Retention of a learned brightness discrimination following ablations of the occipital cortex in the rat

Recovery of pattern discrimination ability in rats receiving serial or one-stage visual cortex lesions

Two groups of 10 hooded rats were trained on a pattern discrimination between horizontal and vertical striped stimuli which were equated for contour-length and total luminous flux, and in which consistent local luminous flux cues were eliminated. In one group of rats, visual cortex removals were performed in two stages with training between the operations. Nine out of the 10 rats were able to relearn the pattern discrimination (median of 344 trials) after the completed bilateral visual cortex lesions in one stage. In agreement with previous studies, none of these animals were able to relearn the discrimination after more than 10 times (550 trial limit) the trials required for original learning. However, several rats with total one-stage lesions could relearn the pattern discrimination if very extended periods of training were given.

Self-produced locomotion restores visual capacity after striate lesions

Rats permitted unrestrained movement in a patterned visual environment during the interval between two-stage vilateral lesions of the visual cortex reacquire a preoperatively learned pattern discrimination. Rats passively transported through the identical visual environment do not. This is the first demonstration that interoperative self-produced locomotion is essential for recovery of function in the visual system.

Central nervous system: recovery of function

Rats with one- or two-stage lesions in the hippocampus, anzygdala, or frontal cortex were tested on a variety of tasks. Even though locus and amount of tissue damage were very similar in the two groups, animals with one-stage lesions were impaired as judged by performance on all problems, while aninmals with two-stage lesionis were not.