During evolution, the brain has become more complex by optimizing the way it organizes its structure, using such a valuable resource as cracks or folds, small cracks and grooves with which it expands its surface by bending inside.
This mechanism has enabled our species to improve certain higher cognitive functions.
In this article we tell you what brain fissures are and what are its main functions and characteristics. We will also describe the cracks, including convolutions and grooves, most relevant to our brain.
What are Brain Fissures?
The human brain is an extremely complex organ formed by millions of nerve cells, as well as glial cells and blood vessels. It is a fundamental part of the central nervous system, responsible for centralizing and processing information about our body and the environment to generate the best possible responses, depending on what each situation requires.
The brain can be divided into hemispheres: the right hemisphere and the left hemisphere; and in turn, in the lobes: the frontal lobe, which is responsible for language and executive functions; the temporal lobe, responsible for hearing or speech; the parietal lobe, responsible for sensory functions; the occipital lobe, the main function is visual processing; and the insula or island cortex, which separates the inferior temporal and parietal lobe and plays a key role in emotional processing and subjective experience.
In neuroanatomy, when describing the different brain structures, cracks are taken into account, which cover the surface of the cortex of the brain and they give it that particular raw characteristic. These “wrinkles” are essential for the proper functioning of this organ; their absence can cause serious disorders, such as lysencephaly (or “smooth brain”), which can lead to motor problems, seizures and other disorders.
Cracks in the brain they can be divided into convolutions and grooves that are found over the entire surface of the crust, Delimiting the different lobes and cerebral hemispheres, and allowing their extension to be greater; so that, evolutionarily speaking, the more the brain has folded inwards, the more it has become more complex over the years, with the consequent increase and improvement of certain cognitive functions of the human species, such as than language or intelligence.
Features and functions
Cerebral fissures, whether convolutions or more or less deep furrows, fulfill important functions; on the one hand, as we commented in the introduction, these folds increase the area of the cerebral cortex and neuronal density (Without having to increase the size of the head), with the consequent improvement of upper cognitive functions in the medium and long term.
On an evolutionary level, this is a big qualitative leap, because otherwise increasing the size of the head and skull would only have been a problem for women in childbirth.
According to most scientific studies, this fold is most common in larger-brained species, like ours, although there appear to be exceptions (as is the case with manatees, with fewer folds than planned for a brain of its size).
However, the formation of fissures depends on other factors that go beyond the growth and expansion of the surface of the cerebral cortex, such as the physical properties of certain parts of the cerebral cortex; for example, the thinner regions of the brain tend to bend more easily and the brain folds into specific and coherent patterns.
On the other hand, although the brain is an interconnected organ, different fissures are used to separate and demarcate areas and structures with different functions, acting as boundaries that aid in the division of tasks.
The main grooves of the brain
There are a multitude of grooves or cracks in the brain. Then we will talk about the best known and most relevant.
1. The interhemispheric groove
The interhemispheric groove, also known as the longitudinal slit, is a fissure in the cortex that divides the brain into two hemispheres, joined by a set of nerve fibers called the corpus callosum. This slot contains a fold in the dura mater (the outer meninges that protect the central nervous system) and the anterior cerebral artery.
2. The lateral groove
The lateral groove or Silvio’s slit is one of the most visible in the brain, as it runs through virtually the entire surface of its cortex. It is located in the lower hemispheres of the brain, Delimitation of the border between the temporal lobe and the parietal lobe. It is also one of the deepest cracks, and underneath is another important structure of the brain: the insula.
3. The central groove
The central groove or Rolando’s fissure is a fissure located in the upper part of the brain and separates the frontal lobe from the temporal lobe, on the border with one side with the motor cortex and, on the other side, with the primary somatosensory cortex. This slit would act as a bridge between motor and sensory information, integrating the two.
4. The parietooccipital groove
The parietoocipital curve or external perpendicular shear it is a crack which originates in the interhemispheric cleft, Be present on the internal face of each cerebral hemisphere. As the name suggests, it separates the parietal lobe from the occipital lobe.
The lateral part of the groove is located in front of the occipital pole of the brain, and the medial part descends and advances. It joins the calcareous slit below and behind the posterior end of the corpus callosum.
5. The limestone furrow
The calcareous groove or fissure is a fissure located in the occipital area of the inner or medial face of the cerebral hemispheres, separating the visual cortex into two parts. It follows a horizontal trajectory until it joins the parietooccipital irrigation.
6. The callous furrow
The groove callosum is located on the medial cerebral surface and separates the corpus callosum from the cingulate, which performs relevant functions in the limbic system. Although the cingulate is usually demarcated as a separate structure, it is part of the frontal and parietal lobes.
The main convolutions of the brain
As with the furrows we saw above, there are also many cracks in the brain in the form of convolutions or twists, characterized in that they are folds with less depth than the grooves and located inside the different brain lobes. Below, we’ll take a look at some of the most important.
1. Fusiform gyrus or rotation
The gyrus or gyrus is located on the basal surface of the cerebral hemisphere, more precisely in the temporal lobe, between the inferior temporal gyrus (outer) and the hippocampal gyrus (inner).
This slit is part of the limbic system, Responsible for emotional processing and plays an important role in facial recognition; damage to this area of the brain can cause prosopagnosia, also called facial blindness.
2. Convolution or cingulate rotation
The cingulate gyrus is an arcuate slit or fold in the brain located on the corpus callosum. Its main function is act as a link or bridge between the limbic system and higher cognitive functions located in the neoscortIt therefore plays a key role in the connection of volitional, motor, mnemonic, cognitive and affective aspects.
3. Convolution or angular rotation
Convolution or angular rotation is a fissure located in the parietal lobe, more precisely between the intraparietal groove and the horizontal branch of Silvio’s fissure.
Angular rotation functions include the processing and interpretation of linguistic, visual and auditory information.. He has connections with the Wernicke region, which is responsible for the auditory decoding of linguistic information.
4. Hippocampal gyrus or rotation
This convolution is located in the inner part of the temporal lobe, surrounding the hippocampus, a fundamental structure in the formation of new memories and in spatial localization.
- Allen, JS, Brussels, J., and Damasio, H. (2005). Structure of the human brain. Research and Science, 340, 68-75.
- Clark, DL; Boutros, NN and Méndez, MF (2012). The brain and behavior: neuroanatomy by psychologists. 2nd edition. The modern manual. Mexico
- Snell, RS (1999). Clinical neuroanatomy. Buenos Aires: Editorial Mèdica Panamericana, SA: 267