1
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Jiménez S, Santos-Álvarez I, Fernández-Valle E, Castejón D, Villa-Valverde P, Rojo-Salvador C, Pérez-Llorens P, Ruiz-Fernández MJ, Ariza-Pastrana S, Martín-Orti R, González-Soriano J, Moreno N. Comparative MRI analysis of the forebrain of three sauropsida models. Brain Struct Funct 2024; 229:1349-1364. [PMID: 38546870 PMCID: PMC11176103 DOI: 10.1007/s00429-024-02788-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Accepted: 03/12/2024] [Indexed: 06/15/2024]
Abstract
The study of the brain by magnetic resonance imaging (MRI) allows to obtain detailed anatomical images, useful to describe specific encephalic structures and to analyze possible variabilities. It is widely used in clinical practice and is becoming increasingly used in veterinary medicine, even in exotic animals; however, despite its potential, its use in comparative neuroanatomy studies is still incipient. It is a technology that in recent years has significantly improved anatomical resolution, together with the fact that it is non-invasive and allows for systematic comparative analysis. All this makes it particularly interesting and useful in evolutionary neuroscience studies, since it allows for the analysis and comparison of brains of rare or otherwise inaccessible species. In the present study, we have analyzed the prosencephalon of three representative sauropsid species, the turtle Trachemys scripta (order Testudine), the lizard Pogona vitticeps (order Squamata) and the snake Python regius (order Squamata) by MRI. In addition, we used MRI sections to analyze the total brain volume and ventricular system of these species, employing volumetric and chemometric analyses together. The raw MRI data of the sauropsida models analyzed in the present study are available for viewing and downloading and have allowed us to produce an atlas of the forebrain of each of the species analyzed, with the main brain regions. In addition, our volumetric data showed that the three groups presented clear differences in terms of total and ventricular brain volumes, particularly the turtles, which in all cases presented distinctive characteristics compared to the lizards and snakes.
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Affiliation(s)
- S Jiménez
- Achucarro Basque Center for Neuroscience, Scientific Park of the University of the Basque Country (UPV/EHU), Leioa, Bilbao, 48940, Spain
| | - I Santos-Álvarez
- Departament Section of Anatomy and Embriology, Faculty of Veterinary, Complutense University, Avenida Puerta de Hierro s/n, Madrid, 28040, Spain
| | - E Fernández-Valle
- ICTS Bioimagen Complutense, Complutense University, Paseo de Juan XXIII 1, Madrid, 28040, Spain
| | - D Castejón
- ICTS Bioimagen Complutense, Complutense University, Paseo de Juan XXIII 1, Madrid, 28040, Spain
| | - P Villa-Valverde
- ICTS Bioimagen Complutense, Complutense University, Paseo de Juan XXIII 1, Madrid, 28040, Spain
| | - C Rojo-Salvador
- Departament Section of Anatomy and Embriology, Faculty of Veterinary, Complutense University, Avenida Puerta de Hierro s/n, Madrid, 28040, Spain
| | - P Pérez-Llorens
- Departament Section of Anatomy and Embriology, Faculty of Veterinary, Complutense University, Avenida Puerta de Hierro s/n, Madrid, 28040, Spain
| | - M J Ruiz-Fernández
- Departament Section of Anatomy and Embriology, Faculty of Veterinary, Complutense University, Avenida Puerta de Hierro s/n, Madrid, 28040, Spain
| | - S Ariza-Pastrana
- Palmitos Park Canarias, Barranco de los Palmitos, s/n, Maspalomas, Las Palmas, 35109, Spain
| | - R Martín-Orti
- Departament Section of Anatomy and Embriology, Faculty of Veterinary, Complutense University, Avenida Puerta de Hierro s/n, Madrid, 28040, Spain
| | - Juncal González-Soriano
- Departament Section of Anatomy and Embriology, Faculty of Veterinary, Complutense University, Avenida Puerta de Hierro s/n, Madrid, 28040, Spain.
| | - Nerea Moreno
- Department of Cell Biology, Faculty of Biological Sciences, Complutense University, Avenida José Antonio Nováis 12, Madrid, 28040, Spain.
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2
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Nelson XJ, Taylor AH, Cartmill EA, Lyn H, Robinson LM, Janik V, Allen C. Joyful by nature: approaches to investigate the evolution and function of joy in non-human animals. Biol Rev Camb Philos Soc 2023; 98:1548-1563. [PMID: 37127535 DOI: 10.1111/brv.12965] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Revised: 04/12/2023] [Accepted: 04/17/2023] [Indexed: 05/03/2023]
Abstract
The nature and evolution of positive emotion is a major question remaining unanswered in science and philosophy. The study of feelings and emotions in humans and animals is dominated by discussion of affective states that have negative valence. Given the clinical and social significance of negative affect, such as depression, it is unsurprising that these emotions have received more attention from scientists. Compared to negative emotions, such as fear that leads to fleeing or avoidance, positive emotions are less likely to result in specific, identifiable, behaviours being expressed by an animal. This makes it particularly challenging to quantify and study positive affect. However, bursts of intense positive emotion (joy) are more likely to be accompanied by externally visible markers, like vocalisations or movement patterns, which make it more amenable to scientific study and more resilient to concerns about anthropomorphism. We define joy as intense, brief, and event-driven (i.e. a response to something), which permits investigation into how animals react to a variety of situations that would provoke joy in humans. This means that behavioural correlates of joy are measurable, either through newly discovered 'laughter' vocalisations, increases in play behaviour, or reactions to cognitive bias tests that can be used across species. There are a range of potential situations that cause joy in humans that have not been studied in other animals, such as whether animals feel joy on sunny days, when they accomplish a difficult feat, or when they are reunited with a familiar companion after a prolonged absence. Observations of species-specific calls and play behaviour can be combined with biometric markers and reactions to ambiguous stimuli in order to enable comparisons of affect between phylogenetically distant taxonomic groups. Identifying positive affect is also important for animal welfare because knowledge of positive emotional states would allow us to monitor animal well-being better. Additionally, measuring if phylogenetically and ecologically distant animals play more, laugh more, or act more optimistically after certain kinds of experiences will also provide insight into the mechanisms underlying the evolution of joy and other positive emotions, and potentially even into the evolution of consciousness.
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Affiliation(s)
- Ximena J Nelson
- Private Bag 4800, School of Biological Sciences, University of Canterbury, Christchurch, New Zealand
| | - Alex H Taylor
- Institut de Neurociències, Universitat Autònoma de Barcelona, Bellaterra, Barcelona, 08193, Spain
- ICREA, Pg. Lluís Companys, 23, Barcelona, Spain
- School of Psychology, The University of Auckland, Private Bag 92019, Auckland, 1142, New Zealand
| | - Erica A Cartmill
- Departments of Anthropology and Psychology, UCLA, 375 Portola Plaza, Los Angeles, CA, 90095, USA
| | - Heidi Lyn
- Department of Psychology, University of South Alabama, 75 S. University Blvd., Mobile, AL, 36688, USA
| | - Lauren M Robinson
- Domestication Lab, Konrad Lorenz Institute of Ethology, University of Veterinary Medicine, Vienna, Savoyenstraße 1a, Vienna, A-1160, Austria
| | - Vincent Janik
- Scottish Oceans Institute, School of Biology, University of St. Andrews, St Andrews, KY16 8LB, UK
| | - Colin Allen
- Department of History & Philosophy of Science, University of Pittsburgh, 1101 Cathedral of Learning, 4200 Fifth Ave, Pittsburgh, PA, 15260, USA
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3
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Kang H, Liu Q, Seim I, Zhang W, Li H, Gao H, Lin W, Lin M, Zhang P, Zhang Y, Gao H, Wang Y, Qin Y, Liu M, Dong L, Yang Z, Zhang Y, Han L, Fan G, Li S. A genome and single-nucleus cerebral cortex transcriptome atlas of the short-finned pilot whale Globicephala macrorhynchus. Mol Ecol Resour 2023. [PMID: 36826393 DOI: 10.1111/1755-0998.13775] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Revised: 02/09/2023] [Accepted: 02/22/2023] [Indexed: 02/25/2023]
Abstract
Cetaceans (dolphins, whales, and porpoises) have large and anatomically sophisticated brains. To expand our understanding of the cellular makeup of cetacean brains and the similarities and divergence between the brains of cetaceans and terrestrial mammals, we report a short-finned pilot whale (Globicephala macrorhynchus) single-nucleus transcriptome atlas. To achieve this goal, we assembled a chromosome-scale reference genome spanning 2.25 Gb on 22 chromosomes and profiled the gene expression of five major anatomical cortical regions of the short-finned pilot whale by single-nucleus RNA-sequencing (snRNA-seq). We identified six major cell lineages in the cerebral cortex (excitatory neurons, inhibitory neurons, oligodendrocytes, oligodendrocyte precursor cells, astrocytes, and endothelial cells), eight molecularly distinct subclusters of excitatory neurons, and four subclusters of inhibitory neurons. Finally, a comparison of snRNA-seq data from the short-finned pilot whale, human, and rhesus macaque revealed a broadly conserved cellular makeup of brain cell types. Our study provides genomic resources and molecular insights into cetacean brain evolution.
