Trajectory estimation in schizophrenia

Two experiments were conducted to investigate the ability of schizophrenia patients to maintain internal representation over time and space. It has be en hypothesized that the ability to guide behavior by internal representati on, mediated by the dorsolateral prefrontal cortex (DLPFC), is impaired in schizophrenia [e.g. Goldman-Rakic, P.S., 1996. The functional parcellation of dorsolateral prefrontal cortex and the heterogeneous facets of schizophr enia. In: Matthysse, S., Levy, D.L. (Eds.), Psychopathology: Evolution of a New Science. Cambridge University Press, Cambridge]. In Experiment 1, subj ects observed a target, which traveled behind an opaque wall during a part of its trajectory. The task was to accurately assess the speed of the targe t by predicting when the target would re-emerge on the other side of the wa ll. In Experiment 2, subjects were asked to estimate the spatial trajectory of an established target path when it was partially occluded from view by another object. Schizophrenia patients were impaired in estimating the spee d of a moving target and in estimating the spatial trajectory, without show ing deficits in the control tasks. These results suggest that schizophrenia patients may not be able to accurately maintain the internal representatio n of a target over time and space. Such deficits may have deleterious conse quences in goal-directed behavior. (C) 2000 Elsevier Science B.V. All right s reserved.