scholarly journals Variation in the strength of allometry drives rates of evolution in primate brain shape

2020 ◽  
Vol 287 (1930) ◽  
pp. 20200807 ◽  
Author(s):  
G. Sansalone ◽  
K. Allen ◽  
J. A. Ledogar ◽  
S. Ledogar ◽  
D. R. Mitchell ◽  
...  
Keyword(s):  
Brain Size ◽  
Three Dimensional ◽  
Shape Evolution ◽  
Evolutionary Time ◽  
Primate Brain ◽  
Rates Of Evolution ◽  
Evolutionary Allometry ◽  
The Relationship ◽  
The Brain ◽  
Brain Shape

Large brains are a defining feature of primates, as is a clear allometric trend between body mass and brain size. However, important questions on the macroevolution of brain shape in primates remain unanswered. Here we address two: (i), does the relationship between the brain size and its shape follow allometric trends and (ii), is this relationship consistent over evolutionary time? We employ three-dimensional geometric morphometrics and phylogenetic comparative methods to answer these questions, based on a large sample representing 151 species and most primate families. We found two distinct trends regarding the relationship between brain shape and brain size. Hominoidea and Cercopithecinae showed significant evolutionary allometry, whereas no allometric trends were discernible for Strepsirrhini, Colobinae or Platyrrhini. Furthermore, we found that in the taxa characterized by significant allometry, brain shape evolution accelerated, whereas for taxa in which such allometry was absent, the evolution of brain shape decelerated. We conclude that although primates in general are typically described as large-brained, strong allometric effects on brain shape are largely confined to the order's representatives that display more complex behavioural repertoires.

Longitudinal Brain Size Measurements in App/Ps1 Transgenic Mice

2010 ◽  
Vol 4 ◽  
pp. MRI.S5885 ◽  
Author(s):  
Trevor J. Vincent ◽  
Jonathan D. Thiessen ◽  
Laryssa M. Kurjewicz ◽  
Shelley L. Germscheid ◽  
Allan J. Turner ◽  
...  
Keyword(s):  
Brain Size ◽  
Three Dimensional ◽  
Gene Mutations ◽  
Mutant Form ◽  
Swedish Mutation ◽  
Significant Difference ◽  
Lateral Width ◽  
Resolution Imaging ◽  
Or Gene ◽  
The Brain

There appear to be species differences among the effects of gene mutations related to familial Alzheimer's disease on the brain during aging. To gain a better understanding of the effects of the Swedish mutation of amyloid precursor protein and the mutant form of human presenilin 1 on mice, commercially available mice from Jackson Laboratory were studied. Three dimensional T2*-weighted imaging was used to monitor the size of brains of APP/PS1 mice monthly, from 6 to 13 months of age. No significant difference was measured in the size of the medial-lateral width, dorsal-ventral height, rostral-caudal length or the volume of the APPSwe/ PS1 mouse brain. Faster and higher-resolution imaging methods are needed to accurately determine if small volume or shape changes occur in mouse brains with age or gene mutations.

Evolution of vertebrate brain size is associated with sexual traits

2020 ◽  
Vol 70 (4) ◽  
pp. 401-416
Author(s):  
Mao Jun Zhong ◽  
Long Jin ◽  
Jian Ping Yu ◽  
Wen Bo Liao
Keyword(s):  
Sexual Size Dimorphism ◽  
Brain Size ◽  
Finite Energy ◽  
Energy Resources ◽  
Testis Size ◽  
Vertebrate Brain ◽  
Sexual Traits ◽  
The Relationship ◽  
The Brain ◽  
Expensive Tissue Hypothesis

