Felix Ströckens & Julia Mehlhorn & Ilias-Dimitrios Karlaftis (Düsseldorf) 1. How Neuron Numbers Change with Age in the Pigeon Brain; 2. Environmental and Behavioral Modulation of Adult Neurogenesis in the Avian Pallium ; 3. Hypothalamic Regulation and Keel Bone Pathology: A Comparative Neuroanatomical Study in Different Hen Breeds