Male/female brain differences? Big data says not so much

Nov 3, 2015

Source: Rosalind Franklin University of Medicine and Science

A research study at Rosalind Franklin University of Medicine and Science has debunked the widely-held belief that the hippocampus, a crucial part of the brain that consolidates new memories and helps connect emotions to the senses, is larger in females than in males.

Lise Eliot, PhD, associate professor of neuroscience at the university’s medical school, headed a team of students in a meta-analysis of structural MRI volumes that found no significant difference in hippocampal size between men and women. Meta-analysis is a statistical technique that allows researchers to combine the findings from many independent studies into a comprehensive review. The team examined findings from 76 published papers, involving more than 6,000 healthy individuals.

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5 comments on “Male/female brain differences? Big data says not so much

  • 1
    maria melo says:

    “Accepted beliefs””? Well, I would be amazed at the expression, but after having watched a TED talk, where a neuroscientist mentioned she used to hear a certain number of neurons that supposedly humans have, but when she tried to find out the source, she didn´t find any, so she had to figure out a technic to make the math . In first place, I would never expect science to rely on “beliefs”, but i guess it does sometimes.

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  • One need not read any further than meta-analysis here.

    File drawer problems, funnel plot problems and agenda bias plague this fuzzy tool of medical and social science. Do you own work!

    Too much criticism of this technique is too much for its users to ignore. A small sample of the problems with meta-analysis and why I pay it no attention.

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  • @OP – Male/female brain differences? Big data says not so much

    I think if we look at the development at comparable ages from gestation to early teens, the data says “quite a lot of differences”! Connections matter, – gross size in adulthood, is NOT everything!

    How a boy’s brain develops in the womb

    Boys in the womb are little testosterone machines. In fact, says Margaret M. McCarthy, a professor of physiology at the University of Maryland who studies early brain development, male babies are born with as much testosterone as a 25-year-old man! After birth, testosterone plummets until a boy reaches puberty.

    Among its many other jobs, testosterone shapes a male’s developing brain. Animal studies show that it pares down the connections between brain cells (synapses) in some places and bulks them up in other places.

    One study found that both male and female rats who were exposed to extra testosterone before birth performed better at maze tests shortly after birth. While scientists aren’t ready to draw conclusions about humans based on this study, it is an indicator that testosterone may improve spatial reasoning.

    Animal studies also show that in any male, some regions make connections typical of males, but some parts remain feminine. “There’s really no such thing as a completely male brain,” McCarthy says. “It’s a mosaic of male and female.”

    How a girl’s brain develops in the womb

    Girls make some testosterone before they’re born, too, but not nearly as much as boys, Berenbaum explains. And while girls do produce female hormones such as estrogen, these seem to have little impact on their developing brains.

    In other words, girls have the brain that boys would have if theirs weren’t reshaped by testosterone.

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  • Neodarwinian
    Nov 3, 2015 at 8:41 pm

    One need not read any further than meta-analysis here.

    I think the differences between browsing at arms-length, and research, are quickly expressed in revealed biases!

    MRI scans certainly do not give enough detail to see neurons and connections.
    Cognitive Skills

    In cognitive skills, the largest and most consistent gender differences are found in verbal, language, and certain spatial skills. For example, girls tend to produce words at an earlier age, have a larger vocabulary, and show a higher level of language complexity beginning in early childhood (Feingold, 1993; Halpern, 2000; Hyde & Linn, 1988). The biggest differences in verbal skills during school-age years—all favoring girls—are in spelling, overall language measures, and writing. Some of these gender differences seem to get smaller during adolescence, whereas differences in other areas (e.g., writing) remain (Halpern, 2000). These differences have remained relatively stable over 30 or more years of research. Differences in other specific skills tend to be small, and some have decreased in recent decades (Campbell, Hombo, & Mazzeo, 2000). Clear and consistent gender differences favoring males exist for some spatial skills such as mental rotation (the ability to visualize how an object would look if you viewed it from a different angle). Differences in these areas emerge at around 9 to 13 years and widen throughout adolescence. Like the verbal skills we discussed above, gender differences in mental rotation have remained stable over the last few decades (Masters & Sanders, 1993; Voyer, Voyer, & Bryden, 1995).

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  • All this raises the question. Why?

    There was a meta-analysis done some years ago that came to the conclusion that there were minuscule variances between men and women. The data were normally distributed. The usual ideologues touted this ” study ” to the sky.

    Then one, perusing the study, looked at the variance from the mean given. It was 0.46. A variance so at odds with the studies conclusion that one was flabbergasted and almost incapable of response. Needless to say this study fell off the radar long ago and I have heard nothing of it in years.

    You do your own work and the conclusion chips fall where they may. You do not correlate the work of others as that makes you meta-analysis immediately suspect. Drug trials use this method, meta-analysis, to enlarge effects of drugs on trial. I see no other use for this technique.

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