Abstract The expensive tissue hypothesis predicts a trade-off between investments in the brain and other energetically costly organs due to the costs associated with their growth and maintenance within the finite energy resources available. However, few studies address the strength of relationships between brain size and investments in precopulatory (ornaments and armaments) and postcopulatory (testes and ejaculates) sexual traits. Here, in a broad comparative study, we tested the prediction that the relationship between brain size and investment in sexual traits differs among taxa relative to the importance of sperm competition within them. We found that brain size was negatively correlated with sexual size dimorphism (SSD) in anurans and primates, and it tended to decrease with SSD in ungulates and cetaceans. However, brain size did not covary significantly with armaments (e.g., canine length, horn, antler, and muscle mass). Brain size was not correlated with postcopulatory sexual traits (testes and ejaculates). The intensity of covariance between brain size and precopulatory sexual traits decreased with increasing relative testis size.

scholarly journals Efficient inverse graphics in biological face processing

2020 ◽  
Vol 6 (10) ◽  
pp. eaax5979 ◽  
Author(s):  
Ilker Yildirim ◽  
Mario Belledonne ◽  
Winrich Freiwald ◽  
Josh Tenenbaum
Keyword(s):  
Face Processing ◽  
Three Dimensional ◽  
Generative Models ◽  
Neural Data ◽  
Primate Brain ◽  
Scene Structure ◽  
Analysis By Synthesis ◽  
The Brain ◽  
Processing Circuit ◽  
Better Than

Vision not only detects and recognizes objects, but performs rich inferences about the underlying scene structure that causes the patterns of light we see. Inverting generative models, or “analysis-by-synthesis”, presents a possible solution, but its mechanistic implementations have typically been too slow for online perception, and their mapping to neural circuits remains unclear. Here we present a neurally plausible efficient inverse graphics model and test it in the domain of face recognition. The model is based on a deep neural network that learns to invert a three-dimensional face graphics program in a single fast feedforward pass. It explains human behavior qualitatively and quantitatively, including the classic “hollow face” illusion, and it maps directly onto a specialized face-processing circuit in the primate brain. The model fits both behavioral and neural data better than state-of-the-art computer vision models, and suggests an interpretable reverse-engineering account of how the brain transforms images into percepts.

Epilogue

2019 ◽  
pp. 184-188
Author(s):  
Elisabeth A. Murray ◽  
Steven P. Wise ◽  
Mary K. L. Baldwin ◽  
Kim S. Graham
Keyword(s):  
Brain Size ◽  
Brain Organization ◽  
Evolutionary Innovation ◽  
Entire Brain ◽  
Evolutionary Success ◽  
Relationship Of ◽  
The Relationship ◽  
The Brain

In the epilogue, a couple of kids befriend a shy stegosaurus; a different stegosaurus worries about the rise of mammals; and a tyrannosaurus presents a situation report. But mainly we consider reptilian brains, the relationship of brain size to intelligence, and the evolutionary success of mammals. Contrary to an internet meme, no one has a “reptilian” or “lizard” brain lurking within. Our entire brain is human. Regarding intelligence, brain organization matters as much as brain size and maybe more. Once dinosaurs became extinct, the mammals that supplanted them had much smaller brains than large dinosaurs had. Instead, the success of mammals depended on the emergence of the neocortex, a new part of the brain. Eventually, this evolutionary innovation came to dominate both the brain and the memories that it contains.

scholarly journals Understanding primate brain evolution

2007 ◽  
Vol 362 (1480) ◽  
pp. 649-658 ◽  
Author(s):  
R.I.M Dunbar ◽  
Susanne Shultz
Keyword(s):  
Life History ◽  
Path Analysis ◽  
Group Size ◽  
Brain Size ◽  
Brain Evolution ◽  
Primate Brain ◽  
The Social ◽  
Large Brain ◽  
Brain Data ◽  
The Relationship

We present a detailed reanalysis of the comparative brain data for primates, and develop a model using path analysis that seeks to present the coevolution of primate brain (neocortex) and sociality within a broader ecological and life-history framework. We show that body size, basal metabolic rate and life history act as constraints on brain evolution and through this influence the coevolution of neocortex size and group size. However, they do not determine either of these variables, which appear to be locked in a tight coevolutionary system. We show that, within primates, this relationship is specific to the neocortex. Nonetheless, there are important constraints on brain evolution; we use path analysis to show that, in order to evolve a large neocortex, a species must first evolve a large brain to support that neocortex and this in turn requires adjustments in diet (to provide the energy needed) and life history (to allow sufficient time both for brain growth and for ‘software’ programming). We review a wider literature demonstrating a tight coevolutionary relationship between brain size and sociality in a range of mammalian taxa, but emphasize that the social brain hypothesis is not about the relationship between brain/neocortex size and group size per se ; rather, it is about social complexity and we adduce evidence to support this. Finally, we consider the wider issue of how mammalian (and primate) brains evolve in order to localize the social effects.