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Affiliation(s)
- Hui Kang
- Marine Mammal and Marine Bioacoustics Laboratory, Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences, Sanya, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Qun Liu
- BGI-Qingdao, BGI-Shenzhen, Qingdao, China.,Lars Bolund Institute of Regenerative Medicine, Qingdao-Europe Advanced Institute for Life Sciences, BGI-Qingdao, Qingdao, China.,Department of Biology, University of Copenhagen, Copenhagen, Denmark.,Qingdao Key Laboratory of Marine Genomics, BGI-Qingdao, Qingdao, China
| | - Inge Seim
- Integrative Biology Laboratory, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Wenwei Zhang
- State Key Laboratory of Agricultural Genomics, BGI-Shenzhen, Shenzhen, China
| | - Hanbo Li
- BGI-Qingdao, BGI-Shenzhen, Qingdao, China.,Lars Bolund Institute of Regenerative Medicine, Qingdao-Europe Advanced Institute for Life Sciences, BGI-Qingdao, Qingdao, China
| | - Haiyu Gao
- Marine Mammal and Marine Bioacoustics Laboratory, Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences, Sanya, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Wenzhi Lin
- Marine Mammal and Marine Bioacoustics Laboratory, Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences, Sanya, China
| | - Mingli Lin
- Marine Mammal and Marine Bioacoustics Laboratory, Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences, Sanya, China
| | - Peijun Zhang
- Marine Mammal and Marine Bioacoustics Laboratory, Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences, Sanya, China
| | | | | | - Yang Wang
- BGI-Qingdao, BGI-Shenzhen, Qingdao, China
| | - Yating Qin
- BGI-Qingdao, BGI-Shenzhen, Qingdao, China
| | - Mingming Liu
- Marine Mammal and Marine Bioacoustics Laboratory, Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences, Sanya, China
| | - Lijun Dong
- Marine Mammal and Marine Bioacoustics Laboratory, Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences, Sanya, China
| | - Zixin Yang
- Marine Mammal and Marine Bioacoustics Laboratory, Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences, Sanya, China
| | | | - Lei Han
- State Key Laboratory of Agricultural Genomics, BGI-Shenzhen, Shenzhen, China
| | - Guangyi Fan
- BGI-Qingdao, BGI-Shenzhen, Qingdao, China.,State Key Laboratory of Agricultural Genomics, BGI-Shenzhen, Shenzhen, China
| | - Songhai Li
- Marine Mammal and Marine Bioacoustics Laboratory, Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences, Sanya, China
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4
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Nieder C, Rosene DL, Mortazavi F, Oblak AL, Ketten DR. Morphology and unbiased stereology of the lateral superior olive in the short‐beaked common dolphin,
Delphinus delphis
(Cetacea, Delphinidae). J Morphol 2022; 283:446-461. [DOI: 10.1002/jmor.21453] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2021] [Revised: 01/10/2022] [Accepted: 01/16/2022] [Indexed: 11/07/2022]
Affiliation(s)
- Carolin Nieder
- Institute of Marine Science, University of Auckland, Leigh Marine Laboratory, 160 Goat Island Road, Leigh New Zealand
| | - Douglas L. Rosene
- Department of Anatomy and Neurobiology Boston University School of Medicine 72 East, Concord St (L 1004), Boston Massachusetts
| | - Farzad Mortazavi
- Department of Anatomy and Neurobiology Boston University School of Medicine 72 East, Concord St (L 1004), Boston Massachusetts
| | - Adrian L. Oblak
- Indiana University School of Medicine, Stark Neurosciences Research Institute, Department of Radiology & Imaging Sciences, 320 W. 15th Street Indianapolis IN
| | - Darlene R. Ketten
- Woods Hole Oceanographic Institution, Biology Department, Marine Research Facility, MS #50 Woods Hole MA USA
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5
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Emerling CA, Springer MS, Gatesy J, Jones Z, Hamilton D, Xia-Zhu D, Collin M, Delsuc F. Genomic evidence for the parallel regression of melatonin synthesis and signaling pathways in placental mammals. OPEN RESEARCH EUROPE 2021; 1:75. [PMID: 35967080 PMCID: PMC7613276 DOI: 10.12688/openreseurope.13795.2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Accepted: 11/25/2021] [Indexed: 11/20/2022]
Abstract
Background: The study of regressive evolution has yielded a wealth of examples where the underlying genes bear molecular signatures of trait degradation, such as pseudogenization or deletion. Typically, it appears that such disrupted genes are limited to the function of the regressed trait, whereas pleiotropic genes tend to be maintained by natural selection to support their myriad purposes. One such set of pleiotropic genes is involved in the synthesis ( AANAT, ASMT) and signaling ( MTNR1A, MTNR1B) of melatonin, a hormone secreted by the vertebrate pineal gland. Melatonin provides a signal of environmental darkness, thereby influencing the circadian and circannual rhythmicity of numerous physiological traits. Therefore, the complete loss of a pineal gland and the underlying melatonin pathway genes seems likely to be maladaptive, unless compensated by extrapineal sources of melatonin. Methods: We examined AANAT, ASMT, MTNR1A and MTNR1B in 123 vertebrate species, including pineal-less placental mammals and crocodylians. We searched for inactivating mutations and modelled selective pressures (dN/dS) to test whether the genes remain functionally intact. Results: We report that crocodylians retain intact melatonin genes and express AANAT and ASMT in their eyes, whereas all four genes have been repeatedly inactivated in the pineal-less xenarthrans, pangolins, sirenians, and whales. Furthermore, colugos have lost these genes, and several lineages of subterranean mammals have partial melatonin pathway dysfunction. These results are supported by the presence of shared inactivating mutations across clades and analyses of selection pressure based on the ratio of non-synonymous to synonymous substitutions (dN/dS), suggesting extended periods of relaxed selection on these genes. Conclusions: The losses of melatonin synthesis and signaling date to tens of millions of years ago in several lineages of placental mammals, raising questions about the evolutionary resilience of pleiotropic genes, and the causes and consequences of losing melatonin pathways in these species.
