Endocranial Morphology of the Extinct North American Lion (Panthera atrox)

The extinct North American lion (Panthera atrox) is one of the largest felids (Mammalia, Carnivora) to have ever lived, and it is known from a plethora of incredibly well-preserved remains. Despite this abundance of material, there has been little research into its endocranial anatomy. CT scans of a skull of P. atrox from the Pleistocene La Brea Tar pits were used to generate the first virtual endocranium for this species and to elucidate previously unknown details of its brain size and gross structure, cranial nerves, and inner-ear morphology. Results show that its gross brain anatomy is broadly similar to that of other pantherines, although P. atrox displays less cephalic flexure than either extant lions or tigers, instead showing a brain shape that is reminiscent of earlier felids. Despite this unusual reduction in flexure, the estimated absolute brain size for this specimen is one of the largest reported for any felid, living or extinct. Its encephalization quotient (brain size as a fraction of the expected brain mass for a given body mass) is also larger than that of extant lions but similar to that of the other pantherines. The advent of CT scans has allowed nondestructive sampling of anatomy that cannot otherwise be studied in these extinct lions, leading to a more accurate reconstruction of endocranial morphology and its evolution.

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Small within the largest: brain size and anatomy of the extinct Neoepiblema acreensis , a giant rodent from the Neotropics

Biology Letters ◽

10.1098/rsbl.2019.0914 ◽

2020 ◽

Vol 16 (2) ◽

pp. 20190914 ◽

Cited By ~ 1

Author(s):

José D. Ferreira ◽

Francisco R. Negri ◽

Marcelo R. Sánchez-Villagra ◽

Leonardo Kerber

Keyword(s):

Brain Size ◽

Imaging Techniques ◽

Cranial Nerves ◽

Ecological Factors ◽

Energetic Cost ◽

Brain Anatomy ◽

Non Invasive ◽

Adaptive Value ◽

Caviomorph Rodents ◽

The Brain

The ecomorphological diversity of caviomorph rodents in South America included giant forms, such as the chinchilloid Neoepiblema acreensis from the Upper Miocene of Brazil. The evolution of the brain anatomy and size of these animals can be now studied with non-invasive imaging techniques and exceptional fossils. Caviomorphs show diversity in the traits of the olfactory bulbs, cerebrum, cerebellum, cranial nerves, and blood vessels. Neoepiblema acreensis had a gyrencephalic brain, with an expansion of the frontal lobe, lacking an evident paraflocculus. Compared to the predictions based on extant taxa, even when considering taphonomical effects, N. acreensis , a rodent that weighted almost 80 kg, had a very low encephalization quotient compared to other rodents. The adaptive value of a low energetic cost and other ecological factors could explain the presence of a small brain in this giant rodent––a pattern we also hypothesize for other Neogene giant rodents.

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A Farewell to the Encephalization Quotient: A New Brain Size Measure for Comparative Primate Cognition

Brain Behavior and Evolution ◽

10.1159/000517013 ◽

2021 ◽

pp. 1-12

Author(s):

Carel P. van Schaik ◽

Zegni Triki ◽

Redouan Bshary ◽

Sandra A. Heldstab

Keyword(s):

Body Size ◽

Cognitive Abilities ◽

Brain Size ◽

Estimation Error ◽

Primate Species ◽

Mammal Species ◽

Mean Values ◽

Encephalization Quotient ◽

Body Sizes ◽

Size Measure

Both absolute and relative brain sizes vary greatly among and within the major vertebrate lineages. Scientists have long debated how larger brains in primates and hominins translate into greater cognitive performance, and in particular how to control for the relationship between the noncognitive functions of the brain and body size. One solution to this problem is to establish the slope of cognitive equivalence, i.e., the line connecting organisms with an identical bauplan but different body sizes. The original approach to estimate this slope through intraspecific regressions was abandoned after it became clear that it generated slopes that were too low by an unknown margin due to estimation error. Here, we revisit this method. We control for the error problem by focusing on highly dimorphic primate species with large sample sizes and fitting a line through the mean values for adult females and males. We obtain the best estimate for the slope of circa 0.27, a value much lower than those constructed using all mammal species and close to the value expected based on the genetic correlation between brain size and body size. We also find that the estimate of cognitive brain size based on cognitive equivalence fits empirical cognitive studies better than the encephalization quotient, which should therefore be avoided in future studies on primates and presumably mammals and birds in general. The use of residuals from the line of cognitive equivalence may change conclusions concerning the cognitive abilities of extant and extinct primate species, including hominins.

