Definitief bewezen: de hersenen van mannen en vrouwen zijn anders, al vóór de geboorte
door Gerard Driehuis, journalist en redacteur welingelichtekringen.nl
25 Maart, 2019
Het is een taboe: beweren dat de hersens van mannen en vrouwen verschillen. Want het zou lijken op het goedpraten van de verschillen in inkomen en macht. Maar het is gewoon zo. De hersens van mannen en vrouwen verschillen. En dat komt niet door opvoeding en cultuur, maar door biologie. Onderzoekers waren in staat bij 118 nog niet geboren baby's in de tweede helft van de zwangerschap de zich ontwikkelende hersenen te bestuderen. En de hersenen van meisjes bleken te verschillen van de hersenen van jongetjes.
Moriah Thomason, van New York University Langone, heeft het onderzoek uitgevoerd om aandoeningen als autisme en aandachtstekortstoornis met hyperactiviteit (ADHD) te begrijpen, die jongens meer treffen dan meisjes. Ze zegt dat ze niet verrast is dat de bedrading van de hersenen verschilt, maar dat het haar wel verrast heeft hoe duidelijk de verschillen zijn. "Er zijn veel verschillen in de organisatie van mannelijke en vrouwelijke foetale hersenen." Het kan het einde betekenen van de strijd of verschillen tussen mannen en vrouwen allemaal zijn aangeleerd of (deels) aangeboren.
Vertaling van een alinea uit onderstaand artikel
De hersenen van mannelijke baby's zijn ontvankelijker voor omgevingsinvloeden dan die van de vrouwelijke baby's," zei ze. "We hebben eerder gezien dat de prenatale hersenen van vrouwelijke baby's stabieler lijken te zijn, meer gekoppeld aan het toekomstig gedrag. Het is alsof de vrouwelijk hersenen een strakkere brein-tot-toekomstig-gedrag-koppeling hebben. Als dat waar is, kan dat gedeeltelijk verklaren waarom de mannelijke hersenen kwetsbaarder én meer programmeerbaar zijn.
Ze zei dat geen van de bevindingen de invloed van de maatschappij op meisjes tijdens hun ontwikkeling uitsluit, maar ze laten ook zien dat de biologie een rol moet spelen. "Er zijn studies die aantonen dat culturele beïnvloeding vanaf dag één gebeurt, maar ik zie geen goed argument voor het feit, dat dit in de baarmoeder al zou gebeuren."
(Vertaald met DeepL.com/Translator en Google Translate)
Proof at last: women and men are born to be different
Tom Whipple, Science Editor
The Times, March 25 2019
New research suggests that differences in male and female brains are at least partly innate, rather than due solely to culture
Published in Developmental Cognitive Neuroscience
It is unlikely to prove that men are better at map reading or women win at multitasking, but a study has found for the first time that brain differences between the sexes begin in the womb.
The research, described as "heroic" because of its complexity, suggests that some of the divergence in male and female neurology is innate, rather than due solely to culture.
Scientists were able to conduct brain scans of foetuses to look for the changes in the connectivity of a growing brain and how it relates to sex.
The work, involving 118 foetuses in the second half of pregnancy, speaks to an occasionally acrimonious debate in neuroscience about the extent to which the differences seen between the brains of men and women reflect fixed biology or the effects of socialisation.
Yesterday some academics strongly questioned the findings, published in Developmental Cognitive Neuroscience.
Moriah Thomason, from New York University Langone, conducted the research in part better to understand conditions such as autism and attention deficit hyperactivity disorder (ADHD), which affect boys more than girls.
"What we are trying to discover is how the functional organisation of the brain begins," she said. "Understanding how the brain becomes assembled may provide insight into its overall architecture." She said that she was not surprised to find differences in the wiring of the brains but was still impressed by how clear it was. "There were many differences in the organisation of male and female foetal brains," she said. "That's what I would expect. From what we know about evolution it seems likely that sexual dimorphism would emerge at an early age."
One of the biggest differences found by Professor Thomason and Muriah Wheelock, the study's lead author, was in connectivity across areas of the brain that are far apart. As they matured in the womb, girls produced more "long-range" networks than boys. It is impossible to know what this means in practice, but Professor Thomason said that one fact that has long intrigued her is that the brains of young boys tend to be more changeable than girls.
"Males are more susceptible to environmental influences than female babies," she said. "We have previously seen that the prenatal brain of the female appears to be more robust, more linked to future behaviour. It's almost as if the female brain has a tighter brain-to-outcome pairing. If that's true that could partially account for the fact the male is more vulnerable, and programmable."
She said that none of the findings precluded the influence of society on girls as they develop, but they also show that biology must play a role. "There are studies that show that sexual acculturation happens from day one, but I don't see a good argument for the fact it is happening in the womb."
Stuart Ritchie, of King's College London, welcomed the study. "I'm pleased to see researchers looking at this kind of very early difference," he said. "If this sort of result was confirmed to be replicable, that is, found in other samples, and reliable, that is, the brain network difference found at this point isn't ephemeral, then it might shed some light on the debate we're having on whether social influences are the cause of the substantial brain sex differences we see in childhood, adolescence and adulthood."
However Gina Rippon, professor of cognitive imaging at Aston University, strongly disagreed. She has written a book, The Gendered Brain, that promises to "shatter the myth of the female brain". She said the study was "heroic" in overcoming the technical difficulties of scanning brains in the womb but accused the researchers of being misleading in their interpretation. "They have potentially really interesting and innovative data which deserves better treatment than this," she said. "In pursuit of a poorly defended hunt-the-difference agenda, they subjected their data to indefensibly weak statistical comparisons and drew unfounded conclusions."
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