Development of visual motion perception in children of patients with schizophrenia and bipolar disorder: a follow-up study

Motion and Form Perception in Childhood-Onset Schizophrenia

(1) Background: Childhood-onset schizophrenia (COS) is a rare type of psychotic disorder characterized by delusions, hallucinations, grossly disorganized behavior, and poor psychosocial functioning. The etiology of COS is unknown, but neurodevelopmental factors are likely to play a critical role. A potential neurodevelopmental anomaly marker is the dorsal visual system dysfunction, which is implicated in motion perception, spatial functions, and attention. (2) Methods: To elucidate the role of the dorsal visual system in COS, we investigated 21 patients with COS and 21 control participants matched for age, sex, education, IQ, and parental socioeconomic status. Participants completed a motion and form coherence task, during which one assesses an individual's ability to detect the direction of motion within a field of moving elements or dots and to recognize a meaningful form or object from a set of fragmented or disconnected visual elements, respectively. (3) Results: The patients with COS were impaired in both visual tasks compared to the control participants, but the evidence for the deficit was more substantial for motion perception than for form perception (form: BF10 = 27.22; motion: BF10 = 6.97 × 106). (4) Conclusions: These results highlight the importance of dorsal visual stream vulnerability in COS, a potential marker of neurodevelopmental anomalies.

Subclinical high schizotypy traits are associated with slower change detection

Patients with schizophrenia often show impairments in visual information processing that have been linked to abnormal magnocellular or dorsal stream functioning. However, such deficits are not consistently reported, possibly due to the broad symptomology inherent to schizophrenia, and/or medication effects. To avoid these latter issues this study employed visual perceptual tasks targeting magnocellular (flicker-defined form contrast threshold), dorsal stream (motion coherence, change detection) and ventral stream (form coherence) processing, and compared performance of groups of high and low sub-clinical schizotypy traits from a neurotypical population (n = 20 per group). Significantly worse performance of high compared with low schizotypy participants was only demonstrated on the change detection task that requires rapid attention acquisition and encoding of the first visual array into short term memory prior to a comparison of a second array presentation. No group differences on the other tasks were established. Given this potentially important effect is apparent in a non-clinical population, there are likely to be implications for understanding visual and attentional abnormalities in the schizophrenia spectrum more broadly.

Using perceptual signatures to define and dissociate condition-specific neural etiology: autism and fragile X syndrome as model conditions

The functional link between genetic alteration and behavioral end-state is rarely straightforward and never linear. Cases where neurodevelopmental conditions defined by a distinct genetic etiology share behavioral phenotypes are exemplary, as is the case for autism and Fragile X Syndrome (FXS). In this paper and its companion paper, we propose a method for assessing the functional link between genotype and neural alteration across these target conditions by comparing their perceptual signatures. In the present paper, we discuss how such signatures can be used to (1) define and differentiate various aspects of neural functioning in autism and FXS, and subsequently, (2) to infer candidate causal (genetic) mechanisms based on such signatures (see companion paper, this issue).

The perception of real and illusory motion in schizophrenia

An illusion of rapid movement is normally perceived when an attentional cue (such as a peripheral flash) preceeds the onset of a line. The movement is perceived as receding away from the cue. This study investigated how this illusion was perceived by people with schizophrenia. Nineteen participants with schizophrenia and 26 healthy matched controls were presented with a series of real, illusory, no motion or combined real and illusory motion stimuli at various target speeds. Detection thresholds were measured to determine the reliability of motion perception. The participants with schizophrenia were not distinguished from the control group in the perception of real motion. However, the motion detection curves for the schizophrenia group revealed a reduction in the perceptual effect of illusory motion in comparison to controls. The findings revealed that people with schizophrenia may be less easily deceived by illusory motion in comparison to healthy participants.

