The brain is a very complex organ, since it stores (in just under 1500 grams of tissue) everything we feel and think, what we wish and believe about the world around us and ourselves. That is why it has always generated an enormous fascination, and why we know it a little better every day.

Traditionally, men and women have been assigned different ways of acting and feeling , which although they could respond to discrepancies in social conditioning, have been the incentive to explore possible dimorphisms in the structure and function of their brains.

The research that has been carried out over the years has not been without controversy, as it is fed by confusing and contradictory findings. So much so, that even today it is difficult to assume that any of them can be the object of global consensus; or considered as a substantial explanatory factor for cognitive-affective, attitudinal and behavioural differences between the sexes.

However, in this article we will explore the results that enjoy certain evidence in this area of scientific knowledge, without forgetting that each of them continues to be studied for a future adjustment of its plausibility and scope. Let us now delve into the differences between the brains of men and women through this summary of the most important findings.

Differences between male and female brains

When comparing the brains of both sexes, one of the details that stands out is that men’s brains are significantly larger and heavier than those of women . On average its volume is 1260 cubic cm, while theirs reaches about 1130. It is estimated that the male brain is 10% larger, and that it weighs between 10% and 12% more. This fact is due to the fact that their body size is also different, to the extent that controlling for such a variable results in a proportional comparison of the absolute difference between brains (which is not linked to intelligence or any other cognitive function).

If we observe the grey substance and the white substance in subjects of both sexes (total number of nerve cells and synaptic connections respectively) it becomes visible that the male has up to 6.5% more neurons and the female has 10% more “networks” (as well as superior neuronal compaction in certain areas). This data indicates a notable dimorphism attributable to sex, with greater clarity in specific regions of the cerebral parenchyma (as will be detailed in successive chapters).

An interesting nuance is that the “adjustment” of the two brains according to body weight precipitates a reversal of this effect, so that men would have more synaptic connections and women more concentration and number of neurons. Recent studies in this regard are beginning to question the (traditionally accepted) fact that either sex has a greater number of such cells or their connections, so it is an unsubstantiated fact.

Naked observation of the brain shows a corpus callosum of higher density among women . Such a structure is composed of a bundle of nerve fibers that has the function of joining the hemispheres, facilitating interaction and mutual collaboration. This area, located in the very depths of the organ, is essential for many daily tasks that would require “integrated” information processing.

Therefore, it has been established as a finding by which to support a supposedly greater laterality in the male (understood as the control of each half of the body by the opposite side of the brain and the specialization of the hemispheres), despite being a fact that does not enjoy total agreement. There are also studies that associate the same connectivity with a greater capacity to contact emotions and with a certain susceptibility to suffering from depression (more common in women).

Observing precisely both hemispheres, slight differences can be seen in the left one (bigger in men) and the right one (which is equated with its opposite in the case of women) , which has offered empirical support to the traditional idea of dissonances between the sexes in dimensions such as language or spatial processing.

Precisely with regard to verbal ability, a difference has been found for the volume and size of the planum temporale (11% larger in women), a structure behind the auditory cortex involved in the neurological development of cognitive functions related to the use and learning of a language. The greater asymmetry in men reflects their tendency towards hemispheric specialization, in contrast to the “holism” characteristic of women (more distributed cognitive functions).

As for the convolutions and clefts (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 that it serves to connect the temporal lobes of the hemispheres through the midline, facilitating their interaction in those born without a corpus callosum (agenesis). We also know that the post-central gyrus is 10% more pronounced among women, which would be associated with central vibration processing and fine motor functions.

As for the cerebral lobes, there is evidence of the accentuated presence of neurons in the temporal neocortex of the male, although the data is inverted in the posterior region, where women have a greater number of neurons on average (speech recognition and face perception). On the other hand, the lower parietal lobe is thicker in males (especially in the left hemisphere), and is related to spatial/mathematical order skills (connection between parts of an object, three-dimensional rotation, speed and tempo perception or distance estimation).

Finally, some frontal lobe structures, such as the orbitofrontal cortex or others, are thicker among women (involved in the development of higher cognitive functions and central inhibition of impulsive acts).

Specific structures and function

In the following we will see which are the specific regions for which some differences between men and women are recognised . These are generally subtle divergences, which are estimated on average, without considering that the neuroplastic processes of human beings are subject to their experience and the circumstances of the environment in which they carry out their daily life. This is why each individual brain can be very different from the standard of the organic sex to which it belongs, and why much of what is described here could be due to cultural or educational causes.

