scholarly journals Intraspecific brain size variation between coexisting sunfish ecotypes

2018 ◽  
Vol 285 (1890) ◽  
pp. 20181971 ◽  
Author(s):  
Caleb J. Axelrod ◽  
Frédéric Laberge ◽  
Beren W. Robinson
Keyword(s):  
Brain Size ◽  
Divergence Time ◽  
Size Variation ◽  
Open Water ◽  
Brain Regions ◽  
Cognitive Demands ◽  
Physiological Processes ◽  
Littoral Habitat ◽  
Pelagic Habitat ◽  
The Relationship

Variation in spatial complexity and foraging requirements between habitats can impose different cognitive demands on animals that may influence brain size. However, the relationship between ecologically related cognitive performance and brain size is not well established. We test whether variation in relative brain size and brain region size is associated with habitat use within a population of pumpkinseed sunfish composed of different ecotypes that inhabit either the structurally complex shoreline littoral habitat or simpler open-water pelagic habitat. Sunfish using the littoral habitat have on average 8.3% larger brains than those using the pelagic habitat. We found little difference in the proportional sizes of five brain regions between ecotypes. The results suggest that cognitive demands on sunfish may be reduced in the pelagic habitat given no habitat-specific differences in body condition. They also suggest that either a short divergence time or physiological processes may constrain changes to concerted, global modifications of brain size between sunfish ecotypes.

scholarly journals Brain size predicts problem-solving ability in mammalian carnivores

2016 ◽  
Vol 113 (9) ◽  
pp. 2532-2537 ◽  
Author(s):  
Sarah Benson-Amram ◽  
Ben Dantzer ◽  
Gregory Stricker ◽  
Eli M. Swanson ◽  
Kay E. Holekamp
Keyword(s):  
Body Mass ◽  
Cognitive Abilities ◽  
Brain Size ◽  
Technical Problem ◽  
Behavioral Flexibility ◽  
Empirical Support ◽  
Brain Regions ◽  
Self Control ◽  
Invasion Success ◽  
The Relationship

Despite considerable interest in the forces shaping the relationship between brain size and cognitive abilities, it remains controversial whether larger-brained animals are, indeed, better problem-solvers. Recently, several comparative studies have revealed correlations between brain size and traits thought to require advanced cognitive abilities, such as innovation, behavioral flexibility, invasion success, and self-control. However, the general assumption that animals with larger brains have superior cognitive abilities has been heavily criticized, primarily because of the lack of experimental support for it. Here, we designed an experiment to inquire whether specific neuroanatomical or socioecological measures predict success at solving a novel technical problem among species in the mammalian order Carnivora. We presented puzzle boxes, baited with food and scaled to accommodate body size, to members of 39 carnivore species from nine families housed in multiple North American zoos. We found that species with larger brains relative to their body mass were more successful at opening the boxes. In a subset of species, we also used virtual brain endocasts to measure volumes of four gross brain regions and show that some of these regions improve model prediction of success at opening the boxes when included with total brain size and body mass. Socioecological variables, including measures of social complexity and manual dexterity, failed to predict success at opening the boxes. Our results, thus, fail to support the social brain hypothesis but provide important empirical support for the relationship between relative brain size and the ability to solve this novel technical problem.

scholarly journals Normative brain size variation and brain shape diversity in humans

Science ◽  
2018 ◽  
Vol 360 (6394) ◽  
pp. 1222-1227 ◽  
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.

scholarly journals Relative Brain Size and Its Relation with the Associative Pallium in Birds

2016 ◽  
Vol 87 (2) ◽  
pp. 69-77 ◽  
Author(s):  
Ferran Sayol ◽  
Louis Lefebvre ◽  
Daniel Sol
Keyword(s):  
Brain Size ◽  
Large Fraction ◽  
Biological Significance ◽  
Size Variation ◽  
Brain Structures ◽  
Brain Regions ◽  
Whole Brain ◽  
Small Areas ◽  
Mosaic Evolution ◽  
The Brain

Despite growing interest in the evolution of enlarged brains, the biological significance of brain size variation remains controversial. Much of the controversy is over the extent to which brain structures have evolved independently of each other (mosaic evolution) or in a coordinated way (concerted evolution). If larger brains have evolved by the increase of different brain regions in different species, it follows that comparisons of the whole brain might be biologically meaningless. Such an argument has been used to criticize comparative attempts to explain the existing variation in whole-brain size among species. Here, we show that pallium areas associated with domain-general cognition represent a large fraction of the entire brain, are disproportionally larger in large-brained birds and accurately predict variation in the whole brain when allometric effects are appropriately accounted for. While this does not question the importance of mosaic evolution, it suggests that examining specialized, small areas of the brain is not very helpful for understanding why some birds have evolved such large brains. Instead, the size of the whole brain reflects consistent variation in associative pallium areas and hence is functionally meaningful for comparative analyses.