Neurocognitive functioning in the early stages of bipolar disorder: visual backward masking performance in high risk subjects

INTRODUCTION

Cognitive deficits, including deficits in early information processing, are associated with remitted bipolar disorder. The temporal relationship between these deficits and the clinical course is not known. The current study investigated whether or not deficits in early information processing were present before the onset and/or during the early stages of bipolar disorder.

METHODS

Unaffected and remitted high risk offspring of well-characterized bipolar parents completed a visual backward masking task. For comparison we included a cohort of unaffected offspring of well parents and a clinically referred group of remitted bipolar patients.

RESULTS

There was no evidence of a deficit in early information processing in well high risk subjects. As expected, the referred patient group had the highest error rates. After excluding the patients, interaction effect showed that the affected remitted high risk subjects performed differently in terms of error rates than unaffected high risk and control subjects. There were no significant differences in response times across study groups. Exploratory analyses revealed an association between a lifetime history of psychosis and increased errors on the task.

CONCLUSIONS

There was no evidence of a vulnerability in early information processing in offspring at risk for bipolar disorder. However, there were emergent changes in performance in the affected remitted high risk group. Psychosis appears to be an important clinical correlate associated with cognitive deficits. Mapping of the early course of bipolar disorder and associated changes in cognition has important implications for establishing critical periods for intervention.

When doors of perception close: bottom-up models of disrupted cognition in schizophrenia

Schizophrenia is a major mental disorder that affects approximately 1% of the population worldwide. Cognitive deficits are a key feature of schizophrenia and a primary cause of long-term disability. Current neurophysiological models of schizophrenia focus on distributed brain dysfunction with bottom-up as well as top-down components. Bottom-up deficits in cognitive processing are driven by impairments in basic perceptual processes that localize to primary sensory brain regions. Within the auditory system, deficits are apparent in elemental sensory processing, such as tone matching following brief delay. Such deficits lead to impairments in higher-order processes such as phonological processing and auditory emotion recognition. Within the visual system, deficits are apparent in functioning of the magnocellular visual pathway, leading to higher-order deficits in processes such as perceptual closure, object recognition, and reading. In both auditory and visual systems, patterns of deficit are consistent with underlying impairment of brain N-methyl-d-aspartate receptor systems.

Prevention inherent in services for women with schizophrenia

OBJECTIVE

Effective care to women with serious mental illness provides an opportunity for prevention of mental health problems in their offspring. The objective of this study is to outline the preventive possibilities of a service targeted to women with schizophrenia.

METHOD

An analysis of recently published literature on women suffering from schizophrenia, focusing on intervention.

RESULTS

Genetic counselling, prenatal care, prevention of obstetrical complications, substance abuse reduction, appropriate antipsychotic treatment, parenting support, safety issues, quality of life, ethics, cultural competence, and advocacy are components of a comprehensive service to women with schizophrenia.

CONCLUSIONS

These components improve maternal health and, by also ensuring fetal and neonatal health, are potentially preventive against schizophrenia in the second generation.

Vernier threshold and the parallel visual pathways in bipolar disorder: a follow-up study

Magnocellular (M) and parvocellular (P) visual pathways participate in the processing of low contrast and colors of objects, respectively. The aim of this study was to investigate M and P pathway functions in bipolar disorder during a depressive episode and after the amelioration of symptoms. Participants (17 patients with type I bipolar disorder and 20 matched healthy controls) received two vernier tasks. During the M pathway test, stimuli were dots with low luminance-contrast (5%), whereas during the P pathway test, isoluminant blue dots were presented against a yellow background. Participants were asked to detect the direction of the horizontal displacement of the dots (left or right). The assessment was performed during a depressive state and during a clinically improved state after 2 months. During the depressive state, the patients showed significantly impaired M and P pathway functions, whereas during the clinically improved state, their performance was better and was statistically indistinguishable from that of the controls. In conclusion, M and P pathways are impaired in depressed bipolar patients. This deficit is ameliorated along with clinical improvement. Further studies are necessary to separately assess cortical and precortical stages of information-processing, and to exclude the possibility of general motivational and attentional impairments.