Visual discrimination by rats with transplacentally induced micrencephaly.

Long-Evans rats with micrencephaly induced by prenatal exposure to methylazoxymethanol acetate and normal controls were trained in a two-choice box to discriminate between stimuli of different brightness (black vs. white) or pattern (horizontal vs. vertical alternating black-and-white stripes). Mild footshock was used to motivate the rats to learn. The micrencephalic rats were impaired in learning the pattern, but not brightness discrimination. These results confirm and extend similar findings with micrencephalic Wistar rats by another laboratory. The visual discrimination performance of micrencephalic rats was similar to that reported for normal rats with lesions in the visual cortical areas.