Cerebellum size is positively correlated with geographic distribution range in anurans

2018 ◽  
Vol 68 (3) ◽  
pp. 309-320 ◽  
Author(s):  
Chun Lin Zhao ◽  
Long Jin ◽  
Mao Jun Zhong ◽  
Feng Xie ◽  
Jian Ping Jiang ◽  
...  
Keyword(s):  
Brain Size ◽  
Behavioral Flexibility ◽  
Brain Regions ◽  
Geographic Range ◽  
Phylogenetic Comparative Methods ◽  
Animal Kingdom ◽  
Geographic Ranges ◽  
Unpredictable Environments ◽  
Energetic Constraints ◽  
The Relationship

AbstractThe ‘cognitive buffer’ hypothesis predicts that the costs of relatively large brains are compensated for later in life by the increased benefits of large brains providing a higher chance of survival under changing environments through flexible behaviors in the animal kingdom. Thus, animals that live in a larger range (with a higher probability of environmental variation) are expected to have larger brains than those that live in a restricted geographic range. Here, to test the prediction of the ‘cognitive buffer’ hypothesis that larger brains should be expected to occur in species living in geographic ranges of larger size, we analyzed the relationship between the size of the geographic range and brain size and the size of various brain regions among 42 species of anurans using phylogenetic comparative methods. The results show that there is no correlation between relative brain size and size of the species’ geographic range when correcting for phylogenetic effects and body size. Our findings suggest that the effects of the cognitive buffer and the energetic constraints on brains result in non-significant variation in overall brain size. However, the geographic range is positively correlated with cerebellum size, but not with optic tecta, suggesting that species distributed in a wider geographic range do not exhibit larger optic tecta which would provide behavioral flexibility to allow for an early escape from potential predators and discovery of new food resources in unpredictable environments.

scholarly journals Comparison of three sampling methods for small-bodied fish in lentic nearshore and open water habitats

2021 ◽  
Vol 193 (5) ◽  
Author(s):  
Joseph E. Merz ◽  
Jesse T. Anderson ◽  
Jesse Wiesenfeld ◽  
Steven C. Zeug
Keyword(s):  
Open Water ◽  
Preliminary Evaluation ◽  
Fish Assemblage Structure ◽  
Beach Seine ◽  
Habitat Types ◽  
Taxa Richness ◽  
Littoral Habitat ◽  
Gear Selectivity ◽  
Pelagic Habitat ◽  
Neutrally Buoyant

AbstractWe performed a preliminary evaluation of a mobile sampling platform with adjustable push net and live box (Platform) against two common methods for sampling small-bodied fish (i.e., 10–100 mm) in two distinct lentic habitats. Nearshore (NS) littoral habitat was sampled by Platform and beach seine, and open water (OW) pelagic habitat by Platform and Kodiak trawl. Our goal was to evaluate the Platform’s ability to describe fish assemblage structure across habitat types in contrast to common techniques restricted to single habitat types that are less comparable due to gear-specific bias. Platform sample speed had a significant positive effect on recapture efficiency of both nearly neutrally buoyant objects and marked fish. Marked fish recapture efficiencies were similar for Platform in NS and OW, indicating similar efficiency across habitat types. Platform capture efficiency was similar to beach seine and greater than Kodiak trawl. With similar sampling time, the Platform collected more individuals and taxa in NS relative to beach seine and in OW relative to Kodiak trawl. Greater taxa detection by the Platform suggests that it may be effective at detecting species that are numerically rare in specific habitats when compared to these methods. Fish CPUE was significantly greater NS regardless of technique. However, by using the Platform, there is greater confidence that this difference was reliable and not a gear selectivity artifact. Overall, this preliminary study demonstrates the Platform’s potential to collect standardized data across NS and OW habitats, track ontogenetic habitat shifts, and detect differences in small-bodied fish taxa richness, relative abundance, and density between NS and OW habitats. Continued experimentation beyond a single reservoir and fish size range is required before consensus can be established regarding the utility of this new push net design.

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 Why big brains? A comparison of models for both primate and carnivore brain size evolution

PLoS ONE ◽  
2021 ◽  
Vol 16 (12) ◽  
pp. e0261185
Author(s):  
Helen Rebecca Chambers ◽  
Sandra Andrea Heldstab ◽  
Sean J. O’Hara
Keyword(s):  
Life History ◽  
Brain Size ◽  
Size Variation ◽  
Ecological Factors ◽  
Brain Evolution ◽  
Brain Regions ◽  
Home Range Size ◽  
Careful Consideration ◽  
Social Brain ◽  
Multiple Variables

Despite decades of research, much uncertainty remains regarding the selection pressures responsible for brain size variation. Whilst the influential social brain hypothesis once garnered extensive support, more recent studies have failed to find support for a link between brain size and sociality. Instead, it appears there is now substantial evidence suggesting ecology better predicts brain size in both primates and carnivores. Here, different models of brain evolution were tested, and the relative importance of social, ecological, and life-history traits were assessed on both overall encephalisation and specific brain regions. In primates, evidence is found for consistent associations between brain size and ecological factors, particularly diet; however, evidence was also found advocating sociality as a selection pressure driving brain size. In carnivores, evidence suggests ecological variables, most notably home range size, are influencing brain size; whereas, no support is found for the social brain hypothesis, perhaps reflecting the fact sociality appears to be limited to a select few taxa. Life-history associations reveal complex selection mechanisms to be counterbalancing the costs associated with expensive brain tissue through extended developmental periods, reduced fertility, and extended maximum lifespan. Future studies should give careful consideration of the methods chosen for measuring brain size, investigate both whole brain and specific brain regions where possible, and look to integrate multiple variables, thus fully capturing all of the potential factors influencing brain size.

