Term in human neuroanatomy referring to several things
In human neuroanatomy, brain asymmetry can refer to at least two quite distinct findings:
Neuroanatomical differences between the left and right sides of the brain
Lateralized functional differences: lateralization of brain function
A stereotypical image of brain lateralisation - demonstrated to be false in neuroscientific research.[1]
Neuroanatomical differences themselves exist on different scales, from neuronal densities, to the size of regions such as the planum temporale, to—at the largest scale—the torsion or "wind" in the human brain, reflected shape of the skull, which reflects a backward (posterior) protrusion of the left occipital bone and a forward (anterior) protrusion of the right frontal bone.[2] In addition to gross size differences, both neurochemical and structural differences have been found between the hemispheres. Asymmetries appear in the spacing of cortical columns, as well as dendritic structure and complexity. Larger cell sizes are also found in layer III of Broca's area.
The human brain has an overall leftward posterior and rightward anterior asymmetry (or brain torque). There are particularly large asymmetries in the frontal, temporal and occipital lobes, which increase in asymmetry in the antero-posterior direction beginning at the central region. Leftward asymmetry can be seen in the Heschl gyrus, parietal operculum, Silvian fissure, left cingulate gyrus, temporo-parietal region and planum temporale. Rightward asymmetry can be seen in the right central sulcus (potentially suggesting increased connectivity between motor and somatosensory cortices in the left side of the brain), lateral ventricle, entorhinal cortex, amygdala and temporo-parieto-occipital area. Sex-dependent brain asymmetries are also common. For example, human male brains are more asymmetrically lateralized than those of females. However, gene expression studies done by Hawrylycz and colleagues and Pletikos and colleagues, were not able to detect asymmetry between the hemispheres on the population level.[3][4]
People with autism have much more symmetrical brains than people without it.[5][6]
^Nielsen, J. A., Zielinski, B. A., Ferguson, M. A., Lainhart, J. E., & Anderson, J. S. (2013). An evaluation of the left-brain vs. right-brain hypothesis with resting state functional connectivity magnetic resonance imaging. PLOS ONE, 8(8), e71275.
^LeMay M (June 1977). "Asymmetries of the skull and handedness. Phrenology revisited". Journal of the Neurological Sciences. 32 (2): 243–53. doi:10.1016/0022-510X(77)90239-8. PMID 874523. S2CID 24210069.
^Hawrylycz MJ, Lein ES, Guillozet-Bongaarts AL, Shen EH, Ng L, Miller JA, et al. (September 2012). "An anatomically comprehensive atlas of the adult human brain transcriptome". Nature. 489 (7416): 391–399. Bibcode:2012Natur.489..391H. doi:10.1038/nature11405. PMC 4243026. PMID 22996553.
^Pletikos M, Sousa AM, Sedmak G, Meyer KA, Zhu Y, Cheng F, Li M, Kawasawa YI, Sestan N (January 2014). "Temporal specification and bilaterality of human neocortical topographic gene expression". Neuron. 81 (2): 321–32. doi:10.1016/j.neuron.2013.11.018. PMC 3931000. PMID 24373884.
^Herbert, M. R. (2004-11-17). "Brain asymmetries in autism and developmental language disorder: a nested whole-brain analysis". Brain. 128 (1). Oxford University Press (OUP): 213–226. doi:10.1093/brain/awh330. ISSN 1460-2156. PMID 15563515.
^Postema, Merel C.; et al. (2019-10-31). "Altered structural brain asymmetry in autism spectrum disorder in a study of 54 datasets". Nature Communications. 10 (1): 4958. Bibcode:2019NatCo..10.4958P. doi:10.1038/s41467-019-13005-8. ISSN 2041-1723. PMC 6823355. PMID 31673008.
neuroanatomy, brainasymmetry can refer to at least two quite distinct findings: Neuroanatomical differences between the left and right sides of the brain Lateralized...
CS1 maint: multiple names: authors list (link) Zaidel, E. (2001). "BrainAsymmetry". International Encyclopedia of the Social & Behavioral Sciences. Elsevier...
predicted the aurofacial asymmetry, which was then found empirically. Explained phenomena include: Contralateral organization of the brain Left-sided orientation...
the right, making it the most asymmetrical structure in the brain. Evidence for this asymmetry has also been seen in great apes. This greater size of the...
fluctuating asymmetry is comparable to the concepts of accuracy and precision in empirical measurements. There are examples from the brain (Yakovlevian...
configuration of the body and therefore remained on either side. Brainasymmetry Lateralization of brain function Chris Smith (11 Aug 2023). "Question of the Week"...
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pp. 72–74, 89–95. ISBN 9780262019507. Harrison, David W. (2015). BrainAsymmetry and Neural Systems Foundations in Clinical Neuroscience and Neuropsychology...
left side of the human brain to be warped slightly backward relative to the right. This is responsible for certain asymmetries, such as how the lateral...
Ambidexterity In cognitive abilities Geschwind–Galaburda hypothesis In brainBrainasymmetry Dual brain theory Bicameralism In eyes Ocular dominance In hands Left-handedness...
ciliogenesis) also play a role in the development of brainasymmetry (handedness being a reflection of brainasymmetry for motor function). In 2019, Wiberg et al...
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modernity – Transition of human species to anthropologically modern behavior Brainasymmetry – Term in human neuroanatomy referring to several things Dual consciousness –...
Montgomery CA, Elder FF, Overbeek PA (1993). "Reversal of left-right asymmetry: a situs inversus mutation". Science. 260 (5108): 679–682. Bibcode:1993Sci...
the effects of lesions in the two hemispheres, split-brain patients, and perceptual asymmetries have aided in the knowledge of speech lateralization....
right-hander's left hand." Brainasymmetry Cross-dominance Dual brain theory Handedness Laterality Lateralization of brain function ^ This article incorporates...
Fluctuating asymmetry (FA), is a form of biological asymmetry, along with anti-symmetry and direction asymmetry. Fluctuating asymmetry refers to small...
PMID 15093637. S2CID 39690729. Le Floch A, Ropars G (October 2017). "Left-right asymmetry of the Maxwell spot centroids in adults without and with dyslexia". Proceedings...
one's testosterone levels as a baby in the uterus could enhance one's brainasymmetry, which may relate to one's linguistic, artistic and musical ability...
Larios C, Lawrence KE, Narr K, et al. (February 2018). "Hemispheric brainasymmetry differences in youths with attention-deficit/hyperactivity disorder"...
"Cerebral networks and functional brainasymmetry: evidence from regional metabolic changes during word repetition". Brain and Language. 63 (1): 108–21. doi:10...
asymmetrically in order to form the normal situs solitus orientation. This induced asymmetry is thought to be achieved by a number of morphological factors that guide...
F, MacKenzie-Graham A, Toga AW, Luders E (January 2015). "Shifting brainasymmetry: the link between meditation and structural lateralization". Social...
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