Variations in human corpus callosum do not predict gender: A study using magnetic resonance imaging.

Byne, William; Bleier, Ruth; Houston, Lanning

doi:10.1037/0735-7044.102.2.222

Cited by 112 publications

(80 citation statements)

References 23 publications

(37 reference statements)

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“…Allen et al (A30; (4)) cited a "striking sex difference" with females being more bulbous, but the difference was significant at only p = 0.038, which, to us, is not so striking. One other group also found females to be more bulbous (A17, (25), p = 0.003), one found males to be more circular (A6, (121), p = 0.05), one found consistent right-handed females to be the least bulbous (A34, (55), p = 0.01), and three found no difference (Al 1, A18, A26; (22,25,50)). De Lacoste-Utamsing and Holloway (Al ; (34)) emphasized that the greater female bulbosity was visually obvious.…”

Section: Splenial Width and Shapementioning

confidence: 98%

Sex Differences in the Human Corpus Callosum: Myth or Reality?

Bishop

Wahłsten

1997

Neuroscience & Biobehavioral Reviews

331

160

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Abstract:It has been claimed that the human corpus callosum shows sex differences, and in particular that the splenium (the posterior portion) is larger in women than in men. Data collected before 1910 from cadavers indicate that, on average, males have larger brains than females and that the average size of their corpus callosum is larger. A meta-analysis of 49 studies published since 1980 reveals no significant sex difference in the size or shape of the splenium of the corpus callosum, whether or not an appropriate adjustment is made for brain size using analysis of covariance or linear regression. It is argued that a simple ratio of corpus callosum size to whole brain size is not an appropriate way to analyse the data and can create a false impression of a sex difference in the corpus callosum. The recent studies, most of which used magnetic resonance imaging (MRI), confirm the earlier findings of larger average brain size and overall corpus callosum size for males. The widespread belief that women have a larger splenium than men and consequently think differently is untenable. Causes of and means to avoid such a false impression in future research are discussed. Keywords: allometry, brain size, effect size, literature review, meta-analysis, morphometry, ratio measures, statistical power Article:IF men and women think differently, their brains must also differ in some way. This holds true, even if the difference emanates largely from experience, because experience changes the brain (39,114). The size of cognitive gender differences has never been very large (58,69), and the difference has almost vanished for several abilities in more recently published reports (47,70). Of course, not all measures of behavior show small sex differences. For example, in the USA, boys possess considerably more knowledge about electronics, automobiles and machinery (58). Among 21 indicators of sexual behavior and sexuality, two (attitude towards casual intercourse and incidence of masturbation) exhibit male-female differences greater than 0.8 standard deviation (95), which is the conventional criterion for a large group difference in psychological research (27), although most (18 out of 21) show differences less than 0.5 standard deviation (SD). However, on tests of cognitive abilities, sex differences are usually small (58). In a review of 287 effect sizes for spatial visualization abilities (118), the average sex difference was 0.37 SD and only one kind of test (mental rotation) met the criterion for even a moderate effect size. For 254 effect sizes involving mathematical performance in 100 published studies, the male average exceeded the female average by only 0.2 SD, but for studies in which the samples were drawn from the general population, females scored slightly better than males (70). Given such small cognitive gender differences, it seems likely that only the most sensitive and refined neurological techniques will be able to locate the relevant difference in brain tissue.Neuroanatomists have scrutinized thousands of pre...

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Section: Splenial Width and Shapementioning

confidence: 98%

Sex Differences in the Human Corpus Callosum: Myth or Reality?

