Sex online 3g
Sex online 3g
These findings are corroborated by a similar analysis of personality traits, attitudes, interests, and behaviors of more than 5,500 individuals, which reveals that internal consistency is extremely rare.
However, if brains are internally consistent in the degree of “maleness-femaleness” of each of their elements, it will still be possible to align brains on a “male-brain–female-brain” continuum (4, 5).
Volumes falling in the “intermediate” zone are colored in white; volumes in the “male-end” and in the “female-end” zones are colored using continuous blue-white and pink-white scales, respectively. Each horizontal line represents the brain of one subject and each column represents a single brain region.
The number above each column corresponds to the region’s number in the AAL atlas and in Table S1. The number of regions at the “intermediate” zone is not depicted because the number of “male-end”, “intermediate”, and “female-end” features always adds up to the number of features included in the analysis (which is the highest value on the )].
To exclude the possibility that this pattern of results was a result of the large age range included in the two samples, as sex/gender differences have been reported to differ in different age groups (13–15), we repeated the same analysis on 625 individuals from the 1000 Functional Connectomes sample (385 females, 240 males) 18–26 y of age.
Substantial variability was seen in 52% of brains, whereas internal consistency was evident in only 2.4% (Table 1, Tables S1 and S2, and Fig.
Rather, such a distinction requires the fulfillment of two conditions: one, the form of the elements that show sex/gender differences should be dimorphic, that is, with little overlap between the forms of the elements in males and females.
Two, there should be a high degree of internal consistency in the form of the different elements of a single brain (e.g., all elements have the “male” form).
The number of subjects in these datasets ranged from 138 to 855.
In each dataset, following an assessment of sex/gender differences in all regions, we focused on the regions showing the largest sex/gender differences (i.e., least overlap between females and males).
Such an alignment may be predicted by the classic view of sexual differentiation of the brain, according to which masculinization and defeminization of the brain are under the sole influence of testosterone (9).
In contrast, more recent evidence that masculinization and feminization are independent processes and that sexual differentiation progresses independently in different brain tissues (10), predicts poor internal consistency (4, 5).
Here we assess the degree of internal consistency in the human brain using data obtained from MRI, a method that allows the simultaneous assessment of multiple brain features in many individuals.