title: Impact of sex and gonadal steroids on neonatal brain structure.
abstract: There are numerous reports of sexual dimorphism in brain structure in children and adults, but data on sex differences in infancy are extremely limited. Our primary goal was to identify sex differences in neonatal brain structure. Our secondary goal was to explore whether brain structure was related to androgen exposure or sensitivity. Two hundred and ninety-three neonates (149 males) received high-resolution structural magnetic resonance imaging scans. Sensitivity to androgen was measured using the number of cytosine, adenine, guanine (CAG) triplets in the androgen receptor gene and the ratio of the second to fourth digit, provided a proxy measure of prenatal androgen exposure. There was a significant sex difference in intracranial volume of 5.87%, which was not related to CAG triplets or digit ratios. Tensor-based morphometry identified extensive areas of local sexual dimorphism. Males had larger volumes in medial temporal cortex and rolandic operculum, and females had larger volumes in dorsolateral prefrontal, motor, and visual cortices. Androgen exposure and sensitivity had minor sex-specific effects on local gray matter volume, but did not appear to be the primary determinant of sexual dimorphism at this age. Comparing our study with the existing literature suggests that sex differences in cortical structure vary in a complex and highly dynamic way across the human lifespan.
authors.affiliation: Department of Psychiatry.
authors.forename: Rebecca C
authors.initials: RC
authors.lastname: Knickmeyer
authors.affiliation: Department of Mathematics, University of North Texas at Denton, Denton, TX, USA.
authors.forename: Jiaping
authors.initials: J
authors.lastname: Wang
authors.affiliation: Department of Biostatistics.
authors.forename: Hongtu
authors.initials: H
authors.lastname: Zhu
authors.affiliation: School of Humanities, The University of Hong Kong, Hong Kong, Hong Kong and.
authors.forename: Xiujuan
authors.initials: X
authors.lastname: Geng
authors.affiliation: Department of Psychiatry.
authors.forename: Sandra
authors.initials: S
authors.lastname: Woolson
authors.affiliation: Department of Psychiatry, Department of Biostatistics.
authors.forename: Robert M
authors.initials: RM
authors.lastname: Hamer
authors.affiliation: Department of Biomolecular Engineering, University of California at Santa Cruz, CA, USA.
authors.forename: Thomas
authors.initials: T
authors.lastname: Konneker
authors.affiliation: Department of Psychiatry, Department of Computer Science, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
authors.forename: Martin
authors.initials: M
authors.lastname: Styner
authors.affiliation: Department of Psychiatry.
authors.forename: John H
authors.initials: JH
authors.lastname: Gilmore
mesh_terms: D000728:Androgens / Q000502:physiology*; D001921:Brain / Q000033:anatomy & histology* / Q000502:physiology*; D005260:Female; D005385:Fingers / Q000502:physiology; D012739:Gonadal Steroid Hormones / Q000502:physiology*; D006801:Humans; D007231:Infant, Newborn / Q000502:physiology*; D008279:Magnetic Resonance Imaging; D008297:Male; D011944:Receptors, Androgen / Q000235:genetics; D012727:Sex Characteristics
chemical_list: D000728:Androgens; D012739:Gonadal Steroid Hormones; D011944:Receptors, Androgen
keywords: androgen; gender; neonate; neuroimaging; sex