On the other hand, there are hypotheses that attribute to testosterone a fundamental role for intersex divergence at the brain level, so it would be a key influence to structure the organ (which would start in gestation). It is understood, therefore, that the findings to be described imply a clear confluence of the biological and the social ; despite the fact that the way in which one and the other contribute to the equation is not yet known with total accuracy. We proceed to enter, with greater depth, into the differences between the brain of men and that of women at the molecular level.

1. Hypothalamus

The hypothalamus is a brain structure whose function is essential for life; it participates in a significant way in the regulation of processes such as temperature, hunger, thirst or circadian rhythms . It coordinates closely with the pituitary gland to orchestrate the entire metabolic regulation of the organism by means of multiple “axes” (gonadal, adrenal, thyroid, etc.).

Available evidence indicates that some of its regions, such as the interstitial nucleus, are larger in males. This reproduces for the medial preoptic area, the area of the brain most intimately associated with mating and reproduction. In these cases it is estimated that men double the gross volumes of women.

The hypothalamic suprachiasmatic nucleus (which regulates circadian and reproductive rhythms) reaches a similar size in both sexes, although it adopts different shapes in each case (rounded in men and oval in women). It is likely that the latter connects differently with brain areas that are distant, which could explain certain differences attributable to sex , such as the greater sensitivity in women to light variation that concurs with seasonal change.

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2. Amygdala

The amygdala is a limbic region related to emotional processing and memory . Studies on this structure indicate that males are up to 10% larger than females, and that it is also linked to different areas for each sex (visual cortex/striation in males and insula/hypothalamus in females).

Such findings indicate a greater emotional reactivity in men to environmental stimuli, and in women to aspects of their own corporeality. Some research suggests that any morphological changes in this structure occur according to the levels of steroids in circulation.

On the other hand, it has been observed that when evoking emotional memories men show intense activation of the right amygdala and women on the left. This nuance has been associated with a differential processing of such information, in which men would emphasize the generality and women would focus on the details. Finally, it is known that the ratio of the proportional magnitudes of the amygdala and the orbitofrontal cortex is higher in women , which makes them able to control impulses more efficiently (as well as plan and use emotion-oriented coping strategies).

3. Hippocampus

The hippocampus is an essential structure for the consolidation of memory in the long-term storage (generating a new memory) as well as for the interaction between emotions and perceptions. The 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 efficiently integrate declarative memories with affective life (adding emotional nuances to what they had experienced). However, recent work (in which the overall size of the brain has been controlled) shows no difference between the sexes, the conclusion being currently more acceptable to the scientific community.

Differences in spatial orientation between the sexes (emphasis on details such as spatial “markers” in women or articulation of schematic mapping in men) have been classically associated with discrepancies in this structure, although the parietal lobe would also contribute in some way. There is much evidence that spatial vision training has extensive resonances on hippocampal neurons, thereby increasing the volume of these regions.

4. Cerebellum

The cerebellum is an essential structure for maintaining posture, balance and level of consciousness. Research conducted to compare the sexes projects a disparate amount of information, but almost always points to a larger volume for males (about 9% ).

This phenomenon is associated with superior motor control in the case of men, and more specifically for what are usually known as gross motor skills (practicing group sports or running, to which their more developed muscle mass also contributes). It would facilitate an adjusted “perception” of one’s body position in space.

5. Ventricles

Our brains have inside them four big empty/interconnected spaces, which are called ventricles . Through them circulates the cerebrospinal fluid, which allows a correct hydration and nutrition of the nervous tissues, as well as their protection in case of impact. Such vaults tend to be of a higher volume in males, which is consistent with the fact that their brains (in general) are also of a higher volume. These structures may be increased in size in some psychopathologies (such as schizophrenia or bipolar disorder type I or II), which is associated with further cognitive impairment.

  • You may be interested in: “The 7 Big Differences between Men and Women”

Other information to take into account

As previously indicated, the male brain has more asymmetries than the female brain, which means that the two hemispheres have more differences between them than in the case of the latter. Furthermore, 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 greater variability between them . This fact could correspond to the organizational contribution of prenatal steroids, which elicit differentiation in such a phase of development (masculinizing a brain that is initially female for all).

What we know about the brain helps us understand why there are differences between men and women in matters such as emotional processing, spatial vision, or language. However, it is essential to keep in mind that every individual has the power to shape his or her brain through experience and habit, whether it is a man or a woman.

Bibliographic references:

  • Joel, D. (2011). ¿Masculino o femenino? Los cerebros son intersexuales. Fronteras de la neurociencia integradora, 5: 57.
  • Kelly, S., Ostrowski, N. y Wilson (2000). Gender Differences in Brain and Behavior (Diferencias de género en el cerebro y el comportamiento). Farmacología, bioquímica y comportamiento, 64, 655-64.