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Affiliation(s)
- Christopher A. Emerling
- Museum of Vertebrate Zoology, University of California, Berkeley, Berkeley, CA, 94720, USA
- Institut des Sciences de l’Evolution de Montpellier (ISEM), CNRS, IRD, EPHE, Université de Montpellier, Montpellier, France
- Biology Department, Reedley College, Reedley, CA, 93654, USA
| | - Mark S. Springer
- Department of Evolution, Ecology, and Organismal Biology, University of California, Riverside, Riverside, CA, 92521, USA
| | - John Gatesy
- Division of Vertebrate Zoology, American Museum of Natural History, New York, NY, 10024, USA
| | - Zachary Jones
- Museum of Vertebrate Zoology, University of California, Berkeley, Berkeley, CA, 94720, USA
| | - Deana Hamilton
- Museum of Vertebrate Zoology, University of California, Berkeley, Berkeley, CA, 94720, USA
| | - David Xia-Zhu
- Museum of Vertebrate Zoology, University of California, Berkeley, Berkeley, CA, 94720, USA
| | - Matt Collin
- Department of Evolution, Ecology, and Organismal Biology, University of California, Riverside, Riverside, CA, 92521, USA
| | - Frédéric Delsuc
- Institut des Sciences de l’Evolution de Montpellier (ISEM), CNRS, IRD, EPHE, Université de Montpellier, Montpellier, France
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6
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Davis DA, Garamszegi SP, Banack SA, Dooley PD, Coyne TM, McLean DW, Rotstein DS, Mash DC, Cox PA. BMAA, Methylmercury, and Mechanisms of Neurodegeneration in Dolphins: A Natural Model of Toxin Exposure. Toxins (Basel) 2021; 13:toxins13100697. [PMID: 34678990 PMCID: PMC8540894 DOI: 10.3390/toxins13100697] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2021] [Revised: 09/19/2021] [Accepted: 09/22/2021] [Indexed: 01/15/2023] Open
Abstract
Dolphins are well-regarded sentinels for toxin exposure and can bioaccumulate a cyanotoxin called β-N-methylamino-l-alanine (BMAA) that has been linked to human neurodegenerative disease. The same dolphins also possessed hallmarks of Alzheimer’s disease (AD), suggesting a possible association between toxin exposure and neuropathology. However, the mechanisms of neurodegeneration in dolphins and the impact cyanotoxins have on these processes are unknown. Here, we evaluate BMAA exposure by investigating transcription signatures using PCR for dolphin genes homologous to those implicated in AD and related dementias: APP, PSEN1, PSEN2, MAPT, GRN, TARDBP, and C9orf72. Immunohistochemistry and Sevier Münger silver staining were used to validate neuropathology. Methylmercury (MeHg), a synergistic neurotoxicant with BMAA, was also measured using PT-GC-AFS. We report that dolphins have up to a three-fold increase in gene transcription related to Aβ+ plaques, neurofibrillary tangles, neuritic plaques, and TDP-43+ intracytoplasmic inclusions. The upregulation of gene transcription in our dolphin cohort paralleled increasing BMAA concentration. In addition, dolphins with BMAA exposures equivalent to those reported in AD patients displayed up to a 14-fold increase in AD-type neuropathology. MeHg was detected (0.16–0.41 μg/g) and toxicity associated with exposure was also observed in the brain. These results demonstrate that dolphins develop neuropathology associated with AD and exposure to BMAA and MeHg may augment these processes.
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Affiliation(s)
- David A. Davis
- Department of Neurology, Miller School of Medicine, University of Miami, Miami, FL 33136, USA; (S.P.G.); (P.D.D.); (D.W.M.); (D.C.M.)
- Correspondence:
| | - Susanna P. Garamszegi
- Department of Neurology, Miller School of Medicine, University of Miami, Miami, FL 33136, USA; (S.P.G.); (P.D.D.); (D.W.M.); (D.C.M.)
| | - Sandra Anne Banack
- Brain Chemistry Labs, Institute for Ethnomedicine, Jackson, WY 83001, USA; (S.A.B.); (P.A.C.)
| | - Patrick D. Dooley
- Department of Neurology, Miller School of Medicine, University of Miami, Miami, FL 33136, USA; (S.P.G.); (P.D.D.); (D.W.M.); (D.C.M.)
| | - Thomas M. Coyne
- Office of the District 21 Medical Examiner, Fort Myers, FL 33907, USA;
| | - Dylan W. McLean
- Department of Neurology, Miller School of Medicine, University of Miami, Miami, FL 33136, USA; (S.P.G.); (P.D.D.); (D.W.M.); (D.C.M.)
| | | | - Deborah C. Mash
- Department of Neurology, Miller School of Medicine, University of Miami, Miami, FL 33136, USA; (S.P.G.); (P.D.D.); (D.W.M.); (D.C.M.)
- Department of Molecular and Cellular Pharmacology, Miller School of Medicine, University of Miami, Miami, FL 33136, USA
- Dr. Kiran C. Patel College of Allopathic Medicine, Nova Southeastern University, Davie, FL 33328, USA
| | - Paul Alan Cox
- Brain Chemistry Labs, Institute for Ethnomedicine, Jackson, WY 83001, USA; (S.A.B.); (P.A.C.)
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7
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Jacobs B, Rally H, Doyle C, O'Brien L, Tennison M, Marino L. Putative neural consequences of captivity for elephants and cetaceans. Rev Neurosci 2021; 33:439-465. [PMID: 34534428 DOI: 10.1515/revneuro-2021-0100] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Accepted: 09/02/2021] [Indexed: 12/20/2022]
Abstract
The present review assesses the potential neural impact of impoverished, captive environments on large-brained mammals, with a focus on elephants and cetaceans. These species share several characteristics, including being large, wide-ranging, long-lived, cognitively sophisticated, highly social, and large-brained mammals. Although the impact of the captive environment on physical and behavioral health has been well-documented, relatively little attention has been paid to the brain itself. Here, we explore the potential neural consequences of living in captive environments, with a focus on three levels: (1) The effects of environmental impoverishment/enrichment on the brain, emphasizing the negative neural consequences of the captive/impoverished environment; (2) the neural consequences of stress on the brain, with an emphasis on corticolimbic structures; and (3) the neural underpinnings of stereotypies, often observed in captive animals, underscoring dysregulation of the basal ganglia and associated circuitry. To this end, we provide a substantive hypothesis about the negative impact of captivity on the brains of large mammals (e.g., cetaceans and elephants) and how these neural consequences are related to documented evidence for compromised physical and psychological well-being.
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Affiliation(s)
- Bob Jacobs
- Laboratory of Quantitative Neuromorphology, Neuroscience Program, Colorado College, Colorado Springs, CO, 80903, USA
| | - Heather Rally
- Foundation to Support Animal Protection, Norfolk, VA, 23510, USA
| | - Catherine Doyle
- Performing Animal Welfare Society, P.O. Box 849, Galt, CA, 95632, USA
| | - Lester O'Brien
- Palladium Elephant Consulting Inc., 2408 Pinewood Dr. SE, Calgary, AB, T2B1S4, Canada
| | - Mackenzie Tennison
- Department of Psychology, University of Washington, Seattle, WA, 98195, USA
| | - Lori Marino
- Whale Sanctuary Project, Kanab, UT, 84741, USA
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8
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Keagy J, Braithwaite VA, Boughman JW. Brain differences in ecologically differentiated sticklebacks. Curr Zool 2017; 64:243-250. [PMID: 30402065 PMCID: PMC5905471 DOI: 10.1093/cz/zox074] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Accepted: 11/20/2017] [Indexed: 11/12/2022] Open
Abstract
Populations that have recently diverged offer a powerful model for studying evolution. Ecological differences are expected to generate divergent selection on multiple traits, including neurobiological ones. Animals must detect, process, and act on information from their surroundings and the form of this information can be highly dependent on the environment. We might expect different environments to generate divergent selection not only on the sensory organs, but also on the brain regions responsible for processing sensory information. Here, we test this hypothesis using recently evolved reproductively isolated species pairs of threespine stickleback fish Gasterosteus aculeatus that have well-described differences in many morphological and behavioral traits correlating with ecological differences. We use a state-of-the-art method, magnetic resonance imaging, to get accurate volumetric data for 2 sensory processing regions, the olfactory bulbs and optic tecta. We found a tight correlation between ecology and the size of these brain regions relative to total brain size in 2 lakes with intact species pairs. Limnetic fish, which rely heavily on vision, had relatively larger optic tecta and smaller olfactory bulbs compared with benthic fish, which utilize olfaction to a greater extent. Benthic fish also had larger total brain volumes relative to their body size compared with limnetic fish. These differences were erased in a collapsed species pair in Enos Lake where anthropogenic disturbance has led to intense hybridization. Together these data indicate that evolution of sensory processing regions can occur rapidly and independently.
