Why Sex Matters for Neuroscience, Research Paper Example

What are the differences in organization between male and female brains?

Shared Features

• Testosterone and estrogen impact brain development
• Hormones interact with the brain to influence development and thus, behavior
• Estrogen, progesterone, and testosterone influence brain development in the womb and during puberty; different levels and combinations of these hormones are reminiscent of different stages of development (Jacobs, 1996)
• The behavioral patterns that influence the distinct behaviors of boys and girls throughout puberty continue to impact them in this manner throughout the remainder of their lives

Male Specific

• In the uterus, female brains come into contact with large amounts of testosterone
• A scientific study found that baby boys tend to explore their non-living environments more than baby girls, demonstrating a focus on surroundings more than people
• During puberty, an influx of testosterone contributes to the teenage boy wanting to be left alone
• Teenage boys wish to socialize lest
• They become interested in sex or other hobbies at this point in their lives
• Teenage boys feel challenged to find their independence and they become stressed if they are unable to do so
• Boys try to find social order or structure among their peers by engaging in conflict and competition
• They are less interested in forming bonds or relationships with other boys in the same manner that girls do

Female Specific

• In the uterus, female brains come into contact with large amounts of estrogen
• Female babies begin studying facial recognition earlier and tend to make eye contact and look upon the faces of relevant adults earlier than male babies
• A scientific study found that baby girls tend to look upon the faces of the adults in their lives ten to twenty times more frequently compared to male babies because they want to understand whether they are gaining approval or disapproval
• Estrogen in the brain encourages teenage girls to remain connected with one another in order to cope with anxieties
• Some rivalry occurs between females because they are subconsciously vying for the attention of the same boys
• Even though teenage girls fight frequently, then can mend their relationships when this is deemed necessary

Gender-Specific Brain Organization

Shared Features

• The amygdala is a part of the brain that is closely tied into the fight or flight instinct
• It is controlled by hormones
• The prefrontal cortex is used to help make decisions and it helps balance the impulse triggered by the amygdala
• The anterior cingulate cortex is the part of the brain that helps people make rational decisions
• The brain is divided into two halves
• The left half of the brain deals with information processing and logic
• The right half of the brain deals with responding to emotions, spatial and visual information, and information processing
• The corpus callosum connects the two halves of the brain, also referred to as hemispheres
• The hippocampus is the memory center of the brain

Male Specific

• In men’s brains, the amygdala is larger
• This part of the brain is immersed with more testosterone in men, which heightens responses and contributes towards aggression (Swaab et al., 1984)
• Men have a smaller prefrontal cortex
• The anterior cingulate cortex is smaller in men, which contributes to greater risk taking
• The corpus callosum is thinner in men, indicating that there is a lesser connectivity between the two halves of the brain compared to women
• Men use the right side of their brain for spatial skills and the left for word and sound recognition
• Men’s brains have less connections in the hippocampus which allow them to be more easily focused
• Men have an overall higher percentage of cerebrospinal fluid and white matter

Female Specific

• In women’s brains, the amygdala is smaller
• The hormones that signal to the amygdala in women persuade them to collect in groups in order to ensure safety (Cahill, 2006)
• Women are more likely to run away from a fight than to actively participate
• The prefrontal cortex is larger in women, which allows them to more carefully consider potential recourses before taking action
• This minimizes the impact of the amygdala
• The anterior cingulate cortex is bigger in the women’s brain and is also associated with the reason that women worry more frequently than men
• Anxiety is four times more common in women
• The corpus callosum is thicker in women, indicating that there is a greater extent of connectivity between the two halves of the brain
• Women are able to use both parts of the brain for processing words and sounds in addition to processing emotions
• The hippocampus is estrogen sensitive so they have 11% more neurons in this part of the brain that assist with language and hearing
• Women have more grey matter in their left orbitofrontal GM
• Women have an overall higher percentage of grey matter
• Women between the ages of 19 and 32 are able to use glucose more quickly in the orbital prefrontal cortex

Brain Differences between Homo and Heterosexuals

• Studies have shown that gay men may be born with a predisposition to be gay based upon their brain characteristics (Swaminathan, 2008)
• According to studies conducted at the Stockholm Brain Institute in Sweden, straight women and gay men have similar brain proportions
• A majority of these similarities are related to the size and activity of the amygdala and the size of the brain overall
• Heterosexual men and lesbian women also share many brain similarities
• In gay men and women, there tended to be more brain flow to the amygdala when either category of experimental subject tended to express anxiety
• The right hemisphere of the brain was found to be slightly larger in heterosexual men and lesbian women
• The right and left hemispheres of the brain were found to be generally equal in straight women and gay men
• It was found that the corpus callosum is larger in gay men than it is in heterosexual men
• PET scans and MRI scans were used to conduct these studies to determine the similarity in brain structure between men and women

Conclusion

• While it is challenging to be truly aware of all of the characteristics that make men and women different, we can use many of the scanning tools to determine the differences that are possible to study
• With new scientific innovation, it is likely that we will gain new understandings of the scientific similarities and differences between the brains of men and women
• It is important to gain an understanding of brain differences because this will allow us to gain a greater comprehension of the relationship between brain structure and behaviors

References

Cahill L. (2006). Why sex matters for neuroscience. Nature Reviews. Neuroscience, 7(6): 477–84.

Jacobs LF. (1996). Sexual selection and the brain. Trends in Ecology & Evolution, 11(2): 82–6

Swaab DF, Hofman MA. (1984). Sexual differentiation of the human brain. A historical perspective. Progress in Brain Research, 61: 361–74.

Swaminathan N. (2008). Study Says Brains of Gay Men and Women Are Similar. Retrieved from http://www.scientificamerican.com/article/study-says-brains-of-gay/