Shifts in brain regions with brain size

Science ◽  
2018 ◽  
Vol 360 (6394) ◽  
pp. 1198.15-1200
Author(s):  
Pamela J. Hines
Keyword(s):  
Brain Size ◽  
Brain Regions

scholarly journals Convergent mosaic brain evolution is associated with the evolution of novel electrosensory systems in teleost fishes

2021 ◽  
Author(s):  
Erika L. Schumacher ◽  
Bruce A. Carlson
Keyword(s):  
Brain Region ◽  
Brain Size ◽  
Brain Evolution ◽  
Brain Regions ◽  
Torus Semicircularis ◽  
Micro Computed Tomography ◽  
Electrosensory System ◽  
Electric Fishes ◽  
Weakly Electric ◽  
Region Size

AbstractBrain region size generally scales allometrically with total brain size, but mosaic shifts in brain region size independent of brain size have been found in several lineages and may be related to the evolution of behavioral novelty. African weakly electric fishes (Mormyroidea) evolved a mosaically enlarged cerebellum and hindbrain, yet the relationship to their behaviorally novel electrosensory system remains unclear. We addressed this by studying South American weakly electric fishes (Gymnotiformes) and weakly electric catfishes (Synodontis spp.), which evolved varying aspects of electrosensory systems, independent of mormyroids. If the mormyroid mosaic increases are related to evolving an electrosensory system, we should find similar mosaic shifts in gymnotiforms and Synodontis. Using micro-computed tomography scans, we quantified brain region scaling for multiple electrogenic, electroreceptive, and non-electrosensing species. We found mosaic increases in cerebellum in all three electrogenic lineages relative to non-electric lineages and mosaic increases in torus semicircularis and hindbrain associated with the evolution of electrogenesis and electroreceptor type. These results show that evolving novel electrosensory systems is repeatedly and independently associated with changes in the sizes of individual brain regions independent of brain size, which suggests that selection can impact structural brain composition to favor specific regions involved in novel behaviors.

scholarly journals Quantitative genetic analysis of brain size variation in sticklebacks: support for the mosaic model of brain evolution

2015 ◽  
Vol 282 (1810) ◽  
pp. 20151008 ◽  
Author(s):  
Kristina Noreikiene ◽  
Gábor Herczeg ◽  
Abigél Gonda ◽  
Gergely Balázs ◽  
Arild Husby ◽  
...  
Keyword(s):  
Body Size ◽  
Brain Size ◽  
Additive Genetic Variance ◽  
Genetic Correlations ◽  
Relative Size ◽  
Strong Support ◽  
Brain Evolution ◽  
Brain Regions ◽  
Independent Evolution ◽  
Mosaic Model

The mosaic model of brain evolution postulates that different brain regions are relatively free to evolve independently from each other. Such independent evolution is possible only if genetic correlations among the different brain regions are less than unity. We estimated heritabilities, evolvabilities and genetic correlations of relative size of the brain, and its different regions in the three-spined stickleback ( Gasterosteus aculeatus ). We found that heritabilities were low (average h 2 = 0.24), suggesting a large plastic component to brain architecture. However, evolvabilities of different brain parts were moderate, suggesting the presence of additive genetic variance to sustain a response to selection in the long term. Genetic correlations among different brain regions were low (average r G = 0.40) and significantly less than unity. These results, along with those from analyses of phenotypic and genetic integration, indicate a high degree of independence between different brain regions, suggesting that responses to selection are unlikely to be severely constrained by genetic and phenotypic correlations. Hence, the results give strong support for the mosaic model of brain evolution. However, the genetic correlation between brain and body size was high ( r G = 0.89), suggesting a constraint for independent evolution of brain and body size in sticklebacks.

scholarly journals Brain regions associated with visual cues are important for bird migration

