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Abstract:
Contour integration is thought to be a paradigmatic example
of dynamic, long-range cortical interactions, and has been found to
be impaired in treatment- refractory schizophrenia. The recent
interest in cognitive plasticity in schizophrenia, along with
nonclinical data on the ability to improve contour integration
performance over time, raised the question of whether patients
would demonstrate normal learning curves on a contour integration
task. Fifteen treatment- refractory schizophrenia patients, 20
non-refractory patients, and 12 nonpatient controls completed a
contour integration task on four consecutive days. The task
involved detecting closed contours within a field of Gabor elements
presented against a uniform gray background. Each session involved
two stimulus sets: one in which stimuli were presented in
increasing order of difficulty and another in a random order. Both
sets contained the same stimuli, and the order of set presentation
was counterbalanced across days and subjects. Results indicated
large main effects of day (performance improved over time),
stimulus set (performance was better on the ordered set), and group
(treatment-refractory patients performed worse than the other
groups). No interactions were significant. These data indicate
intact plasticity and therefore learning potential even among
treatment-refractory schizophrenia patients, who required four days
of stimulus exposure before they performed at normal baseline
levels. The results also indicate that stimulus presentation
conditions are partial determinants of contour integration ability
in patients and controls.
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