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Language and Motor Findings in Benign Megalencephaly

Perceptual and Motor Skills ◽

10.2466/pms.1989.68.3c.1051 ◽

1989 ◽

Vol 68 (3_suppl) ◽

pp. 1051-1054 ◽

Cited By ~ 7

Author(s):

Barbara A. Lewis ◽

Dorothy M. Aram ◽

Samuel J. Horwitz

Keyword(s):

Language Comprehension ◽

Head Circumference ◽

Brain Size ◽

Ct Scans ◽

Age Group ◽

Motor Proficiency ◽

Motor Tests ◽

Motor Difficulties

9 children between the ages of 5 and 12 yr. whose head circumferences were greater than the 98th percentile and showed negative CT scans and histories for disease associated with increased brain size were studied. A battery of language, articulation, intelligence, and motor tests were administered to subjects and in each case to a sibling whose head circumference was normal. Analysis showed few differences in intelligence and language comprehension between the megalencephalic children and their siblings. Significant differences were observed in motor proficiency, with over 50% of the megalencephalic children scoring below the 10th percentile for their age group. Three megalencephalic children displayed articulation errors. All subjects had at least one parent whose head circumference exceeded the 98th percentile. These results suggest a relationship between benign megalencephaly and developmental motor difficulties

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Stroke Atlas: A 3D Interactive Tool Correlating Cerebrovascular Pathology with Underlying Neuroanatomy and Resulting Neurological Deficits

The Neuroradiology Journal ◽

10.1177/197140091302600110 ◽

2013 ◽

Vol 26 (1) ◽

pp. 56-65 ◽

Cited By ~ 11

Author(s):

W.L. Nowinski ◽

B.C. Chua

Keyword(s):

Cranial Nerves ◽

Cerebral Aneurysms ◽

Computer Application ◽

Brain Atlas ◽

Neurological Deficits ◽

Brain Anatomy ◽

Normal Brain ◽

3D Display ◽

Cerebrovascular Pathology ◽

Doctor Communication

Understanding stroke-related pathology with underlying neuroanatomy and resulting neurological deficits is critical in education and clinical practice. Moreover, communicating a stroke situation to a patient/family is difficult because of complicated neuroanatomy and pathology. For this purpose, we created a stroke atlas. The atlas correlates localized cerebrovascular pathology with both the resulting disorder and surrounding neuroanatomy. It also provides 3D display both of labeled pathology and freely composed neuroanatomy. Disorders are described in terms of resulting signs, symptoms and syndromes, and they have been compiled for ischemic stroke, hemorrhagic stroke, and cerebral aneurysms. Neuroanatomy, subdivided into 2,000 components including 1,300 vessels, contains cerebrum, cerebellum, brainstem, spinal cord, white matter, deep grey nuclei, arteries, veins, dural sinuses, cranial nerves and tracts. A computer application was developed comprising: 1) anatomy browser with the normal brain atlas (created earlier); 2) simulator of infarcts/hematomas/aneurysms/stenoses; 3) tools to label pathology; 4) cerebrovascular pathology database with lesions and disorders, and resulting signs, symptoms and/or syndromes. The pathology database is populated with 70 lesions compiled from textbooks. The initial view of each pathological site is preset in terms of lesion location, size, surrounding surface and sectional neuroanatomy, and lesion and neuroanatomy labeling. The atlas is useful for medical students, residents, nurses, general practitioners, and stroke clinicians, neuroradiologists and neurologists. It may serve as an aid in patient-doctor communication helping a stroke clinician explain the situation to a patient/family. It also enables a layman to become familiarized with normal brain anatomy and understand what happens in stroke.