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Affiliation(s)
- Jason Keagy
- Department of Animal Biology, School of Integrative Biology, University of Illinois, Urbana-Champaign, IL 61801, USA.,Department of Integrative Biology, Michigan State University, East Lansing, MI 48824, USA.,BEACON Center for the Study of Evolution in Action, Michigan State University, East Lansing, MI 48824, USA
| | - Victoria A Braithwaite
- Department of Ecosystem Science and Management, Pennsylvania State University, University Park, PA 16802, USA.,Department of Biology, Pennsylvania State University, University Park, PA 16802, USA.,Center for Brain, Behavior and Cognition, Pennsylvania State University, University Park, PA 16802, USA
| | - Janette W Boughman
- Department of Integrative Biology, Michigan State University, East Lansing, MI 48824, USA.,BEACON Center for the Study of Evolution in Action, Michigan State University, East Lansing, MI 48824, USA.,Program in Ecology, Evolutionary Biology and Behavior, Michigan State University, East Lansing, MI 48824, USA
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9
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Flores DA, del Castillo D, Yamada T. Postnatal cranial growth of Risso’s dolphin (Grampus griseus). MAMMALIA 2017. [DOI: 10.1515/mammalia-2016-0052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
AbstractThe short-nosed Risso’s dolphin (
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10
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Knopf JP, Hof PR, Oelschläger HHA. The Neocortex of Indian River Dolphins (Genus Platanista): Comparative, Qualitative and Quantitative Analysis. BRAIN, BEHAVIOR AND EVOLUTION 2016; 88:93-110. [PMID: 27732977 DOI: 10.1159/000448274] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Accepted: 07/06/2016] [Indexed: 11/19/2022]
Abstract
We investigated the morphology of four primary neocortical projection areas (somatomotor, somatosensory, auditory, visual) qualitatively and quantitatively in the Indian river dolphins (Platanista gangetica gangetica, P. gangetica minor) with histological and stereological methods. For comparison, we included brains of other toothed whale species. Design-based stereology was applied to the primary neocortical areas (M1, S1, A1, V1) of the Indian river dolphins and compared to those of the bottlenose dolphin with respect to layers III and V. These neocortical fields were identified using existing electrophysiological and morphological data from marine dolphins as to their topography and histological structure, including the characteristics of the neuron populations concerned. In contrast to other toothed whales, the visual area (V1) of the 'blind' river dolphins seems to be rather small. M1 is displaced laterally and the auditory area (A1) is larger than in marine species with respect to total brain size. The layering is similar in the cortices of all the toothed whale brains investigated; a layer IV could not be identified. Cell density in layer III is always higher than in layer V. The maximal neuron density in P. gangetica gangetica is found in layer III of A1, followed by layers III in V1, S1, and M1. The cell density in layer V is at a similar level in all primary areas. There are, however, some differences in neuron density between the two subspecies of Indian river dolphins. Taken as a whole, it appears that the neocortex of platanistids exhibits a considerable expansion of the auditory field. Even more than other toothed whales, they seem to depend on their biosonar abilities for navigation, hunting, and communication in their riverine habitat.
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Affiliation(s)
- Julian P Knopf
- Institute of Anatomy III (Dr. Senckenbergische Anatomie), Johann Wolfgang Goethe University, Frankfurt am Main, Germany
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11
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Yopak K, Galinsky VL, Berquist R, Frank LR. Quantitative Classification of Cerebellar Foliation in Cartilaginous Fishes (Class: Chondrichthyes) Using Three-Dimensional Shape Analysis and Its Implications for Evolutionary Biology. BRAIN, BEHAVIOR AND EVOLUTION 2016; 87:252-64. [PMID: 27450795 PMCID: PMC5023489 DOI: 10.1159/000446904] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Accepted: 05/13/2016] [Indexed: 11/19/2022]
Abstract
A true cerebellum appeared at the onset of the chondrichthyan (sharks, batoids, and chimaerids) radiation and is known to be essential for executing fast, accurate, and efficient movement. In addition to a high degree of variation in size, the corpus cerebellum in this group has a high degree of variation in convolution (or foliation) and symmetry, which ranges from a smooth cerebellar surface to deep, branched convexities and folds, although the functional significance of this trait is unclear. As variation in the degree of foliation similarly exists throughout vertebrate evolution, it becomes critical to understand this evolutionary process in a wide variety of species. However, current methods are either qualitative and lack numerical rigor or they are restricted to two dimensions. In this paper, a recently developed method for the characterization of shapes embedded within noisy, three-dimensional data called spherical wave decomposition (SWD) is applied to the problem of characterizing cerebellar foliation in cartilaginous fishes. The SWD method provides a quantitative characterization of shapes in terms of well-defined mathematical functions. An additional feature of the SWD method is the construction of a statistical criterion for the optimal fit, which represents the most parsimonious choice of parameters that fits to the data without overfitting to background noise. We propose that this optimal fit can replace a previously described qualitative visual foliation index (VFI) in cartilaginous fishes with a quantitative analog, i.e. the cerebellar foliation index (CFI). The capability of the SWD method is demonstrated in a series of volumetric images of brains from different chondrichthyan species that span the range of foliation gradings currently described for this group. The CFI is consistent with the qualitative grading provided by the VFI, delivers a robust measure of cerebellar foliation, and can provide a quantitative basis for brain shape characterization across taxa.
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Affiliation(s)
- Kara Yopak
- UWA Oceans Institute and the School of Animal Biology, University of Western Australia, Crawley, WA 6009
| | - Vitaly L. Galinsky
- Center for Scientific Computation in Imaging, University of California, San Diego
| | - Rachel Berquist
- Center for Scientific Computation in Imaging, University of California, San Diego
| | - Lawrence R. Frank
- Center for Scientific Computation in Imaging, University of California, San Diego
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12
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Chikina M, Robinson JD, Clark NL. Hundreds of Genes Experienced Convergent Shifts in Selective Pressure in Marine Mammals. Mol Biol Evol 2016; 33:2182-92. [PMID: 27329977 DOI: 10.1093/molbev/msw112] [Citation(s) in RCA: 97] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Mammal species have made the transition to the marine environment several times, and their lineages represent one of the classical examples of convergent evolution in morphological and physiological traits. Nevertheless, the genetic mechanisms of their phenotypic transition are poorly understood, and investigations into convergence at the molecular level have been inconclusive. While past studies have searched for convergent changes at specific amino acid sites, we propose an alternative strategy to identify those genes that experienced convergent changes in their selective pressures, visible as changes in evolutionary rate specifically in the marine lineages. We present evidence of widespread convergence at the gene level by identifying parallel shifts in evolutionary rate during three independent episodes of mammalian adaptation to the marine environment. Hundreds of genes accelerated their evolutionary rates in all three marine mammal lineages during their transition to aquatic life. These marine-accelerated genes are highly enriched for pathways that control recognized functional adaptations in marine mammals, including muscle physiology, lipid-metabolism, sensory systems, and skin and connective tissue. The accelerations resulted from both adaptive evolution as seen in skin and lung genes, and loss of function as in gustatory and olfactory genes. In regard to sensory systems, this finding provides further evidence that reduced senses of taste and smell are ubiquitous in marine mammals. Our analysis demonstrates the feasibility of identifying genes underlying convergent organism-level characteristics on a genome-wide scale and without prior knowledge of adaptations, and provides a powerful approach for investigating the physiological functions of mammalian genes.