2015 ◽  
Vol 11 (11) ◽  
pp. 20150678 ◽  
Author(s):  
Orsolya Vincze ◽  
Csongor I. Vágási ◽  
Péter L. Pap ◽  
Gergely Osváth ◽  
Anders Pape Møller
Keyword(s):  
Visual Cues ◽  
Optic Lobe ◽  
Brain Size ◽  
Relative Size ◽  
Bird Species ◽  
Interspecific Variation ◽  
Brain Regions ◽  
Long Distance ◽  
Migration Distance ◽  
Whole Brain

Long-distance migratory birds have relatively smaller brains than short-distance migrants or residents. Here, we test whether reduction in brain size with migration distance can be generalized across the different brain regions suggested to play key roles in orientation during migration. Based on 152 bird species, belonging to 61 avian families from six continents, we show that the sizes of both the telencephalon and the whole brain decrease, and the relative size of the optic lobe increases, while cerebellum size does not change with increasing migration distance. Body mass, whole brain size, optic lobe size and wing aspect ratio together account for a remarkable 46% of interspecific variation in average migration distance across bird species. These results indicate that visual acuity might be a primary neural adaptation to the ecological challenge of migration.

Synthesis

2019 ◽  
pp. 423-472
Author(s):  
Georg F. Striedter ◽  
R. Glenn Northcutt
Keyword(s):  
Functional Organization ◽  
Brain Size ◽  
Brain Regions ◽  
Brain Areas ◽  
Nervous Systems ◽  
Internal Organization ◽  
Vertebrate Brain ◽  
Relative Brain Size

After summarizing the earlier chapters, which focused on the evolution of specific lineages, this chapter examines general patterns in the evolution of vertebrate nervous systems. Most conspicuous is that relative brain size and complexity increased independently in many lineages. The proportional size of individual brain regions tends to change predictably with absolute brain size (and neurogenesis timing), but the scaling rules vary across lineages. Attempts to link variation in the size of individual brain areas (or entire brains) to behavior are complicated in part because the connections, internal organization, and functions of individual brain regions also vary across phylogeny. In addition, major changes in the functional organization of vertebrate brains were caused by the emergence of novel brain regions (e.g., neocortex in mammals and area dorsalis centralis in teleosts) and novel circuits. These innovations significantly modified the “vertebrate brain Bauplan,” but their mechanistic origins and implications require further investigation.

scholarly journals Selection for reduced fear in red junglefowl changes brain composition and affects fear memory

2020 ◽  
Vol 7 (8) ◽  
pp. 200628
Author(s):  
Rebecca Katajamaa ◽  
Per Jensen
Keyword(s):  
Body Size ◽  
Brain Size ◽  
Prior Experience ◽  
Fear Memory ◽  
Brain Regions ◽  
Preference Learning ◽  
Response To Selection ◽  
Red Junglefowl ◽  
Selection For ◽  
Region Size

Brain size reduction is a common trait in domesticated species when compared to wild conspecifics. This reduction can happen through changes in individual brain regions as a response to selection on specific behaviours. We selected red junglefowl for 10 generations for diverging levels of fear towards humans and measured brain size and composition as well as habituation learning and conditioned place preference learning in young chicks. Brain size relative to body size as well as brainstem region size relative to whole brain size were significantly smaller in chicks selected for low fear of humans compared to chicks selected for high fear of humans. However, when including allometric effects in the model, these differences disappear but a tendency towards larger cerebra in low-fear chickens remains. Low-fear line chicks habituated more effectively to a fearful stimulus with prior experience of that same stimulus, whereas high-fear line chicks with previous experience of the stimulus had a response similar to naive chicks. The phenotypical changes are in line with previously described effects of domestication.

