C-fos induction in forebrain areas of two different visual pathways during consolidation of sexual imprinting in the zebra finch (Taeniopygia guttata).

Two forebrain areas in the hyperpallium apicale and in the lateral nidopallium of isolated male zebra finches are highly active (2-deoxyglucose technique) on exposure to females for the first time, that is first courtship. These areas also demonstrate enhanced neuronal plasticity when screened with c-fos immunocytochemistry. Both are areas involved in the processing of visual information conveyed by the two major visual pathways in birds, strengthening our hypothesis that courtship in the zebra finch is a visually guided behaviour. First courtship and chased birds show enhanced c-fos induction in the hyperpallial area, which could represent neuronal activity reflecting changes in the immediate environment. The enhanced expression of fos in first courtship birds in lateral nidopallial neurons indicates imminent long-lasting changes at the synaptic level that form the substrate for imprinting, a stable form of learning in birds.