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Affiliation(s)
- Maria Chikina
- Department of Computational and Systems Biology, University of Pittsburgh
| | - Joseph D Robinson
- Department of Molecular and Cell Biology, University of California Berkeley
| | - Nathan L Clark
- Department of Computational and Systems Biology, University of Pittsburgh
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13
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Neuroanatomy of the killer whale (Orcinus orca): a magnetic resonance imaging investigation of structure with insights on function and evolution. Brain Struct Funct 2016; 222:417-436. [PMID: 27119362 DOI: 10.1007/s00429-016-1225-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2015] [Accepted: 04/07/2016] [Indexed: 12/18/2022]
Abstract
The evolutionary process of adaptation to an obligatory aquatic existence dramatically modified cetacean brain structure and function. The brain of the killer whale (Orcinus orca) may be the largest of all taxa supporting a panoply of cognitive, sensory, and sensorimotor abilities. Despite this, examination of the O. orca brain has been limited in scope resulting in significant deficits in knowledge concerning its structure and function. The present study aims to describe the neural organization and potential function of the O. orca brain while linking these traits to potential evolutionary drivers. Magnetic resonance imaging was used for volumetric analysis and three-dimensional reconstruction of an in situ postmortem O. orca brain. Measurements were determined for cortical gray and cerebral white matter, subcortical nuclei, cerebellar gray and white matter, corpus callosum, hippocampi, superior and inferior colliculi, and neuroendocrine structures. With cerebral volume comprising 81.51 % of the total brain volume, this O. orca brain is one of the most corticalized mammalian brains studied to date. O. orca and other delphinoid cetaceans exhibit isometric scaling of cerebral white matter with increasing brain size, a trait that violates an otherwise evolutionarily conserved cerebral scaling law. Using comparative neurobiology, it is argued that the divergent cerebral morphology of delphinoid cetaceans compared to other mammalian taxa may have evolved in response to the sensorimotor demands of the aquatic environment. Furthermore, selective pressures associated with the evolution of echolocation and unihemispheric sleep are implicated in substructure morphology and function. This neuroanatomical dataset, heretofore absent from the literature, provides important quantitative data to test hypotheses regarding brain structure, function, and evolution within Cetacea and across Mammalia.
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14
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Berns GS, Cook PF, Foxley S, Jbabdi S, Miller KL, Marino L. Diffusion tensor imaging of dolphin brains reveals direct auditory pathway to temporal lobe. Proc Biol Sci 2016; 282:rspb.2015.1203. [PMID: 26156774 PMCID: PMC4528565 DOI: 10.1098/rspb.2015.1203] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
The brains of odontocetes (toothed whales) look grossly different from their terrestrial relatives. Because of their adaptation to the aquatic environment and their reliance on echolocation, the odontocetes' auditory system is both unique and crucial to their survival. Yet, scant data exist about the functional organization of the cetacean auditory system. A predominant hypothesis is that the primary auditory cortex lies in the suprasylvian gyrus along the vertex of the hemispheres, with this position induced by expansion of 'associative' regions in lateral and caudal directions. However, the precise location of the auditory cortex and its connections are still unknown. Here, we used a novel diffusion tensor imaging (DTI) sequence in archival post-mortem brains of a common dolphin (Delphinus delphis) and a pantropical dolphin (Stenella attenuata) to map their sensory and motor systems. Using thalamic parcellation based on traditionally defined regions for the primary visual (V1) and auditory cortex (A1), we found distinct regions of the thalamus connected to V1 and A1. But in addition to suprasylvian-A1, we report here, for the first time, the auditory cortex also exists in the temporal lobe, in a region near cetacean-A2 and possibly analogous to the primary auditory cortex in related terrestrial mammals (Artiodactyla). Using probabilistic tract tracing, we found a direct pathway from the inferior colliculus to the medial geniculate nucleus to the temporal lobe near the sylvian fissure. Our results demonstrate the feasibility of post-mortem DTI in archival specimens to answer basic questions in comparative neurobiology in a way that has not previously been possible and shows a link between the cetacean auditory system and those of terrestrial mammals. Given that fresh cetacean specimens are relatively rare, the ability to measure connectivity in archival specimens opens up a plethora of possibilities for investigating neuroanatomy in cetaceans and other species.
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Affiliation(s)
| | - Peter F Cook
- Psychology Department, Emory University, Atlanta, GA, USA
| | - Sean Foxley
- FMRIB Centre, University of Oxford, Oxford, UK
| | - Saad Jbabdi
- FMRIB Centre, University of Oxford, Oxford, UK
| | | | - Lori Marino
- The Kimmela Center for Animal Advocacy, Kanab, UT, USA
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15
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Parolisi R, Peruffo A, Messina S, Panin M, Montelli S, Giurisato M, Cozzi B, Bonfanti L. Forebrain neuroanatomy of the neonatal and juvenile dolphin (T. truncatus and S. coeruloalba). Front Neuroanat 2015; 9:140. [PMID: 26594155 PMCID: PMC4635206 DOI: 10.3389/fnana.2015.00140] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Accepted: 10/16/2015] [Indexed: 12/16/2022] Open
Abstract
Knowledge of dolphin functional neuroanatomy mostly derives from post-mortem studies and non-invasive approaches (i.e., magnetic resonance imaging), due to limitations in experimentation on cetaceans. As a consequence the availability of well-preserved tissues for histology is scarce, and detailed histological analyses are referred mainly to adults. Here we studied the neonatal/juvenile brain in two species of dolphins, the bottlenose dolphin (Tursiops truncatus) and the striped dolphin (Stenella coeruleoalba), with special reference to forebrain regions. We analyzed cell density in subcortical nuclei, white/gray matter ratio, and myelination in selected regions at different anterior–posterior levels of the whole dolphin brain at different ages, to better define forebrain neuroanatomy and the developmental stage of the dolphin brain around birth. The analyses were extended to the periventricular germinal layer and the cerebellum, whose delayed genesis of the granule cell layer is a hallmark of postnatal development in the mammalian nervous system. Our results establish an atlas of the young dolphin forebrain and, on the basis of occurrence/absence of delayed neurogenic layers, confirm the stage of advanced brain maturation in these animals with respect to most terrestrial mammals.
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Affiliation(s)
- Roberta Parolisi
- Neuroscience Institute Cavalieri Ottolenghi, University of Turin Orbassano, Italy ; Department of Veterinary Sciences, University of Turin Torino, Italy
| | - Antonella Peruffo
- Department of Comparative Biomedicine and Food Science, University of Padova Legnaro, Italy
| | - Silvia Messina
- Neuroscience Institute Cavalieri Ottolenghi, University of Turin Orbassano, Italy
| | - Mattia Panin
- Department of Comparative Biomedicine and Food Science, University of Padova Legnaro, Italy
| | - Stefano Montelli
- Department of Comparative Biomedicine and Food Science, University of Padova Legnaro, Italy
| | - Maristella Giurisato
- Department of Comparative Biomedicine and Food Science, University of Padova Legnaro, Italy
| | - Bruno Cozzi
- Department of Comparative Biomedicine and Food Science, University of Padova Legnaro, Italy
| | - Luca Bonfanti
- Neuroscience Institute Cavalieri Ottolenghi, University of Turin Orbassano, Italy ; Department of Veterinary Sciences, University of Turin Torino, Italy
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16
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Butti C, Janeway CM, Townshend C, Wicinski BA, Reidenberg JS, Ridgway SH, Sherwood CC, Hof PR, Jacobs B. The neocortex of cetartiodactyls: I. A comparative Golgi analysis of neuronal morphology in the bottlenose dolphin (Tursiops truncatus), the minke whale (Balaenoptera acutorostrata), and the humpback whale (Megaptera novaeangliae). Brain Struct Funct 2014; 220:3339-68. [PMID: 25100560 DOI: 10.1007/s00429-014-0860-3] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Accepted: 07/25/2014] [Indexed: 12/12/2022]
Abstract
The present study documents the morphology of neurons in several regions of the neocortex from the bottlenose dolphin (Tursiops truncatus), the North Atlantic minke whale (Balaenoptera acutorostrata), and the humpback whale (Megaptera novaeangliae). Golgi-stained neurons (n = 210) were analyzed in the frontal and temporal neocortex as well as in the primary visual and primary motor areas. Qualitatively, all three species exhibited a diversity of neuronal morphologies, with spiny neurons including typical pyramidal types, similar to those observed in primates and rodents, as well as other spiny neuron types that had more variable morphology and/or orientation. Five neuron types, with a vertical apical dendrite, approximated the general pyramidal neuron morphology (i.e., typical pyramidal, extraverted, magnopyramidal, multiapical, and bitufted neurons), with a predominance of typical and extraverted pyramidal neurons. In what may represent a cetacean morphological apomorphy, both typical pyramidal and magnopyramidal neurons frequently exhibited a tri-tufted variant. In the humpback whale, there were also large, star-like neurons with no discernable apical dendrite. Aspiny bipolar and multipolar interneurons were morphologically consistent with those reported previously in other mammals. Quantitative analyses showed that neuronal size and dendritic extent increased in association with body size and brain mass (bottlenose dolphin < minke whale < humpback whale). The present data thus suggest that certain spiny neuron morphologies may be apomorphies in the neocortex of cetaceans as compared to other mammals and that neuronal dendritic extent covaries with brain and body size.