Bishop

Wahłsten

1997

Neuroscience & Biobehavioral Reviews

331

160

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“…Previous research has shown that projections through the CC proceed on an anterior-to-posterior gradient that roughly connects cortical regions from the frontal to occipital lobe (Witelson, 1989). The morphology of the CC has been the topic of considerable debate, particularly as it relates to sex differences and lateralization (Byne, Bleier, & Houston, 1988;Denenberg, Kertesz, & Cowell, 1991;Driesen & Raz, 1995;Habib et al, 1991;Jancke & Steinmetz, 1998;Peters et al, 2002;Westerhausen et al, 2003).…”

Section: Pan Troglodytes; Corpus Callosum; Handednessmentioning

confidence: 99%

Sex and handedness effects on corpus callosum morphology in chimpanzees (Pan troglodytes).

Dunham¹,

Hopkins²

2006

Behavioral Neuroscience

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Findings suggest that in humans, sex and hand preference may be associated with the size of the corpus callosum (CC). The authors measured CC morphology from MRIs in 67 chimpanzees (Pan troglodytes) to see whether similar effects were present in this species. Hand preference was assessed by performance on 4 tasks, and chimpanzees were classified as left-handed, right-handed, or ambidextrous. In a subsequent analysis, the chimpanzees were reclassified into 2 groups: righthanded and left-handed. The results revealed no sex difference in CC area, but significant effects of hand preference were found for several CC regions (rostrum body, anterior midbody, posterior midbody, isthmus, and splenium) and for overall CC size, with left-handed chimpanzees exhibiting significantly smaller CC measurements than right-handed chimpanzees. The results indicate that lateralized hand use in chimpanzees, as in humans, is associated with variation in CC size. Keywords Pan troglodytes; corpus callosum; handednessThe corpus callosum (CC) is the major set of fibers connecting homologous and heterologous cortical regions in the left and right cerebral hemispheres as well as some subcortical structures of the brain (Bermudez & Zatorre, 2001;Gazzaniga, 2000). Its presence allows for interhemispheric communication of sensory and motor functions within the brain. Previous research has shown that projections through the CC proceed on an anterior-to-posterior gradient that roughly connects cortical regions from the frontal to occipital lobe (Witelson, 1989). The morphology of the CC has been the topic of considerable debate, particularly as it relates to sex differences and lateralization (Byne, Bleier, & Houston, 1988;Denenberg, Kertesz, & Cowell, 1991;Driesen & Raz, 1995;Habib et al., 1991;Jancke & Steinmetz, 1998;Peters et al., 2002;Westerhausen et al., 2003).The presence of a sexual dimorphism in the human CC was first reported by de LacosteUtamsing and Holloway (1982). In their study, de Lacoste-Utamsing and Holloway found that women had a larger and more bulbous splenium (posterior fifth of the CC) than did men. Furthermore, de Lacoste-Utamsing and Holloway found that when brain weight was accounted for, women had a larger overall CC. Significant findings of a dimorphism favoring a larger total CC area or regional CC area in female humans have been reported in subsequent studies on cadaver specimens as well as from in vivo imaging studies (Achiron, Lipitz, & Achiron, 2001;Bermudez & Zatorre, 2001;Burke & Yeo, 1994 Innocenti, 1989;Witelson, 1989); however, several studies have found no evidence of sex differences in the size of the CC (Bishop & Wahlsten, 1997;Driesen & Raz, 1995;Habib et al., 1991;Horton, Crawford, Harrington, & Downs, 2004;Witelson, 1985).In addition to sex differences in CC morphology, the relationship between handedness and CC morphology has also been considered. In one of the earliest studies, Witelson (1985) found that mixed-handed individuals (those who did not consistently use their right hand for specifi...

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“…6 There is a considerable interindividual variability in the area and shape of the CC in the healthy elderly. Both positive and negative results have been obtained regarding the correlation of CC cross-sectional areas to factors such as sex and handedness, [7][8][9][10][11][12][13][14][15] number of lacunes and the presence of infarcts in the cerebral hemispheres, 16,17 and/or brain size. 18 The mechanism for CC atrophy is poorly understood, but CC atrophy may reflect pathologic changes in subcortical white matter, as reported in patients with multiple sclerosis 19 and vascular dementia.…”

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confidence: 99%