Effect of lesions in the ectostriatum and Wulst on species and individual discrimination in pigeons.

Pigeons were trained on species (pigeon vs. quail) or individual (pigeon vs. pigeon) discrimination in an operant chamber with a video screen. Still video images were used as discriminative stimuli. After the pigeons had accomplished the discrimination tasks, they received lesions of the Wulst or the ectostriatum. While damage to the Wulst did not disrupt either task, the ectostriatal damage caused deficits selectively in individual discrimination. These dissociations between the tasks and between the lesion sites are comparable to the previous experiments on natural and pseudoconcept. Species discrimination seems to share common brain mechanisms with other natural concept discrimination.