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Affiliation(s)
- Camilla Butti
- Fishberg Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, Box 1639, One Gustave L. Levy Place, New York, NY, 10029, USA.
| | - Caroline M Janeway
- Laboratory of Quantitative Neuromorphology, Psychology, Colorado College, 14 E. Cache La Poudre, Colorado Springs, CO, 80903, USA
| | - Courtney Townshend
- Laboratory of Quantitative Neuromorphology, Psychology, Colorado College, 14 E. Cache La Poudre, Colorado Springs, CO, 80903, USA
| | - Bridget A Wicinski
- Fishberg Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, Box 1639, One Gustave L. Levy Place, New York, NY, 10029, USA
| | - Joy S Reidenberg
- Center for Anatomy and Functional Morphology, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY, 10029, USA
| | - Sam H Ridgway
- National Marine Mammal Foundation, 2240 Shelter Island Drive, San Diego, CA, 92106, USA
| | - Chet C Sherwood
- Department of Anthropology, The George Washington University, 2110 G Street NW, Washington, DC, 20052, USA
| | - Patrick R Hof
- Fishberg Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, Box 1639, One Gustave L. Levy Place, New York, NY, 10029, USA
| | - Bob Jacobs
- Laboratory of Quantitative Neuromorphology, Psychology, Colorado College, 14 E. Cache La Poudre, Colorado Springs, CO, 80903, USA
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17
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Alonso-Farré JM, Gonzalo-Orden M, Barreiro-Vázquez JD, Barreiro-Lois A, André M, Morell M, Llarena-Reino M, Monreal-Pawlowsky T, Degollada E. Cross-sectional anatomy, computed tomography and magnetic resonance imaging of the head of common dolphin (Delphinus delphis) and striped dolphin (Stenella coeruleoalba). Anat Histol Embryol 2014; 44:13-21. [PMID: 24527804 DOI: 10.1111/ahe.12103] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2013] [Accepted: 01/08/2014] [Indexed: 11/30/2022]
Abstract
Computed tomography (CT) and low-field magnetic resonance imaging (MRI) were used to scan seven by-caught dolphin cadavers, belonging to two species: four common dolphins (Delphinus delphis) and three striped dolphins (Stenella coeruleoalba). CT and MRI were obtained with the animals in ventral recumbency. After the imaging procedures, six dolphins were frozen at -20°C and sliced in the same position they were examined. Not only CT and MRI scans, but also cross sections of the heads were obtained in three body planes: transverse (slices of 1 cm thickness) in three dolphins, sagittal (5 cm thickness) in two dolphins and dorsal (5 cm thickness) in two dolphins. Relevant anatomical structures were identified and labelled on each cross section, obtaining a comprehensive bi-dimensional topographical anatomy guide of the main features of the common and the striped dolphin head. Furthermore, the anatomical cross sections were compared with their corresponding CT and MRI images, allowing an imaging identification of most of the anatomical features. CT scans produced an excellent definition of the bony and air-filled structures, while MRI allowed us to successfully identify most of the soft tissue structures in the dolphin's head. This paper provides a detailed anatomical description of the head structures of common and striped dolphins and compares anatomical cross sections with CT and MRI scans, becoming a reference guide for the interpretation of imaging studies.
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Affiliation(s)
- J M Alonso-Farré
- Centre for Environmental and Marine Studies (CESAM), University of Aveiro, Campus Universitário de Santiago, 3810-193, Aveiro, Portugal; Parc Zoològic de Barcelona, Parc de la Ciutadella s/n, 08003, Barcelona, Spain
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18
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Hanson A, Grisham W, Sheh C, Annese J, Ridgway S. Quantitative examination of the bottlenose dolphin cerebellum. Anat Rec (Hoboken) 2013; 296:1215-28. [PMID: 23775830 DOI: 10.1002/ar.22726] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 03/05/2013] [Accepted: 04/10/2013] [Indexed: 11/09/2022]
Abstract
Neuroanatomical research into the brain of the bottlenose dolphin (Tursiops truncatus) has revealed striking similarities with the human brain in terms of size and complexity. However, the dolphin brain also contains unique allometric relationships. When compared to the human brain, the dolphin cerebellum is noticeably larger. Upon closer examination, the lobule composition of the cerebellum is distinct between the two species. In this study, we used magnetic resonance imaging to analyze cerebellar anatomy in the bottlenose dolphin and measure the volume of the separate cerebellar lobules in the bottlenose dolphin and human. Lobule identification was assisted by three-dimensional modeling. We find that lobules VI, VIIb, VIII, and IX are the largest lobules of the bottlenose dolphin cerebellum, while the anterior lobe (I-V), crus I, crus II, and the flocculonodular lobe are smaller. Different lobule sizes may have functional implications. Auditory-associated lobules VIIb, VIII, IX are likely large in the bottlenose dolphin due to echolocation abilities. Our study provides quantitative information on cerebellar anatomy that substantiates previous reports based on gross observation and subjective analysis. This study is part of a continuing effort toward providing explicit descriptions of cetacean neuroanatomy to support the interpretation of behavioral studies on cetacean cognition.
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Affiliation(s)
- Alicia Hanson
- National Marine Mammal Foundation, San Diego, California, USA
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19
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Racicot RA, Colbert MW. Morphology and Variation in Porpoise (Cetacea: Phocoenidae) Cranial Endocasts. Anat Rec (Hoboken) 2013; 296:979-92. [DOI: 10.1002/ar.22704] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2012] [Accepted: 03/20/2013] [Indexed: 11/09/2022]
Affiliation(s)
- Rachel A. Racicot
- Department of Geology and Geophysics; Yale University; New Haven Connecticut
| | - Matthew W. Colbert
- Jackson School of Geosciences; The University of Texas at Austin; Austin Texas
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20
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Yopak KE, Lisney TJ. Allometric scaling of the optic tectum in cartilaginous fishes. BRAIN, BEHAVIOR AND EVOLUTION 2012; 80:108-26. [PMID: 22986827 DOI: 10.1159/000339875] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
In cartilaginous fishes (Chondrichthyes; sharks, skates and rays (batoids), and holocephalans), the midbrain or mesencephalon can be divided into two parts, the dorsal tectum mesencephali or optic tectum (analogous to the superior colliculus of mammals) and the ventral tegmentum mesencephali. Very little is known about interspecific variation in the relative size and organization of the components of the mesencephalon in these fishes. This study examined the relative development of the optic tectum and the tegmentum in 75 chondrichthyan species representing 32 families. This study also provided a critical assessment of attempts to quantify the size of the optic tectum in these fishes volumetrically using an idealized half-ellipsoid approach (method E), by comparing this method to measurements of the tectum from coronal cross sections (method S). Using species as independent data points and phylogenetically independent contrasts, relationships between the two midbrain structures and both brain and mesencephalon volume were assessed and the relative volume of each brain area (expressed as phylogenetically corrected residuals) was compared among species with different ecological niches (as defined by primary habitat and lifestyle). The relatively largest tecta and tegmenta were found in pelagic coastal/oceanic and oceanic sharks, benthopelagic reef sharks, and benthopelagic coastal sharks. The smallest tecta were found in all benthic sharks and batoids and the majority of bathyal (deep-sea) species. These results were consistent regardless of which method of estimating tectum volume was used. We found a highly significant correlation between optic tectum volume estimates calculated using method E and method S. Taxon-specific variation in the difference between tectum volumes calculated using the two methods appears to reflect variation in both the shape of the optic tectum relative to an idealized half-ellipsoid and the volume of the ventricular cavity. Because the optic tectum is the principal termination site for retinofugal fibers arising from the retinal ganglion cells, the relative size of this brain region has been associated with an increased reliance on vision in other vertebrate groups, including bony fishes. The neuroecological relationships between the relative size of the optic tectum and primary habitat and lifestyle we present here for cartilaginous fishes mirror those established for bony fishes; we speculate that the relative size of the optic tectum and tegmentum similarly reflects the importance of vision and sensory processing in cartilaginous fishes.
