Gender differences? It’s all in our head

New research has shown that the brains of females and males have different patterns of connectivity, possibly alluding as to why men may not behave the same as women. In this impressively large study published by PNAS, 949 people had the connections of their neuronal clusters mapped, and results indicated significant differences between the wiring of the minds between the two genders.

So what were the connectivity differences? Males often had stronger connectivity profiles within the separate hemispheres compared to females, although females were found to have significantly more inter-hemispheric connectivity across the whole brain. This means that although males have greater connectivity between the front and the back of the two sides of the brain, both of the two hemispheres in females are more intricately connected from left to right.

The study, carried out by Pennsylvania University, was led by Dr Ragini Verma, an associate professor in the department of Radiology. Verma thinks there is a link between these results and differences in behaviour between the genders: “These maps show us a stark difference – and complementarity – in the architecture of the human brain that helps provide a potential neural basis as to why men excel at certain tasks, and women at others.”

In behavioural experiments also run by Pennsylvania University, females outperformed males when it came to testing attention spans, memory retention and facial recognition, whilst males were better at spatial processing and had quicker reaction times. Meanwhile, males generally performed better when only working on one task, whereas females could process several at one time and were also found to have superior social cognition skills.

Such results could be seen as indicative that the connectivity patterns Verma has identified relate to these differences in behaviour, although little was mentioned in the paper about neurological plasticity as a result of external environmental influences. Could it be that a gender-biased lifestyle is shaping such connectivity instead?

When looking at age, the contrast between male and female connectivity increased as the subjects got older. Subjects of both genders below the age of 13 were found to have very similar connectivity profiles, whilst differences were most prominent in those that were 17 or older. This may indicate that puberty could play a part in shaping the dimorphism of adult human brains, almost as much as it influences physical gender-orientated development too, although more research is needed. Tracking the connectivity patterns was done using diffusion tensor imaging, an MRI technique that maps the movement of water particles moving throughout the brain. Being able to see where water moves can allow tracing of the underlying fibres of the brain that are directing the water movement.

Such fibres are composed of large bundles of hundreds of axons of neurons, and show which regions of the brain connect to and influence others.

Modelling the entire profile of all the connections within the brain at a cellular level is still yet to be completely done, but would be the ultimate endeavour in brain mapping. The Human Connectome Project, launched back in 2010, is aiming to do this, although estimations of its completion in 2015 have been met with varying levels of scepticism.

Studies into the connectivity of the brain are no longer novel, but are still providing increasingly interesting results. Although this study looks at neural bundles, being able to study the brain at an even greater resolution is next in the neuroscience agenda. Not only that, but coupled with further research in behaviour and neural development and better imaging techniques, we may one day be able to pinpoint exactly what in our minds make us who we are.

DOI: 10.1073/pnas.1316909110