part of avian pallium arcopallium BTO:0003408 BrendaTissueOBO The arcopallium refers to regions of the avian brain which partially overlap regions homologous to the amygdala of mammals. These regions have formerly been referred to as archistriatum, and before this epistriatum or amygdaloid complex, and a recent change of nomenclature has divided the region into the arcopallium and posterior pallial amygdala. arched pallium