Main differences between men’s and women’s brains

A summary of the differences between the average male and female brain.

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

Traditionally, different ways of acting and feeling have been assigned to men and women.Although they could respond to discrepancies in social conditioning, they 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 free of controversy, since it is full of confusing and contradictory findings. So much so, that even today it is difficult to take for granted that any of them can be the subject of global consensus; or considered as a substantial explanatory factor for cognitive-affective, attitudinal and behavioral differences between the sexes.

Nevertheless, in this article we will explore the results that enjoy certain evidence in this field of scientific knowledge, without ignoring the fact that each of them is still being studied for a future adjustment of their plausibility and scope. Let us now delve into the differences between men's and women's brains through this summary of through this summary of the most important findings.

Differences between male and female brains.

When comparing the brains of the two sexes, one of the details that stands out is that the brain of the males is significantly larger and heavier than the brain of the females.. On average, its volume is 1260 cubic centimeters, while that of the female brain is about 1130 cubic centimeters. It is estimated that the male brain is 10% larger and weighs between 10%-12% more. This fact is due to the fact that the body size of one and the other is also different, to the point that controlling for this variable results in a proportional equalization of the absolute difference between brains (which is not linked to intelligence or any other cognitive function).

If we observe the gray matter and white matter 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 that the female has 10% more "networks" (as well as a superior neuronal compactness in certain areas). This data indicates a notable dimorphism attributable to sex, of greater clarity in specific regions of the brain parenchyma. (as will be detailed in subsequent chapters).

An interesting nuance is that the "adjustment" of the two brains according to body weight precipitates a reversal of this effect, such that males would harbor more synaptic connections and females more concentration and number of neurons. Recent studies in this regard begin 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.

The naked observation of the brain evidences a higher density of corpus callosum among females.. This 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 in the very depths of the organ, is essential in multiple daily tasks that require "integrated" information processing.

For this reason, it has emerged as a finding to support a supposed greater laterality in men (understood as the control of each half of the body by the opposite side of the brain and the specialization of the hemispheres), although this is 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 suffer from depression (more common in women).

Looking precisely at both hemispheres, there are slight differences in the left hemisphere (larger in men) and the right hemisphere (which equals its counterpart in women).This has provided empirical support for the traditional idea of gender dissonance 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. a difference has been found for the volume and size of the planum temporale (11% larger in females), 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 greater asymmetry in males reflects their tendency towards hemispheric specialization, in contrast to the "holism" characteristic of females (more distributed cognitive functions).

As for the convolutions and cystic folds (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 serve to connect the temporal lobes of the hemispheres across the midline, facilitating their interaction in those born without a corpus callosum (agenesis). Likewise, we know that the postcentral gyrus is 10% more pronounced among women, which would be associated with the central processing of vibration and with motor functions of a fine nature.

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

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

Specific structures and function

In the following we will see which are the specific regions for which some differences are recognized between men and women. These are generally subtle differences, which are estimated on average, without considering that the neuroplastic processes of human beings are subject to their experience and to the circumstances of the environment in which they develop their daily lives. It is for this reason that each individual brain can be very different from the standard of the organic sex to which it belongs, and that 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 intersexual divergence at the cerebral level, which would be a key influence in structuring the organ (which would begin in gestation). It is understood, therefore, that the findings to be described imply a clear confluence of the Biological and the socialThe way in which one and the other contribute to the equation is not yet known with complete accuracy. Let us now take a closer look at the differences between the male and female brain at the molecular level.

Hypothalamus

The hypothalamus is a brain structure whose function is essential for life. it plays an important role in the regulation of processes such as temperature, hunger, thirst and circadian rhythms.. It coordinates closely with the pituitary gland to orchestrate the entire metabolic regulation of the organism through multiple "axes" (gonadal, adrenal, thyroid, etc.).

Available evidence indicates that some of its regions, such as the interstitial nucleus, are larger in males. This is also true for the medial preoptic area, the brain area most closely associated with mating and reproduction. In these cases, males are estimated to have twice the raw volumes of females.

The hypothalamic suprachiasmatic 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 distant brain areas, which could explain certain differences attributable to sex, such as the greater sensitivity of women to the light variation associated with seasonal change.such as the greater sensitivity in women to the light variation that coincides with seasonal change.

2. Amygdala

The amygdala is a limbic region related to emotional processing and memory.. Studies on this structure indicate that males show a size up to 10% larger than that of females, and that it is also linked to different areas for each sex (visual cortex/striatum 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 circulating steroid levels.

On the other hand, it has been observed that when evoking emotional memories, men show an intense activation of the right amygdala and women an intense activation of the left amygdala. This nuance has been associated with a differential processing of such information, in which males would emphasize generality and females would focus on details. Finally, it is known that the ratio of the proportional magnitudes of the amygdala and the orbitofrontal cortex is higher in females, which makes them able to control the processing of information.This means that women can 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 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 larger 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 global size of the brain has been controlled) shows no differences between sexes, and this conclusion is currently more acceptable to the scientific community.

The difference in spatial orientation between the sexes (emphasis on details such as spatial "markers" in females or articulation of a schematic mapping in males) have been classically associated with discrepancies in this structure, although the parietal lobe may 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 the maintenance of posture, balance and level of consciousness. Research carried out to compare the sexes projects disparate information, but almost always points to a higher volume in the case of 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 (playing group sports or running, to which their more developed muscle mass also contributes). It would facilitate an adjusted "perception" of the position of one's own body in space.

5. Ventricles

Our brains have inside them four large 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 impacts. Such vaults tend to be larger in males, which is consistent with the fact that their brains (in general) are also larger. These structures may be increased in size in some psychopathologies (such as schizophrenia or bipolar disorder type I or II), which is associated with greater cognitive impairment.

Other data to take into account

As previously indicated, the male brain has more asymmetries than the female brain, which means that the differences between the two hemispheres are more pronounced than in the case of the latter. In addition, very recent research suggests that men are also more different from 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 organizing contribution of prenatal steroids, which elicit differentiation at that stage of development (masculinizing a brain that is initially feminine for everyone).

What we know about the brain helps us to 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, regardless of whether he or she is a man or a woman.

Bibliographical references:

• Joel, D. (2011). Male or Female? Brains are Intersex. Frontiers in integrative neuroscience, 5: 57.
• Kelly, S., Ostrowski, N. and Wilson (2000). Gender Differences in Brain and Behavior. Pharmacology, biochemistry, and behavior, 64, 655-64.