The Ecological Brain

2021 ◽  
pp. 35-50
Author(s):  
Susan D. Healy
Keyword(s):  
Life History ◽  
Selection Pressure ◽  
Brain Size ◽  
Brain Regions ◽  
Range Size ◽  
Overwhelming Evidence ◽  
Sensory Motor ◽  
The Relationship ◽  
Life History Variables

In this chapter, I examine the evidence for a role for the preeminent selection pressure, ecology, in shaping animal brains and in causing changes in brain size within and among species. I describe what ‘ecology’ has meant in comparative analyses, e.g. foraging, range size, and life history variables. I provide evidence for a clear association between ecology and the size of sensory-motor brain regions and go on to use the relationship between space and the hippocampus to show the generality of this relationship beyond food storing. I discuss the strength of the data showing that migration, foraging, and domestication have caused changes in brain size. I conclude that while there is evidence of domestication, in particular, having changed whole brain size, it is at the level of brain regions that there is overwhelming evidence for an effect of ecology on brain size.

Brain size in Hylarana guentheri seems unaffected by variation in temperature and growth season

2017 ◽  
Vol 67 (3-4) ◽  
pp. 209-225 ◽  
Author(s):  
Jun Gu ◽  
Da Yong Li ◽  
Yi Luo ◽  
Song Bei Ying ◽  
Lan Ya Zhang ◽  
...  
Keyword(s):  
Brain Size ◽  
Behavioral Flexibility ◽  
Size Variation ◽  
Brain Regions ◽  
Growth Season ◽  
Food Scarcity ◽  
Size Evolution ◽  
Cognitive Benefits ◽  
Males And Females ◽  
Temperature And Growth

Brain size varies dramatically between vertebrate species. Two prominent adaptive hypotheses – the Cognitive Buffer Hypothesis (CBH) and the Expensive Brain Hypothesis (EBH) – have been proposed to explain brain size evolution. The CBH assumes that brain size should increase with seasonality, as the cognitive benefits of a larger brain should help overcoming periods of food scarcity via, for example, increased behavioral flexibility. Alternatively, the EBH states that brain size should decrease with seasonality because a smaller brain confers energetic benefits in periods of food scarcity. Here, to test the two adaptive hypotheses by studying the effects of variation in temperature and growth season on variations in overall brain size and the size of specific brain regions (viz. olfactory nerves, olfactory bulbs, telencephalon, optic tectum and cerebellum) among Hylarana guentheri populations. Inconsistent with the predictions of both the EBH and the CBH, variation in temperature and growth season did not exhibit correlations with overall brain size and the size of brain regions across populations. Hence, our data do not provide support for either the EBH or the CBH to explain brain size variation in H. guentheri. Furthermore, brain size variation did not differ between males and females in this species. Our findings suggest that both the variation in temperature and growth season did not shape the variation in brain size in H. guentheri.

A Biomarker Combining Imaging and Neuropsychological Assessment for Tracking Early Alzheimer's Disease in Clinical Trials

2018 ◽  
Vol 15 (5) ◽  
pp. 429-442 ◽  
Author(s):  
Nishant Verma ◽  
S. Natasha Beretvas ◽  
Belen Pascual ◽  
Joseph C. Masdeu ◽  
Mia K. Markey ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Clinical Trials ◽  
Cognitive Impairment ◽  
Latent Variable ◽  
Brain Regions ◽  
Disease Assessment ◽  
Latent Variable Analysis ◽  
The Relationship ◽  
Selection Of

Background: Combining optimized cognitive (Alzheimer's Disease Assessment Scale- Cognitive subscale, ADAS-Cog) and atrophy markers of Alzheimer's disease for tracking progression in clinical trials may provide greater sensitivity than currently used methods, which have yielded negative results in multiple recent trials. Furthermore, it is critical to clarify the relationship among the subcomponents yielded by cognitive and imaging testing, to address the symptomatic and anatomical variability of Alzheimer's disease. Method: Using latent variable analysis, we thoroughly investigated the relationship between cognitive impairment, as assessed on the ADAS-Cog, and cerebral atrophy. A biomarker was developed for Alzheimer's clinical trials that combines cognitive and atrophy markers. Results: Atrophy within specific brain regions was found to be closely related with impairment in cognitive domains of memory, language, and praxis. The proposed biomarker showed significantly better sensitivity in tracking progression of cognitive impairment than the ADAS-Cog in simulated trials and a real world problem. The biomarker also improved the selection of MCI patients (78.8±4.9% specificity at 80% sensitivity) that will evolve to Alzheimer's disease for clinical trials. Conclusion: The proposed biomarker provides a boost to the efficacy of clinical trials focused in the mild cognitive impairment (MCI) stage by significantly improving the sensitivity to detect treatment effects and improving the selection of MCI patients that will evolve to Alzheimer’s disease.

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