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Balanoff A, Ferrer E, Saleh L, Gignac PM, Gold MEL, Marugán-Lobón J, Norell M, Ouellette D, Salerno M, Watanabe A, Wei S, Bever G, Vaska P. Quantitative functional imaging of the pigeon brain: implications for the evolution of avian powered flight. Proc Biol Sci 2024; 291:20232172. [PMID: 38290541 PMCID: PMC10827418 DOI: 10.1098/rspb.2023.2172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2023] [Accepted: 01/03/2024] [Indexed: 02/01/2024] Open
Abstract
The evolution of flight is a rare event in vertebrate history, and one that demands functional integration across multiple anatomical/physiological systems. The neuroanatomical basis for such integration and the role that brain evolution assumes in behavioural transformations remain poorly understood. We make progress by (i) generating a positron emission tomography (PET)-based map of brain activity for pigeons during rest and flight, (ii) using these maps in a functional analysis of the brain during flight, and (iii) interpreting these data within a macroevolutionary context shaped by non-avian dinosaurs. Although neural activity is generally conserved from rest to flight, we found significant increases in the cerebellum as a whole and optic flow pathways. Conserved activity suggests processing of self-movement and image stabilization are critical when a bird takes to the air, while increased visual and cerebellar activity reflects the importance of integrating multimodal sensory information for flight-related movements. A derived cerebellar capability likely arose at the base of maniraptoran dinosaurs, where volumetric expansion and possible folding directly preceded paravian flight. These data represent an important step toward establishing how the brain of modern birds supports their unique behavioural repertoire and provide novel insights into the neurobiology of the bird-like dinosaurs that first achieved powered flight.
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Affiliation(s)
- Amy Balanoff
- Center for Functional Anatomy and Evolution, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD 21218, USA
- Division of Paleontology, American Museum of Natural History, New York, NY 10024, USA
| | - Elizabeth Ferrer
- Division of Paleontology, American Museum of Natural History, New York, NY 10024, USA
- Samuel Merritt University, Oakland, CA 94609, USA
| | - Lemise Saleh
- Department of Biomedical Engineering and Radiology, Stony Brook University, Stony Brook, NY 11794, USA
| | - Paul M. Gignac
- Division of Paleontology, American Museum of Natural History, New York, NY 10024, USA
- Department of Cellular and Molecular Medicine, University of Arizona College of Medicine, Tucson, AZ 85724, USA
| | - M. Eugenia L. Gold
- Division of Paleontology, American Museum of Natural History, New York, NY 10024, USA
- Department of Biology, Suffolk University, Boston, MA 02108, USA
| | - Jesús Marugán-Lobón
- Unidad de Paleontología, Departamento Biología, Universidad Autónoma de Madrid, 28049 Cantoblanco (Madrid), Spain
| | - Mark Norell
- Division of Paleontology, American Museum of Natural History, New York, NY 10024, USA
| | | | - Michael Salerno
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Akinobu Watanabe
- Division of Paleontology, American Museum of Natural History, New York, NY 10024, USA
- Department of Anatomy, New York Institute of Technology College of Osteopathic Medicine, Old Westbury, NY 11568, USA
- Life Sciences Department, Vertebrates Division, Natural History Museum, London SW7 5BD, UK
| | - Shouyi Wei
- Department of Physics, New York Proton Center, New York, NY 10035, USA
| | - Gabriel Bever
- Center for Functional Anatomy and Evolution, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Division of Paleontology, American Museum of Natural History, New York, NY 10024, USA
| | - Paul Vaska
- Department of Biomedical Engineering and Radiology, Stony Brook University, Stony Brook, NY 11794, USA
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Watanabe A, Balanoff AM, Gignac PM, Gold MEL, Norell MA. Novel neuroanatomical integration and scaling define avian brain shape evolution and development. eLife 2021; 10:68809. [PMID: 34227464 PMCID: PMC8260227 DOI: 10.7554/elife.68809] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Accepted: 06/15/2021] [Indexed: 12/17/2022] Open
Abstract
How do large and unique brains evolve? Historically, comparative neuroanatomical studies have attributed the evolutionary genesis of highly encephalized brains to deviations along, as well as from, conserved scaling relationships among brain regions. However, the relative contributions of these concerted (integrated) and mosaic (modular) processes as drivers of brain evolution remain unclear, especially in non-mammalian groups. While proportional brain sizes have been the predominant metric used to characterize brain morphology to date, we perform a high-density geometric morphometric analysis on the encephalized brains of crown birds (Neornithes or Aves) compared to their stem taxa—the non-avialan coelurosaurian dinosaurs and Archaeopteryx. When analyzed together with developmental neuroanatomical data of model archosaurs (Gallus, Alligator), crown birds exhibit a distinct allometric relationship that dictates their brain evolution and development. Furthermore, analyses by neuroanatomical regions reveal that the acquisition of this derived shape-to-size scaling relationship occurred in a mosaic pattern, where the avian-grade optic lobe and cerebellum evolved first among non-avialan dinosaurs, followed by major changes to the evolutionary and developmental dynamics of cerebrum shape after the origin of Avialae. Notably, the brain of crown birds is a more integrated structure than non-avialan archosaurs, implying that diversification of brain morphologies within Neornithes proceeded in a more coordinated manner, perhaps due to spatial constraints and abbreviated growth period. Collectively, these patterns demonstrate a plurality in evolutionary processes that generate encephalized brains in archosaurs and across vertebrates.
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Affiliation(s)
- Akinobu Watanabe
- Department of Anatomy, New York Institute of Technology College of Osteopathic Medicine, Old Westbury, United States.,Division of Paleontology, American Museum of Natural History, New York, United States.,Department of Life Sciences Vertebrates Division, Natural History Museum, London, United Kingdom
| | - Amy M Balanoff
- Division of Paleontology, American Museum of Natural History, New York, United States.,Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, United States
| | - Paul M Gignac
- Division of Paleontology, American Museum of Natural History, New York, United States.,Department of Anatomy and Cell Biology, Oklahoma State University Center for Health Sciences, Tulsa, United States
| | - M Eugenia L Gold
- Division of Paleontology, American Museum of Natural History, New York, United States.,Biology Department, Suffolk University, Boston, United States
| | - Mark A Norell
- Division of Paleontology, American Museum of Natural History, New York, United States
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