Sprache und Unterschiede im Gehirn von Mann und Frau

Im Schnitt fällt es Frauen leichter eine Fremdsprache zu erlernen. Ist diese Fähigkeit  kulturell bedingt oder biologisch?

Es sind jedenfalls Unterschiede im Sprachzentrum des Gehirns vorhanden:

Another previous study by the same group led by Dr. Godfrey Pearlson (9) has shown that two areas in the frontal and temporal lobes related to language (the areas of Broca and Wernicke, named after their discoverers) were significantly larger in women, thus providing a biological reason for women’s notorious superiority in language-associated thoughts. Using magnetic resonance imaging, the scientists measured gray matter volumes in several cortical regions in 17 women and 43 men. Women had 23% (in Broca’s area, in the dorsolateral prefrontal cortex) and 13% (in Wernicke’s area, in the superior temporal cortex) more volume than men.

These results were later corroborated by another research group from the School of Communication Disorders, University of Sydney, Australia, which was able to prove these anatomical differences in the areas of Wernicke and of Broca (3). The volume of the Wernicke’s area was 18% larger in females compared with males, and the cortical volume the Broca’s area in females was 20% larger than in males.

Oder in diesem Beitrag:

Cecile Naylor, a neuropsychologist at The Bowman Gray School of Medicine in Winston-Salem, North Carolina, stumbled upon dramatic sex differences almost accidentally as she was studying people with learning disabilities. As part of her study she recruited a control group of 30 men and 30 women „unhindered“ by neurological problems. She gave them an oral spelling test that required them to identify whether a word was exactly four letters long. To take the test, each person lay flat on a table, wearing what Naylor describes as „basically a revised motorcycle helmet.“ The helmet contained devices that measured blood flow through the cortex.

She found no essential difference in how well the men and women scored on the spelling test. An analysis of blood flow, however, showed sex differences in brain activity during the test. In men the patterns of blood flow showed that the most intense brain activity seemed to occur „in a tight linkage“ between two areas known to be involved in language and verbal communication: Wernicke’s area in the left temporal lobe and Broca’s area in the left frontal lobe adjacent to the motor cortex region controlling muscles of the face, jaw, tongue, and throat. The two areas are connected by a thick band of fibers. The standard model for language holds that language making and comprehension arise in Wernicke’s area and then travel via the pathway to Broca’s, where they call up the program that causes the phrases to be spoken.

In women, though, she found no such intense coupling between the two areas. Instead Wernicke’s was actively engaged with two other areas, one behind it in the left temporal lobe. Wernicke’s was also linked to its „mirror“ area in the right temporal lobe. Without further research, Naylor is loath to say what these startling differences mean, but she will speculate a little. „The area behind Wernicke’s lies between the primary visual and auditory regions,“ she says, „so one might argue that women have an additional imaging function“ during the language process. The area opposite Wernicke’s in the right hemisphere is involved in the emotional comprehension and expression aspect of language. If this region is engaged in women, then it is not farfetched to think that during language processes a typical woman brings a richer, more expanded emotional component into play than most men do.

In men, as language impulses move toward speech, only Broca’s area is engaged. In women, Naylor found, „almost every area of the cortex, left and right hemisphere, has some unique relationship with Broca’s during the task, as if there were many independent things going on between Broca’s and lots of different regions.“ Is it almost as if a woman’s brain is „ablaze“ during language processing? „Well,“ Naylor responds carefully, „it suggests some thing more global – that women are recruiting areas of the brain that enable them to use more strategies than men.“

The male arrangement follows the classical model of language function „as a unit independent from the rest of the brain,“ she says, adding that most language-area studies have been made with men. The classical model may be classic for only about 50 percent of the human population. Naylor’s work may also explain why, according to some studies, women recover faster than men from certain types of strokes attacking the core language regions.

Da üblicherweise beide Geschlechter in der Schule gleichermaßen mit Fremdsprachen in Kontakt kommen und diese Lernen müssen erscheint mir eine kulturelle Prägung die großen Unterschiede nicht erklären zu können. Bei einem kulturabhängigen Lernprozess müsste das Gehirn, da der die spätere Menge des Inputs ungewiss ist, den gleichen Weg wählen und diesen dann später lediglich stärker ausbauen. Das ein anderer Weg bestritten wird ist bei einer kulturellen Prägung nicht zu erwarten, weil die Intensität der Beeinflussung ja nicht im voraus abzusehen ist.

Interessant ist auch, dass Sprachen, die früh gelernt werden in der Broca-Area gemeinsam abgelegt werden, später erlernte Fremdsprachen aber einen getrennten Bereich in der Broca-Area erhalten. Dies zeigt, dass beim Erlernen der Sprache bestimmte Zeitfenster vorhanden sind, die den Erwerb der Sprache begünstigen.

Meine Begründung für die besseren Sprachfähigkeiten wäre, dass Gentests zeigen, dass normalerweise die Frau zum Mann gezogen ist, wenn das Paar aus getrennten Stämmen stammte.

Steinzeitliche Partnersuche: Wie Mann und Frau in der Jungsteinzeit zusammen kamen, konnte jetzt die Analyse eines Steinzeitgrabes klären: Die Frauen verließen die Gegenden, in denen sie aufgewachsen waren, und zogen in den Haushalt des Mannes. Er und die Söhne blieben in der Region ihrer Kindheit sesshaft.

Das Frauen, die schneller eine fremde Sprache lernen konnten, eine bessere Position in der neuen Gruppe erreichen konnten (besser am Alltagsleben teilnehmen konnten, besser wichtige Informationen erhalten und weitergeben konnten) und damit auch die Überlebenschancen ihrer Kinder verbesserten leuchtet ein. Sie hatten damit mehr Nachkommen, die sich selbst Fortpflanzen konnten, so dass eine Evolution bei den Frauen stattfinden konnte, die deren Sprachlernfähigkeiten verbesserte. Da Männer blieben wo sie waren, mussten sie seltener eine neue Sprache lernen und diese Fähigkeit brachte ihnen daher weniger Vorteile.