RESEARCH ARTICLE Rozmin Halari Æ Tonmoy Sharma Æ Melissa Hines Chris Andrew Æ Andy Simmons Æ Veena Kumari Comparable fMRI activity with differential behavioural performance on mental rotation and overt verbal fluency tasks in healthy men and women Received: 10 September 2004 / Accepted: 27 June 2005 / Published online: 12 November 2005 Ó Springer-Verlag 2005 Abstract To explicate the neural correlates of sex dif- ferences in visuospatial and verbal fluency tasks, we examined behavioural performance and blood-oxygen- ation-level-dependent (BOLD) regional brain activity, using functional magnetic resonance imaging, during a three-dimensional (3D) mental rotation task and a compressed sequence overt verbal fluency task in a group of healthy men (n=9) and women (n=10; tested during the low-oestrogen phase of the menstrual cycle). Men outperformed women on the mental rotation task, and women outperformed men on the verbal fluency task. For the mental rotation task, men and women activated areas in the right superior parietal lobe and the bilateral middle occipital gyrus in association with the rotation condition. In addition, men activated the left middle temporal gyrus and the right angular gyrus. For verbal fluency, men activated areas in the bilateral superior frontal gyrus, right cingulate gyrus, left pre- central gyrus, left medial frontal gyrus, left inferior frontal gyrus, thalamus, left parahippocampal gyrus and bilateral lingual gyrus, and women activated areas in the bilateral inferior frontal gyrus and left caudate. Despite observing task related activation in the hypothesised areas in men and women, no areas significantly differ- entiated the two sexes. Our results demonstrate com- parable brain activation in men and women in association with mental rotation and verbal fluency function with differential performance, and provide support for sex differences in brain–behaviour relation- ships. Keywords Mental rotation Æ Verbal fluency Æ Functional magnetic resonance imaging Æ Oestrogen Æ Sex differences Æ Humans Introduction Men perform better on average than women on the three-dimensional (3D) mental rotation tasks (Linn and Petersen 1985; Maccoby and Jacklin 1974; Voyer et al. 1995), which requires subjects to imagine what a given object or figure would look like in a different orientation (Kimura 1999). Conversely, women tend to excel on verbal fluency tests (Halpern 1992), which require sub- jects to generate and articulate as many words as they can, beginning with a given letter, in 1 min (Benton et al. 1983; Lezak 1995). These behavioural differences have been suggested to relate to differences in brain laterali- zation, with men performing better than women on certain spatial tasks due to their greater lateralization for these tasks in the right hemisphere, and women per- forming better than men on some verbal tasks (verbal fluency) because these functions are bilaterally repre- sented in the brain (Gur et al. 2000; McGlone 1980). Variations in gonadal hormones play an important role in organizing different sexually dimorphic behaviours (Halpern and Tan 2001) and in modulating activity in brain areas that are associated with higher cognitive functioning (Fink and Summer 1998). Some studies have reported that women perform better on spatial tasks (e.g. mental rotation) during cycle phases characterized R. Halari (&) Centre for Social, Genetic and Developmental Psychiatry, Institute of Psychiatry, De Crespigny Park, P.O. Box 46, London SE5 8AF, UK E-mail: r.halari@iop.kcl.ac.uk Tel.: +44-207-8485253 Fax: +44-207-8480866 T. Sharma Clinical Neuroscience Research Centre, Dartford, UK M. Hines Department of Psychology, City University, London, UK C. Andrew Æ A. Simmons Centre for Neuroimaging Sciences, Institute of Psychiatry, London, UK V. Kumari Department of Psychology, Institute of Psychiatry, London, UK Exp Brain Res (2006) 169: 1–14 DOI 10.1007/s00221-005-0118-7