Neuroscience of sex differences
Psychological sex differences are thought by some to reflect the interaction of genes, hormones, and social learning on brain development throughout the lifespan.
[4][5] The ideas of differences between the male and female brains have circulated since the time of Ancient Greek philosophers around 850 BC.
This may be due to the fact that females have a more intricate evaluation of risk–scenario contemplation, based on a prefrontal cortical control of the amygdala.
Researchers at the University of Toronto say that differences between men and women on some tasks that require spatial skills are largely eliminated after both groups play a video game for only a few hours.
Researchers at the University of Iowa found that the thicker grey matter in the parietal lobe of females led to a disadvantage in mental rotations, and that the larger surface areas of the parietal lobe of males led to an advantage in mental rotations.
The results found by the researches support the notion that gender differences in spatial abilities arose during human evolution such that both sexes cognitively and neurologically developed to behave adaptively.
[17][18] Clinical psychologist Simon Baron-Cohen has defended the neuroscience of sex differences against charges of neurosexism, arguing that "Fine's neurosexism allegation is the mistaken blurring of science with politics," adding that "you can be a scientist interested in the nature of sex differences while being a clear supporter of equal opportunities and a firm opponent of all forms of discrimination in society.
[23] Given that cortical complexity and cortical features have had some evidence of positive correlation with intelligence, researchers postulated that these differences might have evolved for females to compensate for smaller brain size and equalize overall cognitive abilities with males, though the reason for environmental selection of that trait is unknown.
[23] Researchers further analyzed the differences in brain volume, surface area and cortical thickness by testing the men and women on verbal-numerical reasoning and reaction time in separate groups.
It was found that the group of men slightly outperformed the women in both the verbal-numerical reasoning and reaction time tests.
Subsequently, the researchers tested to what extent the differences in performance was mediated by the varying attributes of the male and female brain (e.g. surface area) using two mixed sample groups.
[24] According to the neuroscience journal review series Progress in Brain Research, it has been found that males have larger and longer planum temporale and Sylvian fissure while females have significantly larger proportionate volumes to total brain volume in the superior temporal cortex, Broca's area, the hippocampus and the caudate.
A 2016 meta-analysis of volume differences found a higher HCV in males without correcting for total brain size.
[5] Larger volumes in females were most pronounced in areas in the right hemisphere related to language in addition to several limbic structures such as the right insular cortex and anterior cingulate gyrus.
[30] Early postmortem studies of transgender neurological differentiation were focused on the hypothalamic and amygdala regions of the brain.
Using magnetic resonance imaging (MRI), some trans women were found to have female-typical putamina that were larger in size than those of cisgender males.
Sex differences were evident in other networks, as women also tend to have higher activity in the prefrontal and limbic regions, such as the anterior cingulate, bilateral amygdala, and right hippocampus, while men tend to have a distributed network spread out among the cerebellum, portions of the superior parietal lobe, the left insula, and bilateral thalamus.
The content of β-endorphin (β-EP), an endogenous opioid peptide, has been found to decrease (in varying amounts/brain region) post ovariectomy in female rats within the hypothalamus, hippocampus, and pituitary gland.
Such a change in β-EP levels could be the cause of mood swings, behavioral disturbances, and hot flashes in post menopausal women.
During the menstrual cycle, progesterone increases just after the ovulatory phase to inhibit luteinizing hormones, such as oxytocin absorption.
