Archistriatal lesions impair the acquisition of filial preferences during imprinting in the domestic chick.

The avian archistriatum has been demonstrated to play a role in agonistic behaviours and avoidance learning. However, the extent of its role in learning is unknown. The involvement of the archistriatum in the learning process of filial imprinting was therefore investigated in day-old chicks. Bilateral archistriatal lesions, lateral cerebral area lesions or sham archistriatal penetrations were made in dark-reared, day-old chicks, which were subsequently exposed to either a rotating red box or blue cylinder for 2 x 1 h training sessions. Three hours later, the approach of chicks to their training object and to the other, novel object was measured. Chicks with archistriatal lesions ran a similar distance towards each stimulus and therefore failed to display a preference for their training object. However, chicks with sham archistriatal penetrations or lateral cerebral area lesions exhibited a significant preference for the object they had been trained upon. These results demonstrate that the archistriatum is essential for the expression of an imprinted preference. All chicks approached their training object significantly more on their second compared to their first training exposure, suggesting that some aspects of imprinting behaviour remain intact in chicks with archistriatal lesions. Taken together with the results of previous work, the current data suggest that the archistriatum may be involved in retention of significant aspects of the imprinting experience, or in motivation to approach imprinting objects.