Male brains appeared to be wired front to back, with few connections bridging the two hemispheres.
In females, the pathways criss-crossed between left and right.
These differences might explain why men, in general, tend to be better at learning and performing a single task, like cycling or navigating, whereas women are more equipped for multitasking, say the researchers in the journal Proceedings of the National Academy of Sciences (PNAS).
The same volunteers were asked to perform a series of cognitive tests, and the results appeared to support this notion.
But experts have questioned whether it can be that simple, arguing it is a huge leap to extrapolate from anatomical differences to try to explain behavioural variation between the sexes. Also, brain connections are not set and can change throughout life.
In the study, women scored well on attention, word and face memory, and social cognition, while men performed better on spatial processing and sensori-motor speed.
To look at brain connectivity, the researchers used a type of scan called DTI – a water-based imaging technique that can trace and highlight the fibre pathways connecting the different regions of the brain.
Study author Dr Ruben Gur said: “It’s quite striking how complementary the brains of women and men really are.
“Detailed connectome maps of the brain will not only help us better understand the differences between how men and women think, but it will also give us more insight into the roots of neurological disorders, which are often sex related.”
Prof Heidi Johansen-Berg, a UK expert in neuroscience at the University of Oxford, said the brain was too complex an organ to be able to make broad generalisations.
“We know that there is no such thing as ‘hard wiring’ when it comes to brain connections. Connections can change throughout life, in response to experience and learning.
“Often, sophisticated mathematical approaches are used to analyse and describe these brain networks. These methods can be useful to identify differences between groups, but it is often challenging to interpret those differences in biological terms.”
Dr Michael Bloomfield, Clinical Research Fellow at the Medical Research Council Clinical Sciences Centre in London, said: “It has been known for some time that there are differences between the sexes when it comes to how our bodies work and the brain is no exception.
However, he said care must be taken in drawing conclusions from the study, as the precise relationships between how our brains are wired and our performance on particular tasks needed further investigation.
“We cannot say yet that one is causing the other.
“Furthermore, the measure used in the study, called “connectivity”, is only one aspect of how our brains our wired.
“We think that there can also be differences in certain chemicals in the brain called neurotransmitters, for example, and so we need more research to fully understand how all these different aspects of brain structure and function work together to answer fundamental questions like “how do we think?”.
“One thing that remains unknown is what is driving these differences between the sexes. An obvious possibility is that that male hormones like testosterone and female hormones like oestrogren have different affects on the brain.
“A more subtle possibility is that bringing a child up in a particular gender could affect how our brains are wired.”