Vertebrate Evolution and Movement

2018 ◽  
Vol 3 (04) ◽  
Author(s):  
Sherrondria Buchanan
Keyword(s):  
Comparative Studies ◽  
Size Range ◽  
Brain Size ◽  
Brain Evolution ◽  
Processing Capacity ◽  
Primate Brain ◽  
Complex Organization ◽  
Architectural Principles ◽  
The Brain ◽  
Organizing Principles

Comparative studies of the brain in vertebrates suggest that there are general architectural principles leading to its development and overall improvement. We are beginning to understand the geometric, biophysical and energy constraints that have contributed to the progression and practical organization of the brain. The object of this review is to present current perspectives on primate brain evolution, and to examine some hypothetical organizing principles that underlie the brain's complex organization. It is shown that the development of the cortex coordinates folding with connectivity in a way that produces smaller and faster brains. It will be discussed that at a brain size of about 3500 cm3, equivalent to a brain that is two to three times larger than the modern man, the brain seems to reach its maximum processing capacity. As the brain grows larger than this particular size range, it becomes less proficient it will ultimately restrict any improvement and overall function.

The relationships between brain regions and forelimb dexterity in marsupials (Marsupialia): a comparative test of the principle of proper mass

2000 ◽  
Vol 48 (1) ◽  
pp. 99 ◽  
Author(s):  
Andrew N. Iwaniuk ◽  
John E. Nelson ◽  
Ian Q. Whishaw
Keyword(s):  
Brain Cortex ◽  
Brain Size ◽  
Brain Regions ◽  
Brain Morphology ◽  
Proper Mass ◽  
Contrast Analysis ◽  
Independent Contrast ◽  
The Relationship ◽  
The Brain ◽  
Forelimb Movements

A behavioural index of forelimb dexterity and comparative statistics were used to analyse the relationships between proximal (shoulder, upper and lower forelimb) and distal (wrist, forepaw, digits) forelimb dexterity and four aspects of brain morphology (overall brain, cortex, cerebellum and telencephalon sizes) in 18 species of marsupials. On the basis of the principle of proper mass, it was expected that an increase in forelimb dexterity (either proximal or distal) would be positively correlated with the size of the brain and the three brain components. Using independent contrast analysis to remove the effects of phylogeny revealed three significant correlations between: cortex size and distal dexterity, cerebellum size and proximal dexterity, and telencephalon size and distal dexterity. The relationship between cortex size and distal dexterity was subsequently corroborated by Spearman rank correlations. These results suggest that the execution of finely coordinated forelimb movements may not be dependent upon overall brain size, but may be dependent upon the size of brain components, thus supporting the principle of proper mass.

scholarly journals Normative Brain Size Variation and the Remodeling of Brain Shape in Humans

2017 ◽  
Author(s):  
P. K. Reardon ◽  
Simon N. Vandekar ◽  
Siyuan Liu ◽  
Raihaan Patel ◽  
Min Tae M. Park ◽  
...  
Keyword(s):  
Human Brain ◽  
Brain Size ◽  
Size Variation ◽  
Metabolic Cost ◽  
Brain Network ◽  
Primate Brain ◽  
Neuroimaging Data ◽  
Brain Shape ◽  
Brain Patterning

