title: Cerebral laterality for language is related to adult salivary testosterone levels but not digit ratio (2D:4D) in men: A functional transcranial Doppler ultrasound study.
abstract: The adequacy of three competing theories of hormonal effects on cerebral laterality are compared using functional transcranial Doppler sonography (fTCD). Thirty-three adult males participated in the study (21 left-handers). Cerebral lateralization was measured by fTCD using an extensively validated word generation task. Adult salivary testosterone (T) and cortisol (C) concentrations were measured by luminescence immunoassay and prenatal T exposure was indirectly estimated by the somatic marker of 2nd to 4th digit length ratio (2D:4D). A significant quadratic relationship between degree of cerebral laterality for language and adult T concentrations was observed, with enhanced T levels for strong left hemisphere dominance and strong right hemisphere dominance. No systematic effects on laterality were found for cortisol or 2D:4D. Findings suggest that higher levels of T are associated with a relatively attenuated degree of interhemispheric sharing of linguistic information, providing support for the callosal and the sexual differentiation hypotheses rather than the Geschwind, Behan and Galaburda (GBG) hypothesis.
authors.affiliation: Cognition and Health Research Group, Department of Experimental Psychology, University of Oxford, 9 South Parks Road, Oxford OX1 3UD, UK. Electronic address: marietta.papadatou-pastou@seh.oxon.org.
authors.forename: Marietta
authors.initials: M
authors.lastname: Papadatou-Pastou
authors.affiliation: Cognition and Health Research Group, Department of Experimental Psychology, University of Oxford, 9 South Parks Road, Oxford OX1 3UD, UK. Electronic address: rose.martin@seh.ox.ac.uk.
authors.forename: Maryanne
authors.initials: M
authors.lastname: Martin
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000737:chemistry / Q000378:metabolism; D001921:Brain / Q000000981:diagnostic imaging / Q000502:physiology; D005385:Fingers / Q000502:physiology*; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D007802:Language; D008297:Male; D012463:Saliva / Q000737:chemistry* / Q000378:metabolism; D013739:Testosterone / Q000032:analysis* / Q000378:metabolism; D017585:Ultrasonography, Doppler, Transcranial / Q000379:methods*; D055815:Young Adult
chemical_list: D015415:Biomarkers; D013739:Testosterone
keywords: 2D:4D; Cerebral language lateralization; Functional transcranial Doppler ultrasound (fTCD); Testosterone; Word generation