Cerebral Cortex Advance Access published online on December 17, 2007
Cerebral Cortex, doi:10.1093/cercor/bhm227
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Mapping the Relationship between Cortical Convolution and Intelligence: Effects of Gender
1 Laboratory of Neuro Imaging, Department of Neurology, 2 Ahmanson-Lovelace Brain Mapping Center, Department of Neurology, 3 Jane & Terry Semel Institute for Neuroscience and Human Behavior, UCLA School of Medicine, Los Angeles, CA, USA, 4 Department of Psychiatry Research, The Zucker Hillside Hospital, North-Shore Long Island Jewish Health System, Glen Oaks, NY, USA, 5 Department of Psychiatry, University of Jena, Germany
Address correspondence to Dr Arthur W. Toga, Laboratory of Neuro Imaging, Department of Neurology, UCLA School of Medicine, Neuroscience Research Building, Suite 225, 635 Charles Young Drive South, Los Angeles, CA 90095-7334, USA. Email: toga{at}loni.ucla.edu.
The pronounced convolution of the human cortex may be a morphological substrate that supports some of our species’ most distinctive cognitive abilities. Therefore, individual intelligence within humans might be modulated by the degree of folding in certain cortical regions. We applied advanced methods to analyze cortical convolution at high spatial resolution and correlated those measurements with intelligence quotients. Within a large sample of healthy adult subjects (n = 65), we detected the most prominent correlations in the left medial hemisphere. More specifically, intelligence scores were positively associated with the degree of folding in the temporo-occipital lobe, particularly in the outermost section of the posterior cingulate gyrus (retrosplenial areas). Thus, this region might be an important contributor toward individual intelligence, either via modulating pathways to (pre)frontal regions or by serving as a location for the convergence of information. Prominent gender differences within the right frontal cortex were observed; females showed uncorrected significant positive correlations and males showed a nonsignificant trend toward negative correlations. It is possible that formerly described gender differences in regional convolution are associated with differences in the underlying architecture. This might lead to the development of sexually dimorphic information processing strategies and affect the relationship between intelligence and cortical convolution.
Key Words: cortex • curvature • folding • IQ • MRI • sex