AbstractEvolutionary and developmental increases in primate brain size have been accompanied by systematic shifts in the proportionality of different primate brain systems. However, it remains unknown if and how brain patterning varies across the more than 2-fold inter-individual variation in brain size that occurs amongst typically-developing humans. Using in vivo neuroimaging data from 2 independent cohorts totaling nearly 3000 individuals, we find that larger-brained humans show preferential areal expansion within specific fronto-parietal cortical networks (default mode, dorsal attentional) and related subcortical regions, at the expense of primary sensory/motor systems. This targeted areal expansion recapitulates cortical remodeling across evolution, manifests by early childhood and is linked to molecular signatures of heightened metabolic cost. Our results define a new organizing principle in human brain patterning which governs the highly-coordinated remodeling of human brain shape as a function of naturally-occurring variations in brain size.One Sentence SummaryA hodologically and metabolically expensive brain network is preferentially expanded in larger-brained humans.

scholarly journals The impact of ischemic stroke on connectivity gradients

2018 ◽  
Author(s):  
Şeyma Bayrak ◽  
Ahmed A. Khalil ◽  
Kersten Villringer ◽  
Jochen B. Fiebach ◽  
Arno Villringer ◽  
...  
Keyword(s):  
Functional Connectivity ◽  
Three Dimensional ◽  
Connectivity Matrix ◽  
Continuous Space ◽  
Functional Deficits ◽  
Stroke Research ◽  
Low Dimensional ◽  
The Impact ◽  
The Relationship ◽  
The Brain

AbstractUnderstanding the relationship between localized anatomical damage, reorganization, and functional deficits is a major challenge in stroke research. Previous work has shown that localized lesions cause widespread functional connectivity alterations in structurally intact areas, thereby affecting a whole network of interconnected regions. Recent advances suggest an alternative to discrete functional networks by describing a connectivity space based on a low-dimensional embedding of the full connectivity matrix. The dimensions of this space, described as connectivity gradients, capture the similarity of areas’ connections along a continuous space. Here, we defined a three-dimensional connectivity space template based on functional connectivity data from healthy controls. By projecting lesion locations into this space, we demonstrate that ischemic strokes resulted in dimension-specific alterations in functional connectivity over the first week after symptoms onset. Specifically, changes in functional connectivity were captured along connectivity Gradients 1 and 3. The degree of change in functional connectivity was determined by the distance from the lesion along these connectivity gradients regardless of the anatomical distance from the lesion. Together, these results provide a novel framework to study reorganization after stroke and suggest that, rather than only impacting on anatomically proximate areas, the indirect effects of ischemic strokes spread along the brain relative to the space defined by its connectivity.

scholarly journals Cognitive and behavioral modernity in Homo erectus: skull globularity and hominin brain evolution

2021 ◽  
Vol 84 (4) ◽  
pp. 467-485
Author(s):  
Gary Clark ◽  
Maciej Henneberg
Keyword(s):  
Social Evolution ◽  
Brain Size ◽  
Brain Evolution ◽  
Cranial Base ◽  
Modern Human ◽  
Homo Erectus ◽  
Dietary Factors ◽  
The Brain ◽  
Brain Shape ◽  
Mastoid Region

Abstract In this article we provide evidence that evolutionary pressures altered the cranial base and the mastoid region of the temporal bone more than the calvaria in the transition from H. erectus to H. sapiens. This process seems to have resulted in the evolution of more globular skull shape – but not as a result of expansion of the brain in the parietal regions but of reduction of the cranial base and the mastoid region relative to the parietals. Consequently, we argue that expansion of the parietals seems to be unrelated to brain evolution, but is more a by-product of reduction in other regions of the skull, reduction that may be related to dietary factors. Additionally, these findings suggest that cognitive and behavioural modernity may not necessarily be dependent on brain shape. Also, it cannot be attributed to the change in brain size because H. erectus and modern human cranial capacities overlap substantially. Consequently, we suggest H. erectus possessed the full suite of cognitive adaptations characteristic of modern humans without possessing a globular skull with flared parietals. Our results also support the theory that paedomorphic morphogenesis of the skull was important in the transition from H. erectus to H. sapiens and that such changes may be related to both dietary factors and social evolution.

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