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Affiliation(s)
- Kara E Yopak
- School of Animal Biology, University of Western Australia, Crawley, Australia.
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Abstract
Adult neurogenesis is often considered an archaic trait that has undergone a 'phylogenetic reduction' from amphibian ancestors to humans. However, adult neurogenesis in the hippocampal dentate gyrus might actually be a late-evolved trait. In non-mammals, adult hippocampal neurogenesis is not restricted to the equivalents of the dentate gyrus, which also show different connectivity and functionality compared to their mammalian counterpart. Moving actively in a changing world and dealing with novelty and complexity regulate adult neurogenesis. New neurons might thus provide the cognitive adaptability to conquer ecological niches rich with challenging stimuli.
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22
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Panin M, Gabai G, Ballarin C, Peruffo A, Cozzi B. Evidence of melatonin secretion in cetaceans: plasma concentration and extrapineal HIOMT-like presence in the bottlenose dolphin Tursiops truncatus. Gen Comp Endocrinol 2012; 177:238-45. [PMID: 22554922 DOI: 10.1016/j.ygcen.2012.04.012] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/14/2011] [Revised: 04/11/2012] [Accepted: 04/15/2012] [Indexed: 11/26/2022]
Abstract
The pineal gland is generally believed to be absent in cetaceans, although few and subsequently unconfirmed reports described the organ in some species. The recent description of a complete and photographed pineal body in a bottlenose dolphin (Tursiops truncatus) prompted us to examine a series of 29 brains of the same species, but no gland was found. We then decided to investigate if the main product of the gland, melatonin, was nevertheless produced and present in the plasma of this species. We collected plasma and serum samples from a series of captive bottlenose dolphins for a period of 7 months spanning from winter to summer and we determined the indoleamine concentration by radio-immunoassay (RIA). The results demonstrated for the first time a quantitative assessment of melatonin production in the blood of a cetacean. Melatonin levels were comparable to those of terrestrial mammals (5.15-27.74 pg/ml daylight concentration), with indications of both seasonal and daily variation although the presence of a circadian rhythm remains uncertain. Immunohistochemical analyses using as a marker hydroxyindole-O-methyl-transferase (HIOMT, the key enzyme involved in the biosynthesis of the hormone), suggested extrapineal melatonin production by the retina, the Harderian gland and the gut. The enzyme was unequivocally localized in all the three tissues, and, specifically, ganglion cells in the retina showed a very strong HIOMT-immunoreactivity. Our results suggest that further research might reveal unexplored aspects of melatonin production in cetaceans and deserves special attention and further efforts.
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Affiliation(s)
- Mattìa Panin
- Department of Comparative Biomedicine and Food Science, University of Padova, Legnaro, PD, Italy
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23
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Manger PR, Prowse M, Haagensen M, Hemingway J. Quantitative analysis of neocortical gyrencephaly in African elephants (Loxodonta africana) and six species of cetaceans: Comparison with other mammals. J Comp Neurol 2012; 520:2430-9. [DOI: 10.1002/cne.23046] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Yopak KE. Neuroecology of cartilaginous fishes: the functional implications of brain scaling. JOURNAL OF FISH BIOLOGY 2012; 80:1968-2023. [PMID: 22497414 DOI: 10.1111/j.1095-8649.2012.03254.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
It is a widely accepted view that neural development can reflect morphological adaptations and sensory specializations. The aim of this review is to give a broad overview of the current status of brain data available for cartilaginous fishes and examine how perspectives on allometric scaling of brain size across this group of fishes has changed within the last 50 years with the addition of new data and more rigorous statistical analyses. The current knowledge of neuroanatomy in cartilaginous fishes is reviewed and data on brain size (encephalization, n = 151) and interspecific variation in brain organization (n = 84) has been explored to ascertain scaling relationships across this clade. It is determined whether similar patterns of brain organization, termed cerebrotypes, exist in species that share certain lifestyle characteristics. Clear patterns of brain organization exist across cartilaginous fishes, irrespective of phylogenetic grouping and, although this study was not a functional analysis, it provides further evidence that chondrichthyan brain structures might have developed in conjunction with specific behaviours or enhanced cognitive capabilities. Larger brains, with well-developed telencephala and large, highly foliated cerebella are reported in species that occupy complex reef or oceanic habitats, potentially identifying a reef-associated cerebrotype. In contrast, benthic and benthopelagic demersal species comprise the group with the smallest brains, with a relatively reduced telencephalon and a smooth cerebellar corpus. There is also evidence herein of a bathyal cerebrotype; deep-sea benthopelagic sharks possess relatively small brains and show a clear relative hypertrophy of the medulla oblongata. Despite the patterns observed and documented, significant gaps in the literature have been highlighted. Brain mass data are only currently available on c. 16% of all chondrichthyan species, and only 8% of species have data available on their brain organization, with far less on subsections of major brain areas that receive distinct sensory input. The interspecific variability in brain organization further stresses the importance of performing functional studies on a greater range of species. Only an expansive data set, comprised of species that span a variety of habitats and taxonomic groups, with widely disparate behavioural repertoires, combined with further functional analyses, will help shed light on the extent to which chondrichthyan brains have evolved as a consequence of behaviour, habitat and lifestyle in addition to phylogeny.
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Affiliation(s)
- K E Yopak
- School of Animal Biology and the UWA Oceans Institute, University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia.
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25
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Magnetic resonance microscopy of prenatal dolphins (Mammalia, Odontoceti, Delphinidae) – Ontogenetic and phylogenetic implications. ZOOL ANZ 2012. [DOI: 10.1016/j.jcz.2011.06.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Abstract
Primates are, on average, more intelligent than other mammals, with great apes and finally humans on top. They generally have larger brains and cortices, and because of higher relative cortex volume and neuron packing density (NPD), they have much more cortical neurons than other mammalian taxa with the same brain size. Likewise, information processing capacity is generally higher in primates due to short interneuronal distance and high axonal conduction velocity. Across primate taxa, differences in intelligence correlate best with differences in number of cortical neurons and synapses plus information processing speed. The human brain stands out by having a large cortical volume with relatively high NPD, high conduction velocity, and high cortical parcellation. All aspects of human intelligence are present at least in rudimentary form in nonhuman primates or some mammals or vertebrates except syntactical language. The latter can be regarded as a very potent "intelligence amplifier."
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Malkemper EP, Oelschläger HHA, Huggenberger S. The dolphin cochlear nucleus: topography, histology and functional implications. J Morphol 2011; 273:173-85. [PMID: 21987441 DOI: 10.1002/jmor.11013] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2011] [Revised: 07/08/2011] [Accepted: 08/03/2011] [Indexed: 11/12/2022]
Abstract
Despite the outstanding auditory capabilities of dolphins, there is only limited information available on the cytology of the auditory brain stem nuclei in these animals. Here, we investigated the cochlear nuclei (CN) of five brains of common dolphins (Delphinus delphis) and La Plata dolphins (Pontoporia blainvillei) using cell and fiber stain microslide series representing the three main anatomical planes. In general, the CN in dolphins comprise the same set of subnuclei as in other mammals. However, the volume ratio of the dorsal cochlear nucleus (DCN) in relation to the ventral cochlear nucleus (VCN) of dolphins represents a minimum among the mammals examined so far. Because, for example, in cats the DCN is necessary for reflexive orientation of the head and pinnae towards a sound source, the massive restrictions in head movability in dolphins and the absence of outer ears may be correlated with the reduction of the DCN. Moreover, the same set of main neuron types were found in the dolphin CN as in other mammals, including octopus and multipolar cells. Because the latter two types of neurons are thought to be involved in the recognition of complex sounds, including speech, we suggest that, in dolphins, they may be involved in the processing of their communication signals. Comparison of the toothed whale species studied here revealed that large spherical cells were present in the La Plata dolphin but absent in the common dolphin. These neurons are known to be engaged in the processing of low-frequency sounds in terrestrial mammals. Accordingly, in the common dolphin, the absence of large spherical cells seems to be correlated with a shift of its auditory spectrum into the high-frequency range above 20 kHz. The existence of large spherical cells in the VCN of the La Plata dolphin, however, is enigmatic asthis species uses frequencies around 130 kHz.
