title: Reconstruction of ancestral brains: exploring the evolutionary process of encephalization in amniotes.
abstract: There is huge divergence in the size and complexity of vertebrate brains. Notably, mammals and birds have bigger brains than other vertebrates, largely because these animal groups established larger dorsal telencephali. Fossil evidence suggests that this anatomical trait could have evolved independently. However, recent comparative developmental analyses demonstrate surprising commonalities in neuronal subtypes among species, although this interpretation is highly controversial. In this review, we introduce intriguing evidence regarding brain evolution collected from recent studies in paleontology and developmental biology, and we discuss possible evolutionary changes in the cortical developmental programs that led to the encephalization and structural complexity of amniote brains. New research concepts and approaches will shed light on the origin and evolutionary processes of amniote brains, particularly the mammalian cerebral cortex.
authors.affiliation: Developmental Neurobiology, Kyoto Prefectural University of Medicine, Nishitakatsukasa-cho 13, Taishogun, Kita-ku, Kyoto 603-8334, Japan; Japan Science and Technology Agency, PRESTO, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan. Electronic address: tadnom@koto.kpu-m.ac.jp.
authors.forename: Tadashi
authors.initials: T
authors.lastname: Nomura
authors.affiliation: Graduate School of Science and Engineering, Ehime University, Matsuyama, Ehime 790-8577, Japan.
authors.forename: Yasunori
authors.initials: Y
authors.lastname: Murakami
authors.affiliation: Developmental Neurobiology, Kyoto Prefectural University of Medicine, Nishitakatsukasa-cho 13, Taishogun, Kita-ku, Kyoto 603-8334, Japan.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Gotoh
authors.affiliation: Developmental Neurobiology, Kyoto Prefectural University of Medicine, Nishitakatsukasa-cho 13, Taishogun, Kita-ku, Kyoto 603-8334, Japan.
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Ono
mesh_terms: D000818:Animals; D005075:Biological Evolution; D001921:Brain / Q000033:anatomy & histology* / Q000502:physiology*; D006801:Humans; D055495:Neurogenesis; D014714:Vertebrates / Q000033:anatomy & histology*
keywords: Amniotes; Cerebral cortex; Encephalization; Evolution; Homology; Lamination