Effect of posterior cortical lesion on two versions of the brightness-discrimination task

The brightness-discrimination performancę of normal and posterior decorticate rats was measured in two test situations designed to provide different spatial task characteristics. A Y-maze and an open field with otherwise matched stimulus properties provided tests with many or few spatial characteristics, respectively. In contrast to predictions from visuospatial integrative interpretations of lesion consequences, the present results indicated no attenuation of the typical operative impairment when the reduced spatial-cue tasks were employed. Furthermore, this outcome was common to both simple acquisition/retention (Experiment 1) and successive discrimination reversal (Experiment 2) versions of the tasks. Interpretations of the relative contribution of memory or visuospatial integrative deficits to the measured behavioral consequences are discussed.