Sex differences in semantic language processing: A functional MRI study L.C. Baxter, a,b A.J. Saykin, a,c,d, * L.A. Flashman, a,d S.C. Johnson, b S.J. Guerin, a D.R. Babcock, a and H.A. Wishart a a Brain Imaging Laboratory, Department of Psychiatry/DHMC, Dartmouth Medical School, Lebanon, NH 03756, USA b Barrow Neurological Institute, Phoenix, AZ 85013, USA c Department of Radiology, Dartmouth Medical School, Lebanon, NH 03756, USA d New Hampshire Hospital, Concord, NH 03301, USA Accepted 14 May 2002 Abstract Predictions based on two models of sex differences in cerebral organization of language were compared by examining fMRI patterns of 10 females and 9 males during a semantic processing task. Both groups displayed activation of left inferior frontal gyrus (IFG), left superior temporal gyrus (STG), and cingulate. Females, but not males, showed bilateral IFG and STG activation. Further analyses revealed females had less diffuse left activation and greater right posterior temporal and insula region activation than males. Results support both an interhemispheric and an intrahemispheric model of sex differences in language, suggesting that the models may not be mutually exclusive. Ó 2002 Elsevier Science (USA). All rights reserved. Keywords: Sex differences; Language; Lateralization; Functional MRI; Semantic memory 1. Introduction While there is some debate as to whether sex differences in language exist, a small but significant behavioral sex difference favoring females has been observed for some types of language-based abilities (see Hampson & Kimura, 1992 for review). Two models of differences in neural representation of language, both based on language deficits in males and females following stroke, have been proposed to explain the differences observed on behavioral tasks. McGlone (1977) suggested that females have greater bihemispheric representation of language than males because aphasia was more common in males with left hemisphere damage (48% in males vs. 13% in females). Furthermore, she found that for females only, language deficits were ob- served after both right and left hemisphere damage. Alternately, Kimura (1983) Brain and Language 84 (2003) 264–272 www.elsevier.com/locate/b&l * Corresponding author. Fax: 1-603-650-5842. E-mail addresses: lbaxter@chw.edu (L.C. Baxter), saykin@dartmouth.edu (A.J. Saykin). 0093-934X/02/$ - see front matter Ó 2002 Elsevier Science (USA). All rights reserved. PII:S0093-934X(02)00549-7