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 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 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 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.

The cannabinoid CB1 receptor biphasically modulates motor activity and regulates dopamine and glutamate release region dependently

2012 ◽  
Vol 16 (2) ◽  
pp. 393-403 ◽  
Author(s):  
Alexia Polissidis ◽  
Andreas Galanopoulos ◽  
George Naxakis ◽  
Demetris Papahatjis ◽  
Zeta Papadopoulou-Daifoti ◽  
...  
Keyword(s):  
Locomotor Activity ◽  
Glutamate Release ◽  
Brain Regions ◽  
Cb1 Receptor ◽  
Glutamatergic Neurotransmission ◽  
Extracellular Dopamine ◽  
Cb1 Antagonist ◽  
Subcortical Regions ◽  
Underlying Mechanisms

Abstract Cannabinoid administration modulates both dopaminergic and glutamatergic neurotransmission. The present study examines the effects of high and low dose WIN55,212-2, a CB1 receptor agonist, on extracellular dopamine and glutamate release in vivo via brain microdialysis in the nucleus accumbens (NAc), striatum and prefrontal cortex (PFC) in parallel to its effects on locomotor activity. WIN55,212-2 increased extracellular dopamine in the NAc (1 mg/kg i.p.), striatum (0.1 and 1 mg/kg i.p.) and PFC (1 mg/kg i.p.). Glutamate release was also elevated by WIN55,212-2 in the PFC (1 mg/kg i.p.) whereas in the NAc (0.1 and 1 mg/kg i.p.) and striatum, it was reduced (1 mg/kg i.p.). WIN55,212-2 administration produced hyperlocomotion at the lower dose (0.1 mg/kg i.p.) and hypolocomotion at the higher dose (1 mg/kg i.p.). Co-administration with the CB1 antagonist, SR-141716A (0.03 mg/kg i.p.), prevented the above effects. According to the present results, WIN55,212-2 affected locomotor activity biphasically while exerting converging effects on dopamine activity but diverging effects on glutamate release between cortical and subcortical regions, especially at the higher dose. These findings emphasize the involvement of the CB1 receptor in the simultaneous modulation of dopaminergic and glutamatergic neurotransmission in brain regions involved in reward and locomotion and suggest possible underlying mechanisms of acute cannabinoid exposure and its psychoactive and behavioural manifestations.

scholarly journals Morning-evening variation in human brain metabolism and memory circuits

2013 ◽  
Vol 109 (5) ◽  
pp. 1444-1456 ◽  
Author(s):  
B. J. Shannon ◽  
R. A. Dosenbach ◽  
Y. Su ◽  
A. G. Vlassenko ◽  
L. J. Larson-Prior ◽  
...  
Keyword(s):  
Resting State ◽  
Brain Metabolism ◽  
Functional Organization ◽  
Metabolic Cost ◽  
Brain Regions ◽  
Daily Basis ◽  
Brain Organization ◽  
Critical Function ◽  
Positron Emission ◽  
Mri Scans

It has been posited that a critical function of sleep is synaptic renormalization following a net increase in synaptic strength during wake. We hypothesized that wake would alter the resting-state functional organization of the brain and increase its metabolic cost. To test these hypotheses, two experiments were performed. In one, we obtained morning and evening resting-state functional MRI scans to assess changes in functional brain organization. In the second experiment, we obtained quantitative positron emission tomography measures of glucose and oxygen consumption to assess the cost of wake. We found selective changes in brain organization. Most prominently, bilateral medial temporal regions were locally connected in the morning but in the evening exhibited strong correlations with frontal and parietal brain regions involved in memory retrieval. We speculate that these changes may reflect aspects of memory consolidation recurring on a daily basis. Surprisingly, these changes in brain organization occurred without increases in brain metabolism.

Neuroanatomical and Morphological Trait Clusters in the Ant Genus Pheidole: Evidence for Modularity and Integration in Brain Structure

2015 ◽  
Vol 85 (1) ◽  
pp. 63-76 ◽  
Author(s):  
Iulian Ilieş ◽  
Mario L. Muscedere ◽  
James F.A. Traniello
Keyword(s):  
Social Information Processing ◽  
Brain Structure ◽  
Developmental Trajectories ◽  
Size Variation ◽  
Brain Evolution ◽  
Brain Structures ◽  
Interspecific Variation ◽  
Distinct Species ◽  
Brain Regions ◽  
Brain Organization

A central question in brain evolution concerns how selection has structured neuromorphological variation to generate adaptive behavior. In social insects, brain structures differ between reproductive and sterile castes, and worker behavioral specializations related to morphology, age, and ecology are associated with intra- and interspecific variation in investment in functionally different brain compartments. Workers in the hyperdiverse ant genus Pheidole are morphologically and behaviorally differentiated into minor and major subcastes that exhibit distinct species-typical patterns of brain compartment size variation. We examined integration and modularity in brain organization and its developmental patterning in three ecotypical Pheidole species by analyzing intra- and interspecific morphological and neuroanatomical covariation. Our results identified two trait clusters, the first involving olfaction and social information processing and the second composed of brain regions regulating nonolfactory sensorimotor functions. Patterns of size covariation between brain compartments within subcastes were consistent with levels of behavioral differentiation between minor and major workers. Globally, brains of mature workers were more heterogeneous than brains of newly eclosed workers, suggesting diversified developmental trajectories underscore species- and subcaste-typical brain organization. Variation in brain structure associated with the striking worker polyphenism in our sample of Pheidole appears to originate from initially differentiated brain templates that further diverge through species- and subcaste-specific processes of maturation and behavioral development.

