Perseveration in schizophrenic patients: a neuropsychological approach for research.

Perseveration is a core symptom of schizophrenia, the cause, however, is unknown. It has been shown that for people with frontal lobe lesions, perseveration can be explained with a set-maintenance problem. Perseveration in Parkinson's disease can be explained with problems shifting from one set to another without cues (set-shifting). These disorders can be distinguished using a two-choice task and the Wisconsin Card Sorting Test, that is analysed in phases. Analogs of these tests can be used in animal research. By adding an animal part to the human research, more insight can be gained into the role of specific brain areas in set-maintenance and set-shifting.