Some useful framing for the Ingalhalikar et al. paper I wrote about earlier today — Christian Jarrett, "Getting in a Tangle Over Men's and Women's Brain Wiring", Wired 12/4/2013:
[L]et’s set this new brain wiring study in the context of previous research. Verma and her team admit that a previous paper looking at the brain wiring of 439 participants failed to find significant differences between the sexes. What about studies on the corpus callosum – the thick bundle of fibres that connects the two brain hemispheres? If women really have more cross-talk across the brain, this is one place where you’d definitely expect them to have more connectivity. And yet a 2012 diffusion tensor paper found “a stronger inter-hemispheric connectivity between the frontal lobes in males than females”. Hmm. Another paper from 2006 found little difference in thickness of the callosum according to sex. Finally a meta-analysis from 2009: “The alleged sex-related corpus callosum size difference is a myth,” it says.
OK, one last thing. I don’t know if you saw it, but earlier this year another study involving hundreds of participants used a different technique (resting state fMRI) to examine connectivity in the brain, this time for the purpose of seeing if some people have more left-brain functional hubs and others have more right-brained hubs (they don’t). This obviously isn’t the same focus as the new PNAS paper, but if men and women’s brains really are wired up differently to optimise them for map reading or multitasking etc, you’d think there’d be some important sex differences in the way functional hubs are lateralised (distributed to one side of the brain or the other). In fact, “no differences in gender were observed,” the authors said.
In conclusion – Wow, those are some pretty wiring diagrams! Oh … shame about the way they interpreted them.
Read the rest of this entry »