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Affiliation(s)
- E P Malkemper
- Department of Anatomy III (Dr. Senckenbergische Anatomie), Johann Wolfgang Goethe University Frankfurt am Main, 60590 Frankfurt am Main, Germany
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Ullmann JFP, Cowin G, Collin SP. Magnetic resonance microscopy of the barramundi (Lates calcarifer) brain. J Morphol 2011; 271:1446-56. [PMID: 20967831 DOI: 10.1002/jmor.10887] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Magnetic resonance imaging (MRI) is an established technique for morphological imaging of the central nervous system. Despite its prevalent use in a range of taxa, few studies exist on the brains of teleosts. In this study, we present a detailed analysis of a teleost brain using high-resolution MRI. Images were acquired from a Bruker 16.4 T vertical magnet with a three-dimensional flash T(2)*-weighted image sequence. High contrast was obtained using Magnevist® and the following imaging parameters: a flip angle of 30°, a repetition time of 50 ms, an echo time of 14 ms, and an image matrix of 1024 × 400 × 400. The resulting isotropic resolution of 30 μm allowed us to thoroughly describe the architecture of the barramundi (Lates calcarifer) brain, including descriptions of nuclei, fiber tracts, and cellular layers. A good correspondence, both in contrast and morphology, was found between magnetic resonance images and Nissl-stained brain sections, allowing for an analysis of the benefits and drawbacks of MRI and conventional histology.
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Affiliation(s)
- Jeremy F P Ullmann
- Sensory Neurobiology Group, School of Biomedical Sciences, The University of Queensland, Brisbane 4072, Queensland, Australia.
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Ridgway SH. Neural time and movement time in choice of whistle or pulse burst responses to different auditory stimuli by dolphins. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2011; 129:1073-1080. [PMID: 21361463 DOI: 10.1121/1.3523431] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Echolocating dolphins emit trains of clicks and receive echoes from ocean targets. They often emit each successive ranging click about 20 ms after arrival of the target echo. In echolocation, decisions must be made about the target--fish or fowl, predator or food. In the first test of dolphin auditory decision speed, three bottlenose dolphins (Tursiops truncatus) chose whistle or pulse burst responses to different auditory stimuli randomly presented without warning in rapid succession under computer control. The animals were trained to hold pressure catheters in the nasal cavity so that pressure increases required for sound production could be used to split response time (RT) into neural time and movement time. Mean RT in the youngest and fastest dolphin ranged from 175 to 213 ms when responding to tones and from 213 to 275 ms responding to pulse trains. The fastest neural times and movement times were around 60 ms. The results suggest that echolocating dolphins tune to a rhythm so that succeeding pulses in a train are produced about 20 ms over target round-trip travel time. The dolphin nervous system has evolved for rapid processing of acoustic stimuli to accommodate for the more rapid sound speed in water compared to air.
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Affiliation(s)
- Sam H Ridgway
- National Marine Mammal Foundation, 2240 Shelter Island Drive, Suite 200, San Diego, California 92106, USA.
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Houser DS, Moore PW, Johnson S, Lutmerding B, Branstetter B, Ridgway SH, Trickey J, Finneran JJ, Jensen E, Hoh C. Relationship of blood flow and metabolism to acoustic processing centers of the dolphin brain. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2010; 128:1460-1466. [PMID: 20815480 DOI: 10.1121/1.3442572] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Odontocete brain tissues associated with auditory processing are hypertrophied and modified relative to their terrestrial counterparts. The relationship between the functional demand on these tissues and metabolic substrate requirements is unknown. Using positron emission tomography (PET), relative cerebral blood flow was measured in a bottlenose dolphin. Approximately 60 mCi (13)NH(3) was administered to the dolphin via a catheter inserted into the hepatic vein and threaded proximate to the vena cava. Radiolabel initially appeared as distributed focal points in the cerebellum. Increasing scan time resulted in an increase in the number of focal regions and in the diffusivity of label activity throughout the brain. The time course and spatial distribution of radiolabel was consistent with a cerebral blood supply dominated by the spinal meningeal arteries. Blood flow was predominantly observed in the cerebellum and neocortex, particularly the auditory and visual cortex. Differential brain glucose uptake, previously measured in a separate dolphin, showed good agreement with the differential supply of blood to brain tissues. Rates of blood supply and glucose uptake in the auditory cortex, inferior colliculus, and cerebellum are consistent with a high metabolic demand of tissues which are important to the integration of auditory and other sensory inputs.
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Affiliation(s)
- Dorian S Houser
- National Marine Mammal Foundation, 2240 Shelter Island Drive, San Diego, California 92106, USA.
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Schmidt MJ, Pilatus U, Wigger A, Kramer M, Oelschläger HA. Neuroanatomy of the calf brain as revealed by high-resolution magnetic resonance imaging. J Morphol 2009; 270:745-58. [PMID: 19123244 DOI: 10.1002/jmor.10717] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Here, we want to assess the benefit of high-resolution and high-contrast magnetic resonance imaging (MRI) for detailed documentation of internal brain morphology in formalin-fixed whole head specimens of the full-term calf brain (Bos taurus). Imaging was performed on a Siemens 1.5 T scanner. Optimum contrast was achieved using a 3D sequence with a flip angle of 30 degrees , repetition time (TR) of 20 ms, echo time (TE) of 6.8 ms, and an interpolated matrix of 1024 x 1024. In plane resolution was 0.25 mm. Computer-generated three-dimensional images were reconstructed from the original scans in the coronal plane. This study shows that MRI is capable to identify delicate structures in immature brain specimens. The use of MRI in comparative morphology facilitates the examination of series of brains or brain samples in a reasonable time. The comprehensive description of species- and group-specific brain features in MRI scans of Bos taurus will complement existing data for diagnostic imaging and neuromorphological research, in general, as well as for phylogenetic reconstructions.
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Affiliation(s)
- Martin J Schmidt
- Small Animal Clinic, Justus Liebig-University, Giessen, Germany.
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Huggenberger S, Rauschmann MA, Vogl TJ, Oelschläger HH. Functional Morphology of the Nasal Complex in the Harbor Porpoise (Phocoena phocoenaL.). Anat Rec (Hoboken) 2009; 292:902-20. [DOI: 10.1002/ar.20854] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Oelschläger HHA. The dolphin brain--a challenge for synthetic neurobiology. Brain Res Bull 2007; 75:450-9. [PMID: 18331914 DOI: 10.1016/j.brainresbull.2007.10.051] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2007] [Accepted: 10/17/2007] [Indexed: 11/17/2022]
Abstract
Toothed whales (odontocetes) are a promising paradigm for neurobiology and evolutionary biology. The ecophysiological implications and structural adaptations of their brain seem to reflect the necessity of effective underwater hearing for echolocation (sonar), navigation, and communication. However, not all components of the auditory system are equally well developed. Other sensory systems are more or less strongly reduced such as the olfactory system and, as an exception among vertebrates, the vestibular system (the semicircular canals and vestibular nuclei). Additional outstanding features are: (1) the hypertrophy of the neocortex, pons, cerebellum (particularly the paraflocculus), the elliptic nucleus, the facial motor nucleus and the medial accessory inferior olive and (2) the reduction of the hippocampus. The screening of brain structures with respect to shared circuitry and shared size correlations resulted in central loops also known from other mammals which overlap in the cerebellum and serve in the integration and processing of sensory input. It is highly probable that for dolphin navigation the ascending auditory pathway, including the inferior colliculus and the medial geniculate body, is of utmost importance. The extended auditory neocortical fields project to the midbrain and rhombencephalon and may influence premotor and motor areas in such a way as to allow the smooth regulation of sound-induced and sound-controlled locomotor activity as well as sophisticated phonation. This sonar-guided acousticomotor system for navigation and vocalization in the aquatic environment may have been a major factor if not the key feature in the relative size increase seen in dolphin brains.
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Affiliation(s)
- Helmut H A Oelschläger
- Institute of Anatomy III (Dr. Senckenbergische Anatomie), University of Frankfurt am Main, Germany.
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