The study, by Princeton University and published in the journal PNAS, is the first to identify the adaptive complementarity of sex differences within the connectome – the brain’s networks – by neural mapping.
Instead of investigating individual areas separately, the brain can be analyzed as a whole network, known as the “connectome.” Analysing the brain in this way can provide insights into the organisation and integration of the brain’s networks.
In the sample 949 young people, aged between 8 and 22, brain imaging maps were created to show difference in brain connectivity. The study identified unique sex differences in the brain connectivity between males and females – the majority of difference evident during the course of adolescence.
Analysis of connection statistics, as well of regional and global networks within the brain, presented a comprehensive description of network characteristics:
- Males had greater connectivity, enhanced modularity and transitivity in the supratentorial regions – the area that separates the brain from the nervous system.
- Females showed predominance in connectivity and cross-module participation in between hemispheric areas in the brain.
- The effects were reversed in the cerebellar connections.
Analysis of the developmental changes demonstrated the differences in the trajectories or pathways that brains took in males and females. The changes mainly occurring in adolescence and adulthood.
Dr Madhura Ingalhalikara, research lead, said:
Overall, the results suggest that male brains are structured to facilitate connectivity between perception and co-ordinated action, whereas female brains are designed to facilitate communication between analytical and intuitive processing modes.”
The differences between the sexes has been of interest to both science and society due to the evident gender specific behavioural differences in all species, from fruit fly to modern human.
The differences in behaviour seen in males and females are believed to stem from complementary roles in procreation and social structure. Examples include:
- enhanced motor and spatial skills and greater proclivity for physical aggression in males
- enhanced verbally mediated memory and social cognition in females
In the advent of neuro imaging, studies have found sex differences in the brain that could underlie these differences in behaviour.
- Males have larger crania, proportionate to their larger body size, and a higher percentage of white matter (WM)
- Women demonstrate a higher percentage of gray matter after correcting for intracranial volume effect.
The differences between men and women continue to fascinate, leading to books such as the million copy selling “Why Men Don’t Listen and
Women Can’t Read Maps” by Allan and Barbara Pease.
Interestingly, it was a female, Phyliss Pearson, who created the A-Z Atlas Guide to London and Suburbs.
PNAS: Sex differences in the structural connectome of the human brain: http://www.pnas.org/content/early/2013/11/27/1316909110.abstract
Images from The Human Connectome Project: http://www.humanconnectomeproject.org/