured and analyzed for peak latencies and amplitudes. Participants with SCZ had slower reaction time (RT) and made more errors than did HC participants. Moreover, SCZ participants had lower amplitudes in the 400-600 ms window and the typical MR function for amplitudes of MR was lacking. Interestingly, the scalp activity maps for MR in SCZ exhibited an absence of activation in the left parietal site as shown in HC. Furthermore, deficits of amplitude for MR were positively correlated with positive symptom scores in SCZ. These results provide novel evidence for relationships between the electrophysiological processing of motor imagery and positive symptoms in SCZ. They further suggest that the impaired information processing of motor imagery indexed by amplitudes and specific topographic characteristics of the EEG during MR tasks may be a potentially useful and early defining biomarker for SCZ.

"To see or not to see: that is the question." The "Protection-Against-Schizophrenia" (PaSZ) model: evidence from congenital blindness and visuo-cognitive aberrations

The causes of schizophrenia are still unknown. For the last 100 years, though, both “absent” and “perfect” vision have been associated with a lower risk for schizophrenia. Hence, vision itself and aberrations in visual functioning may be fundamental to the development and etiological explanations of the disorder. In this paper, we present the “Protection-Against-Schizophrenia” (PaSZ) model, which grades the risk for developing schizophrenia as a function of an individual's visual capacity. We review two vision perspectives: (1) “Absent” vision or how congenital blindness contributes to PaSZ and (2) “perfect” vision or how aberrations in visual functioning are associated with psychosis. First, we illustrate that, although congenitally blind and sighted individuals acquire similar world representations, blind individuals compensate for behavioral shortcomings through neurofunctional and multisensory reorganization. These reorganizations may indicate etiological explanations for their PaSZ. Second, we demonstrate that visuo-cognitive impairments are fundamental for the development of schizophrenia. Deteriorated visual information acquisition and processing contribute to higher-order cognitive dysfunctions and subsequently to schizophrenic symptoms. Finally, we provide different specific therapeutic recommendations for individuals who suffer from visual impairments (who never developed “normal” vision) and individuals who suffer from visual deterioration (who previously had “normal” visual skills). Rather than categorizing individuals as “normal” and “mentally disordered,” the PaSZ model uses a continuous scale to represent psychiatrically relevant human behavior. This not only provides a scientific basis for more fine-grained diagnostic assessments, earlier detection, and more appropriate therapeutic assignments, but it also outlines a trajectory for unraveling the causes of abnormal psychotic human self- and world-perception.

Developmental heterochrony and the evolution of autistic perception, cognition and behavior

BACKGROUND

Autism is usually conceptualized as a disorder or disease that involves fundamentally abnormal neurodevelopment. In the present work, the hypothesis that a suite of core autism-related traits may commonly represent simple delays or non-completion of typical childhood developmental trajectories is evaluated.

DISCUSSION

A comprehensive review of the literature indicates that, with regard to the four phenotypes of (1) restricted interests and repetitive behavior, (2) short-range and long-range structural and functional brain connectivity, (3) global and local visual perception and processing, and (4) the presence of absolute pitch, the differences between autistic individuals and typically developing individuals closely parallel the differences between younger and older children.

SUMMARY

The results of this study are concordant with a model of 'developmental heterochrony', and suggest that evolutionary extension of child development along the human lineage has potentiated and structured genetic risk for autism and the expression of autistic perception, cognition and behavior.

Perceptual organization impairment in schizophrenia and associated brain mechanisms: review of research from 2005 to 2010

Perceptual organization (PO) refers to the processes by which visual information is structured into coherent patterns such as groups, contours, perceptual wholes, and object representations. Impairments in PO have been demonstrated in schizophrenia since the 1960s and have been linked to several illness-related factors including poor premorbid functioning, poor prognosis, and disorganized symptoms. This literature was last reviewed in 2005. Since then, electrophysiological (electroencephalographic, event-related potential, and magnetoencephalographic) and fMRI studies in both patient and nonpatient samples have clarified brain mechanisms involved in the impairment, and additional behavioral studies in patients and nonpatients have clarified the computational mechanisms. In addition, data now exist on the functional consequences of PO impairments, in terms of secondary difficulties in face processing, selective attention, working memory, and social cognition. Preliminary data on drug effects on PO and on changes in response to treatment suggest that anomalies in PO may furnish a biomarker for the integrity of its associated biological mechanisms. All of this recent evidence allows for a clearer picture of the nature of the impairment and how it relates to broader aspects of brain and behavioral functioning in schizophrenia.