Sexual dimorphism and asymmetries in the gray–white composition of the human cerebrum

Allen, John S.; Damásio, Hanna; Grabowski, Thomas J.; Bruss, Joel; Zhang, Wei

doi:10.1016/s1053-8119(03)00034-x

Cited by 361 publications

(228 citation statements)

References 48 publications

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“…We confirm previous findings (Allen et al, 2003;Filipek et al, 1994;Peters et al, 1998) that the relative amount of gray matter is slightly higher in female brains, while the relative amount of white matter is slightly higher in male brains. Our data also support the hypothesis that there is less white matter in females compared to males, most likely as a consequence of the higher symmetry of female brains (Kovalev et al, 2003).…”

Section: Resultssupporting

confidence: 92%

“…Following some initial studies using cranial computed tomography (CCT) (Abbott et al, 2000;Hahn et al, 1984;Schwartz et al, 1985), MRI quickly became the method of choice for data collection because MRI allows discriminating between several tissue types (Caviness et al, 1995(Caviness et al, , 1999Kennedy et al, 2003). Several studies focused on the determination of brain compartments and their gender differences (Allen et al, 2002(Allen et al, , 2003Blatter et al, 1995;Filipek et al, 1989Filipek et al, , 1994Sato et al, 2003;Schlaepfer et al, 1995) and changes of compartment volumes with age (Blatter et al, 1995;Courchesne et al, 2000;Ge et al, 2002;Giedd et al, 1996;Harris et al, 1994;Jernigan et al, 2001;Pfefferbaum et al, 1994;Resnick et al, 2003) and tried to find MRI-detectable discriminators of healthy and pathological aging in neurodegenerative diseases (Edland et al, 2002;Jenkins et al, 2000;Wolf et al, 2003Wolf et al, , 2004. Often these studies include a small sample size or a few parameters only.…”

Section: Introductionmentioning

confidence: 99%

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MRI-based volumetry of head compartments: Normative values of healthy adults

Kruggel

2006

NeuroImage

119

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The size of head compartments (head and brain volume, intracranial volume, gray and white matter volume, cerebrospinal fluid volume) and their ratios were determined on the basis of magnetic resonance images of the head acquired in a reference population of 502 healthy subjects. Age-matched subgroups were selected to reveal genderrelated differences and changes with age. Normative data are provided in the form of simple equations that allow transforming measured compartment volumes into z scores, offering the possibility to relate individual data to a larger population. D

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Section: Resultssupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

MRI-based volumetry of head compartments: Normative values of healthy adults

Kruggel

2006

NeuroImage

119

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“…For instance, across and within species, WM-to-GM ratios increase with enlargement of total brain volume following a 4/3 power law (Zhang and Sejnowski, 2000). This phenomenon may account for why reported differences of greater GM/WM ratios in females (Allen et al, 2003;Gur et al, 2002) are not nearly as robust when comparing males and females with similar total brain volumes (Leonard et al, 2008).…”

Section: Total Cerebral Volumementioning

confidence: 98%

Child Psychiatry Branch of the National Institute of Mental Health Longitudinal Structural Magnetic Resonance Imaging Study of Human Brain Development

Giedd

Raznahan

Alexander-Bloch

et al. 2014

Neuropsychopharmacol

286

213

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The advent of magnetic resonance imaging, which safely allows in vivo quantification of anatomical and physiological features of the brain, has revolutionized pediatric neuroscience. Longitudinal studies are useful for the characterization of developmental trajectories (ie, changes in imaging measures by age). Developmental trajectories (as opposed to static measures) have proven to have greater power in discriminating healthy from clinical groups and in predicting cognitive/ behavioral measures, such as IQ. Here we summarize results from an ongoing longitudinal pediatric neuroimaging study that has been conducted at the Child Psychiatry Branch of the National Institute of Mental Health since 1989. Developmental trajectories of structural MRI brain measures from healthy youth are compared and contrasted with trajectories in attentiondeficit/hyperactivity disorder (ADHD) and childhood-onset schizophrenia. Across ages 5-25 years, in both healthy and clinical populations, white matter volumes increase and gray matter volumes follow an inverted U trajectory, with peak size occurring at different times in different regions. At a group level, differences related to psychopathology are seen for gray and white matter volumes, rates of change, and for interconnectedness among disparate brain regions.

