It has been jokingly said that “men are from Mars and women are from Venus.” Often, this is due to the notion that men and women think very differently. When analyzing male and female brains, there are often many similar areas that can be seen and neural activities that can be observed, but differences do also exist. According to Northwestern Medicine, “the male brain is 10 percent larger than the female brain,” but this difference has no effect on intelligence. Additionally, it has been discovered that the female brain contains more gray matter — which helps the body process information in the brain – but men tend to use more gray matter while women tend to use more white matter – which connects processing centers. An important job of the brain is to control hormonal cycles, and for females, these hormonal changes will occur across a monthly cycle. For men, however, a different cycle frequency has been observed.
A recent study has shown that men have a daily hormonal cycle that is linked to activity in their brains. The study was conducted at the University of California, Santa Barbara (UCSB) and involved scanning a 26-year-old caucasian male’s brain multiple times over a period of a month. It is described in the report of the study, published in the Journal of Neuroscience, that every 12-24 hours, the subject would go through a session where he “completed a questionnaire to assess stress, sleep, and mood states, followed by endocrine sampling at 7 a.m. (morning sessions) and/or at 8 p.m. (evening sessions).” Endocrine sampling will be used to determine hormone levels in the body at different times of the day. Additionally, a whole brain structural MRI was done to determine changes in head motion, but the report stated that there was “no significant difference between morning and evening sessions.” Whole-brain morphology assessments were also performed to test the gray matter volume, white matter volume, and cortical thickness of the participant’s brain.
The results of the tests showed a significant change in the brain from morning to night. In the morning, total brain volume and gray matter volume were at their peak but would be lower in the evening. With this, it was reported that these two values shared a positive correlation with steroid hormone concentrations, which include testosterone, estradiol, and cortisol. Cortical thickness shared a positive correlation as well with these values.
In analyzing the results, the researchers noted, “While it is clear that brain morphology exhibits circadian change, the role of steroid hormones in shaping diurnal changes in brain volume is not definitive, as results from the present study are correlational.” No significant relationships between the two could be determined when their correlations were restricted. While nothing may be conclusive, these results indicate that there may be more to look into regarding the cyclic change of brain volume from day to night, which may have an effect on changes in behavior.
Live Science, who talked with the researchers and the participants of the study, notes how those involved with the study were driven by the goal to uncover more about a cycle that is more understood but not as much with men. Elle Murata, a doctoral student in psychology and brain sciences at UCSB and one of the researchers in this study, stated, “this is, I think, another example debunking the myth that hormones are only relevant for females.” Pavel Shapturenka, the subject of the study, added a similar comment, addressing how much of the information out there highlights the hormonal invariability of females, but he appreciates how the study now brings light to how men’s endocrine systems have invariability and a path to a better understanding of the brain function of men.
