The brain is a very complex organ, because it monopolizes (in just under 1500 grams of tissue) everything we feel and think, what we desire and believe about the world around us and about ourselves. This is why he has always aroused enormous fascination, and we are getting to know him a little better every day.
Men and women have traditionally been assigned different ways of acting and feeling, Which, although they may respond to divergences in social conditioning, have been the incentive to explore possible dimorphisms in the structure and function of their brains.
The research that has been conducted over the years has not been without controversy, as it is fueled by confusing and contradictory results. So much so that even today it is difficult to suppose that any of them can be the subject of a global consensus; or considered a substantial explanatory factor for cognitive-affective, attitudinal and behavioral differences between the sexes.
However, in this article we will explore the results that benefit from some evidence in this area of scientific knowledge, without preventing it from continuing to study – each of them for future adjustment of its plausibility and scope. Let’s dig deeper, then, in the differences between a man’s brain and a woman’s brain through this summary of the most important results.
Differences between a man’s brain and a woman’s brain
When comparing the brains of the two sexes, one of the details that comes to mind is that that of men is much larger and heavier than that of women. On average, their volume is 1260 cubic cm, while that of them reaches about 1130. It is estimated that the male brain is 10% larger, and has a weight between 10% -12% higher. This is because the body size of the two is also different, to the point that controlling for such a variable becomes a proportional comparison of the absolute difference between the brains (which is not related to intellect) or to any other cognitive function).
If we observe gray matter and white matter in subjects of both sexes (total number of nerve cells and synaptic connections respectively) it becomes visible that man has up to 6.5% more neurons and that in women, it has 10% more networks “” (as well as greater neuronal compaction in certain areas). These data indicate noticeable gender dimorphism, more pronounced in specific regions of the brain parenchyma (As will be detailed in the successive chapters).
An interesting nuance is that “adjusting” the two brains for body weight precipitates a reversal of this effect, so that males would continue to harbor more synaptic connections and females more focus and neural count. Recent studies in this regard are starting to question the (traditionally accepted) fact that either sex has a greater amount of such cells or their connections, so this is unsubstantiated data.
Bare observation of brain evidence a denser corpus callosum in women. Such a structure is composed of a bundle of nerve fibers that has the function of uniting the hemispheres, facilitating interaction and mutual collaboration. This area, located deep within the organ, is essential in many daily tasks that would require “integrated” information processing.
Therefore, it was erected as a discovery by which to support a supposedly greater laterality in humans (understood as the control of each half of the body on the opposite side of the brain and the specialization of the hemispheres), all and be a fact it does not enjoy full agreement. There are also works that associate the same connectivity with a greater ability to get in touch with emotions and a certain susceptibility to depression (more common in women).
By observing precisely the two hemispheres, slight differences can be observed on the left (larger in men) and on the right (which is equated to its opposite in the case of women), Which provided empirical support to the traditional idea of gender dissonances in dimensions such as language or spatial processing.
Precisely in terms of verbal ability, it was found a difference in the volume and size of the planum temporale (11% greater in women), a structure posterior to the auditory cortex involved in the neurological development of cognitive functions related to the use and learning of a language. The greatest asymmetry in men is reflected in their tendency towards hemispherical specialization, unlike the “holism” specific to women (more distributed cognitive functions).
As for convolutions and fissures (the folds that the brain shows on the outside), it has been found that the anterior commissure is 12% more extensive in women. It is believed to be used to connect the temporal lobes of the hemispheres across the midline, facilitating their interaction in people born without the corpus callosum (agenesis). It is also known that postcentral rotation is 10% more pronounced in women, which would be associated with the treatment of central vibrations and fine motor functions.
Regarding the brain lobes, there is evidence for the increased presence of neurons in the temporal neocortex of men, although the data is reversed in the posterior region, where women on average have the most neurons. (recognition of spoken language and facial perception). On another side, the lower parietal lobe is thicker in humans (Especially in the left hemisphere), and is related to spatial / mathematical skills (connection between parts of an object, three-dimensional rotation, perception of speed and tempo or estimation of distances).
Finally, certain structures of the frontal lobe, such as the orbitofrontal cortex or others, are thicker in women (involved in the development of higher cognitive functions and in the central inhibition of impulsive acts).
Specific structures and functions
From now on we will see which are the specific regions for which certain differences between men and women are recognized. These are usually subtle discrepancies, which are estimated on average, without considering that human neuroplastic processes are subject to their experience and the circumstances of the environment in which they develop on a day-to-day basis. This is why each individual brain can be very different from the organic sex standard to which it belongs, and much of what is described here could be due to cultural or educational causes.