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Relative Brain Size, Encephalization Quotient

Encyclopedia of Evolutionary Psychological Science ◽

10.1007/978-3-319-19650-3_3098 ◽

2021 ◽

pp. 6560-6562

Author(s):

Mateo Peñaherrera Aguirre ◽

Heitor BarcellosFerreira Fernandes ◽

Michael A Woodley of Menie

Keyword(s):

Brain Size ◽

Encephalization Quotient ◽

Relative Brain Size

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Symmetry

10.1093/med/9780190607166.003.0005 ◽

2017 ◽

Author(s):

Robert Laureno

Keyword(s):

Infectious Disease ◽

Computed Tomography ◽

Metabolic Disease ◽

Vascular Disease ◽

Brain Lesions ◽

Ct Scans ◽

Brain Anatomy ◽

Neoplastic Disease

This chapter examines the causes of symmetric neurologic lesions in toxic and metabolic disease, trauma, neoplastic disease, vascular disease, and infectious disease. The importance of symmetry in diagnosis is emphasized. Symmetry can be a problem for the neurologist; especially on computed tomography (CT) scans, symmetric disease can be difficult to notice on the background of symmetric brain anatomy because the eye more quickly detects a one-sided lesion or multifocal asymmetric lesions than symmetric lesions. Symmetry of brain lesions is important to the clinician because it suggests a toxic, metabolic, or other chemically based cause. Diseases with symmetric pathology but unknown cause probably are chemically based; the clue of symmetry gives investigators an opportunity to pursue various avenues of research.

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Predation impacts brain allometry and offspring production in female guppies (Poecilia reticulata)

10.32942/osf.io/3cxue ◽

2021 ◽

Author(s):

Regina Vega-Trejo ◽

David Joseph Mitchell ◽

Catarina Vila Pouca ◽

Alexander Kotrschal

Keyword(s):

Poecilia Reticulata ◽

Brain Size ◽

Relative Size ◽

Reproductive Traits ◽

Brain Evolution ◽

Predation Pressure ◽

Control Fish ◽

Brain Anatomy ◽

Offspring Production ◽

The Impact

Survivorship under predation exerts strong selection on reproductive traits as well as on brain anatomy of prey. However, how exactly predation and brain evolution are linked has not been resolved as current empirical evidence is inconclusive. This may be due to predation pressure having different effects across life stages and/or due to confounding factors in ecological comparisons of predation pressure. Here, we used adult guppies (Poecilia reticulata) to experimentally test the impact of a period of strong predation on brain anatomy and reproduction of surviving individuals. We compared the survivors to control fish, which were exposed to visual and olfactory predator cues but could not be predated on, and found that predation impacted the relative size of female brains. This effect was dependent on body size as larger female survivors showed relatively larger brains, while smaller survivors showed relatively smaller brains when compared to control animals. There were no differences in male relative brain size between the treatments, nor for any specific relative brain region sizes for either sex. Moreover, survivors produced more offspring, but did not show shorter interbrood intervals than controls. Our results corroborate the important, yet complex, role of predation as an important factor behind variation in brain anatomy.

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Normative brain size variation and brain shape diversity in humans

Science ◽

10.1126/science.aar2578 ◽

2018 ◽

Vol 360 (6394) ◽

pp. 1222-1227 ◽

Cited By ~ 72

Author(s):

P. K. Reardon ◽

Jakob Seidlitz ◽

Simon Vandekar ◽

Siyuan Liu ◽

Raihaan Patel ◽

...

Keyword(s):

Brain Size ◽

Size Variation ◽

Metabolic Cost ◽

Brain Regions ◽

Brain Organization ◽

Neuroimaging Data ◽

Subcortical Regions ◽

Human Brains ◽

Brain Shape

Brain size variation over primate evolution and human development is associated with shifts in the proportions of different brain regions. Individual brain size can vary almost twofold among typically developing humans, but the consequences of this for brain organization remain poorly understood. Using in vivo neuroimaging data from more than 3000 individuals, we find that larger human brains show greater areal expansion in distributed frontoparietal cortical networks and related subcortical regions than in limbic, sensory, and motor systems. This areal redistribution recapitulates cortical remodeling across evolution, manifests by early childhood in humans, and is linked to multiple markers of heightened metabolic cost and neuronal connectivity. Thus, human brain shape is systematically coupled to naturally occurring variations in brain size through a scaling map that integrates spatiotemporally diverse aspects of neurobiology.

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