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.

scholarly journals Investment in higher order central processing regions is not constrained by brain size in social insects

2014 ◽  
Vol 281 (1784) ◽  
pp. 20140217 ◽  
Author(s):  
Mario L. Muscedere ◽  
Wulfila Gronenberg ◽  
Corrie S. Moreau ◽  
James F. A. Traniello
Keyword(s):  
Sensory Processing ◽  
Mushroom Body ◽  
Brain Size ◽  
Brain Regions ◽  
Brain Organization ◽  
Complex Behaviour ◽  
Central Processing ◽  
Hymenopteran Species ◽  
Peripheral Sensory ◽  
Evolutionary Neuroscience

The extent to which size constrains the evolution of brain organization and the genesis of complex behaviour is a central, unanswered question in evolutionary neuroscience. Advanced cognition has long been linked to the expansion of specific brain compartments, such as the neocortex in vertebrates and the mushroom bodies in insects. Scaling constraints that limit the size of these brain regions in small animals may therefore be particularly significant to behavioural evolution. Recent findings from studies of paper wasps suggest miniaturization constrains the size of central sensory processing brain centres (mushroom body calyces) in favour of peripheral, sensory input centres (antennal and optic lobes). We tested the generality of this hypothesis in diverse eusocial hymenopteran species (ants, bees and wasps) exhibiting striking variation in body size and thus brain size. Combining multiple neuroanatomical datasets from these three taxa, we found no universal size constraint on brain organization within or among species. In fact, small-bodied ants with miniscule brains had mushroom body calyces proportionally as large as or larger than those of wasps and bees with brains orders of magnitude larger. Our comparative analyses suggest that brain organization in ants is shaped more by natural selection imposed by visual demands than intrinsic design limitations.

scholarly journals The Cerebral Metabolic Consequences of Nitric Oxide Synthase Deficiency: Glucose Utilization in Endothelial and Neuronal Nitric Oxide Synthase Null Mice

1999 ◽  
Vol 19 (2) ◽  
pp. 144-148 ◽  
Author(s):  
Susan E. Browne ◽  
Cenk Ayata ◽  
Paul L. Huang ◽  
Michael A. Moskowitz ◽  
M. Flint Beal
Keyword(s):  
Nitric Oxide ◽  
Nitric Oxide Synthase ◽  
Knockout Mice ◽  
Glucose Utilization ◽  
Brain Regions ◽  
In Vivo Autoradiography ◽  
Subcortical Regions ◽  
Oxide Synthase ◽  
The Brain

Nitric oxide has multiple physiologic roles in the CNS. Inhibiting nitric oxide synthesis might therefore alter functional activity within the brain. We used [14C]-2-deoxyglucose in vivo autoradiography to measure local CMRglc in “knockout” mice lacking the genes for either the endothelial (eNOS) or neuronal (nNOS) isoforms of nitric oxide synthase, and in the progenitor strains (SV129, CS7B1/6). Glucose utilization levels did not significantly differ between nNOS and eNOS knockout mice and C57B1/6 mice in any of the 48 brain regions examined, but were relatively lower in some subcortical regions in SV129 mice.

scholarly journals What Do Language Disorders Reveal about Brain–Language Relationships? From Classic Models to Network Approaches

2017 ◽  
Vol 23 (9-10) ◽  
pp. 741-754 ◽  
Author(s):  
Nina F. Dronkers ◽  
Maria V. Ivanova ◽  
Juliana V. Baldo
Keyword(s):  
Language Processing ◽  
Brain Injuries ◽  
Brain Activity ◽  
Language Disorders ◽  
Brain Regions ◽  
Language Functions ◽  
Subcortical Regions ◽  
Communication Impairments ◽  
The Brain

AbstractStudies of language disorders have shaped our understanding of brain–language relationships over the last two centuries. This article provides a review of this research and how our thinking has changed over the years regarding how the brain processes language. In the 19th century, a series of famous case studies linked distinct speech and language functions to specific portions of the left hemisphere of the brain, regions that later came to be known as Broca’s and Wernicke’s areas. One hundred years later, the emergence of new brain imaging tools allowed for the visualization of brain injuriesin vivothat ushered in a new era of brain-behavior research and greatly expanded our understanding of the neural processes of language. Toward the end of the 20th century, sophisticated neuroimaging approaches allowed for the visualization of both structural and functional brain activity associated with language processing in both healthy individuals and in those with language disturbance. More recently, language is thought to be mediated by a much broader expanse of neural networks that covers a large number of cortical and subcortical regions and their interconnecting fiber pathways. Injury to both grey and white matter has been seen to affect the complexities of language in unique ways that have altered how we think about brain–language relationships. The findings that support this paradigm shift are described here along with the methodologies that helped to discover them, with some final thoughts on future directions, techniques, and treatment interventions for those with communication impairments. (JINS, 2017,23, 741–754)

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