Brain size evolution in anurans: a review

2019 ◽  
Vol 69 (3) ◽  
pp. 265-279 ◽  
Author(s):  
Chun Lan Mai ◽  
Wen Bo Liao
Keyword(s):  
Sexual Selection ◽  
Life History ◽  
Life History Traits ◽  
Developmental Stages ◽  
Brain Size ◽  
Ecological Factors ◽  
Brain Regions ◽  
Sperm Length ◽  
Testis Size ◽  
Size Evolution

Abstract Selection pressure is an important force in shaping the evolution of vertebrate brain size among populations within species as well as between species. The evolution of brain size is tightly linked to natural and sexual selection, and life-history traits. In particular, increased environmental stress, intensity of sexual selection, and slower life history usually result in enlarged brains. However, although previous studies have addressed the causes of brain size evolution, no systematic reviews have been conducted to explain brain size in anurans. Here, we review whether brain size evolution supports the cognitive buffer hypothesis (CBH), the expensive tissue hypothesis (ETH), or the developmental cost hypothesis (DCH) by analyzing the intraspecific and/or interspecific patterns in brain size and brain regions (i.e., olfactory nerves, olfactory bulbs, telencephalon, optic tectum, and cerebellum) associated with ecological factors (habitat, diet and predator risk), sexual selection intensity, life-history traits (age at sexual maturity, mean age, longevity, clutch size and egg size, testis size and sperm length), and other energetic organs. Our findings suggest that brain size evolution in anurans supports the CBH, ETH or DCH. We also suggest future directions for studying the relationships between brain size evolution and crypsis (i.e., ordinary mucous glands in the skin), and food alteration in different developmental stages.

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 Rapid mosaic brain evolution under artificial selection for relative telencephalon size in the guppy (Poecilia reticulata)

2021 ◽  
Author(s):  
Stephanie Fong ◽  
Björn Rogell ◽  
Mirjam Amcoff ◽  
Alexander Kotrschal ◽  
Wouter van der Bijl ◽  
...  
Keyword(s):  
Artificial Selection ◽  
Poecilia Reticulata ◽  
Brain Size ◽  
Brain Evolution ◽  
Brain Regions ◽  
Research Field ◽  
Selected Lines ◽  
Vertebrate Brain ◽  
Offspring Production ◽  
Mosaic Brain Evolution

The vertebrate brain displays enormous morphological variation and the quest to understand the evolutionary causes and consequences of this variation has spurred much research. The mosaic brain evolution hypothesis, stating that brain regions can evolve relatively independently, is an important idea in this research field. Here we provide experimental support for this hypothesis through an artificial selection experiment in the guppy (Poecilia reticulata). After four generations of selection on relative telencephalon volume (relative to brain size) in replicated up-selected, down-selected and control-lines, we found substantial changes in telencephalon size, but no changes in other regions. Comparisons revealed that up-selected lines had larger telencephalon while down-selected lines had smaller telencephalon than wild Trinidadian populations. No cost of increasing telencephalon size was detected in offspring production. Our results support that independent evolutionary changes in specific brain regions through mosaic brain evolution can be important facilitators of cognitive evolution.

The Sexual Brain

2021 ◽  
pp. 81-108
Author(s):  
Susan D. Healy
Keyword(s):  
Sex Differences ◽  
Sexual Selection ◽  
Brain Size ◽  
Female Mate Choice ◽  
Brain Regions ◽  
Good Evidence ◽  
The Other ◽  
Female Mate ◽  
Males And Females ◽  
Hippocampal Structure

Morphological and behavioural differences between the sexes are ubiquitous across the animal kingdom. There is also good evidence for differences in some brain regions between males and females, in humans, some rodents, and many songbirds. I look at the data for sex differences in cognition, of which there are some that show differences in spatial cognition and in hippocampal structure, at least some of which may be explained by variation in hormone levels. The thesis of The Mating Mind by Geoffrey Miller considerably increased interest in using sexual selection to explain variation in brain size. From female mate choice, male–male competition, sperm competition, mating strategy, to parental care, there are some data that appear to support selection acting on one species rather than the other in sexually a selected manner but I conclude that the data are not generally supportive of the Sexual Brain Hypothesis.

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.

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