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Attenuation of perceptual asymmetries in patients with early‐onset schizophrenia: Evidence in favour of reduced hemispheric differentiation in schizophrenia?
- Source :
- Laterality: Asymmetries of Body, Brain and Cognition. 9:79-91
- Publication Year :
- 2004
- Publisher :
- Informa UK Limited, 2004.
-
Abstract
- Lateral biases in visual perception have been demonstrated in normal individuals and in patients with unilateral brain lesions. It has been suggested that the absence of structural and functional asymmetries in schizophrenia could be due to a failure in lateralisation that may be most pronounced in those patients whose illness onset is at an early age. Here we examined lateral biases in patients with schizophrenia of an early onset (N = 21) and a late onset.(N = 19), and their respective age-matched control groups, using the greyscales task, a sensitive measure of asymmetries in visual processing. The stimuli consisted of two rectangles, one above the other, shaded in opposite directions and matched overall for darkness. Participants judged which of the two rectangles looked darker overall. Previous studies using this task in healthy participants have reported a reliable bias, such that the rectangle with the darker end on the left is selected preferentially. Whereas the late-onset patients in this study exhibited a perceptual bias of similar direction and magnitude to that of controls, this was not the case for the early-onset patients, who exhibited significantly less bias than their control group. The reduced perceptual bias seen in the early-onset group, but not the late-onset group, suggests an attenuation of right hemisphere mechanisms dedicated to processing vistiospatial information. The attenuated perceptual asymmetry in the early-onset group only may be consistent with the view that (i) an earlier illness onset reflects a greater loss of hemispheric differentiation and (ii) reduced functional asymmetries in the early-onset group are a manifestation of a failure to allocate functions to one or the other hemisphere.
- Subjects :
- Adult
Male
medicine.medical_specialty
Visual perception
Adolescent
media_common.quotation_subject
Late onset
Audiology
Functional Laterality
Developmental psychology
Neglect
Visual processing
Arts and Humanities (miscellaneous)
Perception
medicine
Humans
In patient
Age of Onset
General Psychology
media_common
Cerebral Cortex
Early onset schizophrenia
General Medicine
Middle Aged
medicine.disease
Schizophrenia
Case-Control Studies
Visual Perception
Female
Psychology
Subjects
Details
- ISSN :
- 14640678 and 1357650X
- Volume :
- 9
- Database :
- OpenAIRE
- Journal :
- Laterality: Asymmetries of Body, Brain and Cognition
- Accession number :
- edsair.doi.dedup.....eb1b287de39e6c0697621de9590ae228