On the other hand, there are hypotheses that assign testosterone a key role for intersex divergence in the brain, so it would be a key influence in the structuring of the organ (which would start during pregnancy). It is therefore understood that the discoveries they will describe involve a clear confluence of the biological and the social; although how the two contribute to the equation is not yet known with full precision. We will delve deeper into the differences between male and female brains at the molecular level.
The hypothalamus is a brain structure whose function is essential for life; therefore remarkably participates in the regulation of processes such as temperature, hunger, thirst or circadian rhythms. It is closely coordinated with the pituitary gland to orchestrate all of the body’s metabolic regulation through multiple “axes” (gonadal, adrenal, thyroid, etc.).
The available evidence indicates that some of its regions, such as the interstitial nucleus, are larger in males. This replicates for the medial preoptic zone, the brain area most closely associated with mating and reproduction. In these cases, it is estimated that men double the gross volume of women.
The suprachiasmatic hypothalamic nucleus (which regulates the rhythms circadian and reproductive) reaches a similar size in both sexes, although it takes different shapes in each case (rounded in men and oval in women). The latter is likely to connect differently with distant brain areas, which could explain some differences attributable to sex., as the greater sensitivity in women to variations in light consistent with seasonal change.
The amygdala is a limbic region related to processing and emotional memory. Studies on such a structure indicate that men are up to 10% larger in size than women, and that it is also related to different areas for each sex (visual / striated cortex in men and insula / hypothalamus in women).
These results indicate greater emotional responsiveness in men to environmental stimuli and in women to certain aspects of their own bodies. Some research suggests that any morphological change in this structure occurs depending on the levels of circulating steroids.
On the other hand, it has been observed that by evoking emotional memories of men, they show an intense activation of the right amygdala and of the left women. This nuance was associated with the differential treatment of this information, in which men would emphasize generality and women would focus on details. Finally, we know that the ratio of the proportional sizes of the amygdala and the orbitofrontal cortex is greater in women, Which makes him able to control impulses more effectively (as well as plan and use emotion-focused coping strategies).
The hippocampus is an essential structure for long-term storage memory consolidation (Generate new memory) as well as for the interaction between emotions and perceptions. Original studies on this issue indicated that women had a greater volume of cells in these bilateral structures, which would explain why they could more effectively integrate declarative memories into emotional life (by adding emotional nuances to the lived experience). However, recent work (in which the overall size of the brain was monitored) shows no difference between the sexes, the conclusion being currently more acceptable to the scientific community.
The difference in spatial orientation between the sexes (emphasis on details such as spatial ‘markers’ in women or the articulation of schematic mapping in men) has classically been associated with deviations in this structure, although that the parietal lobe also contributes. There is ample evidence that spatial vision training has extensive resonances on hippocampal neurons, thereby increasing the volume of these regions.
The cerebellum is an essential structure for maintaining posture, balance and level of consciousness. Research conducted to compare the sexes projects different information, but almost always points a larger volume in the case of men (about 1, 9%).
This phenomenon is associated with greater motor control in men, and more particularly with what is commonly called gross motor skills (playing group sports or running, which also contributes to their more developed muscle mass). This would facilitate an adjusted “perception” of one’s own bodily position in space.
Our brains have it inside four large empty / interconnected spaces, called ventricles. Through them circulates the cerebrospinal fluid, which allows good hydration and good nutrition of the nervous tissues, as well as their protection in the event of impacts. These bends tend to be of a higher volume in men, which is consistent given that their brains (in general) are, too. These structures may increase in size in certain psychopathologies (such as schizophrenia or bipolar I or II disorder), which is associated with greater cognitive impairment.
Other data to consider
As noted above, the male brain has more asymmetries than the female brain, which means that its two hemispheres have more pronounced differences between the two than in the case of the latter. Beyond that, very recent research suggests that men are also more different from each other (in terms of organ structure) than women, which means that there is more variability between them.. This fact could correspond to the organizing contribution of prenatal steroids, which induce differentiation at such a stage of development (masculinizing an initially female brain for all).
What we know about the brain helps us understand why there are differences between men and women in areas such as emotional processing, spatial vision, or language. However, it is essential to keep in mind that every individual has the power to shape their brain through experience and habit, whether they are male or female.
- Joel, D. (2011). Masculine or feminine? Brains are intersex. Frontiers in Integrative Neurosciences, 5:57.
- Kelly, S., Ostrowski, N. and Wilson (2000). Gender Differences in Brain and Behavior. Pharmacology, Biochemistry and Behavior, 64, 655-64.