[Experimental approaches to perceptual dysfunction in schizophrenia]

Starting from the studies of Conrad on early schizophrenia, we quantified the gestaltic alteration that he has described using a visual-motor gestaltic test (Bender test) in acute and chronic schizophrenic patients. We observed that rotations and distortions were significantly higher in chronic patients, and perseverations in acute patients. Global scores and time employed showed significant differences in both groups when compared with controls. Time is classically considered a compensation in the failure. We observed that the Bender gestaltic test allows quantification of perceptual alterations due to the loss of the objective structure of the perception in schizophrenic patients. Aiming to reproduce these findings in an animal model, we proposed a study of pharmacological modification of nucleus accumbens septi (Acc) neurotransmission, traditionally linked with physiopathology of schizophrenia. In this way, we developed a discrimination shape model in a skinner box in trained pigeons, bilaterally implanted in Acc by stereotaxic surgery.

The antagonists of N-methyl-D-aspartic acid (NMDA) glutamatergic receptor induced a significant decrease in performance in the discrimination task, and a significant increase in correcting trials. The last parameter was considered a perseveration, manifestation of a behavioral inflexibility in relationship with environmental changes. The glutamatergic blockade of Acc in rats using a passive avoidance task induced a disturbance in acquisition, and the same procedure in the plus maze test led to a significant decrease in anxiety levels, suggesting additional homologies with schizophrenic psychoses.