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“…In the adult human brain structural sex differences can be found from the macroscopic level (47) down to the ultramicroscopic level (48). Functionally, too, a large number of sex differences in different brain regions have recently been described (49)(50)(51)(52)(53). Sexual differentiation of the human brain is also expressed in behavioral differences, including sexual orientation (homo-, bi-and heterosexuality) and gender identity (22,(54)(55)(56)(57), and in differences at the level of brain physiology and in the prevalence of neurological and psychiatric disorders (57)(58)(59).…”

Section: Sex Differences In the Human Brainmentioning

confidence: 99%

Sexual differentiation of the human brain in relation to gender identity and sexual orientation

Savić

Garcı́a-Falgueras

Swaab

2010

Progress in Brain Research

121

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SummaryDuring the intrauterine period the fetal brain develops in the male direction through a direct action of testosterone on the developing nerve cells, or in the female direction through the absence of this hormone surge. In this way, our gender identity (the conviction of belonging to the male or female gender) and sexual orientation are programmed into our brain structures when we are still in the womb. However, since sexual differentiation of the genitals takes place in the first two months of pregnancy and sexual differentiation of the brain starts in the second half of pregnancy, these two processes can be influenced independently, which may result in transsexuality. This also means that in the event of ambiguous sex at birth, the degree of masculinization of the genitals may not reflect the degree of masculinization of the brain. There is no proof that social environment after birth has an effect on gender identity or sexual orientation.KEY WORDS: gender identity, homosexuality, human brain, sexual orientation, sexual differentiation, transsexuality. Sexual organization and activation of the human brainThe process of sexual differentiation of the brain brings about permanent changes in brain structures and functions via interactions of the developing neurons with the environment, understood in its widest sense. The environment of a developing neuron is formed by the surrounding nerve cells and the child's circulating hormones, as well as the hormones, nutrients, medication and other chemical substances from the mother and the environment that enter the fetal circulation via the placenta. All these factors may have a lasting effect on the sexual differentiation of the brain. The testicles and ovaries develop in the sixth week of pregnancy. This occurs under the influence of a cascade of genes, starting with the sex-determining gene on the Y chromosome (SRY). The production of testosterone by a boy's testes is necessary for sexual differentiation of the sexual organs between weeks 6 and 12 of pregnancy. The peripheral conversion of testosterone into dihydrotestosterone is essential for the formation of a boy's penis, prostate and scrotum. Instead, the development of the female sexual organs in the womb is based primarily on the absence of androgens (1). Once the differentiation of the sexual organs into male or female is settled, the next thing that is differentiated is the brain, under the influence, mainly, of sex hormones on the developing brain cells. The changes (permanent) brought about in this stage have organizing effects; later, during puberty, the brain circuits that developed in the womb are activated by sex hormones. This paradigm of sexual differentiation of the brain has been well established, ever since the first paper by Phoenix et al. (2). The fetal brain is protected against the effect of circulating estrogens from the mother by the protein α-fetoprotein, which is produced by the fetus and binds strongly to estrogens but not to testosterone (3,4). However, estrogens do not only reach th...

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Sexual dimorphism and asymmetries in the gray–white composition of the human cerebrum

Cited by 361 publications

References 48 publications

MRI-based volumetry of head compartments: Normative values of healthy adults

MRI-based volumetry of head compartments: Normative values of healthy adults

Child Psychiatry Branch of the National Institute of Mental Health Longitudinal Structural Magnetic Resonance Imaging Study of Human Brain Development

Sexual differentiation of the human brain in relation to gender identity and sexual orientation

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